CA1085446A - Electrophotographic copying apparatus - Google Patents
Electrophotographic copying apparatusInfo
- Publication number
- CA1085446A CA1085446A CA239,866A CA239866A CA1085446A CA 1085446 A CA1085446 A CA 1085446A CA 239866 A CA239866 A CA 239866A CA 1085446 A CA1085446 A CA 1085446A
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- Canada
- Prior art keywords
- duct
- corona charger
- harmful gases
- original
- adjacent
- Prior art date
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
- G03G21/20—Humidity or temperature control also ozone evacuation; Internal apparatus environment control
- G03G21/206—Conducting air through the machine, e.g. for cooling, filtering, removing gases like ozone
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
- G03G21/20—Humidity or temperature control also ozone evacuation; Internal apparatus environment control
- G03G21/203—Humidity
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Atmospheric Sciences (AREA)
- Biodiversity & Conservation Biology (AREA)
- Ecology (AREA)
- Environmental & Geological Engineering (AREA)
- Environmental Sciences (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Control Or Security For Electrophotography (AREA)
Abstract
TITLE OF THE INVENTION
Electrophotographic Copying Apparatus ABSTRACT OF THE DISCLOSURE
An electrophotographic copying apparatus which is provided with an improved device for preventing disturbance or disorder of transferred images due to deterioration of a photoreceptor surface by harmful gases present within or around a corona charger, which preventing device includes air ducts for evacuating harmful gases out of the apparatus and a heating unit for maintaining the photoreceptor surface in a dry state.
Electrophotographic Copying Apparatus ABSTRACT OF THE DISCLOSURE
An electrophotographic copying apparatus which is provided with an improved device for preventing disturbance or disorder of transferred images due to deterioration of a photoreceptor surface by harmful gases present within or around a corona charger, which preventing device includes air ducts for evacuating harmful gases out of the apparatus and a heating unit for maintaining the photoreceptor surface in a dry state.
Description
~38~446 The present invention relates to an el'ectrophoto-graphic copying apparatus and, more particularly, to a trans-fer type electrophotographic Copyillg apparatus provided with a transferred-image-distur'bancc prevention device incorporat-ed therein.
Conventionally, in the copying apparatus based on a copying system known as the Carlson system, there are employed an electrophotosensitive photoreceptor in the configuration of a drum or an endless belt having thereon an organic photoconductive layer of polyvinyl carbazole (PVK), an inorganic photoconductive layer of CdS (Cadmium Sulfide) or the like, and a corona charger for preliminarily charging the photoconductive layer so as to form an electrostatic latent image thereon through illumination of the original by a light source and projection of image light of the original onto the'photoconductive layer via an optical system.
Subsequently, for example, the latent image thus formed is transferred onto copy paper at'a transfer s~ation, which copy paper bearing the transferred latent image is subsequently de-veloped at a developing device of dry type or wet type to forma visible toner image thereon and finally fixed at a flxing device to be discharged out of the apparatus.
The conventional electrophotographic copying apparatus of the above described type, however, hasthe disadvantage that harmful gases such as ozone and nitrogen -oxides arising from corona discharge of the corona charger accumulate around the corona charger during repeated use of the copying apparatus, which harmful gases gradually deteriorate the surface of the photoconductive layer, thus 3~ resulting in disorder or disturbance of the copied images.
In order to elimiTIate such disadvantages, there has conventionally been proposed a transferred-image-disturbance prevention device in which the harmful gases present within the corona charger are for~ibly drawn by a fan or the like through an opening formed in the upper portion of the corona charger for reduciJIg the density of the harmful ~ases around the photoreceptor surface, which prevention device, however, still has the disadvantage that, since the same is adapted to suck the air into the apparatus housing, vapor of the organic solvent medium in ~.he developing solution is drawn in, when the wet-type developing device is employed, while heat-ed air ~round the fixing device is absorbed in cases where the dry-type developing is adopted. Accordingly, such vapor OT heated air inevitably contacts the photoreceptor surface, causing the latter to deteriorate in the course of time.
On the other hand, the photoreceptor surface, once deterio-rated, tends to easily absorb moisture, and after the same has been left under high-humidity atmospheTe for a long - period of time, for example, during nights or holidays, the quality of the electrostatic latent image to be formed there-on is heavily deteriorated at the initiation of the copying operation due to reduction of charge holding capacity on the photoconductive layer, resulting in disorder or dis-turbance of the copied images. Although the detalled process of the deterioration of the photoreceptor surface due to such harmful gases or reaction products arising from the corona discharge is not clear, it is considered that such deterio-ration is mainly attributable to clouding or corrosion on the surfaces of the optical system elements and the photo-receptor surface due to sticking of gases formed through .
1~854~6i reaction of ionized gases such as O, N0, N02 and the likewith H20 in the air, which trend is especially conspicuous when the apparatus is operated continuously for a long period of time.
It is known that the reaction products of the ordinary corona discharge chiefly includes ozone (03) with very small amount of the nitrogen oxides N0 and N02, of which products, ozone is particularly harmful to the human body to such an e~tent that if ozone of 1 to 2 p.p.m.
in density is inhaled for one to two hours, the mucous is strongly irritated, thus causing diseases such as headache, bronchitis, inflammation around the bronchus or the like.
. For the elimination of such undesirable effects on the human body and also on the optical system including the photoreceptor, there has also been proposed conventionally a device in which the harmful gases in the vicinity of the corona charger are drawn out of the apparatus housing through a discharge opening which is provided with a filter for - decomposing or absorbing ~he reaction products in the harm-ful gases, which device, ~owever, still has the disadvantage that, since the same absorbs the air within the apparatus housing for discharging the same out of the housing, toner particles having ~ery small diameters pass through the filter without being removed,whereby,when the dry-type developing device is employed, or the heated air around the fixing device is undesirably drawn ln, givlng ill-effect on the photoreceptor surface, or the vapor of the organlc solvent medium of the developing solution is sucked in to deteriorate the filter performance in cases where the wet-type develop-ing .device is adopted, a considerable amount of the ~.oss446 reaction products being discharged out of the apparatus hous-ing without having been sufficiently absorbed and decomposed.
The present invention consists of an electrophotographic copying apparatus which comprises a rotatable photoreceptor member having a photoconductive surface for repeated formation of an electrostatic latent image of an original thereon, means disposed around said photoreceptor member and including corona charger means for uniformly cha~ging said surface, exposure means for exposing said charged surface to image light of the original through an optical assembly including an illuminating light source so as to form the electrostatic latent image of the original thereon, and means for eliminating harmful gases generated by said corona charger means disposed within the copying apparatus, said means having duct means having one end adjacent said photoreceptor member and the other end opening out of the apparatus to the outside thereof and being divided into two portions extending along the length thereof, said corona charger means being in the end of one duct portion adjacent said photoreceptor member, and a line fan adjacent the other end of said duct and positioned relative to the two portions of said duct for drawing gases from around said corona charger means through said one duct portion toward said line fan and causing fresh air to flow toward the photoreceptor means through the other duct portion during rotation of said line fan.
According to a preferred embodiment of the present in-vention, the copying apparatus is provided with a trans-ferred-image disturbance prevention device which includes a first air duct disposed between the photoreceptor surface and a first fan, a second air duct provided between _ 5 _ ~5 lV854~6 a second fan located adja-ent to said first fan and a discharge opening of the apparatus housing, and a heating unit disposed below and ad.jacent to the photo-receptor surface. The first and second ducts are each divided into an injection duct and a suction duct by a partition plate disposed therein to form a circulation path of air stream through the discharge opening and the first and second ducts, with the corona charger being enclosed within one open end of a suction passage of the first duct for efficiently evacuating harmful gases in and around the corona charger out of the apparatus housing, while the heating unit heats the photoreceptor surface at comparatively low temperature through heat radiation there-from for maintaining the photoreceptor surface in dry con-dition, by which arrangement, not only the gradual deterio-ration of the photoreceptor surface due to harmful gases and heat is prevented, but clear and definite copied images without disorder or disturbance can be obtained even at an initia.tion of the copying operation afteT a long period of inactivity. I
These and other objects and features of the present invention will become apparent from the following descrip-tion of a preferred embodiment thereof with reference to the attached drawings, in which:
Fig. 1 is a schematic diagram showing a sectional .side view of a copying apparatus according to a preferred embodiment of the present invention, Fig. 2 is a perspective view partly in section showing, on an enlarged scale, construction of a fan in-30 corporated in the-apparatus of Fig. 1, - :
. 6 1~8S446 Fig. 3 is a schematic side sectional view showing an essential part of a modification of a transferred image disturbance prevention device incorporated in the apparatus of Fig. 1, Fig. 4 is a schematic side sectional view showing, on an enlarged scale, a heating unit incorporated in the apparatus of Fig. 1, Fig. 5 is an electrical circuit diagram showing connections of the heating unit of Fig. 4, Fig. 6 is a similar view to Fig. 5, but particu-larly shows a modification thereof, Fig. 7 is a perspective view showing, on an en-larged scale, a modification of the heating unit of Fig. 4, Fig. 8 is a cross sectional view, showing on an enlarged scale, construction of a heating element employed in the heating unit of Fig. 7, . Fig. 9 is a graph explaining the effect of organic solvent medlum vapor on a filter of active carbon, Fig. 10 is a schematic view of a testing device employed for the assess~Lent of the effect of organic solvent medium vapor on the filter of active carbon, and Fig. 11 is a similar view to Fig. 3, but particu-larly shows a modification thereof.
- Before the description of the present invention proceeds, it is to be noted that like parts are designated by like numerals throughout several views of the accompany-ing drawings.
Referring to Fig. 1, there is shown an electro-static latent image transfer type electrophotographic copying apparatus of the wet developing type according to an embodiment ~f the .. .. . . . ... . _ . . , .. . . _ . .. . . .. . _ . _ . _ . _ . _ _ _ . _ . .. .. _ _ _ . , .
~85~6 invention. The copying apparatus l generally comprises a movable platform P horizontally, reciprocatingly supported at the upper portion of the apparatus housing la for placing an original (not shown) to be copied thereon, and a photo-receptor drum 2 having, at the outer periphery thereof, a photoconductive layer 2a of organic material, for example, of PVK (polyvinyl carbazole) or of inorganic material such - as CdS (cadmium sulfide) and rotatably supported approximate-ly in the central portion of the apparatus housing la so as to cause the photoconductive surface 2a to sequentially pass various processing stations disposed therearound, such as a corona charging station provided with a corona charger 3 for preliminarily charging ~he photoconductive surface 2a uniformly, which corona charger 3 includes a casing 3a having an opening 3b directed towaTd the preliminarily charged photoconductive surface 2a and corona wires disposed in the .casing 3a, an exposure station 4 for projecting a light image i - of the original onto the charged photoconductive surface 2a for forming a latent image of the original on the surface 20 2a repeatedly, through a light source 6 for illuminating the original and an optical system A including a reflecting mirror and lens assembly, and a transfer station 5 for transferring the latent image formed on the photoconductive surface 2a - onto transfer material M or copy paper which is fed from a paper roll R supported on a rotatable spool Sp through a plurality of feeding rollers. After the transfer, the copy .
paper cut to a predetermined length by a cutter device k is fed into a developing device C of the wet developing type, with subsequent fixing of the developed image thereon at a fixing device F, and.is then discharged out of the apparatus 1~385446 housing la in a known manner.
It should be noted that the above described arrange-ment of the copying apparatus 1 is conventional except for the provision of a transferred image disturbance prevention device W including a heating unit 18 incorporated therein, which device W and unit 18 are described in detail her e inbe low .
The prevention device W is intended to prevent dis-turbance or disorder of the transferred image resulting from gradual detericration of the photoconductive surface 2a due ' to accumulation of harmful gases such as ozone, nitrogen oxides and the like which are generated followi~g the corona discharge by the corona charger 3, and generally includes an air duct Dl disposed between the photoreceptor surface 2a and a fan 8 mentioned later, another air duct D2 provided between a fan 7 and a louver 17 attached to an opening 03 formed in the apparatus housing la for preventing mixture of the exhaust air with the suction air, and the heating unit 18 mentioned later which is fixedly disposed below the photoreceptor drum 2. 'The fan 7 rotatably disposed adjacent to the fan 8 is for disc'harging heat from the light source 6. The duct Dl is divided into a suction duct 10 and an exhaust duct'll by a partition plate 12 provided within the duct Dl, with one end of the duct 11 facing the photo-receptor surface 2 being arranged to enclose the corona charger 3 therein through an air flow shieIding plate lla which extends downwardly toward the photoreceptor surface 2a from the upper wall of the duct 11 and to which one side wall of the casing 3a of the corona charger 3 is secured, while the other end of the duct Dl is in communication with g .
1~854~6, a casing 8' in which the fan 8 is rotatably housed in a manner described later. The air duct D2 is also divided into a suction duct 9 and an exhaust duct 16 by a partition plate 13, with the fan 7 rotatably disposed adjacent to one end of the ex-haust duct 16 remote from tne opening O3.
It should be noted here that the air ducts Dl and D2 which are divided, by the partition plates 12 and 13, into-the suction ducts 9 and 10 and the exhaust ducts 11 and 16 respectively,constitute an evacuating means having an air circulation path whi.ch includes a suction path and an exhaust path communicating with each other through the open-ing 3b of the charger casing 3a for removing the harmful gases within and around the charger 3, without directly absorbing the air in the apparatus housing la.
Reerring also to Fig. 2, the fan 8 of a cylindri-cal configuration extending across the width of the duct Dl and D2 is provided with many vanes V of arcuate cross section radially outwardly extending from the peripheral surface thereof and is fixedly mounted on a shaft S rotat-ably supported by side walls 8'c of the casing 8' throughcorresponding bearings, with one end of the shaft S being connected to a driving motor M which is fixedly mounted on a frame of the apparatus housing la.
The casing 8' further includes arcuate upper and lower walls 8'a and 8'b secured to the side walls 8'c to define openings l and Q2 for the casing 8' facing the corresponding ends of the duct Dl and D2, and air flow separator rods 14 and 15 fixedly supported by the side walls 8'c at the central portions of the openings l and 2 res-pectively, with the upper and lower w-ll.s 8'a and 8'b being .. . . .
~08S4~6 spaced from the outer periphery of the fan 8 to provide passages gl and g2 therebetween, thus suction and exhaust air flow circulation paths being formed from the louver 17, through the duct 9 of the duct Dl, the passage g2, the duct 10 and the duct 11 of the duct Dl, the passage gl, the duct 16 of the duct D2, and back to the louver 17.
By this arrangement, when a main switch (not shown) is turned on for copying operation, the fan 8 is rotated through energization of the motor M, and the outside air i.s sucked in through the louver 17 into the suction duct 9.
The outside air thus taken into the duct 9 is subsequently blasted toward the corona charger 3 through the passage g2 and the duct 10, and is subsequently led into the duct 11 through the openings 3b of the charger casing 3a and through a space formed between the casing 3a and the partition plate 12, from which duct 11, the air together with the air heated by the light source 6 is discharged through the duct 16 and the louver l7 by the combined effect of the fans 8 and 7.
It should be noted here that the air stream ejected from the duct 10 passe~ thoroughly through the interior of the corona chaTger 3 without flowing toward the mirToT or the like in the vicinity of the exposure station 4 by the suction force of the duct 11 and the presence of the ai~
~flow shielding plate lla, so that haTmful gases such as ozone, nitrogen oxides, etc., in the corona charger 3 or thereabout can effiCiently be discharged out of the appa-ratus housing la together with the heated air in the vicinity of the heat source.6.
As is clear from the above description, according . . . . . ., .. ... . _ . . . . . . , , . _ .. . . . .
~)8~44~i, to the dcvice W , since the air around the ~orona charger 3 is forcibly discharged out of the apparatus, while fresh outside air is positively intToduced toward the charger 3 main]y by the fan 8, efficient air circulation is achieved with markcd improvement in the elimination of the harmful gases as compared with conventional devices wherein air around the corona charger is discharged through a fan together with air inside of the copying apparatus. Further-more, in the device W, most of the air drawn through the duct 11 is air introduced through the suction duct 10, with the air inside the copying apparatus being scarcely mixed therewith, so that organic solvent medium vapor of the developing solution and heated air in the fixing device are not drawn by the air stream through the duct 10, thus deterioration of the photoreceptor sur-face due to such vapor and heat being advantageously elimi-nated.
Referring to Fig. 3, there is shown a modification of the prevention device W of Fig. 1. In this modification W', the fan 7 for discharging the air heated by the light source 6 described as employed in the embodiment of Fig. 1 is dispensed with, and an opening O4 is formed between one edge of the upper wall 8"a of the casing 8" and the corres-ponding edge of the upper wall 16'a of the exhaust duct 16' with the wall 16'a extending approximately horizontally toward the upper wall 8"a of the casing 8".
In the above arrangement of the modification of Fig. 3, when the fan 8 is rotated upon closure of the main switch (not shown), the outside air is drawn into the suction duct 9' through the louver 17, and subsequently . - 12 ... . . . .
~.~8~4~6 directed toward the corona charger 3 through the passage g2 and the duct 10'. The air containing therein the harmful gases present around the corona charger 3 is further drawn into the duct 11' of the duct D'l through the openings 3b formed in the casing 3a of the corona charger 3 and the space provided bctween the casing 3a and the partition plate 12', and then sucked into the exhaust duct 16' of the duct D'2, in which case, the heated air around the light source 6 is also drawn into the exhaust duct 16' through the opening O4 and discharged out of the apparatus housing la through the louver 17 together with the air circulating through the ducts D'2 and D'l in the above described manner, thus the fan 7 required in the embodiment of Fig. 1 being advantageously dispensed with.
- Other functioning and construction of the copying apparatus 1 are similar to those in the embodiment of Fig.
1, so that description thereof is abbreviated for brevity.
: It should be noted here that the single fan or so-called line fan 8 capable of sucking in and discharging air through the two paths in the ducts described as employ-ed in the above devices of Figs. 1 and 3 is not limited to the single one ~but a separate fan may be provided exclusive-ly for each of the suction and exhaust paths of the ducts, although adoption of such single fan results in reduction of manufacturing cost and compact size of the copying apparatus.
It should also be noted here that, since very efficient air circuiation is achieved by the device of the invention, air flow described as directed from the side of the photoreceptor surface toward the corona charger in Figs. l and 3 may be reversed to flow from the corona charger toward , lV854g~6 the photoreceptor surface, for example, by changing the setting position of the corona charger into the duct 10.
~ eferring also to Fig. 4, there is shown, on an enlargcd scale, the heating unit 18 which is incorporated in the prevention device W. The heating unit 18 is intended to hcat the photoreceptor surface 2a ata comparatively low temperature prior to a copying operation for obtaining a clear transferred image even at an initial stage of each copying, and is disposed below the photoreceptor surface 2a in such a manner that an upward air flow therefrom through convection surrounds the photoreceptor surface 2a directly or indirectly. The heating unit 18 includes a low temperature heating element 18' placed, through a heat shielding material 21 and an aluminum plate 22 for conduct-ing heat uniformly, on the bottom portion of a casing 20 of approximately ~-shaped cross section and secured thereto under pressure through a heat insulating member 23 which is suitably fixed to one side wall of the casing 20. The casing 20 is fixedly mounted on a base plate 19 of the apparatus housing la below the photoreceptor drum 2 and is further provided with a protector or grill member 24 disposed at the upper portion thereof for the prevention of fire hazard, should the copy paper sheet hang down during copylng ope-rations. The heating element 18' is a panel heater of the temperature self-control type which is capable of maintain-ing constant ambient temperature, for example, maintaining the surface temperature of the photoreceptor surface 2a in the range of 40 to 50~C without employing any control means such as a thermostat or the like.
Referring also to Figs. 5 and 6, the heating .. . . . . . ... .
108S44~
element 18' is connected in parallel to the power source (not shown) through a plug P, with a main motor M being connected in parallel to the heating element 18' through a main switch SW, so that the element 18' is energized upon in.sertion of the plug P into a receptacle (not shown) leading to the power source irrsepective of the main switch SW being turned on or off.
It should be noted here that the circuit const-ruction for the heating element 18' is not limited to one shown in Fig. 5, but a humidity control switch H.S. such as a humidistat may be further inserted in series with tne element 18' for controlling the humidity in the copying apparatus at a predetermined level as is shown in Fig. 6.
Additionally it may be desirable that a switch (,not shown) which operates opposite to the operation of the main switch SW, or a temperature control means such as a thermostat (not shown) which is disposed near by the photo-receptor drum 2 and is actuated by detecting a temperature surrounding the photoreceptor drum 2 is further inserted in series with the element 18' for preventing t'ne photo-receptor drum 2 from overheating.
From the foregoing description, it is seen that, in the copying apparatus, since the photoreceptor surface 2a is maintained at a temperature level in the range of 40 to 50C even when copying operations are suspended, through the warm air convection, heat radiation and heat conduction from the heating element 18', the disadvantages inherent in the conventional apparatuses such as the disorder of the transferred image due to reduction of charge holding capacity of the photoreceptor surface arising from absorption of mois-ture during suspension of copying operations and the like ~ - 15 -1~8544~
are advanta~eously eliminated. It is needless to say that, since the heat from the element 18' is controlled at the lo~
- 15a -~8S446 temperature level of 40 to 50 c, seaLing material or the like in the copying apparatus is prevented from deterioration due to heat, aging and deformation, while the dry air is effective for prevention of the formatlon of wrinkles or curling at the leading edge of the copy paper sheet.
Referring now to Figs. 7 and 8, there is shown a modification of the heating unit 18 of Fig. 4. In this modification, the heating unit 118 includes a metallic base plate 118a of rectangular shape having opposite ends thereof 10 suitably bent to foTm L-shaped portions thereat for fixedly supporting the plate 118a in spaced relation to the bottom of the apparatus housing la, and a pair of heating elements 118' secured to the lower surface of the base plate 118a through securing plates e fixedly mounted on the elements 118' and corresponding securing screws(not shown). Each of the heating elements 118 further comprises a porcelain casing z of rectangular box-like configuration open at one side to form a cavity therein, and a heat-ing coil h which is wound on a porcelain rod having terminal plates Q at opposite ends thereof and fixedly embedded in the cavity of the casing z with cement m or the like, with the tips of 20 the terminal plates ~ projecting out of the casing z for electrical connection thereto. Upon energization, the heating elements 118' heat the metallic base plate 118a up to a temperature of approximately 60C. Since the function and the electrical connections of the heating elements 118~ are similar to those described with reference to the element 18 of Figs. 4, 5 and 6, detailed description thereof is abbrevi-ated for brevity.
Referring now to Figs. 9 and 10, in order to assess the effect of harmful gases on a filter, the present inven-30 tors carried out a series of experiments employing a testing ~ 16 ~
~38S446 dcvice T as shown in Fig. lO.
The testing dcvice T includes an L-shaped glass tube 201 having an open enlarged portion, at one end there-of, in which a corona charger Cc connected to a high voltage source }-IV and an ammeter ~m is disposed, and having the other end thereof extending, through a cap Sl, into a vessel b containing pure water Pw therein, with an extreme tip of said other end immersed in the pure water Pw, a U-shaped glass tube 203 closed at opposite ends thereof and partially filled with active carbon Cf, an L-shaped glass tube 202 having one end thereof extending, through the cap Sl, into the vessel bl, with an extreme tip of said one end spaced away from the surface of the pure water Pw, and having the other end thereof in communication with one closed end of the U-shaped glass tube 203, an L-shaped glass tube 20~
having one end thereof in communication with the other closed end of the U-shaped glass tube 203 and having the other end thereof extending, through a cap S2, into a vessel b2 containing therein an absorbing liquid ~a of phenolphthalein 90 ml in quantity with an extreme tip of said other end immersed in the absorbing liquid Qa, and another L-shaped glass tube 205 having one end thereof extending, thTough the cap S2, into the vessel b2, with an extreme tip of said one end spaced away from the surface of said absorbing liquid ~a and having the other end thereof 205a communicated with a suitable air pump (not shown). In the experiments, four kinds of differently treated active carbon specimens (A), (B), (C) and (D) were employed, in which specimens, (A) was an active carbon left in the vapor of an organic solvent medium for 28 days, (B) was one left in the same vapor for lV85446 13 days, (C) was one which had bccn used for elimination of ozone foI 52 hours in the absence of the organic solvent medium vapor, and ~D) was one left in a room for 13 days. The air pump (not shown) employed had a flow rate o~ approximately 1000 ml/min., while the charging current of the corona charger Cc was in the region of 410 to 435 ~A. The active carbons (A), (B), (C) and (D) were tested, one by one, by the device T for the assessment of the ozone eliminating capacity thereof !
with sample gases containing predetermined amounts of ozone being passed through the tube 201, the vessel bl, the tube 202, the U-shaped tube 203, the tube 204, the vessel b2 and the tube 205, the results of which are shown in Fig. 9 in graphical form.
. As is clear from curves A, B, C and D in Fig. 9 representing behavior of the coIresponding active carbons (A), (B), (C)- and (D), the ozone eliminating ability of the active carbon filters is heavily deteriorated when such filters are subjected to the vapor of an organic solvent¦
medium.
Conventionally, in the copying apparatus based on a copying system known as the Carlson system, there are employed an electrophotosensitive photoreceptor in the configuration of a drum or an endless belt having thereon an organic photoconductive layer of polyvinyl carbazole (PVK), an inorganic photoconductive layer of CdS (Cadmium Sulfide) or the like, and a corona charger for preliminarily charging the photoconductive layer so as to form an electrostatic latent image thereon through illumination of the original by a light source and projection of image light of the original onto the'photoconductive layer via an optical system.
Subsequently, for example, the latent image thus formed is transferred onto copy paper at'a transfer s~ation, which copy paper bearing the transferred latent image is subsequently de-veloped at a developing device of dry type or wet type to forma visible toner image thereon and finally fixed at a flxing device to be discharged out of the apparatus.
The conventional electrophotographic copying apparatus of the above described type, however, hasthe disadvantage that harmful gases such as ozone and nitrogen -oxides arising from corona discharge of the corona charger accumulate around the corona charger during repeated use of the copying apparatus, which harmful gases gradually deteriorate the surface of the photoconductive layer, thus 3~ resulting in disorder or disturbance of the copied images.
In order to elimiTIate such disadvantages, there has conventionally been proposed a transferred-image-disturbance prevention device in which the harmful gases present within the corona charger are for~ibly drawn by a fan or the like through an opening formed in the upper portion of the corona charger for reduciJIg the density of the harmful ~ases around the photoreceptor surface, which prevention device, however, still has the disadvantage that, since the same is adapted to suck the air into the apparatus housing, vapor of the organic solvent medium in ~.he developing solution is drawn in, when the wet-type developing device is employed, while heat-ed air ~round the fixing device is absorbed in cases where the dry-type developing is adopted. Accordingly, such vapor OT heated air inevitably contacts the photoreceptor surface, causing the latter to deteriorate in the course of time.
On the other hand, the photoreceptor surface, once deterio-rated, tends to easily absorb moisture, and after the same has been left under high-humidity atmospheTe for a long - period of time, for example, during nights or holidays, the quality of the electrostatic latent image to be formed there-on is heavily deteriorated at the initiation of the copying operation due to reduction of charge holding capacity on the photoconductive layer, resulting in disorder or dis-turbance of the copied images. Although the detalled process of the deterioration of the photoreceptor surface due to such harmful gases or reaction products arising from the corona discharge is not clear, it is considered that such deterio-ration is mainly attributable to clouding or corrosion on the surfaces of the optical system elements and the photo-receptor surface due to sticking of gases formed through .
1~854~6i reaction of ionized gases such as O, N0, N02 and the likewith H20 in the air, which trend is especially conspicuous when the apparatus is operated continuously for a long period of time.
It is known that the reaction products of the ordinary corona discharge chiefly includes ozone (03) with very small amount of the nitrogen oxides N0 and N02, of which products, ozone is particularly harmful to the human body to such an e~tent that if ozone of 1 to 2 p.p.m.
in density is inhaled for one to two hours, the mucous is strongly irritated, thus causing diseases such as headache, bronchitis, inflammation around the bronchus or the like.
. For the elimination of such undesirable effects on the human body and also on the optical system including the photoreceptor, there has also been proposed conventionally a device in which the harmful gases in the vicinity of the corona charger are drawn out of the apparatus housing through a discharge opening which is provided with a filter for - decomposing or absorbing ~he reaction products in the harm-ful gases, which device, ~owever, still has the disadvantage that, since the same absorbs the air within the apparatus housing for discharging the same out of the housing, toner particles having ~ery small diameters pass through the filter without being removed,whereby,when the dry-type developing device is employed, or the heated air around the fixing device is undesirably drawn ln, givlng ill-effect on the photoreceptor surface, or the vapor of the organlc solvent medium of the developing solution is sucked in to deteriorate the filter performance in cases where the wet-type develop-ing .device is adopted, a considerable amount of the ~.oss446 reaction products being discharged out of the apparatus hous-ing without having been sufficiently absorbed and decomposed.
The present invention consists of an electrophotographic copying apparatus which comprises a rotatable photoreceptor member having a photoconductive surface for repeated formation of an electrostatic latent image of an original thereon, means disposed around said photoreceptor member and including corona charger means for uniformly cha~ging said surface, exposure means for exposing said charged surface to image light of the original through an optical assembly including an illuminating light source so as to form the electrostatic latent image of the original thereon, and means for eliminating harmful gases generated by said corona charger means disposed within the copying apparatus, said means having duct means having one end adjacent said photoreceptor member and the other end opening out of the apparatus to the outside thereof and being divided into two portions extending along the length thereof, said corona charger means being in the end of one duct portion adjacent said photoreceptor member, and a line fan adjacent the other end of said duct and positioned relative to the two portions of said duct for drawing gases from around said corona charger means through said one duct portion toward said line fan and causing fresh air to flow toward the photoreceptor means through the other duct portion during rotation of said line fan.
According to a preferred embodiment of the present in-vention, the copying apparatus is provided with a trans-ferred-image disturbance prevention device which includes a first air duct disposed between the photoreceptor surface and a first fan, a second air duct provided between _ 5 _ ~5 lV854~6 a second fan located adja-ent to said first fan and a discharge opening of the apparatus housing, and a heating unit disposed below and ad.jacent to the photo-receptor surface. The first and second ducts are each divided into an injection duct and a suction duct by a partition plate disposed therein to form a circulation path of air stream through the discharge opening and the first and second ducts, with the corona charger being enclosed within one open end of a suction passage of the first duct for efficiently evacuating harmful gases in and around the corona charger out of the apparatus housing, while the heating unit heats the photoreceptor surface at comparatively low temperature through heat radiation there-from for maintaining the photoreceptor surface in dry con-dition, by which arrangement, not only the gradual deterio-ration of the photoreceptor surface due to harmful gases and heat is prevented, but clear and definite copied images without disorder or disturbance can be obtained even at an initia.tion of the copying operation afteT a long period of inactivity. I
These and other objects and features of the present invention will become apparent from the following descrip-tion of a preferred embodiment thereof with reference to the attached drawings, in which:
Fig. 1 is a schematic diagram showing a sectional .side view of a copying apparatus according to a preferred embodiment of the present invention, Fig. 2 is a perspective view partly in section showing, on an enlarged scale, construction of a fan in-30 corporated in the-apparatus of Fig. 1, - :
. 6 1~8S446 Fig. 3 is a schematic side sectional view showing an essential part of a modification of a transferred image disturbance prevention device incorporated in the apparatus of Fig. 1, Fig. 4 is a schematic side sectional view showing, on an enlarged scale, a heating unit incorporated in the apparatus of Fig. 1, Fig. 5 is an electrical circuit diagram showing connections of the heating unit of Fig. 4, Fig. 6 is a similar view to Fig. 5, but particu-larly shows a modification thereof, Fig. 7 is a perspective view showing, on an en-larged scale, a modification of the heating unit of Fig. 4, Fig. 8 is a cross sectional view, showing on an enlarged scale, construction of a heating element employed in the heating unit of Fig. 7, . Fig. 9 is a graph explaining the effect of organic solvent medlum vapor on a filter of active carbon, Fig. 10 is a schematic view of a testing device employed for the assess~Lent of the effect of organic solvent medium vapor on the filter of active carbon, and Fig. 11 is a similar view to Fig. 3, but particu-larly shows a modification thereof.
- Before the description of the present invention proceeds, it is to be noted that like parts are designated by like numerals throughout several views of the accompany-ing drawings.
Referring to Fig. 1, there is shown an electro-static latent image transfer type electrophotographic copying apparatus of the wet developing type according to an embodiment ~f the .. .. . . . ... . _ . . , .. . . _ . .. . . .. . _ . _ . _ . _ . _ _ _ . _ . .. .. _ _ _ . , .
~85~6 invention. The copying apparatus l generally comprises a movable platform P horizontally, reciprocatingly supported at the upper portion of the apparatus housing la for placing an original (not shown) to be copied thereon, and a photo-receptor drum 2 having, at the outer periphery thereof, a photoconductive layer 2a of organic material, for example, of PVK (polyvinyl carbazole) or of inorganic material such - as CdS (cadmium sulfide) and rotatably supported approximate-ly in the central portion of the apparatus housing la so as to cause the photoconductive surface 2a to sequentially pass various processing stations disposed therearound, such as a corona charging station provided with a corona charger 3 for preliminarily charging ~he photoconductive surface 2a uniformly, which corona charger 3 includes a casing 3a having an opening 3b directed towaTd the preliminarily charged photoconductive surface 2a and corona wires disposed in the .casing 3a, an exposure station 4 for projecting a light image i - of the original onto the charged photoconductive surface 2a for forming a latent image of the original on the surface 20 2a repeatedly, through a light source 6 for illuminating the original and an optical system A including a reflecting mirror and lens assembly, and a transfer station 5 for transferring the latent image formed on the photoconductive surface 2a - onto transfer material M or copy paper which is fed from a paper roll R supported on a rotatable spool Sp through a plurality of feeding rollers. After the transfer, the copy .
paper cut to a predetermined length by a cutter device k is fed into a developing device C of the wet developing type, with subsequent fixing of the developed image thereon at a fixing device F, and.is then discharged out of the apparatus 1~385446 housing la in a known manner.
It should be noted that the above described arrange-ment of the copying apparatus 1 is conventional except for the provision of a transferred image disturbance prevention device W including a heating unit 18 incorporated therein, which device W and unit 18 are described in detail her e inbe low .
The prevention device W is intended to prevent dis-turbance or disorder of the transferred image resulting from gradual detericration of the photoconductive surface 2a due ' to accumulation of harmful gases such as ozone, nitrogen oxides and the like which are generated followi~g the corona discharge by the corona charger 3, and generally includes an air duct Dl disposed between the photoreceptor surface 2a and a fan 8 mentioned later, another air duct D2 provided between a fan 7 and a louver 17 attached to an opening 03 formed in the apparatus housing la for preventing mixture of the exhaust air with the suction air, and the heating unit 18 mentioned later which is fixedly disposed below the photoreceptor drum 2. 'The fan 7 rotatably disposed adjacent to the fan 8 is for disc'harging heat from the light source 6. The duct Dl is divided into a suction duct 10 and an exhaust duct'll by a partition plate 12 provided within the duct Dl, with one end of the duct 11 facing the photo-receptor surface 2 being arranged to enclose the corona charger 3 therein through an air flow shieIding plate lla which extends downwardly toward the photoreceptor surface 2a from the upper wall of the duct 11 and to which one side wall of the casing 3a of the corona charger 3 is secured, while the other end of the duct Dl is in communication with g .
1~854~6, a casing 8' in which the fan 8 is rotatably housed in a manner described later. The air duct D2 is also divided into a suction duct 9 and an exhaust duct 16 by a partition plate 13, with the fan 7 rotatably disposed adjacent to one end of the ex-haust duct 16 remote from tne opening O3.
It should be noted here that the air ducts Dl and D2 which are divided, by the partition plates 12 and 13, into-the suction ducts 9 and 10 and the exhaust ducts 11 and 16 respectively,constitute an evacuating means having an air circulation path whi.ch includes a suction path and an exhaust path communicating with each other through the open-ing 3b of the charger casing 3a for removing the harmful gases within and around the charger 3, without directly absorbing the air in the apparatus housing la.
Reerring also to Fig. 2, the fan 8 of a cylindri-cal configuration extending across the width of the duct Dl and D2 is provided with many vanes V of arcuate cross section radially outwardly extending from the peripheral surface thereof and is fixedly mounted on a shaft S rotat-ably supported by side walls 8'c of the casing 8' throughcorresponding bearings, with one end of the shaft S being connected to a driving motor M which is fixedly mounted on a frame of the apparatus housing la.
The casing 8' further includes arcuate upper and lower walls 8'a and 8'b secured to the side walls 8'c to define openings l and Q2 for the casing 8' facing the corresponding ends of the duct Dl and D2, and air flow separator rods 14 and 15 fixedly supported by the side walls 8'c at the central portions of the openings l and 2 res-pectively, with the upper and lower w-ll.s 8'a and 8'b being .. . . .
~08S4~6 spaced from the outer periphery of the fan 8 to provide passages gl and g2 therebetween, thus suction and exhaust air flow circulation paths being formed from the louver 17, through the duct 9 of the duct Dl, the passage g2, the duct 10 and the duct 11 of the duct Dl, the passage gl, the duct 16 of the duct D2, and back to the louver 17.
By this arrangement, when a main switch (not shown) is turned on for copying operation, the fan 8 is rotated through energization of the motor M, and the outside air i.s sucked in through the louver 17 into the suction duct 9.
The outside air thus taken into the duct 9 is subsequently blasted toward the corona charger 3 through the passage g2 and the duct 10, and is subsequently led into the duct 11 through the openings 3b of the charger casing 3a and through a space formed between the casing 3a and the partition plate 12, from which duct 11, the air together with the air heated by the light source 6 is discharged through the duct 16 and the louver l7 by the combined effect of the fans 8 and 7.
It should be noted here that the air stream ejected from the duct 10 passe~ thoroughly through the interior of the corona chaTger 3 without flowing toward the mirToT or the like in the vicinity of the exposure station 4 by the suction force of the duct 11 and the presence of the ai~
~flow shielding plate lla, so that haTmful gases such as ozone, nitrogen oxides, etc., in the corona charger 3 or thereabout can effiCiently be discharged out of the appa-ratus housing la together with the heated air in the vicinity of the heat source.6.
As is clear from the above description, according . . . . . ., .. ... . _ . . . . . . , , . _ .. . . . .
~)8~44~i, to the dcvice W , since the air around the ~orona charger 3 is forcibly discharged out of the apparatus, while fresh outside air is positively intToduced toward the charger 3 main]y by the fan 8, efficient air circulation is achieved with markcd improvement in the elimination of the harmful gases as compared with conventional devices wherein air around the corona charger is discharged through a fan together with air inside of the copying apparatus. Further-more, in the device W, most of the air drawn through the duct 11 is air introduced through the suction duct 10, with the air inside the copying apparatus being scarcely mixed therewith, so that organic solvent medium vapor of the developing solution and heated air in the fixing device are not drawn by the air stream through the duct 10, thus deterioration of the photoreceptor sur-face due to such vapor and heat being advantageously elimi-nated.
Referring to Fig. 3, there is shown a modification of the prevention device W of Fig. 1. In this modification W', the fan 7 for discharging the air heated by the light source 6 described as employed in the embodiment of Fig. 1 is dispensed with, and an opening O4 is formed between one edge of the upper wall 8"a of the casing 8" and the corres-ponding edge of the upper wall 16'a of the exhaust duct 16' with the wall 16'a extending approximately horizontally toward the upper wall 8"a of the casing 8".
In the above arrangement of the modification of Fig. 3, when the fan 8 is rotated upon closure of the main switch (not shown), the outside air is drawn into the suction duct 9' through the louver 17, and subsequently . - 12 ... . . . .
~.~8~4~6 directed toward the corona charger 3 through the passage g2 and the duct 10'. The air containing therein the harmful gases present around the corona charger 3 is further drawn into the duct 11' of the duct D'l through the openings 3b formed in the casing 3a of the corona charger 3 and the space provided bctween the casing 3a and the partition plate 12', and then sucked into the exhaust duct 16' of the duct D'2, in which case, the heated air around the light source 6 is also drawn into the exhaust duct 16' through the opening O4 and discharged out of the apparatus housing la through the louver 17 together with the air circulating through the ducts D'2 and D'l in the above described manner, thus the fan 7 required in the embodiment of Fig. 1 being advantageously dispensed with.
- Other functioning and construction of the copying apparatus 1 are similar to those in the embodiment of Fig.
1, so that description thereof is abbreviated for brevity.
: It should be noted here that the single fan or so-called line fan 8 capable of sucking in and discharging air through the two paths in the ducts described as employ-ed in the above devices of Figs. 1 and 3 is not limited to the single one ~but a separate fan may be provided exclusive-ly for each of the suction and exhaust paths of the ducts, although adoption of such single fan results in reduction of manufacturing cost and compact size of the copying apparatus.
It should also be noted here that, since very efficient air circuiation is achieved by the device of the invention, air flow described as directed from the side of the photoreceptor surface toward the corona charger in Figs. l and 3 may be reversed to flow from the corona charger toward , lV854g~6 the photoreceptor surface, for example, by changing the setting position of the corona charger into the duct 10.
~ eferring also to Fig. 4, there is shown, on an enlargcd scale, the heating unit 18 which is incorporated in the prevention device W. The heating unit 18 is intended to hcat the photoreceptor surface 2a ata comparatively low temperature prior to a copying operation for obtaining a clear transferred image even at an initial stage of each copying, and is disposed below the photoreceptor surface 2a in such a manner that an upward air flow therefrom through convection surrounds the photoreceptor surface 2a directly or indirectly. The heating unit 18 includes a low temperature heating element 18' placed, through a heat shielding material 21 and an aluminum plate 22 for conduct-ing heat uniformly, on the bottom portion of a casing 20 of approximately ~-shaped cross section and secured thereto under pressure through a heat insulating member 23 which is suitably fixed to one side wall of the casing 20. The casing 20 is fixedly mounted on a base plate 19 of the apparatus housing la below the photoreceptor drum 2 and is further provided with a protector or grill member 24 disposed at the upper portion thereof for the prevention of fire hazard, should the copy paper sheet hang down during copylng ope-rations. The heating element 18' is a panel heater of the temperature self-control type which is capable of maintain-ing constant ambient temperature, for example, maintaining the surface temperature of the photoreceptor surface 2a in the range of 40 to 50~C without employing any control means such as a thermostat or the like.
Referring also to Figs. 5 and 6, the heating .. . . . . . ... .
108S44~
element 18' is connected in parallel to the power source (not shown) through a plug P, with a main motor M being connected in parallel to the heating element 18' through a main switch SW, so that the element 18' is energized upon in.sertion of the plug P into a receptacle (not shown) leading to the power source irrsepective of the main switch SW being turned on or off.
It should be noted here that the circuit const-ruction for the heating element 18' is not limited to one shown in Fig. 5, but a humidity control switch H.S. such as a humidistat may be further inserted in series with tne element 18' for controlling the humidity in the copying apparatus at a predetermined level as is shown in Fig. 6.
Additionally it may be desirable that a switch (,not shown) which operates opposite to the operation of the main switch SW, or a temperature control means such as a thermostat (not shown) which is disposed near by the photo-receptor drum 2 and is actuated by detecting a temperature surrounding the photoreceptor drum 2 is further inserted in series with the element 18' for preventing t'ne photo-receptor drum 2 from overheating.
From the foregoing description, it is seen that, in the copying apparatus, since the photoreceptor surface 2a is maintained at a temperature level in the range of 40 to 50C even when copying operations are suspended, through the warm air convection, heat radiation and heat conduction from the heating element 18', the disadvantages inherent in the conventional apparatuses such as the disorder of the transferred image due to reduction of charge holding capacity of the photoreceptor surface arising from absorption of mois-ture during suspension of copying operations and the like ~ - 15 -1~8544~
are advanta~eously eliminated. It is needless to say that, since the heat from the element 18' is controlled at the lo~
- 15a -~8S446 temperature level of 40 to 50 c, seaLing material or the like in the copying apparatus is prevented from deterioration due to heat, aging and deformation, while the dry air is effective for prevention of the formatlon of wrinkles or curling at the leading edge of the copy paper sheet.
Referring now to Figs. 7 and 8, there is shown a modification of the heating unit 18 of Fig. 4. In this modification, the heating unit 118 includes a metallic base plate 118a of rectangular shape having opposite ends thereof 10 suitably bent to foTm L-shaped portions thereat for fixedly supporting the plate 118a in spaced relation to the bottom of the apparatus housing la, and a pair of heating elements 118' secured to the lower surface of the base plate 118a through securing plates e fixedly mounted on the elements 118' and corresponding securing screws(not shown). Each of the heating elements 118 further comprises a porcelain casing z of rectangular box-like configuration open at one side to form a cavity therein, and a heat-ing coil h which is wound on a porcelain rod having terminal plates Q at opposite ends thereof and fixedly embedded in the cavity of the casing z with cement m or the like, with the tips of 20 the terminal plates ~ projecting out of the casing z for electrical connection thereto. Upon energization, the heating elements 118' heat the metallic base plate 118a up to a temperature of approximately 60C. Since the function and the electrical connections of the heating elements 118~ are similar to those described with reference to the element 18 of Figs. 4, 5 and 6, detailed description thereof is abbrevi-ated for brevity.
Referring now to Figs. 9 and 10, in order to assess the effect of harmful gases on a filter, the present inven-30 tors carried out a series of experiments employing a testing ~ 16 ~
~38S446 dcvice T as shown in Fig. lO.
The testing dcvice T includes an L-shaped glass tube 201 having an open enlarged portion, at one end there-of, in which a corona charger Cc connected to a high voltage source }-IV and an ammeter ~m is disposed, and having the other end thereof extending, through a cap Sl, into a vessel b containing pure water Pw therein, with an extreme tip of said other end immersed in the pure water Pw, a U-shaped glass tube 203 closed at opposite ends thereof and partially filled with active carbon Cf, an L-shaped glass tube 202 having one end thereof extending, through the cap Sl, into the vessel bl, with an extreme tip of said one end spaced away from the surface of the pure water Pw, and having the other end thereof in communication with one closed end of the U-shaped glass tube 203, an L-shaped glass tube 20~
having one end thereof in communication with the other closed end of the U-shaped glass tube 203 and having the other end thereof extending, through a cap S2, into a vessel b2 containing therein an absorbing liquid ~a of phenolphthalein 90 ml in quantity with an extreme tip of said other end immersed in the absorbing liquid Qa, and another L-shaped glass tube 205 having one end thereof extending, thTough the cap S2, into the vessel b2, with an extreme tip of said one end spaced away from the surface of said absorbing liquid ~a and having the other end thereof 205a communicated with a suitable air pump (not shown). In the experiments, four kinds of differently treated active carbon specimens (A), (B), (C) and (D) were employed, in which specimens, (A) was an active carbon left in the vapor of an organic solvent medium for 28 days, (B) was one left in the same vapor for lV85446 13 days, (C) was one which had bccn used for elimination of ozone foI 52 hours in the absence of the organic solvent medium vapor, and ~D) was one left in a room for 13 days. The air pump (not shown) employed had a flow rate o~ approximately 1000 ml/min., while the charging current of the corona charger Cc was in the region of 410 to 435 ~A. The active carbons (A), (B), (C) and (D) were tested, one by one, by the device T for the assessment of the ozone eliminating capacity thereof !
with sample gases containing predetermined amounts of ozone being passed through the tube 201, the vessel bl, the tube 202, the U-shaped tube 203, the tube 204, the vessel b2 and the tube 205, the results of which are shown in Fig. 9 in graphical form.
. As is clear from curves A, B, C and D in Fig. 9 representing behavior of the coIresponding active carbons (A), (B), (C)- and (D), the ozone eliminating ability of the active carbon filters is heavily deteriorated when such filters are subjected to the vapor of an organic solvent¦
medium.
2~ Referring now to Fig. 11, there is shown another modification of the prevention device W of Fig. 1. In this modification W", the air duct Dl and D2, and $he fan 7 and the louver 17 described as employed in:the embodiment of Fig. 1 are dispensed with, and a corona charger 3' dis-posed adjacent to the photoreceptor surface 2a and having an opening 3'b formed in the casing or shield 3'a thereof is enclosed within an open end of a casing Du fixedly pro-vided above the developing device C. The casing Du further - includes a fan 8' rotatably housed therein in a position adjacent to a closed end thereof, and a partition member - ' ' .
. . . . .. . ... . . . . . . . . . ~ .
1~854~6, d of approximately rectangular cross section fixedly disposed between the charger 3' and the fan 8' within the casing Du, and having one side thereof directed toward the correspond-ing side wall of the casing 3'a, with the other side thereof located adjacent to the fan 8' being closed. The top wall of the partition member d extending over the casing 3'a of the charger 3' has an opening Su corresponding to the opening
. . . . .. . ... . . . . . . . . . ~ .
1~854~6, d of approximately rectangular cross section fixedly disposed between the charger 3' and the fan 8' within the casing Du, and having one side thereof directed toward the correspond-ing side wall of the casing 3'a, with the other side thereof located adjacent to the fan 8' being closed. The top wall of the partition member d extending over the casing 3'a of the charger 3' has an opening Su corresponding to the opening
3'b of the casing 3' to allow air flow to pass therethrough, while an air passage ~ is formed between the top wall of the member d and the inner wall of the casing Du, in which passage a, a filter fl for example, of active carbon is disposed.
The bottom wall of the partition member d is spaced away from the corresponding bottom portion of the casing Du to define a passage ~ therebetween for circulation of air flow through the passage ~, thus another opening ex being formed between the corresponding edges of the bottom wall of -the - member d and the bottom portion of the casi~g Du adjacent to the photoreceptor surface 2a, which opening ex is com-municated with the opening su leading to the passage through the opening 3'b of the casing 3'a. The opening O3 formed in the apparatus housing la is provided with another filter f2 and a fan V mainly for discharging heated gases from the fixing device F and other gases generated in the housing la out of the apparatus.
- Upon rotation of the fan 8', the air within the casing Du circulates around the partition member d, and any gases present in the charger 3' are drawn, together with the circulating air, from the opening su, through the - opening 3'b of the charger 3', the filter fl in the passage ,;the passage ~ and the opening ex, back to the opening . 19 .
854~G
su, by which arrangement, reaction products due to discharg-ing of the corona charger 3' arc continuously eliminated as the same pass through the filter fl, thus the air free from any harmful reaction products being directed toward the photo-receptor surface 2a. Accordingly, disadvantages such as deterioration of the photoreceptor surface 2a, drawing the organic solvent medium vapor from the developing device C
into the filter fl and directing the heated gases from the fixing device F toward the photoreceptor surface 2a are advantageously eliminated.
It is another advantage of the preuention device W" of Fig. 11 that since the corona charger 3', the filter fl and the fan 8' are enclosed in the casing Du, with the air being merely circulated within the casing Du, the reac-tion products due to energization of the corona charger 3' are not discharged out of the apparatus housing la, and consequently the amolmt of harmful products to be exhausted out of the apparatus is almost negligible as compared with that from an apparatus in which such products are directly discharged out of the apparatus. The provision of the separate filter f2 and fan V is particularly effective for evacuating the heated air at the fixing device F, the gases - in the apparatus housing la and also for removing toner parti-, .
cles in cases where a developing device of the dry type is employ-ed.
It should be noted here that each one of the corona charger 3' and the filter fl described as employed in the modification of Fig. 11 is n~t limited to be one in number, but that the number, kinds or positions thereof may be suitably changed to meet the purpose within the scope of the 1~)8~4~i invention.
It i,s needless to say that the transferred image disturbance prevention device described mainly with reference to the copying apparatus of the wet developing type in the fore-going embodiments is readily applicable to a copying appa-Tatus of the dry developing type with minor alterations in the associated arrangement. Similarly, the transferred lmage dils-turbance prevention device described mainly with reference to the copying apparatus of the latent image transfer type in the foregoing embodiments is readily applicable to a copying ap-paratus of developed image transfer type.
Although the present invention has been 'fully ~~''' '' described by way of example with reference to the attached drawings, it should be noted that various changes and modlfi-cations are apparent to those skilled in the art. TherefoTe, unless otherwise such changes and modifications depart from 'the scope of the present invention, they should be construed ,, ,, , , ,as included therein.
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The bottom wall of the partition member d is spaced away from the corresponding bottom portion of the casing Du to define a passage ~ therebetween for circulation of air flow through the passage ~, thus another opening ex being formed between the corresponding edges of the bottom wall of -the - member d and the bottom portion of the casi~g Du adjacent to the photoreceptor surface 2a, which opening ex is com-municated with the opening su leading to the passage through the opening 3'b of the casing 3'a. The opening O3 formed in the apparatus housing la is provided with another filter f2 and a fan V mainly for discharging heated gases from the fixing device F and other gases generated in the housing la out of the apparatus.
- Upon rotation of the fan 8', the air within the casing Du circulates around the partition member d, and any gases present in the charger 3' are drawn, together with the circulating air, from the opening su, through the - opening 3'b of the charger 3', the filter fl in the passage ,;the passage ~ and the opening ex, back to the opening . 19 .
854~G
su, by which arrangement, reaction products due to discharg-ing of the corona charger 3' arc continuously eliminated as the same pass through the filter fl, thus the air free from any harmful reaction products being directed toward the photo-receptor surface 2a. Accordingly, disadvantages such as deterioration of the photoreceptor surface 2a, drawing the organic solvent medium vapor from the developing device C
into the filter fl and directing the heated gases from the fixing device F toward the photoreceptor surface 2a are advantageously eliminated.
It is another advantage of the preuention device W" of Fig. 11 that since the corona charger 3', the filter fl and the fan 8' are enclosed in the casing Du, with the air being merely circulated within the casing Du, the reac-tion products due to energization of the corona charger 3' are not discharged out of the apparatus housing la, and consequently the amolmt of harmful products to be exhausted out of the apparatus is almost negligible as compared with that from an apparatus in which such products are directly discharged out of the apparatus. The provision of the separate filter f2 and fan V is particularly effective for evacuating the heated air at the fixing device F, the gases - in the apparatus housing la and also for removing toner parti-, .
cles in cases where a developing device of the dry type is employ-ed.
It should be noted here that each one of the corona charger 3' and the filter fl described as employed in the modification of Fig. 11 is n~t limited to be one in number, but that the number, kinds or positions thereof may be suitably changed to meet the purpose within the scope of the 1~)8~4~i invention.
It i,s needless to say that the transferred image disturbance prevention device described mainly with reference to the copying apparatus of the wet developing type in the fore-going embodiments is readily applicable to a copying appa-Tatus of the dry developing type with minor alterations in the associated arrangement. Similarly, the transferred lmage dils-turbance prevention device described mainly with reference to the copying apparatus of the latent image transfer type in the foregoing embodiments is readily applicable to a copying ap-paratus of developed image transfer type.
Although the present invention has been 'fully ~~''' '' described by way of example with reference to the attached drawings, it should be noted that various changes and modlfi-cations are apparent to those skilled in the art. TherefoTe, unless otherwise such changes and modifications depart from 'the scope of the present invention, they should be construed ,, ,, , , ,as included therein.
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Claims (3)
1. An electrophotographic copying apparatus which comprises a rotatable photoreceptor member having a photoconductive surface for repeated formation of an electrostatic latent image of an original thereon, means disposed around said photoreceptor member and including corona charger means for uniformly charging said surface, exposure means for exposing said charged surface to image light of the original through an optical assembly including an illuminating light source so as to form the electrostatic latent image of the original thereon, and means for eliminating harmful gases generated by said corona charger means disposed within the copying apparatus, said means having duct means having one end adjacent said photoreceptor member and the other end opening out of the apparatus to the outside thereof and being divided into two portions extending along the length thereof, said corona charger means being in the end of one duct portion adjacent said photoreceptor member, and a line fan adjacent the other end of said duct and positioned relative to the two portions of said duct for drawing gases from around said corona charger means through said one duct portion toward said line fan and causing fresh air to flow toward the photoreceptor means through the other duct portion during rotation of said line fan.
2. An electrophotographic copying apparatus which com-prises a rotatable photoreceptor member having a photocon-ductive surface for repeated formation of an electrostatic latent image of an original thereon, means disposed around said photoreceptor member and including corona charger means for uniformly charging said surface, exposure means for exposing said charged surface to image light of the original through an optical assembly including an illuminating light source so as to form the electrostatic latent image of the original thereon, and means for eliminating harmful gases generated by said corona charger means disposed within the copying apparatus, said means having suction means for drawing away said harmful gases adjacent to the corona charger means and said surface, said suction means including first duct means having one opening adjacent to said corona charger means, and suction fan means connected with said first duct means for generating air flow in the first duct means for drawing said harmful gases generated within said corona charger means through said opening of the first duct means and toward said suction fan, and means for supplying fresh air free from harmful gases toward said photoconductive surface opposed to said corona charger means, said fresh air supplying means including second duct means, one end of the second duct means being adjacent to said photoconductive surface opposed to said corona charger means.
3. An electrophotographic copying apparatus which comprises a rotatable photoreceptor member having a photoconductive surface for repeated formation of an electrostatic latent image of an original thereon, means disposed around said photoreceptor member and including corona charger means for uniformly charging said surface, exposure means for exposing said charged surface to image light of the original through an optical assembly including an illuminating light source so as to form the electrostatic latent image of the original thereon, and means for eliminating harmful gases generated by said corona charger means disposed within the copying apparatus, said means having suction means for drawing away said harmful gases adjacent to the corona charger means and said surface, said suction means including first duct means having one opening adjacent to said corona charger means, and suction fan means connected with said first duct means for generating air flow in the first duct means for drawing said harmful gases generated within said corona charger means through said opening of the first duct means and toward said suction fan, and a filter means disposed within said first duct means for absorbing said harmful gases from said air flow generated by said suction fan means, and means for supplying fresh air free from harmful gases toward said photoconductive surface opposed to said corona charger means, said fresh air supplying means including second duct means, one end of the second duct means being adjacent to said photoconductive surface opposed to said corona charger means and the other end of said second duct means being connected with the discharge side of said suction fan means, whereby the air flow in the first duct means including said harmful gases is forwarded into the second duct means after passing through said filter means and is supplied to said photocon-ductive means through said one end of said second duct means.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP137974/1974 | 1974-11-30 | ||
| JP49137974A JPS5163630A (en) | 1974-11-30 | 1974-11-30 | |
| JP139735/1974 | 1974-12-04 | ||
| JP49139735A JPS5165941A (en) | 1974-12-04 | 1974-12-04 | |
| JP8147/1975 | 1975-01-16 | ||
| JP814775U JPS5190839U (en) | 1975-01-16 | 1975-01-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1085446A true CA1085446A (en) | 1980-09-09 |
Family
ID=27277902
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA239,866A Expired CA1085446A (en) | 1974-11-30 | 1975-11-18 | Electrophotographic copying apparatus |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | USRE30897E (en) |
| CA (1) | CA1085446A (en) |
| DE (1) | DE2553692A1 (en) |
| FR (1) | FR2293003A1 (en) |
| GB (1) | GB1514309A (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2750485C2 (en) * | 1977-11-11 | 1982-06-24 | Agfa-Gevaert Ag, 5090 Leverkusen | Electrostatic copier |
| JP2578841B2 (en) * | 1987-11-12 | 1997-02-05 | キヤノン株式会社 | Image forming device |
| US5307132A (en) * | 1987-11-12 | 1994-04-26 | Canon Kabushiki Kaisha | Image forming apparatus having a controller for discharging air in response to a heating condition of an image fixing device |
| JP2536564Y2 (en) * | 1990-02-13 | 1997-05-21 | 株式会社リコー | Image forming device |
| US5128720A (en) * | 1991-01-18 | 1992-07-07 | Eastman Kodak Company | Device for collecting contamination products and ozone from a corona charger |
| US5291247A (en) * | 1992-09-02 | 1994-03-01 | Eastman Kodak Company | Image forming apparatus having a corona ventilating means |
| JP4021712B2 (en) * | 2002-06-13 | 2007-12-12 | 株式会社リコー | Electrophotographic image forming apparatus and copying machine |
| JP4219864B2 (en) * | 2004-07-06 | 2009-02-04 | シャープ株式会社 | Image forming apparatus |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3324291A (en) * | 1964-07-06 | 1967-06-06 | Xerox Corp | Corona generating device with means to cause air flow therethrough to maintain the parts free of dust accumulation |
| US3288459A (en) * | 1965-03-01 | 1966-11-29 | Xerox Corp | Document feeding apparatus |
| US3382360A (en) * | 1965-09-10 | 1968-05-07 | Xerox Corp | Xerographic charging system having means for providing an air cushion between the charging device and the xerographic drum |
| US3386365A (en) * | 1967-01-16 | 1968-06-04 | Donald D. Jensen | Apparatus and method for producing a fog curtain heat shield |
| JPS5110785B1 (en) * | 1971-01-16 | 1976-04-06 | ||
| JPS4877844A (en) * | 1972-01-19 | 1973-10-19 | ||
| US3936184A (en) * | 1973-05-25 | 1976-02-03 | Canon Kabushiki Kaisha | Electrophotographic copying machine |
-
1975
- 1975-11-18 CA CA239,866A patent/CA1085446A/en not_active Expired
- 1975-11-24 GB GB48200/75A patent/GB1514309A/en not_active Expired
- 1975-11-28 DE DE19752553692 patent/DE2553692A1/en active Pending
- 1975-11-28 FR FR7536569A patent/FR2293003A1/en active Pending
-
1980
- 1980-06-24 US US06/162,610 patent/USRE30897E/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| FR2293003A1 (en) | 1976-06-25 |
| USRE30897E (en) | 1982-04-06 |
| DE2553692A1 (en) | 1976-08-12 |
| GB1514309A (en) | 1978-06-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |