Power supply device and a power supply method for a computer system

• US 5,974,551 A
• Filed: 10/10/1996
• Issued: 10/26/1999
• Est. Priority Date: 10/10/1995
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Kyung-Sang
• Primary Examiner(s): Sheikh, Ayaz R.
• Assistant Examiner(s): Thlang, Eric S.
• Application Number:
  US08/728,684
• Time in Patent Office: 1,111 Days
• Field of Search: 395/750.01, 395/750, 363/65, 363/15, 307/66, 379/413, 364/200, 320/14
• US Class Current: 713/300
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/3246 by software initiated power-off
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

An integrated power supply device and a power supplying method for controlling power supply to a computer system having a main computer body and a monitor. The integrated power supply device includes a wake-up sensor for generating a wake-up signal when the computer system is in use; a power supply controller responsive to said wake-up sensor to control the power supply to the monitor and the main computer body; a power input unit connected to an external power source to transform an alternating current voltage received from the external power source into a constant direct current voltage; a monitor power supply unit responsive to the power supply controller to transform the constant direct current voltage output from the power input unit into a first predetermined voltage and to supply the first predetermined voltage to the monitor for operation; a main body power supply unit responsive to the power supply controller to transform the constant direct current voltage output from the power input unit into a second predetermined voltage and to supply the second predetermined voltage to the main computer body for operation; and a subsidiary power supply unit coupled to the power input unit to transform the constant direct current voltage output from the power input unit into a third predetermined voltage and to supply the third predetermined voltage to the power supply controller for controlling the power supply to the monitor and the main computer body to minimize power consumption.

Claims

1. A power supply device for a computer system having a monitor and a main computer body, said power supply device comprising:

a wake-up sensor generating a wake-up signal when the computer system is in use;

a power supply controller responsive to said wake-up sensor, controlling the power supply to the monitor and the main computer body;

a power input unit connected to an external power source, transforming an alternating current voltage received from said external power source into a constant direct current voltage;

a monitor power supply unit responsive to said power supply controller, transforming the constant direct current voltage output from said power input unit into a first predetermined voltage and supplying said first predetermined voltage to the monitor for operation;

a main body power supply unit responsive to said power supply controller, transforming the constant direct current voltage output from said power input unit into a second predetermined voltage and supplying said second predetermined voltage to the main computer body for operation; and

a subsidiary power supply unit transforming the constant direct current voltage output from said power input unit into a third predetermined voltage and supplying said third predetermined voltage to said power supply controller for controlling the power supply to the monitor and the main computer body.

2. The power supply device of claim 1, further comprised of said power input unit comprising:

a power switch operable in one of an "on" mode and an "off" mode, for enabling an operator to physically turn "on" and turn "off" the computer system;

a high frequency filter connected to said power switch, for filtering high frequency elements from the alternating current voltage supplied from said external power source when said power switch is turned "on";

a rectifier connected to said high frequency filter, for filtering the alternating current voltage output from said high frequency filter and generating the direct current voltage therefrom;

an automatic selector connected to said rectifier, for generating the constant direct current voltage in response to reception of the direct current voltage output from said rectifier.

3. The power supply device of claim 2, further comprised of said automatic selector performing a double voltage rectification of the supplied direct voltage when the supplied direct voltage is 110 Volts, and a full wave voltage rectification of the supplied direct voltage when the supplied direct voltage is 220 Volts.

4. The power supply device of claim 1, further comprised of said monitor power supply unit comprising:

a first transformer coupled to receive the constant direct current voltage from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a first rectifier connected to said first transformer, for rectifying the alternating current voltage from said first transformer into a first direct current voltage;

a first filter connected to said first rectifier, for filtering noise elements from the first direct current voltage from the first rectifier and producing said first predetermined voltage to the monitor for operation;

a first on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a first logic state from said power supply controller; and

a first switching unit connected to said first on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said first transformer according to the power on/off signal.

5. A power supply device for a computer system having a monitor and a main computer body, said power supply device comprising:

a wake-up sensor for generating a wake-up signal when the computer system is in use;

a power supply controller responsive to said wake-up sensor, for controlling the power supply to the monitor and the main computer body;

a power input unit connected to an external power source, for transforming an alternating current voltage received from said external power source into a constant direct current voltage;

a monitor power supply unit responsive to said power supply controller, for transforming the constant direct current voltage output from said power input unit into a first predetermined voltage and supplying said first predetermined voltage to the monitor for operation;

a main body power supply unit responsive to said power supply controller, for transforming the constant direct current voltage output from said power input unit into a second predetermined voltage and supplying said second predetermined voltage to the main computer body for operation;

a subsidiary power supply unit for transforming the constant direct current voltage output from said power input unit into a third predetermined voltage and supplying said third predetermined voltage to said power supply controller for controlling the power supply to the monitor and the main computer body;

said monitor power supply unit further comprising;

a first transformer coupled to receive the constant direct current voltage from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a first rectifier connected to said first transformer, for rectifying the alternating current voltage from said first transformer into a first direct current voltage;

a first filter connected to said first rectifier, for filtering noise elements from the first direct current voltage from the first rectifier and producing said first predetermined voltage to the monitor for operation;

a first on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a first logic state from said power supply controller; and

a first switching unit connected to said first on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said first transformer according to the power on/off signal; and

said subsidiary power supply unit further comprising;

a second transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a second rectifier connected to said second transformer, for rectifying the alternating current voltage from said second transformer into a second direct current voltage; and

a second filter connected to said second rectifier, for filtering noise elements from the second direct current voltage output from the second rectifier and producing said third predetermined voltage to said power supply controller.

6. The power supply device of claim 5, further comprised of said main body power supply unit comprising:

a third transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a third rectifier connected to said third transformer, for rectifying the alternating current voltage from said third transformer into a third direct current voltage;

a third filter connected to said third rectifier, for filtering noise elements from the third direct current voltage output from the third rectifier and producing said second predetermined voltage to the main computer body for operation;

a second on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a second logic state output from said power supply controller; and

a second switching unit connected to said second on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said third transformer according to the power on/off signal.

7. The power supply device of claim 6, further comprised of said power input unit comprising:

a power switch operable in one of an "on" mode and an "off" mode, for enabling an operator to physically turn "on" and turn "off" the computer system;

a high frequency filter connected to said power switch, for filtering high frequency elements from the alternating current voltage supplied from said external power source when said power switch is turned "on";

a fourth rectifier connected to said high frequency filter, for filtering the alternating current voltage output from said high frequency filter and generating the direct current voltage therefrom;

an automatic selector connected to said fourth rectifier, for generating the constant direct current voltage in response to reception of the direct current voltage output from said fourth rectifier.

8. The power supply device of claim 7, further comprised of said automatic selector performing a double voltage rectification of the supplied direct voltage when the supplied direct voltage is 110 Volts, and a full wave voltage rectification of the supplied direct voltage when the supplied direct voltage is 220 Volts.

9. A method for controlling power supply to a computer system having a main computer body, a monitor and input devices using an integrated power supply device, said method comprising the steps of:

initializing said integrated power supply device upon activation of power;

supplying power from said integrated power supply device to the computer system for use including both the main computer body and the monitor, wherein said integrated power supply device comprises a first power supply unit and a second power supply unit, said first power supply unit supplying power to the monitor, and said second power supply unit supplying power to the main computer body;

determining whether there is activity from input devices indicating that the computer system is in use;

when there is activity from the input devices indicating that the computer system is in use, maintaining the power supply from said integrated power supply device to both the main computer body and the monitor;

when there is no activity from the input devices indicating that the computer system is not in use, starting a timer having a first, second, and third predetermined period;

when said timer reaches said first predetermined period, cutting off the power supply to the monitor;

after the power supply to the monitor is cut off, determining whether there is still no activity from the input devices;

when there is activity from the input devices, resupplying power back to the monitor and maintaining the power supply from said integrated power supply device to both the main computer body and the monitor;

when there is still no activity from the input devices, cutting off the power supply to a hard disk drive and a central processing unit of the main computer body when said timer reaches said second predetermined period longer than said first predetermined period;

after the power supply to the hard disk drive and the central processing unit of the main computer body is cut off, determining whether there is still no activity from the input devices;

when there is activity from the input devices, resupplying power back to the monitor, the hard disk drive and the central processing unit of the main computer body, and maintaining the power supply from said integrated power supply device to both the main computer body and the monitor; and

when there is still no activity from the input devices, cutting off the power supply to the main computer body until there is activity from the input devices when said timer reaches said third predetermined period longer than said second predetermined period.

10. A method for controlling power supply to a computer system having a main computer body, a monitor and input devices using an integrated power supply device, said method comprising the steps of:

initializing said integrated power supply device upon activation of power;

determining whether a wake-up signal is generated in response to activity from input devices indicating that the computer system is in use;

when the wake-up signal is not generated in response to non-activity from the input devices indicating that the computer system is not in use, beginning counting until a counted value reaches to one of first, second, and third predetermined value;

when the counted value reaches said first predetermined value, cutting off the power supply to the monitor;

after the power supply to the monitor is cut off, determining whether the wake-up signal is generated in response to activity from input devices;

when the wake-up signal is not generated in response to non-activity from the input devices, determining whether the counted value reaches said second predetermined value greater than said first predetermined value;

when the counted value reaches said second predetermined value, reducing the power supply to the main computer body below a predetermined voltage;

after the power supply to the main computer body is reduced below said predetermined voltage, continuously determining whether the wake-up signal is generated in response to activity from input devices;

when the wake-up signal is not generated in response to non-activity from the input devices, determining whether the counted value reaches said third predetermined value greater than said second predetermined value;

when the counted value reaches said third predetermined value, cutting off the power supply to the main computer body; and

alternatively, automatically resupplying power to both the monitor and the main computer body whenever the wake-up signal is generated in response to activity from the input devices.

11. An apparatus, comprising:

an integrated computer system having a single housing structure including a main computer body and a monitor incorporated;

input devices connected to the main computer body; and

an integrated power supply device, for supplying power to both the monitor and the main computer body for operation upon activation of a power switch, said integrated power supply device controlling the power supply to the monitor and the main computer body based upon activity from the input devices indicating that said computer system is in use, wherein said integrated power supply device further comprises a first power supply unit supplying power to the monitor and a second power supply unit supplying power to the main computer body.

12. The apparatus of claim 11, wherein said integrated power supply device further comprises:

a wake-up sensor generating a wake-up signal when said computer system is in use;

a power supply controller being responsive to said wake-up sensor, said power supply controller controlling the power supply to the monitor and the main computer body;

a power input unit being connected to an external power source, said power input unit transforming an alternating current voltage received from the external power source into a constant direct current voltage;

said first power supply unit corresponding to a monitor power supply unit and being responsive to said power supply controller, the monitor power supply unit transforming the constant direct current voltage output from said power input unit into a first predetermined voltage and supplying said first predetermined voltage to the monitor for operation;

said second power supply unit corresponding to a main body power supply unit and being responsive to said power supply controller, the main body power supply unit transforming the constant direct current voltage output from said power input unit into a second predetermined voltage and supplying said second predetermined voltage to the main computer body for operation; and

a subsidiary power supply unit transforming the constant direct current voltage output from said power input unit into a third predetermined voltage and supplying said third predetermined voltage to said power supply controller for controlling the power supply to the monitor and the main computer body.

13. The apparatus of claim 12, further comprised of said power input unit comprising:

said power switch operable in one of an "on" mode and an "off" mode, for enabling an operator to physically turn "on" and turn "off" said computer system;

a high frequency filter connected to said power switch, for filtering high frequency elements from the alternating current voltage supplied from said external power source when said power switch is turned "on";

a rectifier connected to said high frequency filter, for filtering the alternating current voltage output from said high frequency filter and generating the direct current voltage therefrom;

an automatic selector connected to said rectifier, for generating the constant direct current voltage in response to reception of the direct current voltage output from said rectifier.

14. The apparatus of claim 13, further comprised of said automatic selector performing a double voltage rectification of the supplied direct voltage when the supplied direct voltage is 110 Volts, and a full wave voltage rectification of the supplied direct voltage when the supplied direct voltage is 220 Volts.

15. The apparatus of claim 12, further comprised of said monitor power supply unit comprising:

a first transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a first rectifier connected to said first transformer, for rectifying the alternating current voltage from said first transformer into a first direct current voltage;

a first filter connected to said first rectifier, for filtering noise elements from the first direct current voltage output from the first rectifier and producing said first predetermined voltage to the monitor for operation;

a first on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a first logic state output from said power supply controller; and

a first switching unit connected to said first on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said first transformer according to the power on/off signal.

16. An apparatus, comprising:

an integrated computer system having a single housing structure including a main computer body and a monitor incorporated;

input devices connected to the main computer body;

an integrated power supply device, for supplying power to both the monitor and the main computer body for operation upon activation of a power switch, said integrated power supply device controlling the power supply to the monitor and the main computer body based upon activity from the input devices indicating that said computer system is in use;

said integrated power supply device further comprising;

a wake-up sensor for generating a wake-up signal when said computer system is in use;

a power supply controller responsive to said wake-up sensor, for controlling the power supply to the monitor and the main computer body;

power input unit connected to an external power source, for transforming an alternating current voltage received from said external power source into a constant direct current voltage;

a monitor power supply unit responsive to said power supply controller, for transforming the constant direct current voltage output from said power input unit into a first predetermined voltage and supplying said first predetermined voltage to the monitor for operation;

a main body power supply unit responsive to said power supply controller, for transforming the constant direct current voltage output from said power input unit into a second predetermined voltage and supplying said second predetermined voltage to the main computer body for operation; and

a subsidiary power supply unit for transforming the constant direct current voltage output from said power input unit into a third predetermined voltage and supplying said third predetermined voltage to said power supply controller for controlling the power supply to the monitor and the main computer body;

said monitor power supply unit further comprising;

a first transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a first rectifier connected to said first transformer, for rectifying the alternating current voltage from said first transformer into a first direct current voltage;

a first filter connected to said first rectifier, for filtering noise elements from the first direct current voltage output from the first rectifier and producing said first predetermined voltage to the monitor for operation;

a first on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a first logic state output from said power supply controller; and

a first switching unit connected to said first on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said first transformer according to the power on/off signal;

said subsidiary power supply unit further comprising;

a second transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a second rectifier connected to said second transformer, for rectifying the alternating current voltage from said second transformer into a second direct current voltage; and

a second filter connected to said second rectifier, for filtering noise elements from the second direct current voltage output from the second rectifier and producing said third predetermined voltage to said power supply controller.

17. The apparatus of claim 16, further comprised of said main body power supply unit comprising:

a third transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a third rectifier connected to said third transformer, for rectifying the alternating current voltage from said third transformer into a third direct current voltage;

a third filter connected to said third rectifier, for filtering noise elements from the third direct current voltage output from the third rectifier and producing said second predetermined voltage to the main computer body for operation;

a second on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a second logic state output from said power supply controller; and

a second switching unit connected to said second on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said third transformer according to the power on/off signal.

18. The apparatus of claim 17, further comprised of said power input unit comprising:

a power switch operable in one of an "on" mode and an "off" mode for enabling an operator to physically turn "on" and turn "off" said computer system;

a high frequency filter connected to said power switch, for filtering high frequency elements from the alternating current voltage supplied from said external power source when said power switch is turned "on";

a fourth rectifier connected to said high frequency filter, for filtering the alternating current voltage output from said high frequency filter and generating the direct current voltage therefrom;

an automatic selector connected to said fourth rectifier, for generating the constant direct current voltage in response to reception of the direct current voltage output from said fourth rectifier.

19. The apparatus of claim 18, further comprised of said automatic selector performing a double voltage rectification of the supplied direct voltage when the supplied direct voltage is 110 Volts, and a full wave voltage rectification of the supplied direct voltage when the supplied direct voltage is 220 Volts.

20. A computer system, comprising:

a main computer unit containing a central processing unit and auxiliary devices;

a monitor operatively connected to said main computer unit;

input devices operatively connected to said main computer unit; and

an integrated power supply device included in said main computer unit, for concomitantly supplying power to the monitor, the central processing unit and the auxiliary devices for operation upon activation of a power switch, said integrated power supply device controlling the sequential selective power supply to the monitor, the central processing unit and the auxiliary devices based upon occurrence of one of an activity and non-activity from the input devices indicating whether the computer system is in use, wherein said integrated power supply device comprises a first power supply unit and a second power supply unit, said first power supply unit supplying power to the monitor, and said second power supply unit supplying power to the main computer unit.

21. The computer system of claim 20, wherein said integrated power supply device further comprises:

a wake-up sensor for generating a wake-up signal when the computer system is in use;

a power supply controller responsive to said wake-up sensor, for controlling the power supply to the monitor and the main computer unit including the central processing unit and the auxiliary devices;

a power input unit connected to an external power source, for transforming an alternating current voltage received from said external power source into a constant direct current voltage;

said first power supply unit corresponding to a monitor power supply unit and being responsive to said power supply controller, said monitor power supply unit transforming the constant direct current voltage output from said power input unit into a first predetermined voltage and supplying said first predetermined voltage to the monitor for operation;

said second power supply unit corresponding to a main body power supply unit and being responsive to said power supply controller, said main body power supply unit transforming the constant direct current voltage output from said power input unit into a second predetermined voltage and supplying said second predetermined voltage to the main computer unit for operation; and

a subsidiary power supply unit for transforming the constant direct current voltage output from said power input unit into a third predetermined voltage and supplying said third predetermined voltage to said power supply controller for controlling the power supply to the monitor and the main computer unit.

22. The computer system of claim 21, further comprised of said power input unit comprising:

said power switch operable in one of an "on" mode and an "off" mode, for enabling an operator to physically turn "on" and turn "off" the computer system;

a high frequency filter connected to said power switch, for filtering high frequency elements from the alternating current voltage supplied from said external power source when said power switch is turned "on";

a rectifier connected to said high frequency filter, for filtering the alternating current voltage output from said high frequency filter and generating the direct current voltage therefrom;

an automatic selector connected to said rectifier, for generating the constant direct current voltage in response to reception of the direct current voltage output from said rectifier.

23. The computer system of claim 22, further comprised of said automatic selector performing a double voltage rectification of the supplied direct voltage when the supplied direct voltage is 110 Volts, and a full wave voltage rectification of the supplied direct voltage when the supplied direct voltage is 220 Volts.

24. The computer system of claim 23, further comprised of said monitor power supply comprising:

a first transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a first rectifier connected to said first transformer, for rectifying the alternating current voltage from said first transformer into a first direct current voltage;

a first filter connected to said first rectifier, for filtering noise elements from the first direct current voltage output from the first rectifier and producing said first predetermined voltage to the monitor for operation;

a first on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a first logic state output from said power supply controller; and

a first switching unit connected to said first on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said first transformer according to the power on/off signal.

25. A computer system comprising:

a main computer unit containing a central processing unit and auxiliary devices;

a monitor operatively connected to said main computer unit;

input devices operatively connected to said main computer unit;

an integrated power supply device included in said main computer unit, for concomitantly supplying power to the monitor, the central processing unit and the auxiliary devices for operation upon activation of a power switch, said integrated power supply device controlling the sequential selective power supply to the monitor, the central processing unit and the auxiliary devices based upon occurrence of one of an activity and non-activity from the input devices indicating whether the computer system is in use;

said integrated power supply device further comprising;

a wake-up sensor for generating a wake-up signal when the computer system is in use;

a power supply controller responsive to said wake-up sensor, for controlling the power supply to the monitor and the main computer unit including the central processing unit and the auxiliary devices;

a power input unit connected to an external power source, for transforming an alternating current voltage received from said external power source into a constant direct current voltage;

a monitor power supply unit responsive to said power supply controller, for transforming the constant direct current voltage output from said power input unit into a first predetermined voltage and supplying said first predetermined voltage to the monitor for operation;

a main body power supply unit responsive to said power supply controller, for transforming the constant direct current voltage output from said power input unit into a second predetermined voltage and supplying said second predetermined voltage to the main computer unit for operation; and

a subsidiary power supply unit for transforming the constant direct current voltage output from said power input unit into a third predetermined voltage and supplying said third predetermined voltage to said power supply controller for controlling the power supply to the monitor and the main computer unit;

said power input unit further comprising;

said power switch operable in one of an "on" mode and an "off" mode, for enabling an operator to physically turn "on" and turn "off" the computer system;

a high frequency filter connected to said power switch, for filtering high frequency elements from the alternating current voltage supplied from said external power source when said power switch is turned "on";

a rectifier connected to said high frequency filter, for filtering the alternating current voltage output from said high frequency filter and generating the direct current voltage therefrom; and

an automatic selector connected to said rectifier, for generating the constant direct current voltage in response to reception of the direct current voltage output from said rectifier, said automatic selector performing a double voltage rectification of the supplied direct voltage when the supplied direct voltage is 110 Volts, and a full wave voltage rectification of the supplied direct voltage when the supplied direct voltage is 220 Volts;

said monitor power supply further comprising;

a first transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a first rectifier connected to said first transformer, for rectifying the alternating current voltage from said first transformer into a first direct current voltage;

a first filter connected to said first rectifier, for filtering noise elements from the first direct current voltage output from the first rectifier and producing said first predetermined voltage to the monitor for operation;

a first on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a first logic state output from said power supply controller; and

a first switching unit connected to said first on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said first transformer according to the power on/off signal;

said subsidiary power supply unit further comprising;

a second transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a second rectifier connected to said second transformer, for rectifying the alternating current voltage from said second transformer into a second direct current voltage; and

a second filter connected to said second rectifier, for filtering noise elements from the second direct current voltage output from the second rectifier and producing said third predetermined voltage to said power supply controller.

26. The computer system of claim 25, further comprised of said main body power supply unit comprising:

a third transformer coupled to receive the constant direct current voltage output from said power input unit, for transforming the constant direct current voltage into an alternating current voltage;

a third rectifier connected to said third transformer, for rectifying the alternating current voltage from said third transformer into a third direct current voltage;

a third filter connected to said third rectifier, for filtering noise elements from the third direct current voltage output from the third rectifier and producing said second predetermined voltage to the main computer body for operation;

a second on/off control unit responsive to said power supply controller, for generating a power on/off signal corresponding to a power control signal exhibiting a second logic state output from said power supply controller; and

a second switching unit connected to said second on/off control unit, for limiting an input of the constant direct current voltage from said power input unit into said third transformer according to the power on/off signal.