APPARATUS FOR MEASURING LENGTH AND SPEED OF CONVEYED MATERIAL

PURPOSE:To measure the length of a conveyed material in high accuracy by casting laser light on the conveyed material, obtaining the reflected light including the frequency component which is proportional to the speed, performing counting after frequency dividing, and counting the output of the previous frequency dividing when the output of the frequency dividing at this time is not obtained. CONSTITUTION:Laser light is emitted from a laser unit 50 on a conveyed material. The reflected light is received with a detector 51. Then, the output signal including the frequency component which is proportional to the speed of the conveyed material is obtained. The output signal is inputted into a frequency dividing F/V circuit 56 through a gate circuit 55. After the frequency is divided in the circuit, the signal is inputted into a counter circuit 58 through a pulse processing circuit 57. The signals are counted in the counter 58, and the length of the conveyed material is obtained. The pulse processing circuit 57 outputs the frequency measured before when the output of the frequency dividing is not obtained under the state where the gate circuit is opened. Thus, the measurement can be performed highly accurately even if abnormality occurs on the surface.