# Patent

## Title
Video and audio system capable of saving electric power

## Abstract

A power supply of a video and audio system is coupled to a first switch and a second switch. A power management unit is coupled between the first switch and at least one electronic device. An integrated circuit includes a first circuit and a second circuit. The first circuit is coupled to the power management unit and the at least one electronic device for controlling the operation of the at least one electronic device. The second circuit is coupled to a battery, the first switch, the second switch, and the first circuit for controlling the first switch and the second switch.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This is a division of U.S. patent application Ser. No. 11/381,541 filed May 4, 2006, included herein in its entirety.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video and audio system, and more particularly, to a video and audio system capable of saving electric power.
2. Description of the Prior Art
Please refer to FIG. 1, which is a diagram of a TV system 1 according to the prior art. The TV system 1 comprises a TV tuner 11, an audio processor 13, a TV decoder 15, a main integrated circuit (IC) 14, a power management unit 12, and a power supply 10.
The main IC 14 comprises a microcontroller unit (MCU) 142 and a video processor 141. The MCU 142 controls the operations of the TV tuner 11, the audio processor 13, the TV decoder 15, and the video processor 141. The power management unit 12 receives electric power from the power supply 10, and provides required operation voltages to the TV tuner 11, the audio processor 13, the TV decoder 15, and the main IC 14 correspondingly.
When the TV system 1 is turned off, the MCU 142 sends signals to the TV tuner 11, the audio processor 13, the TV decoder 15, and the video processor 141 to stop all operations. However, the MCU 142 must be in operation all the time to receive input signals, such as signals related to turning on the TV system 1 or setting the time. Since the MCU 142 must react to all input signals immediately, the path of electric power cannot be disconnected, resulting in a constant small current flow from the power management unit 12 to the TV tuner 11, the audio processor 13, and the TV decoder 15. This wastes electric power. With the current trend towards natural and green goods, saving power has become important.
SUMMARY OF THE INVENTION
The claimed invention discloses a video and audio system. The video and audio system comprises a power supply, a first switch coupled to the power supply, a second switch coupled to the power supply, a battery coupled to the second switch, a power management unit coupled to the first switch, at least one electronic device coupled to the power management unit, and an integrated circuit. The integrated circuit comprises a first circuit and a second circuit. The first circuit is coupled to the power management unit and the at least one electronic device. The second circuit is coupled to the battery, the first switch, the second switch, and the first circuit. The first circuit controls the operation of the at least one electronic device, and the second circuit controls the first switch and the second switch.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of a TV system according to the prior art.
FIG. 2 is a diagram of a video and audio system according to the present invention.



DETAILED DESCRIPTION
Please refer to FIG. 2, which is a diagram of a video and audio system 2 according to the present invention. The video and audio system 2 comprises a TV tuner 11, an audio processor 13, a TV decoder 15, a main IC 24, a power management unit 22, a power supply 20, a battery 26, a first switch (SW1) 27, and a second switch (SW2) 29.
The main IC 24 comprises a first circuit 241 and a second circuit 242, a transmission interface being between the first circuit 241 and the second circuit 242. The second circuit 242 controls the first switch 27 and the second switch 29. When the second circuit 242 turns on the first switch 27, the power supply 20 provides electric power to the power management unit 22. Then, the power management unit 22 provides electric power to the first circuit 241. The second circuit 242 sends a command to start the first circuit 241 via the transmission interface, so that the first circuit 241 can control the TV tuner 11, the audio processor 13, and the TV decoder 15 utilizing the electric power provided by the power management unit 22.
The power supply 20 provides electric power to the power management unit 22, and then the power management unit 22 provides electric power to the TV tuner 11, the audio processor 13, the TV decoder 15, and the first circuit 241 according to required operation voltages of the TV tuner 11, the audio processor 13, the TV decoder 15, and the first circuit 241. The battery 26 provides power to the second circuit 242.
When the video and audio system 2 is turned on, the second circuit 242 turns on the first switch 27 so that the power supply 20 provides electric power to the TV tuner 11, the audio processor 13, the TV decoder 15, and the first circuit 241 via the power management unit 22. When the video and audio system 2 is turned off, the second circuit 242 turns off the first switch 27, and thereby disconnects the power supply 20 and the power management unit 22, and no current flows to the power management unit 22.
Since the second circuit 242 includes a real time clock and manages all received signals from a remote control or buttons of the video and audio system 2, the second circuit 242 must stay in an operational mode all the time. That is, no matter whether the video and audio system 2 is turned on or not, electric power must be provided to the second circuit 242 constantly. The video and audio system 2 of present invention separates the power transmission paths into the first circuit 241 and the second circuit 242 of the main IC 24. Even if the video and audio system 2 is turned off, the second circuit 242 still receives electric power from the battery 26 for operating normally.
Additionally, the second circuit 242 comprises a detector 28 coupled to the second circuit 242 and the battery 26. When the detector 28 detects that the voltage of the battery 26 is lower than a predetermined voltage, the second circuit 242 turns on the second switch 29 accordingly, so that the power supply 20 charges the battery 26 to provide electric power to the second circuit 242 for operation. According to another embodiment of present invention, the second circuit 242 periodically turns on the second switch 29 when a time duration of turning off the second switch 29 reaches a predetermined duration calculated by a timer 243 of the second circuit 242, and thereby the battery 26 is periodically charged.
The video and audio system 2 of the present invention can be a TV system or other multimedia systems, such as a DVD player. The power control system of the present invention can be implemented in general electronic products for saving electric power. Electronic devices coupled to the power management unit 22 are not limited to the TV tuner 11, the audio processor 13, and the TV decoder 15. The second circuit 242 can be a microcontroller unit to control the operation of the video and audio system 2. The power supply 20 can be a power supply capable of automatically transferring voltages.
When the video and audio system is turned off, the present invention completely disconnects the power transmission path between the power supply and the power management unit for saving electric power. In addition, the present invention uses a storage battery to provide electric power to the microcontroller unit. Even though the video and audio system is turned off, the microcontroller unit still has electric power to receive input signals or perform other functions, such as setting time, so that the video and audio system can be operated normally.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

## Claims

1. A method of saving electric power, the method comprising:
a first power source providing operational power to a power management unit of a video and audio system, and operational power not being provided to the power management unit of the video and audio system according to a first switch;
a second power source different than the first power source providing power to a circuit controlling the first switch and controlling a second switch periodically electrically coupling the second power source to the first power source; and
the power management unit supplying power to the circuit when the first switch is turned on and the first power source provides operational power to the power management unit;
wherein the second power source is a battery.

2. The method of claim 1, further comprising:
detecting whether a voltage of the battery is lower than a predetermined voltage;
wherein periodically turning on the second switch between the first power supply and the battery comprises turning on the second switch when the voltage of the battery is lower than the predetermined voltage so that the battery is charged by the first power supply.

3. The method of claim 1 further comprising:
calculating a time duration of turning off the second switch between the first power supply and the battery;
wherein periodically turning on the second switch between the first power supply and the battery comprises turning on the second switch when the time duration of turning off the second switch between the first power supply and the battery reaches a predetermined duration so that the battery is charged by the first power supply.

4. A method of saving electric power, the method comprising:
selectively providing operational power to a power management unit of a video and audio system according to a first switch coupled to a first power source;
a second power source different than the first power source continuously providing power to a circuit controlling the first switch and controlling a second switch periodically electrically coupling the second power source to the first power source; and
the power management unit supplying power to the circuit when the first switch is turned on and the first power source provides operational power to the power management unit;
wherein the second power source is a battery.