Abstract:
The present invention is to provide a power supply device for a peripheral device, wherein a power input port of the power supply device is connected to a computer in order to supply power to a charging circuit of the power supply device for charging a rechargeable battery installed therein. When a power output port of the power supply device is connected to the peripheral device, the power supply device will enable an automatic switch assembly thereof to turn on a output switch and supply power from the computer to the peripheral device and enable the rechargeable battery to supply additional power to the peripheral device for compensating the inadequate power supplied by the computer and enabling the peripheral device to be operated in a normal condition.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to power supply and more particularly to an improved power supply device for supplying sufficient power to a peripheral device.  
       BACKGROUND OF THE INVENTION  
       [0002]     Conventionally, a USB (Universal Serial Bus) port of a computer is adapted to couple to one of a plurality of peripheral devices (e.g., a speaker, a modem, a hard disk drive, a CD-ROM drive, a floppy disk drive, etc.), thereby electrically connecting a motherboard of the computer to the peripheral device. Also, a CPU (central processing unit) on the motherboard is communicatively connected to the peripheral device for transmitting signal or vice versa. Further, two power pins and two data pins are provided on the USB port in which the power pins are electrically connected to a power circuit of the motherboard so that power can be supplied to the peripheral device via the power pins when the peripheral device is connected to the USB port.  
         [0003]     However, only a small current (e.g., 5V 400 mA) is supplied from the USB port of the computer to the peripheral device for operation. Such small current, far less than the required power of 5V 1A, is not able to activate the peripheral device. For solving the problem, an additional adaptor is required to couple to the peripheral device for supplying sufficient power thereto. This is very inconvenient since a user has to find an outlet and plug a plug of the adaptor into the outlet prior to converting AC (alternating current) from an external power source into DC (direct current) in the adaptor and supplying DC to the peripheral device. Otherwise, the user is not able to use the peripheral device due to lack of sufficient power. For a portable computer (e.g., notebook computer), this problem is even serious since it is very difficult of finding an I external power source in an outdoor environment. Hence, a need for improvement exists.  
       SUMMARY OF THE INVENTION  
       [0004]     An object of the present invention is to provide a power supply device for a peripheral device, comprising an automatic switch assembly connected to a power input port and a power output port of the device respectively. The power supply device further comprises a charging circuit connected to the power input port and a rechargeable battery of the device respectively. The rechargeable battery is connected to an output switch of the device. The output switch is connected to the power output port and the automatic switch assembly respectively. Whereby connecting the power input port to a computer will supply power from the computer to the charging circuit for charging the rechargeable battery. Hence, connecting the power output port to the peripheral device will enable the automatic switch assembly to turn the output switch on for supplying power from the computer to the peripheral device and enable the rechargeable battery to supply additional power to the peripheral device for compensating the inadequate power supplied by the computer and enabling the peripheral device to be operated in a normal condition. By utilizing the present invention, the above drawback of supplying insufficient power from a USB port of a computer to a peripheral device for operation will then be overcome.  
         [0005]     Another object of the present invention is that in a case of the power input port of the power supply device disconnected from the computer, the automatic switch assembly is adapted to turn off both itself and the output switch in response to detecting reverse current from the peripheral device. As an end, the reverse current will not flow to the rechargeable battery for charging and protection of the rechargeable battery.  
         [0006]     Still another object of the present invention is that the power supply device further comprises a battery voltage detector connected to the rechargeable battery, and a battery voltage low indicator connected to the battery voltage detector. Responsive to detecting an operating voltage of the rechargeable battery being too low by the battery voltage detector, the battery voltage detector lights up the battery voltage low indicator as warning that the battery voltage detector is unable to supply sufficient power. Hence, a user may not connect the peripheral device to the power supply device.  
         [0007]     A further object of the present invention is that the power supply device further comprises a battery protector disposed between the rechargeable battery and the charging circuit and between the rechargeable battery and the output switch. The battery protector is connected to the rechargeable battery, the output switch, and the charging circuit respectively. The battery protector is adapted to detect both an input current and an output current of the rechargeable battery so that in response to the input or the output current of the rechargeable battery being too large, the battery protector cuts off the circuit for disconnecting the rechargeable battery from the circuit as protection of the rechargeable battery for preventing the rechargeable battery from being damaged.  
         [0008]     The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is an electrical block diagram of a first preferred embodiment of the invention; and  
         [0010]      FIG. 2  is an electrical block diagram of a second preferred embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0011]     Referring to  FIG. 1 , there is shown a power supply device  1  for a peripheral device in accordance with a first preferred embodiment of the invention. The power supply device  1  comprises a power input port  11  connected to a computer (e.g., desktop computer, notebook computer, etc.), an automatic switch assembly  12 , a power output port  13  connected to a peripheral device (e.g., a speaker, a modem, a hard disk drive, a CD-ROM drive, a floppy disk drive, etc.), a charging circuit  14 , a rechargeable battery  15  (implemented as a lithium battery in the embodiment but may be replaced by another suitable element in any other embodiments), and an output switch  16 . The power input port  11  is connected to the automatic switch assembly  12 . The automatic switch assembly  12  is connected to the power output port  13 . When the automatic switch assembly  12  is closed (i.e., on), the power input port  11  is electrically connected to the power output port  13 . The charging circuit  14  is connected to the power input port  11 . The charging circuit  14  is connected to the rechargeable battery  15 . The rechargeable battery  15  is connected to the output switch  16 . The output switch  16  is connected to the power output port  13  and the automatic switch assembly  12  respectively. When the power input port  11  is connected to a port (not shown) of a computer, power supplied by the computer will be fed to the charging circuit  14  which in turn charges the rechargeable battery  15 .  
         [0012]     By configuring as above, in a case of the power output port  13  connected to a peripheral device (not shown), the automatic switch assembly  12  is able to detect signal output from the peripheral device for controlling and then turn the output switch  16  on. As such, power of the computer can be supplied to the peripheral device via the power input port  11 , the automatic switch assembly  12 , and the power output port  13  sequentially. At the same time, the rechargeable battery  15  will supply additional power to the peripheral device as a compensation for the inadequate power supplied by the computer. As a result, the peripheral device can operate normally due to sufficient power supply.  
         [0013]     Referring to  FIG. 1  again, the automatic switch assembly  12  comprises a switch  121  and a control circuit  123 . The switch  121  is connected to the power input port  11 . The switch  121  is also connected to the power output port  13 . The control circuit  123  is connected to the switch  121 , the power input port  11 , and the output switch  16  respectively. In a case of the control circuit  123  detected signal output from the peripheral device, the control circuit  123  controls the switch  121  and is aware that the output switch  16  is on. As such, power of the computer can be supplied to the peripheral device via the power input port  11 , the switch  121 , and the power output port  13  sequentially. At the same time, the rechargeable battery  15  will supply additional power to the peripheral device as a compensation for the inadequate power supplied by the computer. As a result, the peripheral device can operate normally due to sufficient power supply.  
         [0014]     Referring to  FIG. 1  again, in the embodiment in a case of the power input port  11  of the power supply device  1  disconnected from the computer, the control circuit  123  of the automatic switch assembly  12  is adapted to open both the switch  121  and the output switch  16  (i.e., off) in response to detecting reverse current from the peripheral device. As an end, the reverse current will not flow to the rechargeable battery  15  for charging. This is a protection arrangement of the rechargeable battery  15 .  
         [0015]     Referring to  FIG. 1  again, the power supply device  1  further comprises a battery voltage detector  17  connected to the rechargeable battery  15 , and a battery voltage low indicator  171  connected to the battery voltage detector  17 . When the battery voltage detector  17  detects that the operating voltage of the rechargeable battery  15  is too low, the battery voltage detector  17  lights up the battery voltage low indicator  171  as warning so that a user can be aware that the battery voltage detector  15  is unable to supply sufficient power. Hence, the user may not connect the peripheral device to the power supply device  1 .  
         [0016]     Referring to  FIG. 1  again, there is provided a battery protector  18  between the rechargeable battery  15  and the charging circuit  14  and between the rechargeable battery  15  and the output switch  16 . The battery protector  18  is connected to the rechargeable battery  15 , the output switch  16 , and the charging circuit  14  respectively. The battery protector  18  is adapted to detect both input current and output current of the rechargeable battery  15 . When input or output current of the rechargeable battery  15  is too large, the battery protector  18  cuts off the circuit so as to disconnect the rechargeable battery  15  from the circuit. This is a protection arrangement of the rechargeable battery  15  for preventing the rechargeable battery  15  from being damaged.  
         [0017]     Referring to  FIG. 1  again, there is provided a discharge voltage regulator  19  between the output switch  16  and the battery protector  18 . The discharge voltage regulator  19  is connected to the output switch  16  and the battery protector  18  respectively. The discharge voltage regulator  19  is adapted to regulate voltage of output power of the rechargeable battery  15  when the rechargeable battery  15  is supplying power to the peripheral device. As an end, voltage of output power of the rechargeable battery  15  can be converted into one required for operating the peripheral device.  
         [0018]     Referring to  FIG. 1  again, the power supply device  1  further comprises a charging controller  110  connected to the charging circuit  14 . The charging controller  110  is further connected to the control circuit  123  of the automatic switch assembly  12 . As such, the control circuit  123  is able to control the charging controller  110  which in turn is adapted to control a charging of the rechargeable battery  15  by the charging circuit  14 .  
         [0019]     Referring to  FIG. 2 , there is shown a power supply device  1  in accordance with a second preferred embodiment of the invention. The power supply device  1  comprises a power input port  21 , a charging circuit  22 , a rechargeable battery  23  (implemented as a lithium battery in the embodiment but may be replaced by another suitable element in any other embodiments), a switch  24 , a control circuit  25 , and a power output port  26 . The power input port  21  is connected to the charging circuit  22 . The charging circuit  22  is connected to the rechargeable battery  23 . The rechargeable battery  23  is connected to the switch  24 . The switch  24  is connected to the power output port  26 . The control circuit  25  is connected to the power input port  21 . Finally, the control circuit  25  is connected to switch  24 .  
         [0020]     By configuring as above, in a case of the power input port  21  connected to a port (not shown) of a computer (e.g., desktop computer, notebook computer, etc.) and the power output port  26  connected to a peripheral device (not shown) (e.g., a speaker, a modem, a hard disk drive, a CD-ROM drive, a floppy disk drive, etc.), the control circuit  25  is able to detect power output from the computer for turning on the switch  24 . As such, power output from the computer can be supplied to the rechargeable battery  23  via the charging circuit  22 . After the rechargeable battery  23  has been charged, the rechargeable battery  23  is able to supply sufficient power to the peripheral device. As a result, the peripheral device can operate normally due to sufficient power supply.  
         [0021]     Moreover, in a case of the power input port  21  of the power supply device  1  disconnected from the computer, the control circuit  25  is adapted to open the switch  24  (i.e., off) in response to detecting a reverse current from the peripheral device. As an end, the reverse current will not flow to the rechargeable battery  23  for charging. This is a protection arrangement of the rechargeable battery  23 .  
         [0022]     While the invention has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.