Patent Publication Number: US-7714464-B2

Title: Load control module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the priority benefit of Chinese application serial no. 200710148134.8, filed on Aug. 28, 2007. All disclosure of the Chinese application is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a load control module. More particularly, the present invention relates to a load control module allowing an electrical equipment to perform diversified control functions. 
   2. Description of Related Art 
   With discovering of electricity by an American Franklin in the 18th century, civilization of human beings advanced a big step. In today&#39;s world, application of the electricity not only contributes productions of social materials, but also widely infiltrates human life in all dimensions. For example, the electrical equipments used in our daily life, such as illumination apparatus, air conditioner, electric fans, food heater . . . etc. are all driven by electric power for working normally. 
   During utilization of the electrical equipments, operation of the electrical equipments is generally controlled by a switch and a load control module, interactively. For example,  FIG. 1  is a circuit block diagram illustrating an application of a conventional illumination apparatus. Referring to  FIG. 1 , the conventional illumination apparatus  100  includes a light-emitting diode (LED)  101  and a diode driver  102 . Referring to  FIG. 1  again, during operation, when the switch  110  is turned on, the conventional illumination apparatus  100  may work normally. Now, a conventional load control module  120  and the LED  101  may receive a supply voltage VS output from the switch  110 , and the LED  101  may be driven by the supply voltage VS. 
   Correspondingly, the conventional load control module  120  converts the supply voltage VS output from the switch  110  into a control voltage VC having a fixed level. Then, the diode driver  102  may adjust a light source generated by the LED  101  to a fixed brightness according to the control voltage VC. On the other hand, when the switch  110  is turned off, the LED  101  and the load control module  120  are cut off from the power supply, and therefore the illumination apparatus  100  maintains a stop working mode, since the illumination apparatus  100  may not provide a light source normally. 
   According to the above description, operation mode of the conventional illumination apparatus  100  under interactive control of the switch  110  and the conventional load control module  120  can only be switched between a normal working mode and the stop working mode. During the normal working mode, the conventional load control module  120  can only adjust the light source generated by the conventional illumination apparatus  100  to the fixed brightness. 
   In other words, circuit performance of a general illumination apparatus or a electrical equipment under control of the switch and the conventional load control module is limited and cannot match a requirement of convenience. Therefore, how to operate the load control module in coordination with an operation of the switch so as to control the electrical equipments to perform diversified control functions has become one of the major subjects to various manufacturers during development of the load control module. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a load control module, which may operate in coordination with an operation of a switch for controlling an electrical equipment to perform diversified control functions. 
   The present invention provides a load control module for an electrical equipment, the electrical equipment is driven by an operation of a switch. The load control module includes an energy storage unit, a signal transforming unit, a first control unit and a second control unit. The energy storage unit determines whether or not to output a reserved voltage according to the operation of the switch, wherein when the switch is turned on, the energy storage unit converts a supply voltage output from the switch into a reserved voltage, and outputs the reserved voltage; and when the switch is turned off, the energy storage continuously outputs the reserved voltage for a predetermined time. 
   Moreover, the signal transforming unit transforms the supply voltage output from the switch into a counting signal when the signal transforming unit is activated. The first control unit filters and rectifies the counting signal to generate an rectified signal, wherein when a level of the rectified signal is switched to a second level, the first control unit latches the level of a clamping signal to the second level, and until the first control unit is reactivated, it may output the clamping signal having a first level. 
   On the other hand, the second control unit outputs a control voltage to control characteristic parameters of the electrical equipment when the second control unit is activated, wherein when the second control unit receives the clamping signal having the first level, the second control unit counts continuously in response to the counting signal, so as to adjust the level of the control voltage according to a counting result. When the second control unit counts up to a predetermined value or receives the clamping signal having the second level, the second control unit stops counting, such that the level of the control voltage may be switched to one of a plurality of predetermined levels according to an inverted signal of the rectified signal. It should be noted that the signal transforming unit, the first control unit and the second control unit are respectively coupled to the energy storage unit, and are driven by the reserved voltage. 
   In an embodiment of the present invention, the first control unit includes a filtering rectifier unit and a latching unit. The filtering rectifier unit filters and rectifies an output signal of the signal transforming unit for outputting the rectified signal. The latching unit outputs the clamping signal according to the rectified signal when the latching unit is activated, wherein when the level of the rectified signal is switched to the second level, the latching unit latches the level of the clamping signal to the second level until the latching unit is reactivated. Moreover, the latching unit is coupled to the energy storage unit, and is driven by the reserved voltage. 
   In an embodiment of the present invention, the second control unit includes a frequency divider, a counting unit, a rough adjusting unit, a multiplexer and a digital-to-analog converter. The frequency divider divides the frequency of the counting signal into a specific frequency to output a square wave signal when the frequency divider is activated. Moreover, the counting unit counts an accumulated value up to a predetermined value according to the square wave signal when the counting unit is activated, and when the counting unit counts up to the predetermined value or receives the clamping signal having the second level, the counting unit stops counting and generates an interrupt signal having the second level. On the other hand, the rough adjusting unit determines to output one of a plurality of level adjusting values according to the inverted signal of the rectified signal and the interrupt signal, so as to generate a specific adjusting value and a control signal, when the rough adjusting unit is activated. When the multiplexer receives the control signal, the multiplexer outputs the specific adjusting value; conversely, the multiplexer outputs the accumulated value. Accordingly, the digital-to-analog converter outputs the control voltage and converts the level of the control voltage according to the accumulated value or the specific adjusting value when the digital-to-analog converter is activated. It should be noted that the frequency divider, the counting unit, the rough adjusting unit, the multiplexer and the digital-to-analog converter are respectively coupled to the energy unit, and are driven by the reserved voltage. 
   In summary, in the present invention, the load control module may still operates continuously for the predetermined time under control of the energy storage unit when the switch is turned off. The signal transforming unit, the first control unit and the second control unit are driven by the reserved voltage. With a different switching speed of the switch, the second control unit may operate in coordination with the actions of the signal transforming unit and the first control unit to regulate the level of the control voltage, or maintain the level of the control voltage in the current state. Therefore, the electrical equipments may perform diversified control functions under control of the load control module operated in coordination with an operation of the switch. 
   In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, a preferred embodiment accompanied with figures is described in detail below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a circuit block diagram illustrating an application of a conventional illumination apparatus. 
       FIG. 2  is a circuit block diagram of a load control module according to an embodiment of the present invention. 
       FIG. 3  is a timing diagram of waveforms according to the embodiment of  FIG. 2 . 
       FIG. 4  is a detailed circuit diagram of an energy storage unit according to an embodiment of the present invention. 
       FIGS. 5A and 5B  are detailed circuit diagrams respectively illustrating a signal transforming unit according to an embodiment of the present invention. 
       FIG. 6  is a detailed circuit diagram illustrating a first control unit according to an embodiment of the present invention. 
       FIG. 7  is a detailed circuit diagram illustrating a second control unit according to an embodiment of the present invention. 
   

   DESCRIPTION OF EMBODIMENTS 
     FIG. 2  is a circuit block diagram of a load control module according to an embodiment of the present invention. The load control module  200  is suitable for an electrical equipment  220  driven by an operation of a switch  210 . Moreover, the load control module  200  includes an energy storage unit  230 , a first control unit  240 , a second control unit  250  and a signal transforming unit  260 . The energy storage unit  230  is coupled to the switch  210 , the first control unit  240 , the second control unit  250  and the signal transforming unit  260 . The first control unit  240  is coupled to the signal transforming unit  260 , and the second control unit  250  is coupled to the first control unit  240  and the signal transforming unit  260 . 
     FIG. 3  is a timing diagram of waveforms according to the embodiment of  FIG. 2 . Referring to  FIG. 2  and  FIG. 3 , the switch  210  switches in response to a switching signal S 31 . For example, when the level of the switching signal S 31  is switched to a first level L 1 , the switch  210  is turned on. Conversely, when the level of the switching signal S 31  is switched to a second level L 2 , the switch  210  is turned off. In the present embodiment, the first level L 1  is assumed to be logic 1, and the second level L 2  is assumed to be logic 0. For convenience, the following embodiments will be described based on the aforementioned assumptions. 
   As to the operation mechanism of the load control module  200 , the load control module  200  is operated in coordination to the action of the switch. When the switch  210  is turned on, the energy storage unit  230  converts a supply voltage VP output from the switch  210  into a reserved voltage V ST , and outputs the reserved voltage V ST  to the first control unit  240 , the second control unit  250  and the signal transforming unit  260 . Conversely, when the switch  210  is turned off, the energy unit  230  may continuously output the reserved voltage V ST  for a predetermined time T P . It should be noted that the energy storage unit  230  further outputs a first reset signal S R1  during a high transition of the reserved voltage V ST , and outputs a second reset signal S R2  when the level of the reserved voltage V ST  drops to a threshold value. 
   For example, at the beginning, i.e. at the time point t 0 , the load control module  200  is activated, and starts to output the reserved voltage V ST  and output the first reset signal S R1  during the high transition of the reserved voltage V ST . Then, during a time point t 1  and a time point t 2 , since a time T S1  is less than the predetermined time T P , the energy storage unit  230  may continuously output the reserved voltage V ST . Similarly, since a time T S2  is less than the predetermined time T P , the energy storage unit  230  may continuously output the reserved voltage V ST  during a time point t 3  and a time point t 5 . However, during a time point t 6  and a time point t 8 , since a time T S3  is greater than the predetermined time T P , the energy storage unit  230  may continuously output the reserved voltage V ST  for the predetermined time T P , and stops outputting the reserved voltage V ST  during a time point t 7  and the time point t 8 . It should be noted that, during a process of continuous decreasing of the reserved voltage V ST , when the level of the reserved voltage V ST  drops to the threshold value (for example 0.5*V ST ), the energy storage unit  230  further outputs a second reset signal S R2 . 
   Moreover, the first control unit  240 , the second control unit  250  and the signal transforming unit  260  are all driven by the reserved voltage V ST . Therefore, when the switch  210  is turned on, the first control unit  240 , the second control unit  250  and the signal transforming unit  260  are then all activated; when the switch  210  is turned off, the first control unit  240 , the second control unit  250  and the signal transforming unit  260  may only maintain an operation for the predetermined time T P . Operation mechanism of the first control unit  240 , the second control unit  250  and the signal transforming unit  260  will be described in detail below. 
   Please referring to  FIG. 2  and  FIG. 3 , when the switching signal S 31  is switched to the first level L 1  at the time point t 0  in the beginning, the signal transforming unit  260  is activated, and transforms the supply voltage VP into a counting signal S CT . Then, the first control unit  240  filters and rectifies the counting signal S CT  to generate a rectified signal S RE , and outputs a clamping signal S LA  having the first level L 1  according to the first reset signal S R1 . 
   On the other hand, the second control unit  250  is first reset in response to the first reset signal S R1 . Then, when the second control unit  250  receives the clamping signal S LA  having the first level L 1 , the second control unit  250  counts continuously in response to the counting signal S CT , so as to adjust the level of a control voltage V CL  according to a counting result. For example, during the time point t 0  and the time point t 1 , the second control unit  250  may continuously receive square waves from the counting signal S CT , and adjust the level of the control voltage V CL  when every three square waves is received. 
   It should be noted that the second control unit  250  stops counting only when the second control unit  250  counts up to a predetermined value or receives the clamping signal S LA  having the second level L 2 . In other words, if the second control unit  250  does not count up to the predetermined value during the time point t 0  and the time point t 1 , the second control unit  250  then stop counting by switching the clamping signal S LA  to the level L 2  after the time point t 1 . Conversely, if the second control unit  250  counts up to the predetermined value during the time point t 0  and the time point t 1 , the second control unit  250  maintains a non-counting state after the time point t 1 . Moreover, during the non-counting period, the level of the control voltage V CL  may be switched to one of a plurality of predetermined levels under control of the second control unit  250  according to an inverted signal /S RE  of the rectified signal. 
   For example, assuming during the time point t 0  and the time point t 1 , the second control unit  250  does not count up to the predetermined value, operation of the first control unit  240  and the second control unit  250  during the time point t 1  and the time point t 8  is then described in detail as below. At the time point t 1 , the switching signal S 31  is switched to the second level L 2 . During a time point t 1  and a time point t 2 , since the rectified signal S RE  may be switched to the second level L 2  along with the variation of the waveform of the counting signal S CT , the first control unit  240  may latch the level of the clamping signal S LA  to the second level L 2 . 
   The second control unit  250  stops counting after the second control unit  250  receives the clamping signal S LA  having the second level L 2 . In other words, during the time point t 2  and the time point t 3 , the second control unit  250  may stop adjusting the level of the control voltage V CL , and therefore the level of the control voltage V CL  will stay unchanged during the time point t 1  and the time point t 3 , shown as a curve CV 1 . 
   Next, when the switching signal S 31  is switched back to the second level L 2  at the time point t 3 , the second control unit  250  is in the non-counting state at the present, and the level of the control voltage V CL  may be switched to one of the predetermined levels LAT 1 ˜LAT 3  under control of the second control unit  250  according to an inverted signal /S RE  of the rectified signal. For example, as shown of the curve CV 1 , the level of the control voltage V CL  is switched to the predetermined level LAT 1  at the time point t 5 . 
   Moreover, at the time point t 6 , the switching signal S 31  is switched back to the second level L 2 . Since the time T S3  for the switch  210  being in a turned off state is greater than the predetermined time T P , the load control module  200  may only operate continuously during the time point t 6  and the time point t 7 , and will be disabled during the time point t 7  and the time point t 8 . Correspondingly, when the load control module  200  maintains a disabled state, the second control unit  250  forces the level of the control voltage V CL  being switched to the lowest level, and until the load control module  200  is reactivated at the time point t 8 , the level of the control voltage V CL  may be re-adjusted. 
   It should be noted that before entering the disable state, the second control unit  250  is first reset in response to the second reset signal S R2 . Moreover, when the load control module  200  is reactivated, the load control module  200  repeats the operations performed during the time to and the time point t 8 . 
   In addition, assuming the second control unit  250  counts up to the predetermined value during the time point t 0  and the time point t 1 , operation of the first control unit  240  and the second control unit  250  during the time point t 1  and the time point t 8  is then described in detail as below. At the time point t 1 , the switching signal S 31  is switched to the second level L 2 . During the time point t 1  and the time point t 2 , since the second control unit  250  is now in the non-counting state, the level of the control voltage V CL  may be switched to one of the predetermined levels LAT 1 ˜LAT 3  under control of the second control unit  250  according to the inverted signal /S RE  of the rectified signal. For example, as shown of the curve CV 2 , the level of the control voltage V CL  is switched to the predetermined level LAT 1  during the time point t 2  and the time point t 3 . 
   Next, when the switching signal S 31  is again switched back to the second level L 2  at the time point t 3 , the level of the control voltage V CL  may be switched to one of the predetermined levels LAT 1 ˜LAT 3  again under control of the second control unit  250  according to the inverted signal /S RE  of the rectified signal. For example, as shown of the curve CV 2 , the level of the control voltage V CL  is switched to the predetermined level LAT 2  during the time point t 5  and the time point t 6 . 
   Moreover, when the switching signal S 31  is again switched back to the second level L 2  at the time point t 6 , the load control module  200  maintains the disabled state during the time point t 7  and the time point t 8 , and the level of the control voltage V CL  is switched to the lowest level. Before entering the disable state, the second control unit  250  is first reset in response to the second reset signal S R2 . 
   In summary, when the switching signal S 31  is switched to the first level L 1  at the time point t 0  in the beginning, the load control module  200  starts to continuously adjust the level of the control voltage V CL , until a turn-on state of the switch  210  is quickly switched in response to the switching signal S 31 , i.e. until the time point t 1 , the load control module  200  may adjust the level of the control voltage V CL  according to the inverted signal /S RE  of the rectified signal. On the other hand, at the time point t 6 , the switching signal S 31  is switched to the second level L 2 . Since the time T S3  for the switch  210  being in a turned off state is greater than the predetermined time T P , the load control module  200  will be reactivated to repeat the operation performed during the time to and the time point t 8 . Therefore, the electrical equipment  220  may perform diversified control functions under control of the load control module  200  operated in coordination with an operation of the switch  210 . 
   For example, the electrical equipment  220  is assumed to be an illumination apparatus. During the time point t 0  and the time point t 1 , the level of the control voltage V CL  received varies continuously, and the illumination apparatus may continuously increase a brightness of its light source according to the level of the control voltage V CL , until the turn-on state of the switch  210  is quickly switched, i.e. until the time point t 1 , along with the quick switching of the switch  210 , the brightness of the light source of the illumination apparatus may be switched to one of a plurality of predetermined brightness. Conversely, when the time for the switch  210  being in the turned off state is greater than the predetermined time T P  (for example two seconds), the load control module  200  will be reactivated, such that the brightness of the light source of the illumination apparatus can be adjusted under control of the load control module  200  operated in coordination with the operation of the switch  210 . 
   Accordingly, compared with the conventional techniques, the illumination apparatus can only provide the light source with a fixed brightness under control of the conventional control module  120  operated in coordination with the operation of the switch  210 , when the illumination apparatus is activated. However, the brightness of the light source of the illumination apparatus may be adjusted under control of the present control module  200  operated in coordination with the operation of the switch  210 , when the illumination apparatus is activated. In other words, the electrical equipment controlled by the switch may perform diversified control functions under control of the load control module  200  of the present embodiment. 
   Similarly, the electrical equipment  220  is assumed to be a food heater. During the time point t 0  and the time point t 1 , the food heater may continuously increase a temperature of its heat source according to the level of the control voltage V CL , until the turn-on state of the switch  210  is quickly switched, i.e. until the time point t 1 , the temperature of the heat source of the food heater may be switched to one of a plurality of predetermined temperatures under control of the food heater according to the control voltage V CL . 
   Moreover, the electrical equipment  220  is assumed to be an air conditioner. During the time point t 0  and the time point t 1 , the air conditioner may correspondingly decrease the room temperature according to the level of the control voltage V CL , until the turn-on state of the switch  210  is quickly switched, i.e. until the time point t 1 , the room temperature may be switched to one of a plurality of predetermined temperatures under control of the air conditioner according to the control voltage V CL . 
   To fully convey the concept of the invention to those skilled in the art, the inner structures of the energy storage unit  230 , the first control unit  240 , the second control unit  250  and the signal transforming unit  260  will be further described in detail below. 
     FIG. 4  is a detailed circuit diagram of an energy storage unit according to an embodiment of the present invention. For convenience, the switch  210  is added to  FIG. 4 . Referring to  FIG. 4 , the energy unit  230  includes a diode D 1 , resistors R 1 ˜R 2 , a capacitor C 1 , a regulator  410  and a reset circuit  420 . An anode of the diode D 1  is coupled to the switch  210 . A first end of the resistor R 1  is coupled to a cathode of the diode D 1 . The resistor R 2  is coupled between a second end of the resistor R 2  and the ground. The capacitor C 1  is also coupled between the second end of the resistor R 2  and the ground. The regulator  410  is coupled to a first end of the resistor R 2 , and the reset circuit  420  is coupled to the regulator  410 . 
   During operation, when the switch  210  is turned on, the supply voltage VP output from the switch  210  passes through the diode D 1  and drops on the resistors R 1  and R 2 . A voltage difference formed by the resistors R 1  and R 2  is then stored in the capacitor C 1 , and the regulator  410  then transforms the voltage difference into the reserved voltage V ST  and continuously outputs the reserved voltage V ST . Conversely, when the switch  210  is turned off, the capacitor C 1  discharges the stored voltage difference to the resistor R 2  within the predetermined time T P . Therefore, the regulator  410  may still output the reserved voltage V ST  for the predetermined time T P , when the switch  210  is turned off. Wherein the predetermined time T P  is determined by a capacitance of the capacitor C 1  and a resistance of the resistor R 2 , and is determined by the regulator  410  and a load there behind. On the other hand, the reset circuit  420  may continuously detect the level of the reserved voltage V ST , so as to output the first reset signal S R1  during the high transition of the reserved voltage V ST , and output the second reset signal S R2  when the level of the reserved voltage V ST  drops to the threshold value. 
     FIGS. 5A and 5B  are detailed circuit diagrams respectively illustrating a signal transforming unit according to an embodiment of the present invention. It should be noted that circuit structure of the signal transforming unit  260  can be changed according to an actual requirement of the load control module  200 . For example, when the supply voltage VP of an AC signal is applied to the load control module  200 , the circuit structure of the signal transforming unit  260  is shown as  FIG. 5A , wherein the signal transforming unit  260  includes a filter  510  and a Schmitt trigger  520 . The filter  510  is used for filtering a noise of the supply voltage VP. The Schmitt trigger  520  is coupled to the energy unit  230 , such that the Schmitt trigger  520  may be activated in response to the reserved voltage V ST . Moreover, the Schmitt trigger  520  may transform the filtered supply voltage VP into the counting signal S CT  when the Schmitt trigger  520  is activated. 
   However, when the supply voltage VP of a DC signal is applied to the load control module  200 , the signal transforming unit  260  may be composed of a voltage-controlled oscillator (VCO)  530  shown in  FIG. 5B . The VCO  530  is coupled to the energy unit  230 , such that the Schmitt trigger  520  may be activated in response to the reserved voltage V ST . Moreover, the VCO  530  generates the counting signal S CT  according to the level of the supply voltage VP when the VCO  530  is activated. 
     FIG. 6  is a detailed circuit diagram illustrating a first control unit according to an embodiment of the present invention. Referring to  FIG. 6 , the first control unit  240  includes a filtering rectifier unit  610  and a latching unit  620 . To fully convey the concept of the invention to those skilled in the art, the inner structures of the filtering rectifier unit  610  and the latching unit  620  will be further described in detail below. 
   Referring to  FIG. 6  again, the filtering rectifier unit  610  includes capacitors C 2 ˜C 3 , a diode D 2  and resistors R 3 ˜R 5 . A first end of the capacitor C 2  is coupled the signal transforming unit  260 . The resistor R 3  is coupled between a second end of the capacitor C 2  and the ground. An anode of the diode D 2  is coupled to the second end of the capacitor C 2 . The capacitor C 3  and the resistor R 4  are coupled between a cathode of the diode D 2  and the ground, respectively. The resistor R 5  is coupled between the cathode of the diode D 2  and the latching unit  620 . 
   Referring to  FIG. 3  and  FIG. 6 , operation of the filtering rectifier unit  610  will be described below. During the time point t 0  and the time point t 1 , the filtering rectifier unit  610  may receive the square waves from the counting signal S CT , and the capacitor C 2  and the resistor R 3  may transform the square waves of the counting signal S CT  into a plurality of pulses. After being rectified by the diode D 2  and being filtered by the resistor R 4  and the capacitor C 3 , the pulse forms the rectified signal S RE  having the first level L 1 . Conversely, during the time point t 1  and the time point t 2 , the filtering rectifier unit  610  cannot receive the square waves from the counting signal S CT , and the filtering rectifier unit  610  outputs the rectified signal S RE  having the second level L 2 . 
   Deduced by analogy, during the time point t 2  and the time point t 6 , the filtering rectifier unit  610  outputs the rectified signal S RE  having the first level L 1  according to the counting signal S CT . Conversely, during the time point t 6  and the time point t 7 , the filtering rectifier unit  610  outputs the rectified signal S RE  having the second level L 2 . 
   Referring to  FIG. 6  again, the latching unit  620  includes Schmitt triggers  621  and  622 , diodes D 3  and D 4 , and a resistor R 6 . The Schmitt triggers  621  and  622  are coupled to each other. An anode of the diode D 3  and a cathode of the diode D 4  are coupled to the Schmitt trigger  621 , respectively. The resistor R 6  is coupled between a cathode of the diode D 3  and the Schmitt trigger  622 . 
   Referring to  FIG. 3  and  FIG. 6 , operation of the latching unit  620  will be described below. The Schmitt triggers  621  and  622 , the diode D 3  and the resistor R 6  form a feedback circuit. Based on the feedback circuit, when the level of the rectified signal S RE  received by the latching unit  620  is switched from the first level L 1  to the second level L 2 , the latching unit  620  latches the level of the clamping signal S LA  to the second level L 2 , until the latching unit  620  receives the first reset signal S R1  through the diode D 4 . 
   For example, at the time point t 0 , the level of the clamping signal S LA  is switched to the first level L 1  in response to the first reset signal S R1  received by the diode D 4 . Then, during the time point t 0  and the time point t 1 , the latching unit  620  receives the rectified signal S RE  having the first level L 1  and outputs the clamping signal S LA  having the first level L 1 . However, at the time point t 1 , since the level of the rectified signal S RE  is switched from the first level L 1  to the second level L 2 , the latching unit  620  latches the level of the clamping signal S LA  to the second level L 2 , and until the time point t 8 , the latching unit  620  will again switch the level of the clamping signal S LA  to the first level L 1  according to the first reset signal S R1 . 
     FIG. 7  is a detailed circuit diagram illustrating a second control unit according to an embodiment of the present invention. Referring to  FIG. 7 , the second control unit  250  includes a frequency divider  710 , a counting unit  720 , a rough adjusting unit  730 , a multiplexer  740 , a digital-to-analog converter  750  and a buffer  760 . The frequency divider  710  is coupled to the signal transforming unit  260 . The counting unit  720  is coupled to the frequency divider  710 . The rough adjusting unit  730  is coupled to the counting unit  720  and the first control unit  240 . The multiplexer  740  is coupled to the counting unit  720 , the rough adjusting unit  730  and the first control unit  240 . The digital-to-analog converter  750  is coupled between the counting unit  720  and the buffer  760 . 
   Referring to  FIG. 3  and  FIG. 7 , during operation, the frequency divider  710 , the counting unit  720 , the rough adjusting unit  730 , the multiplexer  740 , the digital-to-analog converter  750  and the buffer  760  are respectively coupled to the energy unit  230 , and are driven by the reserved voltage V ST . Moreover, the frequency divider  710  divides the frequency of the counting signal S CT  into a specific frequency when the frequency divider  710  is activated, so as to output a square wave signal S RW . For example, in the present embodiment, the frequency divider  710  divides the frequency of the counting signal S CT  with 3 to generate the square wave signal S RW  shown as  FIG. 3 . 
   The counting unit  720  includes a counter  721 , an AND gate  722  and an inverter  723 . The counter  721  counts an accumulated value P AU  up to the predetermined value according to the square wave signal S RW  when the counter  721  is activated, and outputs a state signal S T  having the first level L 1  when counting up to the predetermined value. On the other hand, one end of the AND gate  722  receives an inverted signal of the state signal S T  through the inverter  723 , and another end of the AND gate  722  receives the clamping signal S LA . With variation of the state signal S T  and the clamping signal S LA , the AND gate  722  outputs an interrupt signal S B  to the counter  721 . It should be noted that when the level of the interrupt signal S B  is the second level L 2  (for example logic 0), the counter  721  stops counting. Namely, when one of the clamping signal S LA  and the inverted signal of the state signal S T  has the second level L 2  (for example logic 0), the counter  721  stops counting. 
   The rough adjusting unit  730  includes an AND gate  731 , a level selector  732  and an inverter  733 . One end of the AND gate  731  receives an inverted signal of the interrupt signal S B  through the inverter  733 , and another end of the AND gate  731  receives the inverted signal /S RE  of the rectified signal. When the inverted signal of the interrupt signal S B  and the inverted signal /S RE  of the rectified signal are simultaneously switched to the first level (for example logic 1), the AND gate  731  outputs an enable signal. The level selector  732  selects one of a plurality of level adjusting values to be a specific adjusting value P SF  when the enable signal is received, and outputs the specific adjusting value P SF  and a control signal to the multiplexer  740 . In other words, when the interrupt signal S B  is switched to the second level L 2  (for example logic 0), namely, when the counter  721  stops counting, the level selector  732  outputs the specific adjusting value P SF  and the control signal to the multiplexer  740 , as long as the inverted signal /S RE  of the rectified signal is switched to the first level L 1  (for example logic 1). 
   On the other hand, the multiplexer  740  receives the accumulated value P AU  and the specific adjusting value P SF . When the multiplexer  740  receives the control signal output from the level selector  732 , the multiplexer  740  outputs the specific adjusting value P SF  to the digital-to-analog converter  750 . Conversely, the multiplexer  740  outputs the accumulated value P AU  to the digital-to-analog converter  750 . In other words, the digital-to-analog converter  750  receives the accumulated value P AU  output from the counter  721 , or receives the specific adjusting value P SF  output from the level selector  732 . Then, the digital-to-analog converter  750  converts the level of the control voltage V CL  according to the received value. 
   For example, as shown in  FIG. 3 , during the time point t 0  and the time point t 1 , since the clamping signal S LA  maintains the first level L 1 , the counter  721  may continuously increase or decrease the accumulated value P AU . Accordingly, the digital-to-analog converter  750  may control the level of the control voltage V CL  according to the value variation of the accumulated value P AU . However, if the accumulated value P AU  is not counted up to the predetermined value during the time point t 0  and the time point t 1 , with the quick switching of the switch  210  in response to the switching signal S 21  during the time point t 1  and the time point t 2 , the counter  721  stops counting according to the clamping signal S LA  having the second level L 2 , and the multiplexer  740  outputs the accumulated value P AU  having a fixed value to the digital-to-analog converter  750  during the time point t 2  and the time point t 3 . Therefore, shown as the curve CV 1 , the level of the control voltage VCL maintains a fixed level during the time point t 1  and the time point t 3 . 
   On the other hand, if the accumulated value P AU  is counted up to the predetermined value during the time point t 0  and the time point t 1 , namely, the interrupt signal S B  is switched to the second level L 2  (for example logic 0) after the time point t 1 , the multiplexer  740  outputs the specific adjusting value P SF  to the digital-to-analog converter  750  during the time point t 2  and the time point t 3  with the quick switching of the switch  210 ,. Since the level adjusting values in the level selector  732  respectively correspond to the predetermined levels LAT 1 ˜LAT 3 , the level of the control voltage V CL  is switched to one of the predetermined levels LAT 1 ˜LAT 3  during the time point t 2  and the time point t 3 , shown as the curve CV 2 . 
   Furthermore, the buffer  760  is coupled between the digital-to-analog converter  750  and the electrical equipment  220 , and is used for buffering and outputting the control voltage V CL  output from the digital-to-analog converter  750  when the buffer is activated. It should be noted that the counter  721 , the level selector  732  and the buffer  760  are further coupled to the energy storage unit  230 , and are driven by the reserved voltage V ST . Moreover, the frequency divider  710 , the counter  721  and the level selector  732  may further receive the first reset signal SRI and the second reset signal S R2  output from the energy storage unit  230 , such that the counter  721  may re-perform a counting operation according to the first reset signal S R1  and the second reset signal S R2 ; the frequency divider  710  may re-perform a dividing operation according to the first reset signal S R1  and the second reset signal S R2 ; and the level selector  732  may be reset according to the first reset signal S R1  and the second reset signal S R2 . 
   In summary, in the present invention, the load control module may still operate continuously for a predetermined time under control of the energy storage unit when the switch is turned off. The signal transforming unit, the first control unit and the second control unit are driven by the reserved voltage. With a different switching speed of the switch, the second control unit may operate in coordination with the actions of the signal transforming unit and the first control unit to regulate the level of the control voltage, or maintain the level of the control voltage in the current state. Therefore, the electrical equipments may perform diversified control functions under control of the load control module operated in coordination with the operation of the switch. 
   It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.