Electrophotography, which is a method for visualizing image information by forming an electrostatic latent image, is currently employed in various fields. The term “electrostatographic” is generally used interchangeably with the term “electrophotographic.” In general, electrophotography comprises the formation of an electrostatic latent image on a photoreceptor, followed by development of the image with a developer containing a toner, and subsequent transfer of the image onto a transfer material such as paper or a sheet, and fixing the image on the transfer material by utilizing heat, a solvent, pressure and/or the like to obtain a permanent image.
The basic electrophotographic process, as taught by C. F. Carlson in U.S. Pat. No. 2,297,691, involves placing a uniform electrostatic charge on a photoconductive insulating layer, exposing the layer to a light and shadow image to dissipate the charge on the areas of the layer exposed to the light, and developing the resulting latent electrostatic image by depositing on the image a finely divided electroscopic material referred to in the art as “toner”. The toner will normally be attracted to those areas of the layer which retain a charge, thereby forming a toner image corresponding to the latent electrostatic image. This powder image may then be transferred to a support surface such as paper. The transferred image may subsequently be permanently affixed to the support surface as by heat. Instead of latent image formation by uniformly charging the photoconductive layer and then exposing the layer to a light and shadow image, one may form the latent image by directly charging the layer in image configuration. The powder image may be fixed to the photoconductive layer if elimination of the powder image transfer step is desired.
Generally, standard process controls systems may be used to monitor the application of toners. The system measures the scattered light from the primary colored toners developed in a solid area patch. However, the control parameters of these systems need to be changed when used to monitor the application of black toners. The switching of parameters is due to the fact that carbon black is typically used to create black toners. Whereas colored toners are known to scatter infrared light (940 nm), black toners made from carbon black absorb such light. Thus, the parameters of the process controls system must be changed during the electrophotographic process to accommodate the use of such black toners.
These additional steps to accommodate the use of the black toners increase the time of the electrophotographic process and add levels of complexity to the electrophotographic system's control system.
Therefore, there is a need for a black toner that exhibits similar light scattering qualities as primary colored toners and thus can be monitored by a process controls system using the same parameters as those used for primary colored toners. The use of such black toner will quicken the electrophotographic process and eliminate the additional steps presently taken by the control system.