In a laser printer which can print a two-color image during a single rotation of a photoreceptor, undesirable color mixing occurs. This is due to the fact that the first color toner is mixed into the second developer by the second magnetic brush development method. To restrain the color mixing, separation technique of the mixed black toner from the second developer was proposed previously by reversing charge polarity of the mixed black toner. This paper describes the practical effect of the technique in continuous printing test.
The mixing black toner amount into the color developer is reduced by optimizing development conditions and a separation electrode roller biased to positive potential is installed in the second developer apparatus to eliminate the mixed toner. As a result, amount of black toner mixed into the second color image was saturated to a limited value, and distinct two-color image could be maintained at the end of 100 thousands continuous printing.

View full abstract

The cone-like structure causing image defects in amorphous silicon photoreceptor is analyzed by the Raman scattering, infrared absorption, SIMS and electron spin resonance. The almost of all cone-like structures grow up around the substrate and these are amorphous states. The SiHz and (SiH₂)_n are contained in the cones and the total hydrogen content is about 20 % and the ESR spin density is about 40 % larger than those in the plane surface. The principal features of cone-like structure can be characterized by the existence of large amount of dihydride bonding.

View full abstract

Charging curves of dual component developers were described by the functional form,
(q_m-q)/(q_m-q₀)=exp(- t/τ),
where q is the developer charge at mixing time t, q_m, is the asymptotic (or maximum) charge, q₀ is the value of q at t=0, and τ is the time constant which inversely corresponds to the developer charging rate. By using the formula, the effects of the following factors on q_m and τ were observed:
(a) Carbon black content of toner,
(b) Colloidal silica mixed with toner,
(c) Toner impaction,
(d) Carrier contamination with free carbon black,
(e) Temperature and humidity.

View full abstract

The contact condition at substrate/CGL (charge generation Layer) was analyzed using different work function metals and two kinds of pigments (lead phthalocyanine/PbPc and fluorenonebisazo pigment/ Azo). From D. C. transient current and low frequency capacitance measurements, the contacts of PbPc/low-work-function metals and PbPc/high-work-function metals are Schottky and Ohmic, respectively. Azo CGL exhibits the insulating behavior because of low carrier concentration. These contact conditions were well reflected in the xerographic characteristics of photoreceptors.

View full abstract