Patent Publication Number: US-2004041532-A1

Title: Control circuit of a fan having an accessory lamp

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a control circuit of a fan having an accessory lamp, and more particularly to a control circuit of a fan having an accessory lamp, wherein the fan of the present invention has a simplified construction, has a lower cost of fabrication, and the lamp will not be overheated.  
       [0003] 2. Description of the Related Art  
       [0004] A first conventional fan having an accessory lamp in accordance with the prior art shown in FIG. 1 comprises a lamp  10 A, a lamp circuit  11 A, a fan motor  12 A, a fan circuit  13 A, and a housing  14 A. The lamp circuit  11 A and the fan circuit  13 A are connected to an electric power respectively. The lamp circuit  11 A is provided with a switch S 1 ′ for controlling the lamp  10 A, and the fan circuit  13 A is provided with a switch S 2 ′ for controlling the fan motor  12 A.  
       [0005] However, the first conventional fan has the following disadvantages.  
       [0006] 1. When the lamp  10 A is used during a long-term, it produces much heat, thereby greatly increasing the temperature in the housing  14 A, so that the housing  14 A and the parts contained in the housing  14 A are easily worn out or burned.  
       [0007] 2. The lamp  10 A is constantly maintained at a high temperature state, thereby greatly shortening the lifetime of the lamp  10 A.  
       [0008] A second conventional fan having an accessory lamp in accordance with the prior art shown in FIGS. 2 and 3 comprises a lamp  10 B, a lamp circuit  11 B, a fan motor  12 B, a fan circuit  13 B, and a housing  14 B. The lamp circuit  11 B and the fan circuit  13 B are connected to an electric power respectively. The lamp circuit  11 B is provided with a switch S 1 ″ for controlling the lamp  10 B, and the fan circuit  13 B is provided with a switch S 2 ″ for controlling the fan motor  12 B. A heat sensor  16 B is mounted between the lamp circuit  11 B and the fan circuit  13 B. The heat sensor  16 B detects the high temperature of the lamp  10 B, and may start the fan motor  12 B automatically, so that the lamp  10 B may be cooled by the fan motor  12 B.  
       [0009] However, the second conventional fan has the following disadvantages.  
       [0010] 1. The heat sensor  16 B is expensive, thereby increasing the cost of fabrication.  
       [0011] 2. The precision of detection of the heat sensor  16 B is affected when the room temperature reaches a very high value.  
       [0012] 3. The heat sensor  16 B opens and closes the fan motor  12 B according to the temperature values. When the temperature of the lamp  10 B is slightly smaller than the sensing temperature, the heat sensor  16 B closes the fan motor  12 B, so that the temperature of the lamp  10 B is increased. At this time, the heat sensor  16 B opens the fan motor  12 B again. Thus, the fan motor  12 B is opened and closed intermittently, thereby greatly shortening the lifetime of the fan motor  12 B.  
       [0013] 4. The fan motor  12 B is opened and closed intermittently, thereby producing noise.  
       SUMMARY OF THE INVENTION  
       [0014] The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional fan having an accessory lamp.  
       [0015] The primary objective of the present invention is to provide a control circuit of a fan having an accessory lamp, wherein when the lamp is lighted, the fan motor may also be simultaneously operated to drive the fan to operate slowly, so as to cool the lamp and the parts contained in the housing, thereby preventing the lamp and the parts from being worn out due to overheat, and thereby increasing the lifetime of the lamp and the parts contained in the housing.  
       [0016] Another objective of the present invention is to provide a control circuit of a fan having an accessory lamp, wherein the fan motor will not be closed and opened continuously and intermittently, thereby increasing the lifetime of the fan motor.  
       [0017] A further objective of the present invention is to provide a control circuit of a fan having an accessory lamp, wherein the capacitor has a cheaper price, thereby reducing the cost of fabrication.  
       [0018] A further objective of the present invention is to provide a control circuit of a fan having an accessory lamp, wherein the lamp will not be overheated.  
       [0019] In accordance with the present invention, there is provided a control circuit of a fan having an accessory lamp, comprising a lamp, a lamp circuit, a fan motor, a fan circuit, and a capacitor, wherein:  
       [0020] the lamp circuit has a first end connected to an electric power and a second end connected to the ground;  
       [0021] the lamp is located on the lamp circuit;  
       [0022] the fan circuit has a first end connected to the electric power and a second end connected to the ground;  
       [0023] the fan motor is located on the fan circuit; and  
       [0024] the capacitor is mounted between the lamp and the fan motor.  
       [0025] Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0026]FIG. 1 is a circuit diagram of a first conventional control circuit of a fan having an accessory lamp in accordance with the prior art;  
     [0027]FIG. 2 is a schematic structural view of a second conventional control circuit of a fan having an accessory lamp in accordance with the prior art;  
     [0028]FIG. 3 is a circuit diagram of the second conventional control circuit of a fan having an accessory lamp in accordance with the prior art;  
     [0029]FIG. 4 is a circuit diagram of a control circuit of a fan having an accessory lamp in accordance with a preferred embodiment of the present invention;  
     [0030]FIG. 5 is a schematic operational view of the control circuit of a fan having an accessory lamp as shown in FIG. 4 in use;  
     [0031]FIG. 6 is a schematic operational view of the control circuit of a fan having an accessory lamp as shown in FIG. 4 in use; and  
     [0032]FIG. 7 is a reference table of experimental data of the control circuit of a fan having an accessory lamp in accordance with the preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0033] Referring to the drawings and initially to FIG. 4, a control circuit of a fan having an accessory lamp in accordance with a preferred embodiment of the present invention comprises a lamp  10 , a lamp circuit  11 , a fan motor  12 , a fan circuit  13 , a housing  14 , and a capacitor  20 .  
     [0034] The lamp  10  is mounted in the housing  14 .  
     [0035] The lamp circuit  11  has a first end connected to an electric power  30  and a second end connected to the ground. The lamp  10  is located on the lamp circuit  11 . The lamp circuit  11  is provided with a first switch S 1  located adjacent to the electric power  30  for controlling the lamp  10 .  
     [0036] The fan motor  12  is mounted in the housing  14 .  
     [0037] The fan circuit  13  has a first end connected to the electric power  30  and a second end connected to the ground. The fan motor  12  is located on the fan circuit  13 . The fan circuit  13  is provided with a second switch S 2  located adjacent to the electric power  30  for controlling the fan motor  12 .  
     [0038] The capacitor  20  has a predetermined impedance as shown FIG. 7. The capacitor  20  is mounted between the lamp  10  and the fan motor  12 . Preferably, the capacitor  20  has a first end connected to the first end of the lamp circuit  11  and located between the lamp  10  and the electric power  30 , and has a second end connected to the first end of the fan circuit  13  and located between the fan motor  12  and the electric power  30 . Preferably, the first end of the capacitor  20  is located between the first switch S 1  and the lamp  10 , and the second end of the capacitor  20  is located between the second switch S 2  and the fan motor  12 .  
     [0039] Referring to FIGS. 5 and 7, when the second switch S 2  of the fan circuit  13  is pressed, the fan circuit  13  is connected to the electric power  30 , thereby forming a closed loop, so that the fan motor  12  may drive the fan to rotate. At this time, the capacitor  20  is connected to the lamp  10  in a serial manner, and the capacitor  20  together with the lamp  10  is connected to the fan motor  12  in a parallel manner. The lamp  10  has an impedance mush smaller than that of the capacitor  20 , so that the voltage of the lamp  10  may be neglected, and most of the voltage is located on the two ends of the capacitor  20 . In such a manner, the current will not pass through the lamp  10 , so that the lamp  10  will not be lighted. Thus, when the second switch S 2  of the fan circuit  13  is pressed, the fan motor  12  may be operated individually, and the lamp  10  will not be lighted.  
     [0040] Referring to FIGS. 6 and 7, when the first switch S 1  of the lamp circuit  11  is pressed, the lamp circuit  11  is connected to the electric power  30 , thereby forming a closed loop, so that the lamp  10  may be lighted immediately. At this time, the capacitor  20  is connected to the fan motor  12  in a serial manner, and the capacitor  20  together with the fan motor  12  is connected to the lamp  10  in a parallel manner. Thus, the capacitor  20  an the fan motor  12  may form a serial loop, and the fan motor  12  may form an inductive load. In such a manner, the impedance of the fan motor  12  cannot be neglected, so that the voltage of the fan motor  12  cannot be neglected. Thus, the voltage is distributed on the capacitor  20  and the fan motor  12 , so that the current may pass through the fan motor  12 , thereby starting and operating the fan motor  12  through the capacitor  20 . Thus, when the first switch S 1  of the lamp circuit  11  is pressed, the lamp  10  may be lighted and the fan motor  12  may also be operated.  
     [0041] Accordingly, when the lamp  10  is lighted, the fan motor  12  may also be simultaneously operated to drive the fan to operate slowly, so as to cool the lamp  10  and the parts contained in the housing  14 , thereby preventing the lamp  10  and the parts from being worn out due to overheat, and thereby increasing the lifetime of the lamp  10  and the parts contained in the housing  14 . In addition, the fan motor  12  will not be closed and opened continuously and intermittently, thereby increasing the lifetime of the fan motor  12 . Further, the capacitor  20  has a price mush smaller than that of the heat sensor as disclosed in the prior art, thereby reducing the cost of fabrication. Further, the lamp  10  will not be overheated. Further, the fan motor  12  may drive the fan to operate slowly, so as to cool the lamp  10  and the parts contained in the housing  14 , thereby preventing from incurring noise during the cooling process.  
     [0042] As shown in FIG. 7, when the capacitance of the capacitor  20  is equal to 4 μf, and the power of the lamp  10  and the fan is equal to 100W, the lamp  10  will consume a voltage equal to 2.3V, and the voltage of the fan motor  12  is equal to 44V. On the other hand, when the capacitance of the capacitor  20  is equal to 4.5 μf, and the power of the lamp  10  and the fan is equal to 250W, the lamp  10  will consume a voltage equal to 0.7V, and the voltage of the fan motor  12  is equal to 47V. Preferably, the optimum capacitance of the capacitor  20  is ranged between 4 μf and 5 μf, and the optimum power of the lamp  10  is ranged between 40W and 250W.  
     [0043] Accordingly, in the control circuit of a fan having an accessory lamp in accordance with the present invention, the capacitor  20  is mounted between the lamp  10  and the fan motor  12 . By using the relationship of the impedance of the capacitor  20 , the lamp  10  and the fan motor  12 , operation of the lamp  10  may start the fan motor  12  automatically, and operation of the fan motor  12  will not start the lamp  10 .  
     [0044] While the preferred embodiment(s) of the present invention has been shown and described, it will be apparent to those skilled in the art that various modifications may be made in the embodiment without departing from the spirit of the present invention. Such modifications are all within the scope of the present invention.