Toner particle size measurement

Measuring Toner Particle Size Distributions Using Spatial Frequency Analysis... 

The correlation analyses of toner particle size and size distribution parameters and image quality characteristics of toner deposits as measured by the spectral dependence of contrast transfer function and noise show high coefficients of correlation Specifically the Wiener spectrum data appear to yield the weight geometric mean and standard deviation of the toner population in this study. Therefore the Wiener spectrum may be another analytical tool in characterizing particle populations. It must be pointed out that the analysis reported here is mainly empirical. Further work is needed to refine the models and to examine the limits of applicability of these tests. Factors such as particle clumping, non-uniform depositions and optical limitations are specific areas for examination. 

ASTM F751 -83 (1997), Measuring particle size of wide-size range dry toners, 450... 

The statistical fluctuation or noise level of a toner image is also by these postulates dependent on the particle size distribution. The function which relates the statistical fluctuations to spatial frequency is the Wiener spectrum, which is the Fourier transform of the optical density autocorrelation function. In terms of toner images, it is a measure of the dimensional extent over which the presence or absence of a particular toner particle will contribute to density. The density fluctuations can be measured as a function of position, normally with a slit aperture. This is schematically represented in Figure 6 where the left-hand sketch is related to large particles and the right-hand one to small particles. The density data can be used to calculate noise power or Wiener spectrum (8). Formally, the Wiener spectrum is ... 

Mazumder, M. K., E-SPART Analyzer Its Performance and Application to Powder and Particle Technology Processes, KONA, No. 11, 1993, pp. 105-118. Mazumder, M. K., R. E. Ware, T. Yokoyama, B. J. Rubin, and D. Kamp, Measurement of Particle Size and Electrostatic Charge Distributions on Toners Using E-SPART Analyzer, IEEE Trans. Ind. Appl., 27, 1991, pp. 611-619. McLean, K. J., Cohesion of Precipitated Dust Layer in Electrostatic Precipitators, J. Air Pol. Contrl. Assoc., 27, 11, Nov. 1977, pp. 1100-1103. Misev, T. A., Powder Coatings, Chemistry and Technology, Wiley, NY, 1991, p. 292. 

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