1. Field of Invention
This invention pertains to a wireless monitoring system with a self-powered transmitter. More particularly, this invention pertains to a self-powered pulse transmitter monitoring a parameter and wirelessly transmitting information relating to that variable to a receiver, where the information is converted to information displayed to the operator, such as through a heads-up display for a vehicle.
2. Description of the Related Art
In the field of automobiles, it is well known that a driver must not only pay attention to the driving environment, but also upon the operating conditions of the vehicle itself. With respect to the driving environment, the driver must be aware at all times of the condition and direction of the roadway on which the driver is traveling, including weather conditions, traffic, and physical condition of the surface. With respect to operating conditions of the vehicle, it is important to monitor the speed of the vehicle and various vehicle parameters, such as the fuel level, oil pressure, and engine temperature.
However, there are certain external conditions in which it is difficult and dangerous to maintain eye contact with the driving environment and still monitor the operating conditions of the vehicle. Accordingly, devices are known for accomplishing both by projecting various vehicle parameters onto the windshield of the vehicle.
For example, U.S. Pat. No. 3,887,273, issued to Griffiths on Jun. 3, 1975, and titled “Speedometer optical projection system,” discloses a system for projecting a speedometer or other instrument reading as a virtual image into the field of view of the vehicle operator. Griffiths discloses an optical projection system that corrects for aberrations from using the vehicle windshield as a projection screen for displaying the vehicle parameters.
U.S. Pat. No. 4,988,976 issued to Lu on Jan. 29, 1991, titled “Head-up display with magnetic field speed detecting means,” discloses a heads-up display system for a vehicle. Lu also discloses an electromagnetic inducer disposed on a tire for calculating the speed of the vehicle regardless of the tire size.