Power supply of display apparatus with universal serial bus device

• US 6,345,364 B1
• Filed: 04/07/1999
• Issued: 02/05/2002
• Est. Priority Date: 04/11/1998
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Joo-Hyoung
• Primary Examiner(s): AUVE, GLENN ALLEN
• Application Number:
  US09/287,340
• Time in Patent Office: 1,035 Days
• Field of Search: 713/300, 713/320, 713/323, 713/324, 713/310, 713/340
• US Class Current: 713/324
• 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 1/3265 Power saving in display device
• CPC Class Codes: G09G 1/005 Power supply circuits
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

a power supply of the display apparatus includes a switching mode power supply forming the main power supply of the display apparatus. The power supply of this invention includes an auxiliary power supply for supplying power with a universal serial bus (USB) hub. The power supply further includes a display power management signaling (DPMS) control circuit for managing the power saving between the full-on, standby, suspend, and power-off modes, a relay switch is provided across the power line directed to the main power supply. The DPMS control circuit responds to input status of the horizontal and vertical synchronization signals (Hsync, Vsync) and, in the power-off mode, it produces a control signal that cuts off the relay switch. The power supply of this invention provides a stable supply power with the USB hub even if the display apparatus enters the power-off mode of DPMS. Further, the power supply of this invention can cut off power supply directed to the main power supply when the display apparatus enters the power-off mode.

Claims

1. A power supply of display apparatus having universal serial bus (USB) hub, the power supply comprising:

a rectifier converting an AC input voltage into a DC output voltage;

a first power supply circuitry for generating regulated output voltage required to energize a display when it receives the rectifier output voltage;

a second power supply circuitry for supplying power to the USB hub, in which the second power supply circuitry receives said DC output voltage from said rectifier as input to said second power supply circuitry;

a power switch disposed between the output of the rectifier and an input of the first power supply circuitry; and

a controller outputting a control signal that switches said power switch so that no power is supplied to said first power supply circuitry in response to display power management signals input to said controller, said display power management signals corresponding to a power-off mode.

2. The power supply of claim 1, wherein the second power supply circuitry comprises a DC/DC converter for outputting desired voltage to the USB hub.

3. The power supply of claim 2, said second power supply circuitry further comprising an auxiliary power supply converting said DC output voltage from said rectifier to a desired DC voltage for input to said DC/DC converter.

4. The power supply of claim 1, wherein the first power supply circuitry comprises a switching mode power supply (SMPS) circuitry.

5. The power supply of claim 1, wherein the display power management signals comprise a horizontal and a vertical synchronization signal (Hsync, Vsync) provided by a system host.

6. The power supply of claim 1, wherein the power switch comprises a relay switch and relay drive circuitry, wherein the relay switch is a single pull single throw (SPST) switch wherein power to said first power supply circuitry is interrupted when said SPST switch is open.

7. A power supply of a display apparatus having a universal serial bus hub, the power supply comprising:

a rectifier for converting input AC voltage to output DC voltage;

a display power management signaling power switch having an input and an output, said input of said display power management signaling power switch connected to the DC output of said rectifier;

a pulse width modulation circuit having an input and an output, said input of said pulse width modulation circuit connected to said output of said display power management signaling power switch;

a transformer having an input and an output, said input of said transformer connected to said output of said display power management signaling power switch, said output of said pulse width modulation circuit connected to said transformer;

a power output circuit connected to said output of said transformer, output of said power output circuit being used to power a display of said display apparatus;

an auxiliary power supply having an input and an output, said input of said auxiliary power supply being connected to said DC output of said rectifier;

a microcontroller having horizontal and vertical synchronization signals as inputs and having said output of said auxiliary power supply as an input, said microcontroller producing a control signal as output which is used to control said display power management signaling power switch; and

a DC to DC converter having an input and an output, said input of said DC to DC converter connected to said output of said auxiliary power supply and said output of said DC to DC converter connected to a universal serial bus hub.

8. The power supply of claim 7, wherein said display power management signaling power switch can be either in an open or a closed state, said display power management signaling power switch being in an open state only when both said horizontal and said vertical synchronization signals are in an inactive state, thus denying power to said pulse width modulation circuit, said transformer, said power output circuit and said display while power is continuously being delivered to said universal serial bus hub.

9. The power supply of claim 7, wherein said display power management signaling power switch comprises:

a bias resistor having a first end and a second end, said first end of said bias resistor connected to said control signal output of said microcontroller;

a transistor having a base terminal, an emitter terminal, and a collector terminal, said emitter terminal being connected to electrical ground, said base terminal being connected to said second end of said bias resistor;

a diode having a cathode and an anode, said anode connected to said collector terminal of said transistor and said cathode connected to said auxiliary power supply;

a coil having a first end and a second end, said first end connected to said collector terminal of said transistor and said second end connected to said cathode of said diode; and

a single pole single throw switch connected between said output of said rectifier and said input of said transformer, said single pole single throw switch being in the proximity of said coil allowing current in said coil to open and close said single pole single throw switch depending on the control signal output from said microcontroller.

10. A method of denying power to a display device while continuing to provide power to a universal serial bus hub, comprising the steps of:

splitting rectified DC power to energize a first circuit and a second circuit, said first circuit energizes said display device while said second circuit energizes a universal serial bus hub;

inactivating both horizontal and vertical synchronization signals;

converting said inactive horizontal and vertical synchronization signals into an active control signal; and

opening a power switch by said active control signal, said power switch being placed between a rectifier and said first circuit, said active control signal denying power to said first circuit by said active control signal while maintaining power delivered to said second circuit and said universal serial bus hub.

11. The method of claim 10, said first circuit comprising:

a transformer having a first input and an output, said first input being connected to said power switch on a side of said power switch opposite said rectifier;

a pulse width modulation circuit having an input and an output, said input being connected to said first input of said transformer and said output being electrically connected to a second input of said transformer; and

an output circuit having an input connected to said output of said transformer, said output of said output circuit being electrically connected to said display device.

12. The method of claim 11, said second circuit comprising:

an auxiliary power supply having an input and an output, said input being electrically connected to said rectified DC power, said output being connected to said power switch and a microprocessor, said auxiliary power supply outputting a first DC voltage; and

a DC/DC converter having an input and an output, said input being electrically connected to said output of said auxiliary power supply and said output being connected to said universal serial bus hub, said DC/DC converter receiving said first DC voltage and delivering a second DC voltage to said universal serial bus hub.