Apochromatic “Process” lenses have been higher to utilized as the copying lens for the electrofax process of the “Photostat” type, being accompanied by such shortcomings that, in the case of non-sensitized white electrofax papers in combination with fluorescent chemical lamps as the illuminating light source for the original, the visual best focus differ appreciably from the best focus for the actinic ray—near ultraviolet ray with a maximum effect at about 370 mµ in wavelength—, and furthermore that, the slow speed of these lenses, F/9 or so at full aperture but are to be stopped down to ca. F/22 for better results, hinder the practicability of the electrofax copying Process.
A special apochromatic lens of F/5.6 relative aperture and of 180 mm focal length was designed and manufactured, whose chromatic aberration was so corrected that the image plane for λ 370 mµ coincide with that for visual d-line (λ 588 mµ), with the result that no altering of focus from the visual best focus be necessary, either in case of white electrofax papers combined with chemical lamps or dye-sensitized electrofax papers combined with tungsten lamps. Further, the designing principle of the lens was to attain satisfactory performance at unit magnification (natural size copying) and at full aperture, being same in the former respect with, but differen in the latter respect from, the designing principle of “Process” lenses.
The new lens is of the “Orthometar” type, but is perfectly symmetric with respect to the central diaphragm. It covers sharply, at unit magnification, the angular field of 530°, or the object of 368 mm diameter.

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Here is reported the results of facsimile with a electrophotographic paper (rose bengal sensitized zinc oxide paper). Block diagrams of this system and continuous recording equipment are shown in Fig. 1 and 2, The received samples are shown in Fig. 3 and 4 which were transmitted through the basic group (48 kc band) of 12 Mc coaxial cable line.

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In this report we announce the results obtained on the basic dyes, Pinacyanole, Trypaflavine and Malachite Green. These dyes showed lower sensitization than those giveln by acid dyes, Rose Bengale and Erythrosin.

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Some reports have been published on Xeroradiography, in which Xerography or Electrofax was not promising in the radiography because of its lower sensitivity than that of the usual photography.
We tried some experimental studies on the phosphor sensitization of the zinc oxide in order that we may apply the Electrofax for the radiography.
At a value of X-ray intensity (25 kV, 8 mA), the ratio of the photocurrent to the dark current of the zinc oxide only was given by 8.5. On the other side, the phosphor sensitization improved this ratio as follows:

Photoconductor	Phosphors	Photocurrent/dark current
ZnO	………	8.5
ZnO+Rose Bengale	ZnS (Cu, Al)	380
ZnO	BaSO4(Pb)	2400

The sensitive plates used in the experiments were made as sandwich type which a thin sheet of phosphors was inserted between a photoconductor layer and a base material. X-ray is irradiated onto the surface of the photoconductor and excites the phosphor thrgugh the photoconductor layer.
The radiation produced from the phosphor also sensitizes the photoconductor.

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It is known that zinc oxide undergoes a memory mechanism when irradiated by light. We have observed this effect of zinc oxide powder dispersed in a dielectric resin which is used as a photosensitive material in the electrophotographic process.
After corona charging, the surface potential were measured on the specimens having different irradiation histories. Lowering of the initial potential and increase of its dark decay velocity were observed in comparison with the dark adapted specimens. The results obtained were as follows.
The degree of the drop of initial potent.ial by irradiation mainly depends on the light intensity rather than the quantity. When the light intensity is weak enough, the drop can not be observed, though the surface potential afier charging drops under the similar irradiation.
The initial potential increases with the resin to zinc oxide volume ratio of dispersed layer, but the percentage of the drop (V/V_d, where V is potential, V_d in the itial potential of dark adapted specimens) is not so much different in all ratro of resrn to zmc oxlde wrthm our expenmental regron (35-70 volume per cent of resin.)
The time required for the recovery of the irradiation effect is independent only on V/V_d, if resin content is decided, and under the same V/Vd, it increases with the resin content. It has been said that the memory effect is caused almost by photo-desorption of chemisorbed oxygen and the recovery by the readsorption in dark state. Our experiments suggest that the binder resin disturbs the oxygen readsorption by zinc oxide.
In other hand, the photoresponse of the surface conductivity was also measured. It is observed that the decay rate is slow compared with the rise, and becomes more slow as the resin content increases. In those phenomena, the results of the surface potential measurements qualitatively agreed with those of conductivity measurement.

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The photoconductivity of pressed and sintered ZnO in powder-form was observed.
Photoconductivity of sample of zinc oxide has been measured by micro amperemeter and d. c amplifier on sintered ZnO samples in the temperature range from 100°C to 1000°C, for 3 hrs, and specimens were observed with a electoron-microscope.
The manner of electrical conductivity change with temperature is quite differeis two regions of temperature. In high temperature region above 400°C, the conductivity increases rapidly with the increasing temperature while below 400°C the decrease of conductivity is fairly slow. In vefy high temperature region the dark currents increasing rapidly, the ZnO sintered in 1000°C loses photoconductivity.

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It is necessary to choose developers suitable for each kind of electrofax papers to obtain good quality of electrophotographic print. Particulary for the purpose of developing half tone electrostatic images, fine grain development is necessary. The author describes the tested results conceming of various kind of toners, carriers and papers. Tests were achieved on gray scale development, resolution of print, tribo-electricities of materials and development of half tone images, obtaining some concrete data.

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The powder image on electrofax paper is inclined to have a striped pattern. This phenomenon is based on the irregularity of the charge density generated from corona discharge around the wire electrode. To research it in detail, electrostatic charge patterns are observed on a single wire electrode fixed over the electrofax paper with or without a semicylindrical shield cover. Then, it became clear that the bands of weak charge density come out at right angles to the wire electrode and under constant points of the wire. Therefore, the direction of the wire electrode was made not at right angles to the directionof scanning motion. The uniformity of the charge distribution improved remarkably.

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