Patent EP-1248157-A2 (EP)
Inventor: NAKASHIMA YOSHIHIRO
IPC: G03G13/08
Filed: 2002-04-03
Abstract: The object is to prevent the occurrence of the selective
consumption development. 
     The first aspect of the invention is a toner being characterized in
that the medium-resistance external additive coating ratio of toner particles
of which mother particles have equivalent particle diameters smaller than
an equivalent particle diameter of a mother particle diameter equal to the
mean particle diameter of the toner is set to be higher than a virtual
reference curve in synchronous distribution of the equivalent particle
diameters of synchronous medium-resistance external additive particles
relative to the equivalent particle diameters of mother particles, wherein
assuming that the medium-resistance external additive coating ratio of a
toner particle of which a mother particle has an equivalent particle
diameter equal to the roughness of a developing roller or the mean particle
diameter of the toner is a reference value, the virtual reference curve is
obtained to satisfy that the medium-resistance external additive coating
ratio is constant at the reference value. 
     The second aspect of the invention is a toner being characterized in
that the medium-resistance external additive coating ratios of toner
particles in a range in which mother particles have equivalent particle
diameters smaller than d1 and in a range in which mother particles have
equivalent particle diameters larger than d2 are set to be higher than a
virtual reference curve in synchronous distribution of the equivalent
particle diameters of synchronous medium-resistance external additive
particles relative to the equivalent particle diameters of mother particles,
wherein assuming that the medium-resistance external additive coating 
ratio of a toner particle with a diameter between d1 and d2 is a reference
value wherein d1 is an equivalent particle diameter of a mother particle
equal to the roughness of the developing roller and d2 is an equivalent
particle diameter of a mother particle diameter equal to the mean particle
diameter of the toner (d1<d2), the virtual reference curve is obtained to
satisfy that the medium-resistance external additive coating ratio is
constant at the reference value. 
     The third aspect of the invention is a toner being characterized in
that the medium-resistance external additive coating ratio of toner particles
in a range in which mother particles have equivalent particle diameters
larger than the roughness of the developing roller or than an equivalent
particle diameter of a mother particle diameter equal to the mean particle
diameter of the toner is set to be higher than a virtual reference curve in
synchronous distribution of the equivalent particle diameters of
synchronous medium-resistance external additive particles relative to the
equivalent particle diameters of mother particles, wherein assuming that
the medium-resistance external additive coating ratio of a toner particle of
which a mother particle has an equivalent particle diameter equal to the
roughness of a developing roller or the mean particle diameter of the toner
is a reference value, the virtual reference curve is obtained to satisfy that
the medium-resistance external additive coating ratio is constant at the
reference value. 
     The fourth aspect of the invention is an image forming apparatus
comprising a photoreceptor on which an electrostatic latent image is
formed, a developing unit for developing the electrostatic latent image on
the photoreceptor with a toner, a transfer means for transferring the 
developed image on the photoreceptor, and a fusing means for fusing the
transferred image, the image forming apparatus being characterized in that
said toner is a toner of any one of the aforementioned aspects.