An electrophotographic color image forming apparatus including a multiple
number of photoreceptors for multiple development colors including black,
is constructed such that the photoreceptors satisfy the following
relation:
0.5<(X/Y)<0.8,
where X represents the reduction in film thickness (.ANG.) per
1.times.10.sup.7 mm of the traveling distance of the photoreceptor for
black development and Y represents the reduction in film thickness (.ANG.)
per 1.times.10.sup.7 mm of the traveling distance of the photoreceptors
for the other development colors. This limitation is aimed at
differentiating the abrasion resistance of the photoreceptors between that
for black and that for colors and designating the reduced amounts of the
film thickness per unit traveling distance to fall within the
predetermined ranges, whereby it is possible to prevent the drum for black
development, which is used most frequently, alone, from being worn away at
an earlier time. Accordingly, both the drums for black and for colors can
be replaced at approximately the same time, to the maintenance cost can be
reduced.
Une image électrophotographique de couleur formant l'appareil comprenant un nombre multiple de photorécepteurs pour des couleurs multiples de développement comprenant le noir, est construite tels que les photorécepteurs satisfont la relation suivante : 0.5
