The present invention is directed, in general, to electronic devices and, more specifically, to an apparatus and method for reducing the level of power consumption in an electronic device when the electronic device is operating in a standby mode or low-power mode. 
In electronic devices it is sometimes desirable to operate the device in a standby mode (also called a low-power mode) rather than to turn off all power to the device when the device is not in use.  For example, in a television set it is customary to continually supply power to the heating elements of the electronic circuitry even when the set is otherwise turned off.  This permits the electronic circuitry that operates the various components of the television set (e.g., circuitry that operates the cathode ray tube of the television screen) to very quickly achieve the proper level of operation when the set is turned on.  If one did not keep the set minimally powered in a standby mode it would be necessary to wait for the heating elements of the set to warm up when the set was turned on. 
Therefore, it is desirable and useful to use the standby mode in electronic devices such as radio sets, television sets, stereo sets, and other similar types of electronic devices.  The amount of energy that is consumed when an electronic device is in standby mode is small in comparison to the amount of power that the electronic device uses when the set is turned on.  However, because the use of standby mode in electronic devices is so widespread and because the use of standby mode does consume electric power, the power that is consumed by standby mode in the aggregate is quite large.  To realize the magnitude of the aggregate power consumption due to use of the standby mode, one may multiply the small amount of power consumed in one television set that is operating in standby mode by the millions of television sets that exist in the world today. 
Certain improvements in electronic design within the last few years have reduced the amount of power consumption that is due to the operation of standby mode circuitry.  Because the aggregate amount of standby mode power consumption is still quite large, however, there still remains a need to find additional ways to further reduce the level of standby mode power consumption in electronic devices. 
To address this problem, it is a primary object of the present invention to provide an apparatus and method for reducing the level of power consumption in an electronic device that is operating in standby mode. 
It is a further object of the present invention to provide a means for reducing the amount of power consumption in an electronic device that is operating in standby mode by at least fifty percent. 
The apparatus and method of the present invention will be described as an apparatus and method for reducing the level of power consumption in a television set that is operating in a standby power mode.  It is important to realize that the apparatus and method of the present invention is not limited to only a television set.  Those skilled in the art will readily understand that the principles of the present invention may also be successfully applied to other types of electronic devices.  However, in the descriptions that follow, a television set is employed for illustration purposes
In the preferred embodiment of the invention, the invention comprises a standby cycle timer circuit coupled within a television power supply circuit capable of operating in a standby mode.  The standby cycle timer causes the power supply circuit to alternate between its standard standby mode and a shutdown power mode.  In a shutdown power mode, all power from the power supply circuit to other circuit elements is turned off.  After a predetermined period of time has elapsed, the shutdown power mode is terminated and the standby power mode is resumed.  After another predetermined period of time has elapsed, the standby power mode is terminated and the shutdown power mode is resumed.  The alternation of the standby power mode and the shutdown power mode continues until the television receives an xe2x80x9conxe2x80x9d signal to power up the television for normal operation. 
If the time that the shutdown power mode is in operation is equal to the time that the standby power mode is in operation, then the power consumption of the combination is half of the power consumption required to otherwise operate in only the standby power mode.  If the time that the shutdown power mode is in operation is greater than the time that the standby power mode is in operation, then the power consumption of the combination will be less than half of the power consumption required to otherwise operate in only the standby power mode.  Therefore, the invention provides a significant reduction in the amount of power needed to operate a television in a standby power mode. 
In a typical television power supply circuit, a pulse width modulator circuit controls the operation of the power supply circuit by alternately turning the power on and off in the primary side of a flyback transformer circuit.  The pulse width modulator circuit puts the power supply circuit into standby mode turning off the power for longer periods of time. 
The standby cycle timer of the present invention is coupled to the pulse width modulator circuit.  The standby cycle timer alternately sends xe2x80x9conxe2x80x9d and xe2x80x9coffxe2x80x9d signals to said pulse width modulator circuit.  When the standby cycle timer sends an xe2x80x9conxe2x80x9d signal, the pulse width modulator circuit causes the power supply circuit to operate in a standby mode.  When the standby cycle timer sends an xe2x80x9coffxe2x80x9d signal, the pulse width modulator circuit causes the power supply circuit to operate in a shutdown mode.  The standby cycle timer causes the xe2x80x9conxe2x80x9d and xe2x80x9coffxe2x80x9d signals to be sent to the pulse width modulator circuit at specific time intervals.  The time intervals are predetermined by the choice of particular values for certain circuit elements in the standby cycle timer. 
The standby cycle timer automatically alternates between sending the required xe2x80x9conxe2x80x9d and xe2x80x9coffxe2x80x9d signals to the pulse width modulator circuit.  The alternate xe2x80x9conxe2x80x9d and xe2x80x9coffxe2x80x9d signals control the pulse width modulator so that it causes the power supply circuit to automatically alternate between the standby mode and the shutdown mode.  When the television receives an external signal to resume normal operation, the standby cycle timer automatically ceases sending the alternate xe2x80x9conxe2x80x9d and xe2x80x9coffxe2x80x9d signals, and sends only an xe2x80x9conxe2x80x9d signal to the pulse width modulator circuit so that the power supply circuit can provide continuous operating power to the television. 
When the television receives an external signal to cease normal operation, the standby cycle timer automatically resumes sending the alternate xe2x80x9conxe2x80x9d and xe2x80x9coffxe2x80x9d signals to the pulse width modulator circuit to resume alternating between the standby mode and the shutdown mode. 
The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the Detailed Description of the invention that follows.  Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention.  Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention.  Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form. 
Before undertaking the Detailed Description, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms xe2x80x9cincludexe2x80x9d and xe2x80x9ccomprisexe2x80x9d and derivatives thereof, mean inclusion without limitation; the term xe2x80x9cor,xe2x80x9d is inclusive, meaning and/or; the phrases xe2x80x9cassociated withxe2x80x9d and xe2x80x9cassociated therewith,xe2x80x9d as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term xe2x80x9ccontroller,xe2x80x9d xe2x80x9cprocessor,xe2x80x9d or xe2x80x9capparatusxe2x80x9d means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same.  It should be noted that the functionality, associated with any particular controller may be centralized or distributed, whether locally or remotely.  Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.