Electrostatic printing directly onto paper

This invention provides for an improved high speed printer using electrostatic means. The paper used is ordinary paper that is first dried to increase its electrical resistance. The electrostatic image is produced directly on the ordinary paper and then the electrostatic image is developed and fixed thereon. The invention includes details of the heating means.

BACKGROUND OF THE INVENTION 
This invention relates to a high speed printer using an electrostatic 
image. 
Speed-up of the central processors of electronic computer systems is 
necessitating corresponding speed-up of the printers which are output 
terminal units of such computer systems. There are various types of 
printers put in use. One of them transfers and fixes the electrostatic 
image to the printing paper by developing and visualising the 
electrostatic image with coloured loaded grains, forming in advance the 
electrostatic image on the sensitive plate which forms photoconductive 
substance layer on the supporting member, or developes and fixes it after 
transfering the aforesaid electrostatic image on the printing paper. 
Relating to this case there are U.S. Pat. No. 3,673,598 as a method of 
forming the electrostatic image and U.S. Pat. No. 3,220,933 is proposed as 
developer and fixing apparatus. 
Both of the above-mentioned methods have a drawback of the trouble in 
maintenance because of using the sensitive plate which is easily damaged 
and deteriorated. 
SUMMARY OF THE INVENTION 
This invention provides an improved high speed printer which is so 
constructed that a desired electrostatic image is formed by having loaded 
grains adhered selectively on the printing paper of ordinary paper, 
directly after drying it in advance to increase the electric resistance 
thereof, requiring neither sensitive plate nor speciality printing paper. 
OBJECTS OF THE INVENTION 
The first object of this invention is to increase the resistance of the 
printing paper by drying it in advance of printing. 
The second object of this invention is to form a desired electrostatic 
image directly by using printing paper made of ordinary paper. 
The third object of this invention is to dry the printing paper by the 
heating member mounted around the circumference of the heating drum. 
The fourth object of this invention is to dry the printing paper by feeding 
it closely adhered to the circumference of the heating drum by rotating 
the heating drum equipped with the heating member all over the 
circumference thereof. 
The fifth object of this invention is to dry the printing paper from the 
aperture openings around the circumference of the heating drum with the 
aid of the hot air blown therethrough.

DETAILED DESCRIPTION OF THE INVENTION 
Referring first to FIG. 1, numeral 1 is a printing paper made of ordinary 
paper, numeral 2 is a hopper to store the printing paper 1, numeral 3 is a 
heating drum for drying the printing paper by the heating plate 4, numeral 
5 is an electrostatic image former to form the desired characters, 
symbols, numerals, etc, on the relative printing paper 1 by adhering the 
loaded grains 7 selectively controlled by the aperture board 6 to the 
above-mentioned printing paper. The numeral 8 is a developer which forms 
the electrostatic image formed on the printing paper into a visible dust 
figure by developing it by the thermo-softened loaded coloured grains, 
numeral 9 is a fixing apparatus for fixing the visible grain image formed 
by the developer 8 by thermo-fusing. Numeral 10 is a stacker which 
temporarily stores the printed paper. Numeral 11 and 12 indicate driving 
rollers and numerals 13, 14 indicates guide rollers. 
An embodiment of the heating plate 4 of the above-mentioned heated drum is 
shown in FIG. 2 and FIG. 3 and the heater 16 of Ni-Cr wire is bent and put 
into the semi-cylindrical external cover suitable for the heating drum by 
holding it in mica 17. Numeral 18 is a terminal and, numeral 19 is a 
fixing aperture. The heating drum 3 is constructed by fitting the heating 
plate 4 over the half of the circumference of the brass made flange 20 by 
fitting a setscrew in the fixing aperture and the remaining part of the 
circumference is fitted with the brass made non-heating part 22 as shown 
in FIG. 1 & 4. The printing paper 1 is so positioned as to contact the 
surface of the heating plate 4 at the time of printing because the said 
heating drum 3 is fixed to the frame body by the supporting shaft (not 
shown) which projects to the brass made side plate 23. 
FIG. 5 shows another embodiment of the heating drum 3, wherein the 
supporting shaft 24 projecting from the side plate 23 is rotatably 
supported to the frame member (not shown) so that the printing paper 
passes through on the outer circumference in close contact therewith, 
whereas the heating plate 4 is secured by the setscrew 21 to the flange 20 
of the drum so that it will cover the whole surface of the circumference. 
FIG. 6 is another embodiment of the heating drum 3, wherein plural aperture 
25 are provided over half of the outer circumference of the brass made 
drum to form the heating plate 4, the heater 27 may be built in the brass 
made blast pipe 26 mounted on the side plate 23 on one side, hot air is 
supplied in the drum by means of the air blower 28 mounted on the edge of 
the blast pipe 26 and the hot air is blown from the apertures 25 so that 
the printing paper 1 which passes through on the heating plate may be 
dried. 
Incidentally, description of the aforesaid U.S. Pat. No. 3,673,598 can be 
applied to an electrostatic image forming apparatus 6 and the aforesaid 
U.S. Pat. No. 3,220,833 to a developer 8 and a fixing apparatus 9. 
Next the operation will be explained with reference to the construction 
shown in FIG. 1. The printing paper 1 is continuously fed when the driving 
rollers 11 and 12 are rotated in the direction of the arrow mark by a 
motor, etc, (not shown). Electrostatic images of characters, numerals, 
symbols, etc, are formed, as the printing paper 1 has adhered thereto 
loaded grains 7 which are selectively controlled by the aperture board 6 
over its surface after being dried by the heating plate 4 of the heating 
drum 3. This electrostatic image can be maintained for sufficient time by 
increasing the electric resistance by drying the printing paper 1. 
Accordingly, clear visible figure of characters, numerals, symbols, etc, 
are formed thereafter on the printing paper 1 by making visible dust 
figures with the developer 8 and furthermore by heat fusing with the 
fixing apparatus. 
As mentioned above in details, this invention avoids the sensitive plate 
which is easily damaged, deteriorated and difficult in maintenance, 
because this invention allows electrostatic images to be formed with 
loaded grains adhered on the printing paper only after increasing the 
electric resistance by drying the printing paper in advance and then they 
are developed and fixed. Furthermore, there are many advantages in 
economy, since cheap ordinary paper can be used in printing.