Abstract:
A built-in back-up power device operates a high-power apparatus for a short time period to prevent the loss of data or damage to the apparatus when power from a utility power source is interrupted. The built-in back-up power device includes a battery and a charger. The charger charges the battery when power is provided from the utility power source. During a power interruption or outage, the battery outputs back-up power to the high-power apparatus. A computer with such a built-in back-up power device is also provided.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a back-up power device and its application. More particularly, the present invention relates to a built-in back-up power device and its application. 
     2. Discussion of the Related Art 
     Computers have become so inexpensive that their use is widespread. Many computers are used, for example, in controlling production lines, calculation, and entertainment. A good back-up power source is thus becoming more important to prevent data loss in a power outage, interruption or glitch. The typical back-up power source is an uninterrupted power supply (UPS), which is designed to provide the computer with a stable power source to continue normal operations for a relatively long period of time after a power outage has occurred. For example, a work station is typically equipped with an UPS to allow uninterrupted operation. To provide such a stable power source over a relatively long period of time, a UPS is complex and expensive beyond the reach of the average user. 
     FIG. 1 is a block diagram showing a personal computer  11  equipped with conventional UPS  12 . Internal power supply  13  of personal computer  11  includes electromagnetic interference (EMI) filter and power factor controller (PFC)  131 , AC/DC converter  132 , DC/DC converter  133 , and feedback circuit  134 . EMI filter and PFC  131  eliminate noise in the AC input power. The filtered AC input power is converted to high-voltage DC power by AC/DC converter  132 . Then, the high-voltage DC power is converted to low-voltage DC power by DC/DC converter  133  to provide an operating voltage to personal computer  11 , which includes, for example, a mainboard, a floppy disk drive, a hard disk drive (HDD), a compact disc read-only memory (CD-ROM) reader. Feedback circuit  134  adjusts the filtered AC input power in response to the high-voltage DC power output. Thus, since there is no power-storing unit in internal power supply  13 , the low-voltage DC power output is interrupted immediately after the AC input power is interrupted. When such a power interruption occurs, personal computer  11  is improperly shut down. In computers running high-level operating system such as Windows 95/98, Windows NT, or UNIX, a power interruption can leave the operating system in an inconsistent state, leading to loss of data and time and labor expenses in restoring the operating system to a consistent state. 
     UPS  12  avoids data loss from a power interruption by providing stable AC input power. As shown in FIG. 1, UPS  12  includes EMI filter and PFC  121 , AC/DC converter  122 , DC/AC converter  123 , charger  124 , and battery  125 . When the AC input power from the utility power source is operating, the filtered AC input power provides a converted AC power through the AC/DC converter  122  and DC/AC converter  123 . The converted AC power is supplied to internal power supply  13  and is used to charge battery  125  through charger  124 . When a power interruption occurs, battery  125  discharges to maintain a DC output to DC/AC converter  123  which, in turn, maintains the converted AC power. Hence, UPS  12  provides internal power supply  13  with stable AC input power during a power interruption for as long as battery  125  can continue to supply the DC output to DC/AC converter  123 . 
     UPS  12  suffers, however, from some disadvantages. First, UPS  12  is complex and expensive. For home or simple office use, the cost of an expensive UPS outweighs its benefits of preventing data loss. Since only 3 to 5 minutes of uninterrupted power is required to shut down a computer properly during a power interruption, a simpler and less expensive back-up power unit which provides a personal computer power only for such a short period is desired. 
     SUMMARY OF THE INVENTION 
     The present invention provides a built-in backup power device which can provide a high-power apparatus with back-up power for a short period to respond to a power interruption. 
     The present invention also provides a personal computer with built-in back-up power device to prevent data loss and inconsistent operating system state during a power interruption. 
     In accordance with the present invention, the back-up power device includes a power-storing unit (e.g., a battery) connected to a charger. Under normal operation, the charger charges the battery. During power interruption, the battery discharges to provide a personal computer with back-up power, for 2 to 10 minutes. 
     In accordance with another aspect of the present invention, the back-up power device preferably includes an output circuit, such as a pumping circuit or a DC/DC converter, for converting the back-up power to a power suitable for operating various units of the personal computer. The back-up power device includes a controller operatively coupled to the charger and the output circuit. Under normal operating conditions, the controller controls the charger&#39;s charging of the battery. During a power interruption, the controller controls the output circuit to output suitable power for operating the personal computer. 
     In accordance with the another aspect of the present invention, the back-up power device preferably includes a power detector and an indicator. The power detector detects whether or not utility power is normal and the indicator indicates whether normal operating conditions prevail. During a power interruption, the indicator indicates power interruption to alert a user, so that a pre-determined shut-down procedure can be followed to thereby avoid data loss and inconsistent operating system state. In one embodiment, the back-up power device includes an auxiliary power source which operates the charger. 
     In accordance with the present invention, a computer with a back-up power device is provided. Under normal operating conditions, the back-up power device stores back-up power. During a power interruption, the back-up power device provides the computer with the stored back-up power for a short period ranging from 2 to 10 minutes. The computer includes electronic units such as a mainboard, a floppy disk drive, hard disk drive, and a compact disc read-only memory (CD-ROM) reader. The computer further includes an internal power supply for converting utility power or the back-up power to low-voltage DC power to operate memory units. The internal power supply further includes an AC/DC converter for converting the utility power to a high-voltage DC power, and a DC/DC converter for converting the high-voltage DC power to low-voltage DC power (e.g., at the operating voltage of the computer). 
     In accordance with another aspect of the present invention, in one embodiment, the battery and the charger are electrically connected to an input terminal of the DC/DC converter and to an output terminal of the AC/DC converter respectively. In another embodiment, the battery and the charger are electrically connected to the electronic units and to an output terminal of the DC/DC converter respectively. The built-in back-up power device can be removably mounted, and is coupled to the personal computer by using connectors. 
     The present invention is better understood upon consideration of the following detailed description with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic block diagram showing the use of a personal computer equipped with a conventional uninterrupted power supply. 
     FIG. 2 is a schematic block diagram showing a computer equipped with a built-in back-up power device, according to one embodiment of the present invention. 
     FIG. 3 is a detailed block diagram showing the computer with the built-in back-up power device of FIG.  2 . 
     FIG. 4 is a schematic block diagram showing a computer equipped with a built-in back-up power device, according to another embodiment of the present invention. 
     FIG. 5 is a detailed block diagram showing the computer with the built-in back-up power device of FIG.  4 . 
     FIG. 6 is a perspective diagram showing the use of a built-in back-up power device according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 2 shows a schematic block diagram showing a computer equipped with a built-in back-up power device, according to one embodiment of the present invention. Built-in back-up power device  21  is mounted in personal computer  11 . Built-in back-up power device  21  includes charger  211  and battery  212 . Built-in back-up power device  21  is therefore simpler than those of a conventional uninterrupted power supply. The simpler construction allows built-in back-up power device  21  to be inexpensive and compact enough to be conveniently mounted in personal computer  11 . Internal power supply  13  of personal computer  11  is conventional, and thus not further described here. Under normal operating conditions, charger  211  charges battery  212 , using the high-voltage DC power from AC/DC converter  132 . During power interruption, battery  212  discharges to provide the DC/DC converter  133  with back-up power at a high DC voltage. DC/DC converter  133  converts the back-up power to a low DC voltage (e.g., the operating voltage of personal computer  11 ) to supply electronic units  22  of personal computer  11 . Electronic unit  22  typically includes, for example, a mainboard, a floppy disk drive, a hard disk drive, and a CD-ROM reader. Battery  212  supplies about 2 to 10 minutes of power at personal computer  11 &#39;s normal rate of power consumption, sufficient to properly save data into the hard disk drive or properly shut down the personal computer. Built-in back-up power device  11  thus provides the average user an inexpensive alternative to a conventional uninterrupted power supply. 
     FIG. 3 is a detailed block diagram showing a computer with the built-in back-up power device of FIG.  2 . Utility power is received as an AC input signal. After being filtered to eliminate electromagnetic interference, the AC input power is converted to a high voltage DC power signal, indicated by voltage V dc  by AC/DC converter  132 . AC/DC converter  132  typically includes bridge rectifier  134  and filter capacitor C. Power detector  216  detects presence of voltage V dc . Under normal operating conditions, controller  215  sets charger  211  in an “ON” state and pumping circuit  214  in an “OFF” state. Charger  211  charges the battery  212  by using the high-voltage DC power V dc . During a power interruption, detector  216  outputs an “AC FAIL” signal to controller  215  to alert controller  215  of the power interruption. Controller  215  then sets charger  211  in an “OFF” state and pumping circuit  214  in an “ON” state. In this configuration, the back-up power stored in battery  212  is converted to a high-voltage DC power using pumping circuit  214  and is provided to an input terminal  1331  of DC/DC converter  133 . The high-voltage DC power is converted to a low voltage DC power (e.g., an operating voltage of personal computer  11 ) to operate electronic units  22  of personal computer  11 . At the same time, the indicator  217  alerts the user of the abnormal power condition, using, for example, a flashing light or an audible sound. Built-in back-up power device  21  can also include auxiliary power source  213  to operate charger  211 . 
     In the embodiment shown in FIG. 3, charger  211  is electrically connected to an output terminal of AC/DC converter  132  to receive the high DC voltage V dc . A second embodiment which provides further safety is shown in FIG.  4 . FIG. 4 is a schematic block diagram showing another computer equipped with a built-in backup power device. The internal structure of built-in back-up power device  21  of FIG. 4 is substantially the same as that described above. In this instance, however, built-in back-up power device  21  is electrically connected between DC/DC converter  133  and electronic units  22  to receive the low-voltage DC power to comply with safety standards. 
     FIG. 5 is a detailed block diagram showing the computer with the built-in back-up power device of FIG.  4 . In internal power supply  13  of FIG. 5, after the utility power is filtered to eliminate electromagnetic interference by EMI filter  131 , AC/DC converter  132  provides high voltage DC power (voltage V dc ). The high voltage DC power is then stepped down by DC/DC converter  133  to low voltage DC power. 
     Built-in back-up power device  21  receives utility power as the AC input power. Power detector  216  detects the state of the utility power at all times, and provides an output signal, which is transformed by optical coupling transistor  53  as an input signal to signal processing circuit  52 , charger  211 , and DC/DC converter  51 . Under normal operating conditions, charger  211  is in an “ON” state and DC/DC converter  51  is in an “OFF” state. Charger  211  charges the battery  212  using the low-voltage DC power from DC/DC converter  133 . During a power interruption, optical coupling transistor  53  transmits an “AC FAIL” signal to signal processing circuit  52 , charger  211  and the DC/DC converter  51 . Charger  211  switches to an “OFF” state and DC/DC converter  51  switches to an “ON” state. Consequently, the backup power stored in battery  212  is converted to DC power at a suitable voltage by DC/DC converter  51 , which is then provided to the electronic units  22  of personal computer  11 . At the same time, indicator  217  is enabled by the “AC FAIL” signal to alert the user of the power interruption. Indicator  217  can be implemented by any output circuit providing, for example, flashing light or sound. 
     Signal processing circuit  52  is electrically connected to an output terminal of DC/DC converter  133  to receive a “power good” (P.G.) signal, which indicates low voltage DC output power is provided under normal operating conditions. During a power interruption, signal processing circuit  52  sends a feedback signal to DC/DC converter  133  to stop DC/DC converter  133 &#39;s operations. 
     FIG. 6 is a perspective view showing use of a built-in back-up power device in an equipment housing or case  111 , according to the present invention. Built-in back-up power device  21  can be installed in any available space in case  111  of personal computer  11 . Such space can be, for example, a conventional 5¼-inch floppy disk drive bay. Thus, built-in back-up power device  21  can be provided a housing designed to fit a 5¼-inch floppy disk drive bay. Built-in back-up power device  21  can then be coupled through connectors  61  and  62  to internal power supply  13 . For greater convenience, built-in back-up power device  21  can be removably mounted. 
     A built-in back-up power device of the present invention can be used to operate any of numerous high-power apparati for short time periods of power interruption (e.g., 10 minutes). 
     While the invention has been described above in the specific and preferred embodiments, the present invention is not so limited. On the contrary, various modifications and variations within the scope of the present invention are possible. The present invention is set forth in the appended claims.