JPS5931069B2 - Electrophotographic image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrophotography, and more particularly to improvements in image forming processes for obtaining good images.

The plate-shaped photoreceptor conventionally used in electrophotography comes into contact with the developer and other members during development or when unnecessary developer is removed from the surface of the photoreceptor. Easy to cause scratches. This makes it difficult for some conventional photoreceptors to be used in a stable state for a long period of time. A screen-shaped photoreceptor having a large number of fine openings has been invented as a photoreceptor that does not have the problems of the plate-shaped photoreceptor described above. These screen photoreceptors constructed of a grid or net of conductive members and a photoconductive member do not require steps such as removing unnecessary developer using strong frictional force. Therefore, regarding the above-mentioned problems, the screen photoreceptor can be used for image formation in a stable state for an extremely long period of time. However, when a corona discharge is applied to the screen photoreceptor for a long time, the surface state changes. The above-mentioned change in the surface condition of the photoreceptor means that microscopic dust particles of about 0.1 to 50μ and microscopic water droplets, etc. whose main component is silicon oxide (SiO2) floating in the air, are caused by corona discharge. It has been found that the cause is that the photoreceptor receives an electric charge, and as a result, the above-mentioned dust particles and the like adhere to the photoreceptor. That is, the dust particles adhering to the photoreceptor reduce the surface resistance value of the photoreceptor. In the case of a screen photoreceptor in which the flow of ions and the passage of charged toner particles are controlled by the potential generated at the openings, the decrease in the surface resistance value is particularly undesirable. The decrease in the resistance value inhibits the good passage of ion currents and the like through the photoreceptor aperture, resulting in the produced image having low contrast.If the surface resistance value further decreases, the produced image becomes unsuitable for practical use. Incidentally, the decrease in the surface potential of the screen photoreceptor is not only due to the adhesion of minute substances and minute water droplets as mentioned above, but also due to the fact that the photoconductive material, insulating material, etc. that make up the screen photoreceptor have a slight hygroscopicity. In some cases, the surface resistance of the screen photoconductor decreases due to the atmosphere (including indoor humidity due to air conditioning and weather conditions), and when the volume resistance of the photoconductive material decreases due to moisture absorption, the surface resistance of the screen photoconductor decreases. The contrast of the electrostatic latent image obtained is reduced. When the surface resistance decreases due to the atmosphere as described above, it is a problem because the quality of the created image deteriorates.
The present invention aims to solve the above-mentioned problems caused by a decrease in surface resistance of photoreceptors, and is particularly effective for screen photoreceptors. In the electrophotographic method of forming an image using a screen photoreceptor having a large number of fine openings, the present invention dries the screen photoreceptor during or before the image forming process, and improves the surface resistance of the photoreceptor. It is characterized by maintaining a high level of

The present invention also provides an electrophotographic image forming apparatus for forming images using the screen photoreceptor, in which heating means is provided near the moving path of the screen photoreceptor, and the screen photoreceptor passing near the heating means is heated. This is an electrophotographic image forming apparatus characterized by removing moisture. Furthermore, in the above-mentioned image forming apparatus, an electronic photograph characterized in that a casing for holding heated gas from the heating means is provided along the movement path of the screen photoreceptor at a position where movement of the screen photoreceptor cannot be prevented. It is an image forming apparatus. In the present invention, it is possible to use a resistance wire heater or a lamp that emits heat as a means for drying the screen photoreceptor, but it is also possible to use dry air or heated warm air to dry the screen photoreceptor. Filling the area near the body is also an effective means. However, when wind or hot air is actively applied to the screen photoreceptor, care must be taken to ensure that there is no harmful dust in the air. Otherwise, the dust mixed in the gas flow applied to the photoreceptor will clog the opening of the photoreceptor, and furthermore, the silicon oxide dust will cause a decrease in the surface resistance of the photoreceptor. The reason why it is also effective in the above-mentioned image formation to forcibly apply dehumidified gas using a static eliminator, desiccant, etc. to the screen photoreceptor as a gas flow for drying the screen photoreceptor has already been described. Here, we will explain how to apply temperature (including appropriate hot air) to the screen photoreceptor, which can achieve even greater effects. That is, when applying a gas flow to the screen photoreceptor in this way,
It is preferable to use a dust removal means, and as the dust removal means, it is preferable to use a general filter such as a cloth filter for coarse dust of about 50 μm or more, and to use an electric precipitator for finer dust. When using this electrostatic precipitator, warm air within a suitable temperature range improves the behavior of ions emitted from the electrodes of the precipitator, increasing the dust collection effect. Another advantage of using warm air is that the warm air increases the relative humidity near the screen photoreceptor, which improves the screen photoreceptor compared to the humidity in the room such as an office where the device is installed. Allows the body to dry. Furthermore, removing moisture from the photoreceptor itself maintains a good insulation state of the insulating member and photoconductive member that make up the surface of the screen photoreceptor, and as a result, it is possible to charge the screen to a sufficient potential. This makes it possible to form a particularly preferable primary electrostatic latent image with a high potential.
Furthermore, since the attenuation of the primary latent image can be reduced, it is effective in retention copying. Furthermore, when applying hot air is used as the dehumidifying means, depending on the characteristics of the photoconductive member used,
It activates the charge action inside the photoconductive member and obtains good results in primary latent image formation. If the hot air is made to exist around the screen photoreceptor, it becomes possible to apply the corona discharge used as a latent image forming means with high efficiency. Furthermore, when the surroundings of the screen photoreceptor are high temperature, the above-mentioned dust adhering to the photoreceptor also removes the hot air sucked in, thereby further accelerating the drying of the photoreceptor and obtaining the above effect. . As for the temperature of the hot air, if you want to warm up the screen photoreceptor for a short time, you can blow hot air at about 50 to 60°C, but if you want to keep warm air around the photoreceptor all the time, you can blow it around room temperature. It is sufficient to use warm air heated to 5 to 10°C. Note that the optimum temperature of the hot air has a slightly higher or lower range depending on the characteristics of the screen photoreceptor used, and the present invention is not limited to the above range. Hereinafter, the present invention will be described in further detail according to Examples and embodiments.

In the present invention, the term "primary electrostatic latent image" refers to an electrostatic latent image formed on a screen photoreceptor (hereinafter simply referred to as "screen") according to an original image in a predetermined process, and refers to a secondary electrostatic latent image. An electrostatic latent image refers to a latent image formed on a chargeable member by modulating the ion flow using the primary electrostatic latent image, and a retention copy refers to a latent image formed by modulating the ion flow using the primary electrostatic latent image. This means forming an image over a period of time. First, FIG. 1 is an enlarged sectional view showing the structure of a screen used in an embodiment of the present invention described below. Also, according to Figures 2 to 5,
An example process for forming a latent image using the screen shown in FIG. 1 will be described. Note that the present invention can of course be applied to screens other than those described here, and is by no means limited to these screen configurations or latent image forming processes. A screen 1 shown in FIG. 1 has a photoconductive member 3 and an insulating member 4 arranged in a laminated manner on a conductive member 2 having a large number of fine openings so that the conductive member 2 is exposed.

The conductive member 2 is made by etching a metal plate such as stainless steel or nickel to form fine openings, electroplating, or weaving metal wires into a net shape.

A mesh value of 100 to 400 would be appropriate for the conductive member 2 for copying purposes from the viewpoint of resolution. The photoconductive member 3 is produced by vapor deposition of a Se alloy or the like, or by spray coating with a dispersion of an insulating resin containing particles of Cds, pbO, or the like. The insulating member 4 may be made of a solvent-based organic insulating material such as epoxy resin, acrylic resin, silicone resin, etc. by spraying or vacuum deposition. As for the material and manufacturing method of the screen, the technology for plate-shaped photoreceptors in conventional electrophotography can be applied. In addition, the conductive member 2
In order to create the members 3, 4 so as to expose the conductive member 2, it is possible to cover the conductive member 2 from one side or grind the members 3, 4 that have gone around.

2 to 5 are explanatory diagrams showing the process of forming an electrostatic latent image using the screen 1, which has the characteristic that holes can be injected into the photoconductive member even in a dark area. Take the screen shown below as an example.

In the figure, the photoconductive member 3 uses holes as its main carrier. S
A semiconductor made of e or its alloy is used. Figure 2 is 1
The results of the next voltage application step are shown, and the insulating member 4 is uniformly charged with negative polarity using a charging means such as a corona discharger.

Due to the above-mentioned charging, holes are transferred to the photoconductive member 3 via the conductive member 2.
is injected into the interior of the insulating member 4 and captured at the interface near the insulating member 4.
Note that 5 in the figure indicates a corona discharger. Figure 3 shows the results of performing the secondary voltage application process and the image irradiation process almost simultaneously.
As the next voltage application, a corona discharge using a voltage obtained by superimposing a positive bias voltage on an AC voltage is used as a power source.

In the figure, reference numeral 6 indicates a bright area D of a document serving as an original image, a dark area, 7 a light beam, and 8 a corona discharger. Through each of the above steps, an electrostatic latent image is formed on the screen 1, and the electrostatic contrast of the latent image is increased over time or by full-surface irradiation to form a primary electrostatic latent image. FIG. 4 shows the results of irradiating the screen 1 over its entire surface.

Due to this entire surface irradiation, the surface potential of the screen 1 does not change in bright areas, but rapidly changes to a potential proportional to the amount of surface charge on the insulating member 4 in dark areas, forming a primary electrostatic latent image.
Note that 9 in the figure indicates a light ray. FIG. 5 shows a state in which the ion flow is modulated by the primary electrostatic latent image on the screen 1, and a positive image of the original image due to charges is formed on the recording member.

In the figure, 10 is a corona wire of a discharger, 11 is an electrode member, 12 is an image carrier capable of retaining charges (hereinafter referred to as copying paper as an example), and 13 and 14 are power sources. The above copy paper 12
is placed near the insulating member 4 side of the screen 1, while the wire 10 is placed on the side of the screen 1 where the conductive member 2 is exposed, and the corona ion flow from the wire 10 is directed between the wire 10 and the electrode member 11. is applied to the copy paper 12 using the potential difference. At this time, in the bright portion of the screen, an electric field indicated by a solid line α is generated due to the charges forming the primary electrostatic latent image. From this, the ion flow indicated by the chain line is prevented from passing through the screen and flows into the exposed conductive member 2. On the other hand, screen 1
An electric field indicated by a solid line β is generated on the dark side of the ion beam, and the ion flow reaches the copy paper 12 without canceling the electrostatic latent image, although it has a polarity opposite to that of the primary electrostatic latent image. Note that since the primary electrostatic latent image is formed on the insulating member 4 as described above, it is possible to make the electrostatic contrast based on the amount of charge extremely high. Furthermore, since the attenuation of the formed charge can be minimized, secondary electrostatic latent images can be formed many times using the same primary electrostatic latent image, and many copies of the image can be created using the same primary electrostatic latent image. It becomes possible to obtain a retention copy. Next, the present invention will be explained in more detail according to embodiments.

This embodiment is an electrophotographic copying apparatus shown in the sectional view of FIG. 6, in which the screen described in FIG. 1 is used as the photoreceptor. In FIG. 6, a copying device 15 is a device that can create a large number of copied images at high speed, and the casing 1
A drum-shaped screen 17 having the same structure as the screen 1 is installed inside the screen 6 in a structure in which a conductive member is exposed on the inner surface. The support body that supports the screen 17 in a cylindrical shape has a ring-shaped member at both ends and a connecting band extending in the direction of the rotation axis that connects the members, and the screen is inserted into the opening formed by the ring-shaped member and the connecting member. Attach with adhesive, etc. Furthermore, removable flanges are installed on both sides of the support, and by removing the flanges, the corona discharger can be installed or adjusted inside the support. A ball bearing is fixed in the center of the flange, and the bearing part is connected to the fixed shaft 1.
8 , the support body having the screen 17 becomes rotatable around the shaft 18 . A corona discharger 19 is arranged near the screen 17, which is rotated in the direction of the arrow by a drive means (not shown), and applies a primary voltage. 20 is a corona discharger that applies a secondary voltage, and the discharger 20 has a shield plate on the opposite side of the screen 17 that is optically open, and simultaneously discharges and irradiates the original image. Further, 21 is a lamp for irradiating the entire surface.

A corona discharger 22 placed inside the screen 17 is provided for the purpose of keeping the amount of modulated ions constant.When modulating the ion flow using the primary electrostatic latent image,
During the modulation of the ion flow or when the modulation is stopped, the ion flow containing ions of opposite polarity to the modulation ion flow is passed through the screen 1.
This is a corona discharger added to 7. Reference numeral 23 provided to the discharger 22 via the screen 17 is an auxiliary electrode, which is made of an insulating material or a conductive material, and in the case of a conductive material, a voltage of the same polarity as that of the corona discharge may be applied. This discharger 2
A corona discharger 24 provided adjacent to 2 is a discharger for forming a secondary electrostatic latent image, and both of these dischargers 22 and 24 are fixed by a rail 26 provided on the insulating block 25 of the fixed shaft 18. It is removably mounted in the axial direction. Reference numeral 27 denotes a pre-irradiation lamp which causes fatigue on the screen due to initial image irradiation and prevents this from appearing in the image.

The wall 28 provided so as to surround a portion of the latent image forming means and the screen 17 is for preventing dust from adhering to the screen 17 and for performing the screen drying of the present invention well. And 29 is a screen drying hot air generating means, and this generating means 29 includes the air blowing section 29A and the heating section 2.
9B, dust collection section 29C, blowing section 29D to screen 17
have. Next, regarding the image irradiation system, there is a document placement section 30 in the upper part of the housing 16.
has a document holding plate 31 made of a flexible material and a document mounting table 32 made of glass.

Further, above the mounting section 30 is a first mirror 33 that scans the entire stroke of the mounting section, and moves 1/2 distance in the same direction as the mirror 33 at 1/2 the speed of the mirror 33. A second mirror 34 is arranged. Note that the support body 3 of the mirror 33
A lamp 37 for illuminating the original is fixedly attached to the screen 5 , and the support 35 and the support 36 of the second mirror 34 operate in synchronization with the rotation of the screen 17 . The original image reflected by the second mirror 34 reaches a lens section 38 having an aperture mechanism, and further changes its optical path by a third mirror 40, a fourth mirror 41, and a fifth mirror 42, and reaches the screen 17. In the figure, numeral 39 denotes a housing having a lens portion 38 and mirrors 40, 41, and 42 fixed thereto. Next, regarding the system for forming a visible image, numeral 43 facing the corona discharger 24 via a screen is an insulating drum, which is rotated in the direction of the arrow by a drive means (not shown) about a shaft 43A. The insulating drum 43 has an insulating layer of 5 to 100 μm made of mylar material on an aluminum conductive drum serving as a support, and a bias voltage is applied to the conductive drum portion when forming a secondary electrostatic latent image. do. A developing device 44 around the insulating drum 43 performs development while conveying the toner around the magnetic poles. A paper feed table 45 is arranged below the developing device 44, and has the capacity to load approximately 2,000 to 4,000 sheets of copy paper 46, and is arranged such that the top of the copy paper 46 is always at a constant height. The uppermost position is optically detected and automatically set at a predetermined position by a driving means (not shown) depending on the amount of copy paper used. The copy paper 46 is sent out from the top by a feed roller 47 and reaches a developed image transfer section 50 by a pair of transport rollers 48 and 49. In the transfer section 50, 51 is a corona discharger for transfer, 52 is a corona discharger for facilitating separation, 53 is a separation means, and includes an endless belt 54 with holes, a suction mechanism 54A, and a suction mechanism 54A of the belt. It has suspended conveyance rollers 55, 56, and 57. The copy paper 46 separated by the separation means 53 is transferred to a conveyor belt 58.
The image reaches the fixing device 59. The fixing device 59 is a roller type fixing device using a heat roller 60 having a heat source disposed inside. The copy paper 46 that has passed through the fixing device 59 is conveyed to a paper discharge tray 62 by a pair of conveyance rollers 61. Reference numeral 63 provided around the insulating drum 43 is a cleaning means. Excess developer on the drum 43 is rubbed off by a cleaning blade 64 of the means 63, and the drum 43 is further cleaned by a corona discharger 65. After the residual charge on the image forming apparatus 43 is removed, the image forming apparatus 43 is prepared for the next image forming process. Hereinafter, an embodiment of the above-mentioned copying apparatus will be described. The screen 17 has a 250-mesh metal net made of woven stainless steel wires with a diameter of about 30 μm as a conductive member as a base, and on top of that a Cds resin dispersion and resin insulators. are sequentially applied from one side by a spray method, and the maximum thickness of the photoconductive member is approximately 40 μm and the insulating member is approximately 510 μm, thereby obtaining the structure shown in FIG. 1 above.

The support supporting the screen 17 starts rotating in the direction of the arrow when the main switch is turned on, and at the same time hot air is blown from the hot air generating means 29 in the direction of rotation of the screen 17, drying one screen and drying other screens. gives the screen the effect of The above screen 17 has a circumferential speed of 160 m.
After rotating at m/Sec and receiving uniform light irradiation from the lamp 27, the corona discharger 19 applying +8k
While receiving the secondary voltage application by the corona discharger 20 to which the AC 8kv was applied, the bright area was
1ux. The original image is irradiated for about seconds. And the screen 17 is 4001ux by the lamp 21. sec
By irradiating the entire surface with irradiation, a primary electrostatic latent image having an electrostatic contrast of 300V is obtained on the screen 17. Thereafter, the secondary electrostatic latent image is formed by rotating the screen 17 and the insulating drum 43 in the direction of the arrow at a circumferential speed of 400 m71/Sec. At this time, the distance between the two members 17 and 43 is set to three times at the ion modulation position, the conductive support of the insulating drum 43 is grounded, and -5k is applied to the conductive member of the screen 17. and corona discharger 2
4 -12k (-7 for the conductive member of the screen 17
Kv), and -5k for the shield member of the discharger 24.
A voltage of v is applied to form a secondary electrostatic latent image. As a result, a secondary electrostatic latent image with a potential contrast of 500 between the bright and dark areas of the original image is obtained on the insulating layer of the drum 43.
The latent image formed as described above is developed in a developing device 44 using positively charged toner. By the way, if retention copying is performed only by the above process, 100
After the second ion modulation, the potential contrast on the insulating layer decreases to 350 V, which tends to cause a slight decrease in density in the developed image. To solve this problem, the corona discharger 22 has +2 kV (screen 17
A voltage of +7kv) is applied to the conductive member of the discharger 22, and the auxiliary electrode 23 of the discharger 22 is
An adjustment process performed by applying −8 kV at a distance may be incorporated into the retention copy. The above adjustment process is preferably performed about once every two times of ion modulation, and the result is 10
At the end of 0 retention copies, the potential contrast decreases by only about 8%, and the image after development is the same as the first one.
There is almost no difference from the image created by the second modulation. By the way, in order to perform retention copying in a better condition, the voltage applied to the discharger 24 may be changed according to the number of copies, and in this case, the voltage applied to the discharger 22 may be changed to It may be controlled in relation to the value of . The visualized image on the insulating layer created as described above is transferred to copy paper conveyed from the paper feed tray 45 at the transfer section 50. Thereafter, the copy paper 46 with the toner image is separated by a separating means 53 and fixed by a fixing device 59, and then placed on a paper output tray 62.
The image is automatically conveyed to the top, and the formation of the copy image is completed. By the way, the hot air from the hot air generating means 29 is used to promote and maintain drying of the screen 17 by the wall 28 provided so as to surround the starne 17, thereby maintaining good latent image formation. Furthermore, since the hot air from the generating means 29 has gone through a dust removal process, there is no fear of dust etc. adhering to the screen 17, and since the air pressure around the screen 17 is higher than the outside of the wall 28, toner and Surrounding dust, etc. may cause damage to the wall 2.
It also prevents it from entering the inside of 8. Hereinafter, the hot air generating means 29 that produces these various effects will be explained in more detail with reference to FIG. FIG. 7 is a perspective view of the hot air generating means 29, with some of the constituent parts cut away to clearly show the internal structure.

The warm air generating means 29 includes a blowing section, a heating section, and a heating section in the order of movement of the wind.
It is divided into four parts: a dust collection part and a blowing part, and the sucked air is heated, removed from dust, and then blown onto the screen. Hereinafter, each part will be explained in detail in order C according to the air flow path. A support side plate 68 that supports the blower fan 66 and duct 67 in the blower section 29A is firmly supported by a blower fan support stay 69, and the stay 69 has an opening in the passageway portion through which the airflow can flow. .

Furthermore, the stay 69 constitutes a part of the device main body. It is firmly supported on the side plate 70. The blower fan 66 is rotated by a drive source such as a motor (not shown), and the airflow in the direction of the arrow by the fan 66 is directed to a dust removal filter 71 installed on the side of the blower fan 66 of the support stay 69 so that it can be pulled out and replaced.
The first dust removal is performed through the By the way, this filter 71 is made of a fiber material and is used mainly for the purpose of removing coarse dust, and the installation position of the filter 71 is not limited to the above, but may be on the air suction port side of the blower fan 66. Next, explaining the heating section 29B, a heating section branch stay 72 is firmly supported on the side plate 70, and an L-shaped member 73 is fixed on both sides of the stay 72 with screws or the like. A heater 74 is detachably attached to the heater 74.

The heater 74 has a casing 75 made of a heat insulating material such as asbestos so as to surround the air flow path, and a heater 76 made of a coiled nichrome wire or the like is installed inside the casing 75. . Preferably, this heater 76 can increase the heating efficiency of the air flow by increasing its contact area with the air flow, and may have a sheet shape in addition to a coil shape. By the way, the end of the heater 76 is fixed to a heat insulating plate 77 with screws or the like, and the heater 76 is configured to generate heat by applying a voltage to the heater 76 from the outside. The airflow that has passed through the heating section 29B then reaches the dust collecting section 29C in a heated state. In the dust collecting section 29C, a dust collector 79 is fixed to a dust collecting section support stay 78 firmly supported on the side plate 70 with screws.

The dust collector 79 has a configuration in which a needle-shaped discharge electrode 80 made of a conductive thin plate is fixed to a conductive support member 81 connected to a high-voltage power supply section with insulating screws 82 such as resin screws. Further, both ends of the support member 81 are sandwiched between insulating members 83 such as ceramics. Conductive thin plates 8 are provided at the upper and lower parts of the member 83.
4 is fixedly installed, and the member 83 and thin plate 84 constitute an airflow passage. The air flow further reaches the blowing section 29D described below due to the wind pressure from the fan 66. The blowing section is provided in order to uniformly and in a preferable direction give to the screen 17 a flow of air that has been heated and dust-removed by the heating section 29B and the dust collection section 29C. This blowing part 29D has a structure in which a duct 86 is firmly supported by a duct stay 85 whose both ends are fixed to the side plate 70, similarly to the above-mentioned parts. The duct 86 has an air flow dispersion plate 87 installed inside the duct so that the blown air flow is uniform before reaching the screen 17.
will be established. By the way, in this embodiment, the air flow is
However, depending on the rotation or movement speed of the screen, the blowing direction is not limited to the above state, and severe turbulence etc. may occur. It is best to set it in a direction that prevents this.

In the embodiment which is an embodiment of the present invention described above, the hot air generating means 29 is shown in a state where each part is separated in the figure, but in reality, a shielding member is used to prevent the atmosphere around the generating means 29 from mixing. to seal the gap.

Now, considering the arrangement of each part constituting the generation means 29, in this embodiment, it is constructed in the order of the blowing part 29A1, the coarse dust removal filter 71, the heating part 29B, the dust collection part 29C, and the blowing part 29D. be. By removing dust from the heated air stream using an electric precipitator, the dust can be charged in a sufficiently dry state, so that it can be sufficiently charged and the dust removal efficiency can be increased. Further, by generating corona discharge in heated air, the amount of discharge can be increased, which is preferable. The operation of the warm air generating means 29 will be described below. First, a rotor-type fan 66 was used for the air blowing section 29A, but it is preferable to a screw-type fan in the sense that it sends airflow in the direction of the rotation axis of the screen 17.

Next, the filter 71 is provided for the purpose of removing comparatively coarse dust of 50 μm or more using a fiber-filled bed filter or a cloth filter. The heating section 29B heats the air flow and absorbs moisture, but excessive heating leads to thermal expansion of the screen 17, which is undesirable as it causes the screen 17 to sag or become distorted. Furthermore, heating of excess soil may have an adverse effect on other constituent members or reduce dust collection efficiency, so it is preferable to use a heating temperature that has relatively small thermal expansion and that provides excellent ionic behavior without reducing dust collection efficiency. In addition to room temperature, a temperature of about 5 to 10° C. is suitable for the above-mentioned device configuration. The heating temperature depends on the shape of the screen used.
Material. The permissible range is determined according to characteristics and other conditions. By the way, as a temperature control means for the heating section 29B, a conventional heat-sensitive member is provided near the heater 76 or in the air flow path. Incidentally, in addition to the heating means, it is also possible to use a dryer using a desiccant. Furthermore, in the dust collection section 29C, 0
．． The purpose is to remove relatively fine dust of about 1 to 50 microns. There are many types of dust collection methods, but filter-based ones are undesirable because they impair the flow of air, whereas electrostatic precipitators like the one in the embodiment are suitable because they do not block the flow of gas. The principle of dust collection is that fine dust is charged by corona ions from the electrode, and is pulled to the dust collection electrode by the action of the surrounding electric field, thereby collecting the dust. Therefore, a needle end-shaped electrode is preferable to a wire-shaped electrode because it is relatively easier to obtain a discharge current as a discharge electrode, but a wire-shaped electrode may of course be used. In addition, as for the voltage applied to the electrode, it is preferable to apply a voltage of negative polarity in order to obtain a large discharge current.On the other hand, in the embodiment device, the flow rate of the air flow is determined by the heating capacity of the heating section 29B and the dust collection efficiency of the dust collection section. From this point of view, 1 to 0.1 m/Sec is preferable. In the final blowing section 29D, a duct applies a heated airflow uniformly to the screen. To this end, a dispersion plate is placed inside the duct in an appropriate direction, and in embodiments where the screen is configured in a drum shape, it is placed approximately tangential to the screen in order to prevent pressure loss in the air flow. . As described above, the present invention makes it possible to form a latent image in good condition by drying the screen.
That is, it is possible to form a primary electrostatic latent image with a high potential, and furthermore, it is possible to minimize the attenuation of the formed primary latent image, resulting in a great effect on retention copying. Further, by applying hot air for the drying process, corona discharge for forming a latent image can be performed with high efficiency. Furthermore, since the moisture contained in the dust adhering to the screen is also removed, the drying of the screen is further promoted and the above-mentioned effect is enhanced. Although a screen having a three-layer structure is illustrated in FIG. 1 as an example, the present invention is not limited to the screen illustrated in any way in terms of the shape and structure of the screen.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view illustrating the configuration of an exemplary screen;
Figures 2 to 4 are explanatory diagrams of the primary latent image forming process using the screen in Figure 1, Figure 5 is an explanatory diagram of the secondary latent image forming process, and Figure 6 is an image forming process according to the present invention. FIG. 7 is a diagram illustrating the configuration of a copying machine showing an embodiment of the apparatus, and is a partially cutaway perspective view of a hot air generating means embodying the present invention. In the figure, 1... Screen, 2...
Conductive member, 3...Photoconductive member, 4...
Insulating member, 5... Corona discharger, 6...
・Manuscript, 10...Corona wire, 11...
...Electrode member, 15... Copying device, 16...
... Housing, 17 ... Screen, 19.20
．． 22.24... Corona discharger, 21.27.
... Lamp, 29 ... Warm air generation means, 2
9A...Blower section, 29B...Heating section,
29C...Dust collecting section, 29D...Blowing section, 30...Document placement section, 33.34.40.4
1.42...Mirror 37...Lamp, 43...Insulated drum, 44...Developer, 45...Paper feed tray, 46...Copy paper, 50...Transfer section, 53...Separation means, 59...Fixer, 66...Blower fan, 67...Duct, 71...Railter, 74...Heater, 76...Heater, 77...Insulation plate, 79... ...Dust collector, 86...Duct.

Claims (1)

[Claims] 1 A drum-shaped screen photoreceptor, a wall that encloses the screen photoreceptor, and a means for introducing dust-removed heated air into the wall, and the dust-removal/heated air introduction means is a blowing means. An electrophotographic image forming apparatus comprising: a heating means disposed sequentially in the direction of air flow; and an electrostatic precipitator utilizing a corona discharge phenomenon.