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FlowCam – Printer Toner Quality Assurance Application Note

Printer Toner Quality Assurance with the FlowCam Particle Analyser

The shape and size of printer toner particles affect image resolution and printer efficiency. The uniformity of a printer toner particle affects the distribution of charge the particle holds and as a result can affect image quality.

Image characterisation can be used to determine shape, size, circularity and material uniformity of printer toner particles during and after production (Fig. 1).

In this application note, we demonstrate that the FlowCam®, a flow imaging microscope, and paired image analysis software VisualSpreadsheet® can be used for rapid quality control characterisation of printer toner.

Sample Preparation

Toner was added to deionized water to form an aqueous slurry. The slurry was analyzed on the FlowCam and images of each toner particle were captured by VisualSpreadsheet, the FlowCam’s imaging analysis software. Of the 40+ physical particle properties measured by VisualSpreadsheet for each particle, Circularity and Equivalent Spherical Diameter (ESD) were used to evaluate the uniformity and quality of the toner particles.

The Analysis

The slurry was introduced into the FlowCam, where it was pulled down through the flow cell and every individual printer toner particle was imaged. VisualSpreadsheet assembled a collage file of all particle images from the sample run and measured all particle properties from these images (Fig. 1).

Each particle image is associated with an ID number and correlated particle property values. Every particle property is measured to 4 decimal places, and all property values 40+ measured particle property values can be exported from VisualSpreadsheet into CSV format for easy data manipulation and study (Fig. 2 & Table 1).

A filter was built in VisualSpreadsheet to differentiate printer toner images that met the specified quality parameters from those that did not. This filter was built with an allowed ESD of 4 µm to 8 µm, and an allowed circularity of 0.80 to 1.00, where 1.00 is a perfect circle/ sphere. VisualSpreadsheet calculates the percentage of images that meet the specified parameters.

VisualSpreadsheet produces a Summary Statistics table that displays selected particle property statistics in real-time to reflect the analysis. This enables quick evaluation of particle property statistics for each analysis (Table 2).

Printer Toner

Figure 1. Black printer toner particles imaged by the FlowCam. Particles are shown in order of decreasing circularity, where 1 is a perfect circle. Circularity value is shown beneath each image.

Summary

In this study, we demonstrate that the FlowCam particle analyser coupled with VisualSpreadsheet software allows the user to analyse printer toner particle quality using image characterisation and measured particle properties. A QA/QC filter can be implemented to assess the overall quality of each sample analysed.

Image characterisation is essential to determine measures of circularity (uniformity), the primary property for quality control analysis in printer toner manufacturing. Diagnostic assessment of size classes and extraction of conformational images allows the end user to rapidly identify outliers in the sample during and after the manufacturing process. The combination of particle size and shape monitoring provided by the FlowCam improves the process of quality control required among printer toner manufacturers.

The FlowCam is well suited for a wide variety of applications which require rapid, quantitative results. The intuitive design of this instrument allows an operator to carry out on-site testing of a product with conformational data, reporting and statistics. The FlowCam particle analyser offers a rapid method of sample preparation coupled with image recognition capabilities of VisualSpreadsheet software.