Abstract:
An uninterruptible power supply unit can communicate with a computer being in a suspend or sleep state. The uninterruptible power supply unit includes a first unit which transmits a first signal for informing the computer that the power supply from the commercial power is stopped via a first communication interface; and a second unit which transmits a second signal for activating the computer from the suspend or sleep state via second communication interface, the second unit being in an active state when the computer is in the suspend or sleep state.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an uninterruptible power supply unit (an “UPS”), and more particularly, to an UPS used with a computer. 
   DESCRIPTION OF THE RELATED ART 
   Generally, an UPS serves to keep a computer operating by supplying power thereto when the power supply from the commercial power is stopped, for example, a power failure or breaker trip due to overload occurs. An UPS uses an inverter to convert a direct current (DC) from a battery into an alternating current (AC). 
   Japanese Patent Laid-Open No. 06-161610 discloses an UPS which communicates with a computer. The computer operates by being supplied with electric power from the UPS having a backup power supply (a battery). When the computer detects that a power failure occurs to the UPS by a signal transmitted from the UPS via a communication cable, the computer is shut down voluntarily. Normally, for a connection between the computer and the UPS, a RS-232C interface (cable) is used. 
   According to the above described system, the computer can be shut down before the battery of the UPS consumes its electric power. 
   By the way, when the computer is under the suspend or sleep control, the computer normally breaks the connection at RS-232C interface. Therefore, the computer can not detect the power failure of the UPS. As a result, the computer is shut down before it is normally shut down when the power of the battery of the UPS exhausts. 
   Thus, there has been a problem in that when the UPS is used, suspend or sleep control cannot be conducted on the computer by the UPS. 
   SUMMARY OF THE INVENTION 
   The present invention has an object to provide an UPS that allows a computer to operate under the suspend or sleep control. 
   According to one aspect of the present invention, the UPS includes a first unit which transmits a first signal for informing the computer that the power supply from the commercial power is stopped via a first communication interface; and a second unit which transmits a second signal for activating the computer from the suspend or sleep state via second communication interface, the second unit being in an active state when the computer is in the suspend or sleep state before the first unit transmits the first signal. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     These and other objects, features and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawing, in which  FIG. 1  is a diagram showing a configuration of an embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention will be now explained in detail below in reference to the accompanying drawing. 
   Referring to  FIG. 1 , a computer system includes an UPS  1  and a computer  10 . 
   The UPS  1  includes an electromagnetic interference (EMI) filter  2  for power supply, a battery  4 , a DC/AC inverter  5 , a power switching circuit  3 , a signal generator circuit  7 , an EMI filter  8  for line, a line switching circuit  9  and a control circuit  6 . 
   The EMI filter  2  receives the commercial power (AC) and outputs it to the power switching circuit  3  after filtering a surge, noise or the like in the commercial power. The battery  4  outputs a DC to the DC/AC inverter  5 . The DC/AC inverter  5  converts the DC to an AC and outputs the AC to the power switching circuit  3 . The power switching circuit  3  selectively outputs the AC of the EMI filter  2  or the AC of the DC/AC inverter  5 . 
   The signal generator circuit  7  generates a ring signal and outputs it to line switching circuit  9  under control of the control circuit  6  when a power failure occurs, namely, when the power supply from the commercial power stops. The EMI filter  8  is connected to a telephone line and the line switching circuit  9 , and filters a noise in the telephone line. The line switching circuit  9  selectively outputs the ring signal of the signal generator circuit  7  or an output of the EMI filter for line  8 . 
   The control circuit  6  detects a power failure or an abnormality in the commercial power, controls the signal generator circuit  7  and the switchings performed in the power switching circuit  3  and the line switching circuit  9 . 
   In detail, when a power failure occurs or the control circuit  6  detects an abnormality in the commercial power, the control circuit  6  outputs a switch control signal to the power switching circuit  3  and the line switching circuit  9 . The power switching circuit  3  switches to the output of the battery  4  in response to the switch control signal. The line switching circuit  9  switches from the normal telephone line to the output of the signal generator circuit  7  in response to the switch control signal. 
   The computer  10  includes an AC/DC power supply circuit  11 , a central processing unit (CPU)  12  and a modem circuit  13 . The AC/DC power supply circuit  11  receives the AC power from the output switching circuit  3  via a power supply cable, and supplies the DC power to devices in the computer apparatus  10 . The CPU  12  is connected to the control circuit  6  in the UPS  1  via an RS-232C cable. Alternatively, the connection may be through a USB port, a firewire port, or any similar interface. The modem circuit  13  is connected to the line switching circuit  9  in the UPS  1  via a modular cable (telephone line cable). Alternatively, the line switching circuit  9  may be connected to a local area network port, using, e.g., a wake-up network card. The modem circuit  13  is a telephone modem and performs modulation and demodulation of data, regeneration of a carrier, automatic equalization or the like. 
   In operation, normally, the UPS  1  supplies the commercial power to the computer apparatus  10 . 
   When a power failure or an abnormality occurs in the commercial power, the control circuit  6  transmits the switch control signal to the power switching circuit  3 . In response to the signal, the power switching circuit  3  outputs power from the battery  4  to the computer  10 . 
   On the other hand, the line switching circuit  9  is normally connected to the telephone line. However, when the power failure occurs, in response to the switch received from the control circuit, the line switching circuit  9  outputs the ring signal generated by the signal generator circuit  7  to the modem circuit  13 . 
   Upon receiving the ring signal, the modem circuit  13  sends a wake up signal for activation to the CPU  12  only when the computer  10  is in the suspend or sleep control state. Then, the computer  10  wakes up. 
   The control circuit counts a certain delay time which at least lasts until the computer  10  wakes up after sending the ring signal to the computer  10 . Then, the control circuit  6  starts data communication with the CPU  12  via the RS-232C interface and sends a power failure detection signal. 
   In the computer  10  having received the power failure detection signal from the UPS  1 , the CPU  12  starts the shut-down of a running operating system. After the computer  10  is completely shut down, the UPS  1  turns off the output (power) to the computer  10 . 
   In the above-described computer system, the sending of the ring signal via the modular cable (telephone line) and the sending of the wake up signal from the modem circuit having received the ring signal to the CPU  12  may be replaced with the sending of a call signal via another network and the sending of the wake up signal from a circuit having received the call signal to the central processing unit, respectively, as far as the equivalent functions can be carried out. Besides, the interface for data communication may be any interface other than the RS-232C interface. 
   As described above, when a power failure is detected, the computer  10  is activated before the power failure detection signal is output thereto. Thus, even if the computer  10  has been in the suspend or sleep control state, it can receive the power failure detection signal from the UPS  1  via the RS-232C interface and be normally shut down. 
   Moreover, in the computer system, functions of the modem circuit  13  commonly used in computers can be used, the circuit configuration can be simplified and the cost can be reduced. 
   While this invention has been described in conjunction with the preferred embodiments described above, it will now be possible for those skilled in the art to put this invention into practice in various other manners.