1. The Field of the Invention
The present invention relates generally to power management devices within a powered system. More particularly still, the present invention relates to managing the power requirements of a system having a plurality of independently powered and operable devices integrated in a single system.
2. Prior Art
Power conservation in consumer appliances has come a long way from the early days of simply turning the appliance off. Simple timing devices were added to the appliance to turn it on at a select time and then turn it off at another select time in one attempt to conserve energy, while providing the consumer with some added flexibility. Another way of determining when it was appropriate to power an apparatus off was to monitor the level of activity for that appliance. When the level of inactivity for the appliance reached a certain level, the system would go into a sleep mode and power down entirely. Either the appliance had to be manually turned on again, or the sleep mode could be ended, but in any event the information of activity at the time of suspension would be lost and the system would start over.
Next, appliances became integrated so that the operation of the main unit would control the individual devices. This was helpful where commonality was desired. For example, audio components have become integrated such that the amplifier portion, the tuner portion, the tape playback portion, and the CD drive portion all share the same power source and can be selectively turned on and off by the user while the main system is still powered on. For example, the user may be listening to the tuner and have turned off the tape player and the CD player. These type of components, however, require that the user actively turn off the device rather than the device turning off automatically upon lack of use. Further, in these component systems, the subsystems typically do not function or operate should the main unit be powered down.
In another consumer appliance area, the computer industry, energy conservation is an important feature in many peripheral devices and main systems. For example, many monitors are now Energy Star compliant such that they turn off after a given period of inactivity. This conserves energy and if the device is a video monitor, it lessens the exposure of the user to the magnetic field generated. Likewise, many printers are now Energy Star compliant in that they power down after a preselected level of inactivity when no print operations have been requested. Even before Energy Star standards had been established and agreed upon, hard disk drives would power down after a certain level of inactivity as would floppy disk drives and CD drives. During all this inactivity, however, the main system would stay active and online at full power regardless of the status of the peripheral devices connected to the main system.
Laptop computers, typically with their great need to conserve energy because of limited battery life, have optimized the art of powering down specific components within the system. Again, screens have been powered down, as have hard disk drives, as have other peripheral devices that typically drain power with constant steady use. But these power management improvements are still lacking in that if the main system needs to be powered down, then the entire system is nonfunctional.
Accordingly, what is needed is an improved way of managing power to different components within a consumer appliance even if the main powered element is to be shut down due to inactivity.