Electrostatic image magnetic developing process

DETAILED DESCRIPTION An object of the present invention is to provide a process for development producing developed images of high fidelity and stable image quality.
Another object of the present invention is to provide a process for development producing developed images of sufficient and uniform density and high resolution and free from fog.
A further object of the present invention is to provide a process for development which gives images of good quality and high density even at a high temperature and high humidity.
According to the present invention, there is provided a process for development which comprises: arranging an electrostatic image bearing member having electrostatic images on the surface and a developer carrying member at a predetermined space, an insulating magnetic developer containing 10-50% by weight of magnetic toner particles of 20-35 microns in size being carried on the developer carrying member in a thickness thinner than the predetermined space, and transferring the insulating magnetic developer to the electrostatic image bearing member in the presence of magnetic field.
Further in the above-mentioned process for development, distribution of particle size of the toner particles is preferably that toner particles of 20-35 microns in size are contained in an amount of 10-35% by weight, toner particles of not more than 5 microns are contained in an amount of not more than 1% by weight, preferably not more than 0.
5% by weight, toner particles of exceeding 35 microns in size are not more than 10% by weight, preferably not more than 6% by weight and the remaining is toner particles of 5-20 microns in size.
By selecting the above mentioned distribution of particle size of the toner, stable and good images can be produced regardless of change of humidity, and even when many sheets of copy are produced, distribution of size of toner particles is kept constant and a stable development can be effected.