A device for monitoring a rotating shaft is provided. The device measures strain in the shaft and provides angular velocity and torque in the shaft. The device includes a sensor, sensor conditioning circuitry, a microprocessor, and a transmitter, all located on a rotating shaft. The device obtains power by harvesting mechanical energy of the rotating shaft itself. Coils are provided rotating with the shaft and permanent magnets are mounted adjacent the rotating shaft so electrical energy is induced in the coils as they rotate through the magnetic field of the permanent magnets. A battery or capacitor is connected to the coils for storing energy. A microprocessor is connected to the sensors, the storage device, and the transmitter for managing power consumption and for monitoring the amount of electrical energy stored in the storage device and for switchably connecting the storage device to the transmitter when the stored energy exceeds a threshold.
RELATED APPLICATIONS
This patent application is related to the following U.S. patent applications: Ser. No. 09/731,066, filed Dec. 6, 2000, incorporated herein by reference; Ser. No. 09/757,909, filed Jan. 10, 2001, incorporated herein by reference; Ser. No. 09/801,230, filed Mar. 7, 2001, incorporated herein by reference; Ser. No. 09/768,858, filed Jan. 24, 2001, incorporated herein by reference; Ser. No. 09/114,106, filed Jul. 11, 1998, incorporated herein by reference; Ser. No. 09/457,493, filed Dec. 8, 1999, incorporated herein by reference; Ser. No. 60/362,432, filed Mar. 7, 2002, incorporated herein by reference; Ser. No. 60/443,120, filed Jan. 28, 2003, incorporated herein by reference; Ser. No. 10/379,224, incorporated herein by reference; and Ser. No. 10/379,223, filed Mar. 5, 2003, incorporated herein by reference.
This application is a continuation-in-part of the Ser. No. 10/379,223 application.
An apparatus is provided, for reducing power consumption in a system operating in a power saving mode, comprising a controller, an oscillator circuit and a voltage regulator. The controller provides a first control signal and a second control signal. The oscillator circuit, connected to the controller, wherein the controller controls the oscillator circuit according to the second control signal. The voltage regulator providing electric power to the oscillator circuit, connected to the controller, wherein the controller controls the voltage regulator according to the first control signal.
An object of the present invention is to provide a power generating device which makes it possible to easily generate electric power in a rotating system, such as a wheel including a tire, without impairing the performance and reliability of the rotating system. In the case where the power generating device is mounted to a rotating body such as a tire, the direction of gravity applied to a weight is changed with the rotation of the rotating body to cause beams to be deflected, so that the positions of the deflected beams and the weight are fluctuated in synchronization with the period of the rotation to cause the position of a coil to be displaced. Thereby, the weight is vibrated in the vertical direction in synchronization with the period of the rotation of the rotating body to change the magnetic flux density crossing the coil. As a result, AC electromotive forces are generated in the coil to enable electric power to be generated.
