Abstract:
A detection system for detecting fan&#39;s connection and disconnection states includes a detection module connected to a fan and a host. The fan has four external connection terminals for connecting to the detection module. Two of the four external connection terminals are a rotation speed control terminal, via which a detection signal and a rotation speed control signal are transmitted from the detection module to the fan, and a rotation speed feedback terminal, via which a fed back detection signal and a fan rotation speed signal are transmitted from the fan to the detection module. The host determines whether the fan is connected to or disconnected from the detection module according to whether or not a fed back detection signal is received by the detection module from the fan.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a detection module, device and system for detecting fan&#39;s connection and disconnection states; and more particularly, to a detection module, device and system for detecting whether a fan is connected to a control circuit board. 
       BACKGROUND OF THE INVENTION 
       [0002]    Generally, a computer room has a large number of computers housed therein. These computers produce a high amount of heat during operation thereof. For the computers to operate in an environment having a constant temperature condition, fans are mounted in the computer room to remove the computer produced heat from the computer room. Usually, a control circuit board and a plurality of fans connected thereto together constitute a fan module. 
         [0003]    Since the computer room is generally staffless and adopts closed-off management, the control circuit board of the fan module is connected to a remote server apparatus, so that the connection state and the operation state of the fans can be monitored and determined from the remote server apparatus. 
         [0004]    Most of the currently available fans are provided with four external connection terminals.  FIG. 1  is a block diagram of a fan module being currently used to achieve the purpose of remotely monitoring the fans in a computer room. As shown, the fan module includes a control circuit board  10 , to which at least one fan  17  is connected. The control circuit board  10  includes a power supply unit  11  and a processor unit  12  connected to the power supply unit  11 . The power supply unit  11  is connected to an external power supply and supplies the power to the processor unit  12  and the at least one fan  17  for them to operate. The processor unit  12  is able to generate a fan rotation speed control signal, which can be, for example, a pulse width modulation (PWM) signal, to the fan  17  via a fan rotation speed driving circuit  14  for driving the fan  17  to operate and controlling the fan&#39;s rotation speed. On the other hand, the fan  17 , during operation thereof, is able to generate a fan rotation speed signal (FG) to the processor unit  12  via a fan rotation speed feedback circuit  15 . The processor unit  12  is further connected to a connection state detection unit  13  for receiving a connection signal from the fan  17 . 
         [0005]    Therefore, the fan  17  used with the control circuit board  10  has total five external connection terminals, namely, a positive power terminal  171 , a negative power terminal  172 , a connection signal terminal  173 , a rotation speed control input terminal  174  and a fan rotation speed feedback terminal  175 . The positive and the negative power terminal  171 ,  172  are respectively connected to a positive and a negative power output terminal of the power supply unit  11  for receiving power supply from the power supply unit  11 . The connection signal terminal  173  is connected to the connection state detection unit  13  of the control circuit board  10 . The rotation speed control signal generated by the processor unit  12  of the control circuit board  10  is transmitted to the fan  17  via the rotation speed control input terminal  174 . When being driven by the rotation speed control signal to operate, the fan  17  correspondingly generates the fan rotation speed signal (FG) during operation thereof for feeding back to the processor unit  12  of the control circuit board  10  via the fan rotation speed feedback terminal  175 . 
         [0006]    The connection state detection unit  13  of the control circuit board  10  can be, for example, a pull-up resistor or an optically coupled isolation circuit; and the connection signal terminal  173  electrically connected to the connection state detection unit  13  is grounded or connected to a high-level signal. In  FIG. 1 , the connection signal terminal  173  is grounded at the fan side, and the connection state detection unit  13  is a pull-up resistor for generating a high-level connection signal. 
         [0007]    Please refer to  FIGS. 2A to 2C . When the fan  17  is not connected to the control circuit board  10 , the connection signal generated by the connection state detection unit  13 , such as a pull-up resistor, is a high-level signal (HS), and the connection signal received by the processor unit  12  is high, as shown in  FIG. 2A . On the other hand, when the fan  17  is connected to the control circuit board  10 , the connection state detection unit  13  is connected to the fan  17  via the connection signal terminal  173  and is further grounded, so that the high-level connection signal (HS) generated by the connection state detection unit  13  flows to ground, and the connection signal received by the processor unit  12  from the connection state detection unit  13  changes from high to low (LS), as shown in  FIG. 2B . Alternatively, when the fan  17  is removed, i.e. when the fan  17  is disconnected from the control circuit board  10 , the connection signal received by the processor unit  12  from the connection state detection unit  13  changes from low (LS) to high (HS) again, as shown in  FIG. 2C . 
         [0008]    According to the high level or the low level of the connection signal received at the pin of the processor unit  12  that is connected to the connection state detection unit  13 , the remote server apparatus determines whether the fan  17  is connected to the control circuit board  10  or not. 
         [0009]    The above-described conventional fan module is disadvantageous because the processor unit  12  requires an additional pin for receiving the connection signal, the control circuit board  10  must include an additional detection unit, and the fan  17  also has to increase an additional external connection terminal, namely, the connection signal terminal  173 . For the control circuit board  10 , it must have increased wiring space in response to the additional pin of the processor unit  12  and the additional detection unit. Further, the increased pin and detection unit inevitably results in complicated manufacturing process and expanded area of the control circuit board. Similarly, the additional external connection terminal on the fan also results in more complicated manufacturing process of the fan. All these factors in turn result in increased cost and product volume of the fan module. 
       SUMMARY OF THE INVENTION 
       [0010]    A primary object of the present invention is to provide a fan detection design that utilizes two existing external connection terminals of a fan, i.e. a rotation speed control terminal and a rotation speed feedback terminal, to detect the fan&#39;s connection signal. This design is applicable to a conventional fan but saves one external connection terminal from the fan. 
         [0011]    Another object of the present invention is to provide a fan detection design that omits the connection state detection unit from a detection module, so that the required wiring spaces in the detection module and the fan connected thereto are reduced to enable simplified manufacturing process and decreased volume of the detection module and of the fan. 
         [0012]    To achieve the above and other objects, in one aspect of the present invention, a detection module for detecting at least one fan&#39;s connection and disconnection states is provided. The fan has a positive power terminal, a negative power terminal, a rotation speed control terminal and a rotation speed feedback terminal, and generates a fan rotation speed signal during operation thereof. The detection module includes a power supply unit and a processor unit. The power supply unit is connected to the positive and the negative power terminal of the fan, so as to provide an external power supply to the fan via the positive and the negative power terminal. The processor unit is connected to the power supply unit and generates a detection signal and a rotation speed control signal to the fan via the rotation speed control terminal. The rotation speed control signal drives the fan to operate and accordingly generate the fan rotation speed signal to the processor unit via the rotation speed feedback terminal. The detection signal is also fed back from the fan to the processor unit via the rotation speed feedback terminal. With these arrangements, the detection module determines whether the fan is connected thereto according to whether or not a fed back detection signal is received by the processor unit from the fan. 
         [0013]    In another aspect of the present invention, a detection device for detecting fan&#39;s connection and disconnection states is provided. The detection device includes a fan having a positive power terminal, a negative power terminal, a rotation speed control terminal and a rotation speed feedback terminal; and a detection module including a power supply unit and a processor unit. The power supply unit is connected to the positive and the negative power terminal of the fan, so as to provide an external power supply to the fan via the positive and the negative power terminal. The processor unit is connected to the power supply unit and generates a detection signal and a rotation speed control signal to the fan via the rotation speed control terminal. The rotation speed control signal drives the fan to operate and accordingly generate a fan rotation speed signal to the processor unit via the rotation speed feedback terminal. The detection signal is also fed back from the fan to the processor unit via the rotation speed feedback terminal. With these arrangements, the detection device determines whether the fan is connected to the detection module according to whether or not a fed back detection signal is received by the processor unit from the fan. 
         [0014]    In a further aspect of the present invention, a detection system for detecting fan&#39;s connection and disconnection states is provided. The detection system includes a fan having a positive power terminal, a negative power terminal, a rotation speed control terminal and a rotation speed feedback terminal; a detection module including a power supply unit and a processor unit; and a host connected to the detection module via a communication connection unit. The power supply unit is connected to the positive and the negative power terminal of the fan, so as to provide an external power supply to the fan via the positive and the negative power terminal. The processor unit is connected to the power supply unit and generates a detection signal and a rotation speed control signal to the fan via the rotation speed control terminal. The rotation speed control signal drives the fan to operate and accordingly generate a fan rotation speed signal to the processor unit via the rotation speed feedback terminal. The detection signal is also fed back from the fan to the processor unit via the rotation speed feedback terminal. With these arrangements, the host of the detection system determines whether the fan is connected to the detection module according to whether or not a fed back detection signal is received by the processor unit from the fan and then transmitted to the host via the communication connection unit. 
         [0015]    The power supply unit is connected to an external power supply. The detection device further includes a connection interface, to which the positive power terminal, the negative power terminal, the rotation speed control terminal and the rotation speed feedback terminal of the fan are connected. The processor unit first transmits the detection signal to the fan before the power supply unit provides the external power supply to the fan. Then, the processor unit also transmits the detection signal to the fan when the fan rotation speed signal generated by the fan to the processor unit has a value of zero. In the present invention, the detection signal has a frequency and a mark-space ratio different from those of the rotation speed control signal. 
         [0016]    According to the present invention, the host of the detection system determines whether the fan is connected to the detection module according to whether or not a fed back detection signal is received by the processor unit from the fan and then transmitted to the host via the communication connection unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
           [0018]      FIG. 1  is a block diagram of a conventional fan module; 
           [0019]      FIG. 2A  is a graph showing a connection signal that indicates a fan in the conventional fan module of  FIG. 1  is not connected to a control circuit board of the fan module; 
           [0020]      FIG. 2B  is a graph showing a connection signal that changes from a high level to a low level to indicate a disconnected fan in the conventional fan module of  FIG. 1  is then connected to the control circuit board of the fan module again; 
           [0021]      FIG. 2C  is a graph showing a connection signal that changes from a low level to a high level to indicate a connected fan in the conventional fan module of  FIG. 1  is then disconnected from the control circuit board of the fan module again; 
           [0022]      FIG. 3  is a block diagram of a detection device according to the present invention; 
           [0023]      FIG. 4  is a block diagram of a detection system according to the present invention; 
           [0024]      FIG. 5  is a graph showing a detection signal and a fed back detection signal that indicates a fan is not connected to a detection module of the detection device of  FIG. 3  or of the detection system of  FIG. 4 ; 
           [0025]      FIG. 6  is a graph showing a detection signal and a fed back detection signal that indicates a fan is connected to the detection module of the detection device of  FIG. 3  or of the detection system of  FIG. 4 ; 
           [0026]      FIG. 7  is a graph showing a rotation speed control signal and a fed back fan rotation speed signal that indicates a fan is connected to the detection module of the detection device of  FIG. 3  or of the detection system of  FIG. 4 ; and 
           [0027]      FIG. 8  is a graph showing a detection signal and a fed back fan rotation speed signal that indicate a connected fan has been disconnected from the detection module of the detection device of  FIG. 3  or of the detection system of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    The present invention will now be described with some preferred embodiments thereof and with reference to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals. 
         [0029]    Please refer to  FIG. 3  that is a block diagram of a detection device according to a preferred embodiment of the present invention. As shown, the detection device includes a detection module  20  having at least one fan  30  connected thereto. The fan  30  has a positive power terminal  31 , a negative power terminal  32 , a rotation speed control terminal  33 , and a rotation speed feedback terminal  34 . Via the positive power terminal  31  and the negative power terminal  32 , electric power is supplied to the fan  30  for the same to operate. Via the rotation speed control terminal  33 , a rotation speed control signal is input to the fan  30  for driving the fan  30  to rotate and controlling the fan&#39;s rotation speed. Via the rotation speed feedback terminal  34 , a fan rotation speed signal generated by the fan  30  during actual operation thereof is output to the detection module  20 . 
         [0030]    The detection module  20  includes a power supply unit  21  and a processor unit  22 , and can be, for example, a control circuit board. The power supply unit  21  receives an external power supply, and is connected via a positive power circuit  23  and a negative power circuit  24  to the positive power terminal  31  and the negative power terminal  32  of the fan  30 , respectively, such that the received external power supply is supplied to the fan  30  via the positive and the negative power terminal  31 ,  32 . Generally, the fan used with a heat-producing electronic product has a power supply of 12V. The processor unit  22  is connected with the power supply unit  21 , and is used to generate a detection signal and the above-mentioned rotation speed control signal to the fan  30  via the rotation speed control terminal  33 . On the other hand, the above-mentioned fan rotation speed signal and the detection signal are returned from the fan  30  to the processor unit  22  via the rotation speed feedback terminal  34 . 
         [0031]    More specifically, the processor unit  22  is connected via a driving circuit  25  to the rotation speed control terminal  33  of the fan  30 , and is connected via a rotation speed detection circuit  26  to the rotation speed feedback terminal  34  of the fan  30 . Therefore, the rotation speed control signal and the detection signal are sent to the fan  30  via the driving circuit  25  and the rotation speed control terminal  33 ; and the fan rotation speed signal and the fed back detection signal are sent from the rotation speed feedback terminal  34  to the processor unit  22  via the rotation speed detection circuit  26 . According to an embodiment of the present invention, the processor unit  22  can be, for example, a microcontroller unit (MCU). 
         [0032]    Particularly, the detection signal is sent by the processor unit  22  to the fan  30  either before the fan  30  receives the power supply from the power supply unit  21  or when a value of the fan rotation speed signal received by the processor unit  22  is zero, i.e. when the processor unit  22  does not receive the fan rotation speed signal from the fan  30 , so as to detect whether the fan  30  is connected to the detection module  20  or not. The detection signal generated by the processor unit  22  would not be fed back from the rotation speed feedback terminal  34  of the fan  30  to the processor unit  22  when the fan  30  is not connected to the detection module  20  or any one of the positive power terminal  31 , the negative power terminal  32 , the rotation speed control terminal  33  and the rotation speed feedback terminal  34  of the fan  30  is not connected to the detection module  20 . 
         [0033]    In the present invention, the rotation speed control signal is a pulse width modulation (PWM) signal, and the detection signal is a signal having a frequency and a mark-space ratio different from those of the PWM signal of the rotation speed control signal. 
         [0034]      FIG. 4  is a block diagram of a detection system according to a preferred embodiment of the present invention. In practice, the detection module  20  and the fan  30  are mounted in a place where heat dissipation is needed, such as a computer room. A host  40  at a remote location is connected to the detection module  20  via a communication connection unit  41 , which can be a bus, for example. The external power supply received by the power supply unit  21  is provided by the host  40 . The rotation speed control signal and the detection signal generated by the processor unit  22  as well as the fan rotation speed signal and the fed back detection signal all are sent to the host  40  via the communication connection unit  41 . Therefore, the host  40  can determine the connection state between the fan  30  and the detection module  20  based on whether the detection signal is fed back from the fan  30  and received by the processor unit  22 . 
         [0035]    How the connection state between the detection module  20  and the fan  30  can be determined is now described with reference to  FIGS. 5 to 8 . Herein, the fan rotation speed signal is a PWM signal having a frequency of 10 KHz and a mark-space ratio of 50%; and the detection signal is also a PWM signal but having a frequency of 1 KHz and a mark-space ratio of 5%. 
         [0036]    As shown in  FIG. 5 , the processor unit  22  of the detection module  20  first transmits a detection signal (DS) to the fan  30  via the rotation speed control terminal  33 . However, the processor unit  22  does not receive any fed back detection signal (FDS) from the rotation speed feedback terminal  34  of the fan  30 , and in  FIG. 5 , it is shown the fed back detection signal (FDS) is zero. Therefore, it is determined the fan  30  is not connected to the detection module  20 , or any one of the positive power terminal  31 , the negative power terminal  32 , the rotation speed control terminal  33  and the rotation speed feedback terminal  34  of the fan  30  is not connected to the detection module  20 . 
         [0037]    As shown in  FIG. 6 , the processor unit  22  of the detection module  20  first transmits a detection signal (DS) to the fan  30  via the rotation speed control terminal  33 ; and then the processor unit  22  receives a fed back detection signal (FDS) from the rotation speed feedback terminal  34  of the fan  30 . Therefore, it is determined the fan  30  is connected to the detection module  20 . 
         [0038]    Please refer to  FIG. 7 . When it is detected that the fan  30  is connected to the detection module  20 , the processor unit  22  then transmits a rotation speed control signal (PWM) to the fan  30  via the rotation speed control terminal  33  for driving the fan  30  to operate. The fan  30  in operating correspondingly generates a fan rotation speed signal (FG) to the detection module  20  via the rotation speed feedback terminal  34 . 
         [0039]    Please refer to  FIG. 8 . In the case the fan  30  is removed from the detection device of  FIG. 3  or the detection system of  FIG. 4 , the fan  30  is no longer connected to the detection module and no fan rotation speed signal (FG) is received by the processor unit  22  via the rotation speed feedback terminal  34 , i.e. the fan rotation speed signal (FG) is zero. At this point, the processor unit  22  will transmit a detection signal (DS) again to the fan  30  via the rotation speed control terminal  33 . When the processor unit  22  does not receive a fed back detection signal (FDS) from the fan  30  via the rotation speed feedback terminal  34 , that is, the fed back detection signal is zero as shown in  FIG. 8 , it is determined the fan  30  is not connected to the detection module  20 . 
         [0040]    As can be found from the above description, in the present invention, two existing external connection terminals of the fan, i.e. the rotation speed control terminal and the rotation speed feedback terminal, are directly used to detect the fan&#39;s connection signal. This design is applicable to a conventional fan but saves one external connection terminal from the fan and omits the connection state detection unit from the control circuit board. With the present invention, the required wiring spaces in the control circuit board and the fan are reduced to enable simplified manufacturing process and decreased volume of the control circuit board and of the fan. 
         [0041]    The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.