Over the years, many attempts have been made to reduce the power consumption of battery powered electronic devices, thereby yielding longer battery operation. For obvious reasons, many of these attempts have focused on reducing the amount of power consumed by such devices while the device is on, but not in use. Hence, a reduction in power consumption has been achieved by slowing or stopping certain components of the device after the device or devices have been inactive for a predetermined period of time, which may or may not be set by the user. Clearly, therefore, it is critical to maintaining proper device performance accurately to determine when to slow or power down the device without disrupting the user's work, until further operation is needed.
For example, in the field of portable personal computers, when a computer's disk drive has not been accessed for a predetermined amount of time, for example, two minutes, the drive is powered down or caused to operate in a reduced power consumption mode, often referred to as "standby mode," such that the drive consumes less power, thereby reducing the overall power consumption of the computer. Thereafter, when a drive access is attempted, full power is reapplied to the drive and the drive spins up and is ready to be accessed.
Another example of a device capable of operation in a reduced power consumption mode is a device known as a radio mouse. Typically, after expiration of a predetermined amount of time in which the mouse has not been used, a microcontroller included in the mouse causes the mouse to operate in a reduced power consumption mode. This may be accomplished, for example, by writing the contents of a volatile memory device within the microcontroller, which is accessed by the microcontroller during operation of the mouse, to a nonvolatile memory device, which is slower than the microcontroller's volatile memory device. Power is then removed from the volatile memory device and is removed from or reduced to other components of the mouse. When the user is again ready to use the mouse, the user must move the mouse or click a mouse button provided thereon, at which point a signal is sent to wake up the mouse.
Although the above-described methods accomplish their primary goal, that is, to reduce in the amount of power consumed by the device, they suffer certain deficiencies, the most obvious of which is the time delay experienced by the user in waiting for the device to return to full power mode so that it can be used for its intended purpose. Referring to the disk drive example, the user must wait for power to be reapplied to the drive and the drive to spin up before access can be made thereto. With regard to the radio mouse, because the wake up signal is not sent until the user actually attempts to use the mouse to input data, the user may experience a delay of up to several seconds in inputting the data while the necessary operations for awakening the mouse are performed.
Hence, although it is possible for a user to wait for a device to return to full power state when he or she is again ready to use the device, it is not particularly desirable to require him or her to do so. On the other hand, there are inherent limits on the speed with which a device can be transitioned from a reduced power consumption to a full power mode.
Therefore, what is needed is a means for causing a device operating in a reduced power consumption mode to return to a full power mode immediately before the user is ready to use the device, such that the device has already returned to the full power mode by the time the user attempts to operate the device.