A new type of image storable organic photoreceptor has been designed combining the switching phenomena in Cu · TCNQ (7, 7, 8, 8-tetracyanoquinodimethane) charge transfer complexes with a photoconductor in electrophotography. The double layered photoreceptor designed consists of an organic photoconductor over-layer of PVK (poly-N-vinylcarbazole)-TeNF (2, 4, 5, 7-tetranitrofluorenone) and a switching under-layer involving Cu · TCNQ microcrystalline particles dispersed in polymer binder. The write-in due to the usual xerographic method induces the switching phenomena in a thin switching layer from highly resistive off-state to low resistive on-state corresponding to the exposure image. For the subsequent read-out by corona charge, charge carriers injected from the bottom electrode through the highy conductive switching layer in on-state eliminate the surface corona charge to form the latent image on the surface of the photoreceptor. The present photoreceptor provides a possibility of the practical application to an electrostatic duplication master.

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Characteristics of magnetic brush reversal development by using high electrical resistive carrier beads were investigated. Conditions for getting sufficient print density were analyzed, in particular electrical and mechanical forces acting on toner and supplying ability of toner were considered. Theoretical results were confirmed by experiments at 1m/sprinting speed.
Results of these analyses were as follows :
(1) Toner to develop latent image was provided from the uppermost carrier layer.
(2) Image force of toner charge on carrier beads and mechanical force by magnetic brush should be included in developing forces acting on toner.
(3) Optical print density D was ensured to be greater than 1. 0 by using two developing rolls with magnetic-to-recording medium speed ratio, v_d/v_p , to be 0.5.

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Novel τ-form metal-free phthalocyanine (τ-H₂Pc) was developed by the crystal transformation of α-form H₂Pc and a double layered photoreceptor, the charge generation layer of which was the τ-H₂Pc, was manufactured and tested. The system composed of the τ-H₂Pc and an oxazole derivative as the charge transport layer showed a high sensitivity at about 800 nm and the half decay exposure (600 → 300 V) achieved under 5 mJ/m². The photoreceptor showed a good stability also in repetitive printing tests and the life was proven over 100, 000 prints. From the results of surface potential decay experiments, the carrier generation efficiency of the photoreceptor appeared to be a linear dependence of the applied electric field.

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The purpose of this investigation is to design and develop an instrumental system which is capable of measuring electrical charge and/or potential distrbution on an insulating surface by displaying it graphically in the form of soft and hard copies.
Test sample is a metal plate coated with silicone resin which is corona-charged before measurement. The plate is set on a turning table whose rotating rate is programmable under P. L. L. control. A detection probe head coupled to a charge sensitive amplifier located about 1 mm above the sample. The sample is scanned on the rotated table and the probe is moved forward the center at the same time. The signal from the charge amplifier is stored to microcomputer PC-8801. The memorized data give a map of charge distribution on a CRT display or in the form of photographic print.

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