Capacitive toner level detection

An electrophotographic printing engine having stations for charging a photoconductor, selectively discharging portions of the charged photoconductor to form a latent electrostatic image, developing the latent image with solid electrophotographic toner particles, transferring the developed image to a copy sheet and fixing the developed image on the copy sheet, wherein the printing engine further comprises a toner level sensor, comprising:

• at least one waste container having an electrically conductive container body, said container body defining a container cavity for holding solid electrophotographic toner particles;
• and
• a sensor assembly disposed within said container, said sensor assembly being electrically isolated from said body, said sensor assembly configured for sensing a level of said solid electrophotographic toner particles within said container cavity, said sensor assembly comprising a capacitive sensor and having a first electrode plate and a second electrode plate spaced apart from said first electrode plate to present opposing surfaces to each other, said fist electrode plate configured for being electrically connected to a virtual ground and said second electrode plate configured for being connected to a voltage signal source, said opposing surfaces of the two plates coated with a non-stick coating to inhibit solid toner material particles between the plates from adhering to surfaces of the plates wherein the plates form a capacitor having a capacitance dependent upon the level of the solid toner particles between the two plates.