440-443Yarn hairiness is determined using projection of hairs perpendicular to the yarn axis. Measurement is done using photo cell which receives light from a small area above the yarn surface. The hairs that project beyond the specific adjusted distance – which is generally 3 mm – intercept the beam of light that falls on the photo cell, causing photo cell to generate a signal. Using this signal, number of hairs in a given length of yarn can be determined. However, the measurement does not cover full circumference of the yarn. A theory is developed in the present work to overcome this problem
