A method of building threshold matrices for stochastic screening by using the actual size and shape of imaged pixel andor pixel agglomerate instead of the nominal one, in the stage of calculating appropriate threshold matrices. The method has the steps of acquiring a biological signal that emulates the arterial pulse wave from a sensor. The anode active material layer is formed by using a dispersion medium having a swelling degree of 10% or less to the binder, specifically pure water or the like.