Coating material for eliminating ozone and electronic image processing apparatus having the same

An apparatus for forming an image by electrostatic charge comprises an image forming part including a photoconductive drum and an electrostatic charger for forming an image by electrostatic charge, and an ozone eliminating filter located in the air flow generated by the rotation of the photoconductive drum. The ozone eliminating filter includes a coating layer made of a coating material to eliminate ozone in the ambient air. The coating material includes an ozone eliminating substance an organic binder and a foaming agent. The ozone eliminating filter may be made of adhesive double-coated tape which includes an ozone eliminating substance on one side.

BACKGROUND OF THE INVENTION 
The present invention relates to coating material and an electronic image 
processing apparatus. More specifically, it relates to coating material 
for eliminating ozone and an electronic image processing apparatus having 
the same which forms an image by means of electrostatic charge. By way of 
clarity, in the specification the word "eliminating" is defined to be both 
decomposing and adsorbing. 
Electronic image processing apparatuses containing an 
electrostatically-charging image forming part generate ozone during the 
steps of charging a photoconductive member to a predetermined level of 
electric charge, transforming a toner image from the photoconductive 
member to a sheet of material paper, and removing the sheet having the 
received toner image from the photoconductive member. In these steps, 
activated particles of oxygen are generated by the inelastic collision of 
oxygen molecules and the charged particles generated by ionization of the 
air, due to corona discharge. The activated particles and oxygen molecules 
react to generate ozone. 
The ozone can be adsorbed by the surface of the photoconductive member, 
forming an oxidized layer which lowers the resistance of the surface of 
the photoconductive member. If the photoconductive member is made of an 
organic photoconductive material, the photoconductive member can react 
with the ozone, lowering the sensitivity of the photoconductive member. 
These may cause improper developing by, for example, fading and spreading 
of the image on the photoconductive member. 
Furthermore, the ozone generated in the electronic image processing 
apparatuses is discharged to the outside by a fan or the like, increasing 
the ozone concentration in the ambient air. A high concentration of ozone 
in the ambient air can have an adverse affect on the human body. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide coating material for 
eliminating ozone which can form an ozone eliminating filter to 
efficiently eliminate ozone. 
It is another object of the present invention to provide an ozone 
eliminating filter for efficiently eliminating ozone. 
It is a further object of the present invention to provide an ozone 
eliminating filter which is easily installed. 
It is yet another object of the present invention to provide an electronic 
image processing apparatus wherein ozone is efficiently eliminated. 
It is yet another object of the present invention to provide an electronic 
image processing apparatus which decreases the ozone concentration in the 
exhaust air of the apparatus. 
(1) According to an aspect of the present invention, coating material for 
eliminating ozone comprises a substance for eliminating ozone, an organic 
binder and a foaming agent. 
The coating material herein forms an ozone eliminating filter, consisting 
in a porous layer which incorporates the ozone eliminating substance 
foamed by means of the foaming agent. This ozone eliminating filter is of 
large area for contact with ozone molecules, whereby ozone may be 
effectively eliminated. 
(2) According to another aspect of the present invention, an ozone 
eliminating filter comprises an adhesive double-coated tape, and a 
substance for eliminating ozone adhered to at least one side of the 
adhesive double-coated tape. 
Since the ozone eliminating filter incorporates the adhesive double-coated 
tape, the filter can be easily placed in positions in an electronic image 
processing apparatus where ozone is generated. Thus, the ozone eliminating 
filter can efficiently eliminate ozone in the apparatus. 
(3) According to another aspect of the present invention, an electronic 
image processing apparatus is for forming an image by means of 
electrostatic charge. The apparatus comprises an image forming part having 
a photoconductive drum and an electrostatic charging device for forming an 
image by means of electrostatic charge, and an ozone eliminating filter 
disposed in the air flow generated by the rotation of the photoconductive 
drum. 
In the electronic image processing apparatus, the image forming part forms 
an image on the photoconductive drum by means of electrostatic charge. The 
electrostatic charging device generates ozone as a side effect. The ozone 
is circulated in the air flow generated around the photoconductive drum by 
the rotation of the photoconductive drum. However, the circulating ozone 
is eliminated by the ozone eliminating filter located in the air flow. 
Accordingly, the concentration of ozone in the electronic image processing 
apparatus is decreased, whereby deterioration of the photoconductive drum 
due to contact with ozone is minimized, and the concentration of ozone is 
decreased in the exhaust air. 
These and other objects and advantages of the present invention will be 
more fully apparent from the following detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 is a sectional schematic view showing a copying machine to which an 
embodiment of the present invention is applied. In the figure, a copying 
machine body 11 has a contact glass 12 in the upper surface and an 
original holder 13 thereon which can be opened. On the right side of the 
machine body in the figure, detachable paper cassette cases 14 and 15 are 
attached. On the left side of the machine body 11, a copy tray 18 is 
attached wherein copied paper is received. 
In the machine body 11, an optical exposure system 19 for obtaining 
information from the original image is located in the upper portion. The 
exposure system 19 consists of a light source, mirrors, etc. Disposed in 
the central portion of the machine body 11 is an image forming part 10. A 
paper transportation path 27 is provided between the paper cassette cases 
14 and 15 and the image forming part 10, and a paper discharging path 28 
is provided to the left of the image forming part 10. Provided between the 
paper discharging path 28 and the copy tray 18 is a fixing unit 30 for 
fixing a transferred image onto the transported sheet. 
FIG. 2 shows the structure of the image forming part 10. A photoconductive 
drum 20 on which an electrostatic latent image is formed is located in the 
central part of the image forming part 10. Surrounding the photoconductive 
drum 20, there are a main charger 21 for charging the photoconductive drum 
20 to a predetermined level of electric charge; a blank lamp unit 32 for 
trimming and masking an electrostatic latent image on the photoconductive 
drum 20; a developing unit 22 for developing the electrostatic latent 
image; a transferring device 23 for transferring a toner image to a sheet 
of material paper; a detaching device 24 for detaching the sheet from the 
photoconductive drum 20; a cleaning unit 25 for removing toner from the 
photoconductive drum 20; and an erasing lamp unit 31 for erasing electric 
charge remaining on the photoconductive drum 20, in that order. The 
photoconductive drum 20 is driven by a driving motor (not shown) to rotate 
in the direction shown by the arrow, whereby an air flow, as shown by the 
double arrows, is generated around the photoconductive drum 20. 
In the image forming part 10, the main charger 21 and each of the like 
surrounding the photoconductive drum 20 has a coating layer 34, or an 
ozone eliminating filter, made of coating material for eliminating ozone, 
on the outer surface against the air flow. The coating material for 
eliminating ozone used in the coating layers 34 includes, for example, a 
substance for decomposing ozone or a substance for adsorbing ozone. The 
ozone decomposing substance may be a powder of palladium carbon, a metal 
oxide such as manganese dioxide or lead peroxide, a metal such as nickel 
or rhodium, or a binary composite oxide consisting of titanium and 
silicone. A powder of the binary composite oxide consisting of titanium 
and silicone increases ozone decomposing efficiency when it is used with 
manganese dioxide. The ozone adsorbing substance may be activated carbon, 
silica gel or alumina. 
The coating layers 34 of the ozone eliminating material can be formed of 
coating material consisting of an organic binder with an ozone eliminating 
substance dispersed in the binder, on the outer surfaces of the main 
charger 21, etc. The organic binder used in the coating material may be an 
emulsion including a polymer of polyacrylicester type (for example, 
polycyanoacrylate), polymetacrylicester type, poly(vinyl acetate) type or 
polyethylene type; a copolymer of vinyl acetate/acrylicester type or 
styrene/butadiene type; acetal resin; butylal resin; polyimide resin; or 
polyamide resin. These kinds of organic binder usually consist of a solid 
component which ranges from 2 to 100 weight percent--preferably from 5 to 
50 weight percent. The mixing ratio of the ozone eliminating substance to 
an organic binder of 100 parts by weight--may range from 3 to 100 parts by 
weight, preferably from 5 to 50 parts by weight. If the parts of the ozone 
eliminating substance were less than 3 parts by weight, sufficient ozone 
eliminating effect would not be obtained. Moreover, if the parts of the 
ozone eliminating substance were more than 100 parts by weight, the 
manufacturing cost would be increased without further benefits. 
Furthermore, the coating layers 34 of the ozone eliminating substance 
could easily become detached in such cases. 
The coating material for making the coating layers 34 for the elimination 
of ozone may be foamable. A foamable coating material may consist of a 
foaming agent added to a coating material consisting of an ozone 
eliminating substance, an organic binder as described above, and a 
solvent. The foaming agent is, for example, sodium bicarbonate, ammonium 
carbonate, dinitrosopentamethylenetetramine, azobisformamide, 
azobisisobutyronitryl, bariumazodicarboxylate, or trihydrazinotriazine. 
More specifically, foaming material can be selected from the following: 
(1) A mixture of manganese dioxide of 80 parts by weight, butylal resin of 
10 parts by weight, and ammonium carbonate of 0.05 parts by weight, which 
are dissolved in ethanol of 100 parts by weight. 
(2) A mixture of palladium carbon powder of 95 parts by weight, butylal 
resin of 10 parts by weight, and dinitrosopentamethylenetetramine of 0.03 
parts by weight, which are dissolved in ethanol of 100 parts by weight. 
(3) A mixture of mixed powder of manganese dioxide and binary composite 
oxide consisting of titanium and silicon of 100 parts by weight, acrylic 
resin of 10 parts by weight, and azobisformamide of 0.08 parts by weight, 
which are dissolved in toluene of 80 parts by weight. 
The coating material including an ozone eliminating substance described 
above may be applied to a device by, typically, spraying or brush 
painting. The solvent is removed from the applied coating substance by, 
typically, a heating process at 100.degree. C. for one minute, whereby the 
ozone eliminating substance is baked on, to form the coating layers 34 for 
eliminating ozone on the main charger 21, etc. 
Wherein the foaming material is used, porous coating layers 34 for 
eliminating ozone are formed by means of the foaming agent. 
The operation of the above embodiment will henceforth be described. 
In the copying machine, negative corona discharging is carried out at the 
main charger 21, the transferring device 23, and the detaching device 24 
of the image forming part 10, while image processing is taking place. 
Ozone is generated as a side effect at the main charger 21, the 
transferring device 23, and the detaching device 24. 
The ozone is circulated around the photoconductive drum 20 due to the air 
flow surrounding the photoconductive drum 20. The air flow encounters the 
coating layers 34 for the elimination of ozone, whereby the ozone in the 
air flow is decomposed or adsorbed by the ozone eliminating substance of 
the coating layers 34. Thus, the ozone generated at the main charger 21, 
etc., is effectively eliminated. Therefore, the concentration of ozone in 
the copying machine is decreased, whereby the photoconductive material of 
the photoconductive drum 20 is maintained at quality; and the 
concentration of ozone in the exhaust air is also decreased. 
Wherein the coating material includes a foaming agent, the applied layers 
34 for the elimination of ozone are made porous. Thereby, the coating 
layers 34 have maximal surface for contact with ozone molecules, whereby 
ozone is effectively eliminated. 
MODIFICATIONS 
(a) Instead of the coating layers 34 as in the above embodiment, a porous 
filter including an ozone eliminating substance may be provided, for 
example, between the main charger 21 and the blank lamp unit 32, or 
between the blank lamp unit 32 and the developing unit 22. 
Although an additional member, i.e., a filter, must be required in this 
embodiment, the filter may be provided with a large surface which includes 
the ozone eliminating substance for contact with ozone, whereby ozone is 
effectively eliminated. 
(b) Instead of the coating layers 34 in the above embodiment, a tape-like 
shaped filter, shown in FIG. 3, for eliminating ozone may be employed 
which is affixed to the main charger 21, etc. 
In FIG. 3, the filter 40 consists of an adhesive double-coated tape 41 
having adhesive layers 41a on both sides, one of which contains a powder 
42 of an ozone eliminating substance. 
The filter 40 can be easily affixed to the main charger 21, etc., and may 
be easily replaced, so that high efficiency of eliminating ozone can be 
maintained in an electronic image processing apparatus. 
(c) A filter for eliminating ozone in accordance with the present invention 
may be used in a driving motor, a detaching device, and a processing 
cartridge having a lattice which consists of plates separate from each 
other by a small gap, in order to let exhaust air escape. 
EXPERIMENTS 
Experiment 1 
A coating material was made by adding vanadium oxide of 50 parts by weight 
to a solid binder of 100 parts by weight which consisted of a polymer 
emulsion of poly(vinyl acetate) containing solid of 5 weight percent. 
The obtained coating material was used to coat parts in a copying machine 
in a similar manner to the parts as shown in FIG. 2, and then it was dried 
to form the coating layers. 
A copying process was carried out in the copying machine incorporating the 
coating material. Ozone concentration in the exhaust air from the copying 
machine was measured with an ozone monitor (EG-2001; Ebara-jitsugyosha) 
just after 100 copies were made. The ozone concentration was 0.2 ppm. 
Experiment 2 
A coating material was made by dissolving a mixed powder of 100 parts by 
weight of manganese dioxide and a binary composite oxide of titanium and 
silicon, acrylic resin of 10 parts by weight, and azobisformamide of 0.08 
parts by weight into toluene of 80 parts by weight. 
The obtained coating material was used to coat the parts in a copying 
machine in a similar manner to the parts as shown in FIG. 2, and then the 
material was dried to form coating layers. The formed applied layers had a 
porous surface. 
The ozone concentration of the copying machine was measured in a like 
manner to Experiment 1. The ozone concentration was 0.1 ppm. 
COMATIVE EXAMPLE 
The ozone concentration of an ordinary copying machine which has no coating 
layers of the present invention was measured in a like manner to 
Experiment 1. 
The ozone concentration was 1.5 ppm. 
Various details of the invention may be changed without departing from its 
spirit not its scope. Furthermore, the foregoing description of the 
embodiments according to the present invention is provided for the purpose 
of illustration only, and not for the purpose of limiting the invention as 
defined by the appended claims and their equivalents.