SPEED MEASURING APPARATUS

PURPOSE:To measure speed at a high accuracy with a higher spectrum characteristic of a special frequency, by performing a spatial processing of a received light signal of an image sensor for taking a surface pattern of an object to be measured with AC amplification. CONSTITUTION:A signal of light received by a CCD line sensor 1 is amplified by an amplifier 2 and subjected to AC amplification and a binary code processing in a signal processing circuit section 3, an output of which is inputted into a frequency measuring device 12 through an A/D conversion circuit 4, adders 5 and 6, a subtractor 7, an amplifier 8, a D/A converter 9, an integrator 10 and an LPF 11. The frequency measuring device 12 and a microcomputer 13 calculate the cycle of the frequency of a signal cleared of noise with an CPF 11 to determine a speed and a moving distance is obtained by time integration.