Photocopying – Contact printing – Light boxes
Patent
1991-07-16
1994-03-29
Pendegrass, Joan H.
Photocopying
Contact printing
Light boxes
355217, 365112, 430 48, G03G 1500, G03G 500
Patent
active
052989470
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an image-recording process for forming electrostatic latent images of high resolving power on electrostatic information recording medium, a system for carrying out such a process and a method for making such a device.
BACKGROUND OF THE INVENTION
As so far known in the art, there is available a process for recording and reproducing electrostatic images wherein "image exposure" is carried out with the application of voltage between both the electrodes of a photosensitive member and electrostatic information recording medium which are located in opposite relation to each other, thereby forming an electrostatic latent image of high resolving power on electrostatic information recording medium.
Such an electrostatic image-recording process is illustrated in FIG. 1, in which electrostatic information recording medium is shown at 1, a photosensitive member at 2, a photoconductive layer support at 2a, an electrode of the photosensitive member at 2b, a photoconductive layer at 2c, an insulating layer at 1a, an electrode of electrostatic information recording medium at 1b, an insulating layer support at 1c and a power source at E.
Referring to FIG. 1,. exposure is carried out through the photosensitive member 2. The photosensitive member 2 is constructed by providing the transparent electrode 2b formed of a 1000 .ANG. thick ITO on the support 2a formed of a 1-mm thick glass and providing the photoconductive layer 2c of about 10 .mu.m in thickness on the electrode 2b. The electrostatic information recording medium 1 is located in opposite relation to the photosensitive member 2 through a gap of about 10 .mu.m. The electrostatic information recording medium 1 is formed by providing the A1 electrode 1b of 1000 .ANG. in thickness on the insulating layer support 1c by vapor deposition and providing the insulating layer 1a of 10 .mu.m in thickness on the electrode 1b.
As illustrated in FIG. 1a, electrostatic information recording medium 1 is first set with respect to the photosensitive member 2 through a gap of about 10 .mu.m.
Then, voltage is applied between the electrodes 2b and 1b from the power source E, as illustrated in FIG. 1a. In the dark, no change will take place between both the electrodes, because the photoconductor 2c is a high resistant. However, when a voltage higher than the Paschen's discharge voltage is impressed to the gap depending upon the magnitude of the applied voltage or leakage currents from the substrate electrode, discharge takes place through the gap, forming electrostatic charges corresponding to the discharge on electrostatic information recording medium. When the photoconductive layer 2c is irradiated with light incident from the photoconductive layer support 2a, it generates photocarriers (electrons, holes) at the irradiated region, and charges opposite in polarity to the electrode of electrostatic information recording medium store through the photoconductive layer 2c toward its surface. In the meantime, as the proportion of voltage assigned to the air gap exceeds the Paschen's discharge voltage, corona discharge or field emission takes place between the photoconductive layer 2c and the insulating layer 1a, so that charges can be extracted from the photoconductive 2c and accelerated by the electric field, causing accumulation of the charges on the insulating layer 1a.
After the completion of exposure, the photosensitive member and electrostatic information recording medium are short-circuited, as shown in FIG. 1c. It is noted that while voltage supply has been described as put off by opening the switch, this may also be achieved by short-circuiting both the electrodes. Then, the electrostatic information recording medium 1 is removed, as shown in FIG. 1d, to complete the formation of an electrostatic latent image. By putting on off the voltage applied in this way or, in other words, using a voltage shutter, it is possible to form an electrostatic latent image; it is possible to dispense with such a mechanical or optical shutter as used with ordinary cam
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Aono Takashi
Ichimura Kohji
Iijima Masayuki
Obata Hiroyuki
Utsumi Minoru
Dai Nippon Printing Co. Ltd.
Pendegrass Joan H.
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