| CPC G03G 5/047 (2013.01) [G03G 5/0696 (2013.01); G03G 5/144 (2013.01); G03G 15/75 (2013.01)] | 8 Claims |
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1. An electrophotographic apparatus, comprising:
an electrophotographic photosensitive member configured to bear a toner image for forming an image on a recording material and comprising a charge generation layer;
the charge generating layer comprising a charge generating substance comprising a titanyl phthalocyanine pigment or a hydroxygallium phthalocyanine pigment;
a charging unit configured to charge the electrophotographic photosensitive member; and
an exposure unit configured to expose a surface of the charged electrophotographic photosensitive member;
the exposure unit comprising a light emitting diode array including a plurality of light emitting diode elements, wherein
when a graph with a horizontal axis representing Iexp and a vertical axis representing Vexp obtained by repeating (1) to (4)
(1) setting a surface potential of the electrophotographic photosensitive member at 0 V,
(2) charging the electrophotographic photosensitive member for 0.005 second so that an absolute value of the surface potential of the electrophotographic photosensitive member becomes 500 V,
(3) exposing the charged electrophotographic photosensitive member to light having a wavelength of 805 nm and a light quantity of Iexp [μJ/cm2] 0.02 second after a start of the charging, and
(4) determining the absolute value of the surface potential of the electrophotographic photosensitive member measured 0.06 second after the start of the charging as Vexp [V]
at a temperature of 23.5° C. and a relative humidity of 50% RH while varying Iexp from 0.000 to 1.000 μJ/cm2 at intervals of 0.001 μJ/cm2 is normalized as a normalized graph with a horizontal axis x and a vertical axis y such that, with a light quantity at Vexp=250 V in the graph being I1/2 [μJ/cm2], a horizontal axis coordinate x corresponding to Iexp=10·I1/2 [μJ/cm2] is x=1, and a horizontal axis coordinate x corresponding to Iexp=0 [μJ/cm2] is x=0, and a vertical axis coordinate y corresponding to Vexp=500 V is y=1 and a vertical axis coordinate y corresponding to Vexp [V] at Iexp=10·I1/2 [μJ/cm2] is y=0,
in the normalized graph, a minimum value of a normalized radius of curvature R calculated from the following Equation (E1) is 0.24 or less,
 and
given that Iexp corresponding to x at which the normalized radius of
curvature R is the minimum value is E min [μJ/cm2], the light emitting diode array is configured to expose the charged electrophotographic photosensitive member to a quantity of light whose average light quantity satisfies 0.8×E min or more and 1.1×E min or less,
the titanyl phthalocyanine pigment has crystal grains with a crystal form showing peaks at Bragg angles 2θ of 9.8°±0.3° and 27.1°±0.3° in an X-ray diffraction spectrum using CuKα radiation, and has a peak in a range of 50 to 150 nm in a crystal grain size distribution measured using small-angle X-ray scattering, and a half width of the peak is 100 nm or less, and
the hydroxygallium phthalocyanine pigment has crystal grains with a crystal form showing peaks at Bragg angles 2θ of 7.4°±0.3° and 28.2°±0.3° in an X-ray diffraction spectrum using CuKα radiation, and has a peak in a range of 30 to 50 nm in a crystal grain size distribution measured using small-angle X-ray scattering and a half width of the peak is 50 nm or less.
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