Abstract:
The present invention is directed to a method for testing the operation of a cooling apparatus of an information handling system. The method may include determining a first rotational speed for operating a fan of the cooling apparatus, with the first rotational speed being less than a maximum rotational speed of the fan. The method includes signaling the fan to rotate at the first rotational speed, and detecting a current rotational speed of the fan. The method includes comparing the detected current rotational speed of the fan to the first rotational speed of the fan, and if the detected current rotational speed is substantially equal to or greater than the first rotational speed of the fan, continuing an initialization process of the information handling system; and if the detected current rotational speed of the fan is less than the first rotational speed, causing further testing of the fan.

Description:
REFERENCE TO RELATED APPLICATIONS 
   This application claims the priority of U.S. provisional patent application No. 60/601,491, filed Aug. 13, 2004, which is incorporated herein in its entirety by reference. 

   FIELD OF THE INVENTION 
   The present invention generally relates to the field of cooling systems for electronic devices, and particularly to a system and method for determining the operational status of a cooling system during initialization of the electronic device. 
   BACKGROUND OF THE INVENTION 
   Electronics devices, such as desktop computers, tower computers, servers, tablet computers, notebook computers and other similar devices utilize various methods and apparatus to reduce thermal build-up, or the accumulation of waste heat, within their chassis. These apparatus sometimes include a cooling device, such as a fan, to circulate air within the chassis and/or exchange air inside the chassis with air external to the chassis to help reduce thermal build-up. However, cooling devices, such as fans, can create problems of their own. These problems include, for example, noise, vibration, and an increased failure rate for the overall cooling system due to the fact that these devices have moving parts. 
   Previously, when the electronic device has been initialized, the cooling device, or fan, has been operated in order to determine if it was operational. Feedback from the cooling device may have been provided by, for example, a tachometer on the motor of the cooling device to detect the rotational speed of the motor. Heretofore, the cooling device was often tested at full or maximum rotational speed to assure valid operation at that speed, which contributed to the noise and vibration generated by the system at system start-up. If it was detected that the full rotational speed could not be attained, an error message was displayed and operation of the system was halted to prevent potential loss of data or damage to the system due to poor or nonexistent cooling. 
   Therefore, it would be desirable to provide a system and method for testing the operation of a cooling device, or fan, in a manner that avoids the high level of noise and vibration generated by the fan at full rotational speed while still being capable of determining the operational status of the fan, and, in those cases where it has been determined that the fan cannot reach maximum cooling capacity, but may still be capable of providing sufficient cooling. The invention may allow the electronic device to operate at some range of operating levels supportable by the reduced cooling capacity of the fan at a lower rotational speed. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is directed to a system and method for testing the operation of a cooling device for an electronic device, such as a cooling fan. The present invention may allow testing of the cooling device at relatively lower speeds than the maximum operational speed of the cooling device, and thereby reducing noise generated by the cooling device during initialization and testing of the electronic device. Furthermore, the present invention may inform the user of a failing cooling device, while still permitting use of the electronic device when the cooling device is only able to provide less than an optimal level of cooling to the electronic device. 
   In one aspect of the present invention, a method is disclosed for testing the operation of a cooling apparatus of an information handling system,. The method may include determining a first rotational speed for operating a fan of the cooling apparatus, with the first rotational speed being less than a maximum rotational speed of the fan. The method may further include signaling the fan to rotate at the first rotational speed, and detecting a current rotational speed of the fan. The method may also include comparing the detected current rotational speed of the fan to the first rotational speed of the fan, and if the detected current rotational speed is substantially equal to or greater than the first rotational speed of the fan, continuing an initialization process of the information handling system; and if the detected current rotational speed of the fan is less than the first rotational speed, causing further testing of the fan. 
   In another aspect of the present invention, a system for implementing the aforedescribed method is disclosed. 
   It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description serve to explain the principles of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which: 
       FIG. 1  is a system block diagram of the system initialization software (or firmware) and fan speed control. 
       FIG. 2  is a flow chart of the fan test system. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. 
   Referring generally now to  FIGS. 1 through 2 , exemplary embodiments of the present invention are shown wherein a system and method for changing the operating characteristics of a system  100 , such as an information handling system, based upon the operational status of the cooling apparatus of the system is disclosed. 
   Generally, the invention comprises a method of operating the cooling apparatus, and a system implementing the method of operating the cooling apparatus, that determines the cooling capability of the cooling apparatus, and is highly suitable for implementing as a part of an initialization process or procedure for an information handling system, but may also be used at other points in time after the initialization process of the information handling system. The invention is illustratively described in terms of a cooling fan of a cooling apparatus of an information handling system, although application to a cooling apparatus utilizing other devices other than fans may also be used. 
   Referring to  FIG. 1 , a system block diagram of the system initialization software (or firmware) and a fan speed control is shown. The system initialization firmware  110  may be any software or code that is used to initialize a system into an operating state, and usually performs some level of testing as initialization is being performed. An example of this system initialization firmware  110  is the BIOS (Basic Input Output System) software which initializes the processor, memory, storage and other components and peripherals in many computer systems. Additionally, the BIOS performs tests on various devices during initialization, and these tests are often referred to as the POST (Power On Self Test). During the POST, tests are performed to provide reasonable assurance that the processor, memory, storage devices and peripherals are operational. In some embodiments of the POST, errors are reported as messages on a display during the initialization and testing, or are optionally signaled using beep codes when a display for the verbal messages is unavailable. In the present embodiment, additional tests may be added to the tests of the POST that are directed to the testing of the cooling apparatus of the system, such as a cooling apparatus that includes one or more cooling fans. 
   As a part of the POST or other testing or initialization of the system at start up, the system initialization firmware  110  may initiate operation of the cooling fan at a specified rotational speed by sending commands to the fan speed control  120 , which controls the rotational speed of the cooling fan  130 . The fan speed control  120  directs the cooling fan to run or operate at the speed indicated by the system initialization firmware  110 . The rotational speed specified by the firmware  110  is preferably less than the maximum operating rotational speed of the cooling fan  130 , which reduces the noise produced by the fan and thus the noise produced by the information handling system, as well as reducing wear on the cooling fan. The specified rotational speed may be a predetermined rotational speed, or may be varied by the firmware  110  according to various factors present on the information handling system. For example, the specified rotational speed may fall within a range of approximately 50% to approximately 90% of the maximum rotational speed, although other fractions of the maximum rotational speed out side of this range may also be employed as the specified speed. 
   The system initialization firmware  110  may pause for a predetermined period of time to allow the cooling fan  130  to spin up and achieve the specified rotational speed. After waiting for the predetermined period of time, the firmware  110  may send another command to the fan speed control  120  that requests detection of the current rotational speed of the cooling fan  130 . The fan speed control  120  may perform a tachometer measurement of the speed of the cooling fan  130  after receiving the command, or optionally may measure the speed of the fan  130  by other means including, but not limited to, optical interrupters and reed switches, which are known to those skilled in the art. Optionally, rather than making a single measurement of the rotational speed at the end of the predetermined period of time, the fan speed control  120  may continuously monitor the rotational speed of the fan for some portion of the predetermined period of time to detect if the fan reaches the specified rotational speed at any point during the period. 
   Once a rotational speed of the cooling fan is measured, the operating speed information is returned to system initialization firmware  110  for analysis. If the returned rotational speed information is a speed that is less than expected, e.g., less than the specified rotational speed, or less than some tolerance range of rotational speed below the specified rotational speed, the firmware  110  may interpret that there is a problem with the cooling fan, such as the fan has failed, is failing, or is otherwise prevented from proper operation by factors such as dirt buildup on the fan, blockage of air flow vents, and the like. An error message may be displayed on a screen of the information handling system to inform the user of the problem. Optionally, a second rotational speed for the fan  130  may be requested by the firmware  110  through the fan speed control  120 . After a second period of delay following the second request to allow the fan  130  to reach the requested speed, the system initialization firmware  110  may again request a detection of the current speed of the fan  130  from the fan speed control  120 . 
   If the rotational speed reported back to the firmware  110  after the second delay period is greater than a predetermined threshold rotational speed, it may be determined that the cooling fan is operating at a level of reduced effectiveness. Preferably, the predetermined threshold rotational speed corresponds to a minimum level of cooling that provides sufficient heat removal from the information handling system to maintain a minimum level of operation of the system to perform some operations, such as saving and backing up data or other operations that will enable shut down of the system for making repairs or replacements on the system. The user may be provided information on the nature and/or effect of the problem through one or messages provided on the display of the information handling system. Optionally, the user may be requested or required to acknowledge the problem before the system proceeds further with the system initialization process. The user may acknowledge the fact that the cooling system is malfunctioning and there may be a possibility of a thermal shutdown of the system, along with the related potential of loss of data. As a further option, the user may be instructed to take certain actions, such as, for example, saving or backing up data to a safe location, checking the vents of the information handling system for blockages, checking for dirt or dust buildup on the fan, as well as taking other actions to prevent the loss of data or to possibly remedy the problem. However, if the speed reported by the fan speed control  120  is below the predetermined threshold rotational speed, the system initialization firmware  110  may determine that the cooling fan  130  is not able to operate at a speed that may provide sufficient cooling for any level of operation of the information handling system. In this case, an error message may be displayed to inform the user of the circumstances, and the initialization of the system may be stopped. 
   Referring to  FIG. 2 , a flow chart of an exemplary operation process of the system initialization software (or firmware) for initialization and testing of a cooling apparatus is shown. In this exemplary operation, the automatic fan speed control may be temporarily disabled, and the firmware may attempt to initiate fan operation (block  210 ) at a specified first predetermined speed by sending commands to the fan speed control  120 , and the first predetermined speed may be less the maximum operating speed for the fan to reduce noise, and wear on the fan, such as approximately 50% of the maximum operating speed of the fan. A delay may be provided to allow the fan  130  to reach the first predetermined speed specified by the firmware (block  215 ). The current rotational speed of the fan  130  may be measured (block  220 ). The measured speed may be compared by the firmware with the specified speed (block  225 ). Optionally, a message may be displayed to a user that indicates that the testing is occurring, such as, for example, “Checking system cooling fan operation, please wait.” If the measured speed is approximately at the specified speed, or possibly higher, or possibly slightly lower, the firmware may determine that the fan appears to be operational (block  290 ), and therefore the system initialization process may continue. Note that the measured speed may be somewhat lower than the first predetermined speed specified by the firmware and the fan may still be considered to be fully operational. For example, if the first predetermined speed is 50% of the maximum rotational speed, then an acceptable speed for continuing the initialization process of the information handling system may be anything over 45% of the maximum rotational speed. If the measured speed (block  220 ) is less than the range of acceptable predetermined rotational speeds, the fan may be failing and the fan may then be directed to operate at full or maximum rotational speed (block  230 ). A delay may be provided to allow the fan to attempt to reach the maximum rotational speed (step  235 ). The actual rotational speed of the cooling fan may then be measured (block  240 ), and it may then be determined if the measured rotational speed of the fan is within a range that is capable of providing adequate cooling for the information handling system. This determination may be performed by comparing the actual operating speed of the fan with a predetermined threshold rotational speed. If the actual operating speed is above this predetermined threshold speed, it may be determined (block  245 ) that the fan is operating at a speed that it is capable of providing sufficient cooling for the information handling system, but the cooling fan still has the potential of failing. If it is determined that the fan is not operating above the predetermined threshold rotational speed (block  245 ), the user may be warned that the fan is failing (block  250 ) and the initialization or operation of the system may be discontinued to prevent additional problems. 
   If it is determined that the fan is operating above the predetermined threshold rotational speed (block  245 ), the fan is set to operate at full speed if not already instructed to operate at full speed (block  260 ) so that it will operate at its maximum rotational capability, which may not be the originally specified capacity of the fan, but may provide adequate cooling of the information handling system for most conditions. The user may be warned through a displayed message that the fan is failing (block  265 ) and may not be providing adequate cooling, and the user may be requested to acknowledge this situation. The firmware may wait for the user to acknowledge the problem (block  270 ), and upon such acknowledgement, the system initialization may be continued (block  275 ). At this point, the fan may be locked into operating at or close to its maximum rotational speed to help provide as much cooling to the information system as possible, even if the operating system software of the information handling system detects temperatures that would normally slow down or shut off operation of the cooling fan, thus overriding this operating system control of the fan. 
   It is believed that the system and method of the present invention and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.