Real-time speed display apparatus

Claim 1

A real-time display apparatus for displaying the speed of a vehicle having a transmission shaft, with lights of different colors, comprising: detection means for detecting the speed of the vehicle, said detection means including means, responsive to rotation of the transmission shaft of the vehicle, for outputting a speed signal in the form of a pulse signal having a pulse rate which varies as a function of the speed of revolution of the transmission shaft; control means coupled to said detection means for generating a display control signal in response to the speed signal, said control means including a clock generator for generating a clock signal, a timing gate having first and second inputs respectively electrically connected to said detection means and said clock generator, for converting the speed signal into a periodic signal having the same number of pulses as that of the speed signal during predetermined periods of time, the periods of time being controlled by the clock signal, a counter, electrically connected to said timing gate, for counting the number of pulses of the periodic signal during each of the predetermined periods of time, an encoder, connected to said counter, for encoding the count of said counter at the end of each predetermined period of time to obtain a sequence of code signals, and a decoder, connected to said encoder, for decoding the sequence of code signals to obtain the display control signal; and display means, coupled to said control means, for generating different colors of light in response to the display control signal.