Electrical computers and digital processing systems: support – Computer power control
Reexamination Certificate
2000-10-30
2004-05-11
Butler, Dennis M. (Department: 2116)
Electrical computers and digital processing systems: support
Computer power control
C713S300000, C713S320000
Reexamination Certificate
active
06735705
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates generally to power switching devices for controlling electrical and/or electronic appliances, accessories and equipment. More particularly, our invention relates to power switching systems that monitor step changes in the current drawn by at least one of a plurality of devices connected to the system, and, in response, cause other devices connected to the system to be switched on or off. Representative prior art is seen in U.S. Patent class 713, Subclasses 300-324.
II. Description of the Prior Art
Current sensing devices are known in the art for controlling the power supplied by one or more secondary electrical outlets, in response to current changes sensed at a primary outlet that supplies power to a controlling device. For example, power strips are commonly employed for powering electronic appliances, including computer systems, high fidelity and stereo equipment, home theatre installations and the like. Typical power strips are equipped with multiple electrical outlets, and they are designed to be plugged directly into a U.S. standard 120 volt or foreign 240 volt wall outlet that provide power. They are equipped with a plurality of separate, electrical power outlets that provide power to numerous individual electronic components.
In high quality power strips, the output voltage may be conditioned and smoothed by the circuitry. Power spikes and voltage transients and the like are removed by appropriate circuits, including filter networks and the like. Higher quality power strips condition the A/C power distributed to computers and peripherals through their various outlets, and they may electronically shape the output power waveform. Most power strips provide some protection from power surges and transients. A pilot light, usually amber or red in color, provides a visual indication when the strip is properly plugged into an acceptable A/C outlet. A master power switch and one or more switches for controlling individual outlets may be included. High quality power strips that protect equipment from power spikes and voltage transients are ideal for use with computer systems.
Most modern computer installations usually include one or more power strips to provide power to the various components. For example, the main computer unit (i.e., comprising the motherboard and ancillary boards within a suitable cabinet), a printer, and the video monitor are often supplied by a single power strip. Other computer peripherals, such as scanners, external modems, occasionally tape backup units, and the like are also plugged into the master power strip. Where numerous outlets are needed, one or more secondary power strips may be plugged into the master power strip, in master-slave relation.
Relatively recently, small computer systems have adopted several facets of so-called “green” technology. Newer PC's (i.e., “personal computer”) systems, for example, can be instructed to enter a “power conservation mode” that “powers down” hard drives and the like after predetermined time intervals. PC systems of this type typically implement green technology through the operating system or BIOS software. Often the “green settings” offered by the system BIOS are selectable by the user simply by addressing the CMOS memory options prior to system booting. Green PC's can power up directly by using the ATX “power” switch, and they typically power down through software. When the various hard drives in large network file servers, for example, are powered down after periods of monitored inactivity, wear can be reduced, and potentially damaging heat can be reduced. Many modern video monitors include green adaptations that extend their useful lives and conserve power by powering down their cathode ray tubes and deflection circuitry after predetermined periods of inactivity. This powering down process is also an important power conservation and environmental consideration when multiplied by millions of PC's. It is also mandated by recent EPA regulations.
However, when a newer computer invokes the “green” power saving mode, many peripherals connected to the power strip are left running. Despite the fact that the system may shut down, the hard drive(s) and/or video, and other peripherals may be left “on,” thereby generating heat and wasting power. This can occur even in the standby mode. In complex, multi-component computer systems involving expensive audio systems with sub woofers, large tape backups and other accessory items, fifty to one hundred watts of power can be wasted. It would be advantageous if the CPU would also deactivate computer peripherals when the green power cycle is triggered. Further, it would be even more desirable if green computers would thereafter turn on peripherals when CPU activity commences, without requiring the user to tediously manually switch each device on.
There are other disadvantages with power strips. Before using the main on-off switch on a typical power strip, a prudent user must first power down the computer by instructing the operating system to “shut down.” Even after the somewhat time consuming shutdown routine is completed, the peripherals remain “on,” consuming power. Conventional power strips must be manually switched to disable peripherals. But the power strips are often placed on the floor beneath the user's desk, well away from convenient reach. The main switch is often obscured, if not completely hidden, by a randomly entangled mass of jumbled power cords leading all over the room. What inevitably happens is that the (industrial, business or military) user simply cannot be bothered, and the peripherals are left on.
Conventional power strips are awkward to place properly when used with complex home stereo systems, or with home theater applications. A modern home theater system may comprise a large screen television, a stereo receiver, a VCR, a cable decoder and/or a satellite receiver, a DVD system, a high power audio amplifier unit, one or more cassette or CD players, and several speaker systems, including at least one high powered sub-woofer. When power strips are used for centralized switching, numerous power cords are exposed, and the sight may not be aesthetically pleasing. Further, audio-visual components cannot conveniently be powered up or powered down in unison. Smaller power strips are inadequate because they have too few outlets.
U.S. Pat. No. 4,675,537, issued Jun. 23, 1987, discloses a power strip comprising a primary outlet and a plurality of separate, slave outlets for computer peripherals. The slave outlets can be controlled by condition-responsive sensing. The circuit derives a sensing signal in response to current through one of the outlets. The sensing signal triggers cascaded op-amps that ultimately fire an SCR to energize a downstream relay that controls one or more desired peripherals.
U.S. Pat. No. 5,465,366 derives a power-switching signal by monitoring the video data lines connected to a computer monitor, instead of monitoring input power lines of a device. It can thus control several peripheral devices.
U.S. Pat. No. 5,594,672 shows a software-intensive means of controlling peripherals by monitoring the digital data path between them and the host computer connection.
U.S. Pat. No. 5,821,924 shows a system that derives information from the video data bus to generate peripheral power control signals.
U.S. Pat. No. 5,483,464 illustrates a system using a digital control signal derived from a “green” computer controlling peripherals.
Bus connections are also monitored in the power saving, peripheral control devices of U.S. Pat. Nos. 5,603,040, 5,477,476 and 5,359,540.
Some prior art power switching systems monitor the incoming A/C current drawn by a monitored device by observing the voltage drop across one or more current-sensing resistors. Such resistors are disposed in series with the incoming power connection, so all of the sampled A/C current that powers the sampled device passes through them. Since the power dissipated by such resistors increase
Egbert Thomas E.
Johnson Cyril L.
Lyon Robert B.
Stein Mark
Butler Dennis M.
Carver Stephen D.
Patel Nitin C
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