JP2003043894A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove the electric discharge products sticking to a photoreceptor surface and to obstruct the abnormal image occurring in such electric discharge products with an image forming device which forms the image by electrostatically charging the photoreceptor, exposing the photoreceptor after the electrostatic charge to form an electrostatic latent image, forming this electrostatic latent image to a visible image as a toner image and transferring this toner image to a transfer material. SOLUTION: Product removing means 13 having a product removing member 30 deposited with zeolite is touched to the surface of the photoreceptor 1 and this zeolite is contacted with the photoreceptor surface to adsorb the electric discharge products sticking to the photoreceptor surface on the zeolite and even more an electrostatic charger 3 is arranged in a dry atmosphere and the photoreceptor 1 is electrostatically charged in the dry atmosphere, by which the amount of the electric discharge products sticking to the surface of the photoreceptor 1 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charger for charging a photosensitive member, an exposing unit for exposing the charged photosensitive member to form an electrostatic latent image on the photosensitive member, and an electrostatic latent image for the electrostatic latent image. The present invention relates to an image forming apparatus having a developing device that visualizes a toner image.

[0002]

2. Description of the Related Art In an image forming apparatus of the above type, which is configured as a copying machine, a facsimile machine, a printer, or a multifunction machine having at least these two functions, a charger accompanies a discharge around the photosensitive member during operation. Is provided, the discharge product generated by the discharge adheres to the surface of the photoconductor, and the discharge product absorbs moisture in the air when the humidity is high to reduce the resistance, thereby reducing the resistance of the surface of the photoconductor. Lower. This may cause an abnormal image such as an image blur on the photoconductor. If a member that presses against the surface of the photoconductor, such as a cleaning member, is configured to scrape off the photoconductor surface in a relatively large amount together with the discharge products, the occurrence of abnormal images can be prevented. Inevitably suffers from shortcomings.

Therefore, various structures have been proposed in the past for removing the discharge products attached to the surface of the photoconductor while suppressing the life of the photoconductor. For example, a discharge product removing device having a water applying member for applying water to the surface of the photoconductor and a water removing member for removing water from the surface of the photoconductor is one example (see Japanese Patent Laid-Open No. 60-49352). . This discharge product removal device utilizes the property that the discharge product generated on the surface of the photoconductor dissolves in water, and has the advantage of being able to remove the discharge product relatively effectively.

However, since the surface of the photoconductor is generally hydrophobic, when water is applied to the surface of the photoconductor, the water becomes sparse water droplets due to the hydrophobicity of the surface of the photoconductor. Adhere to. Therefore, when water is applied to the surface of the photoconductor, even if the discharge product dissolves in the water, the aqueous solution containing the discharge product becomes water droplets and adheres to the surface of the photoconductor in a sparse manner. Such water droplets are wiped off, but at the time of the wiping off, the water droplets on the surface of the photoconductor exist in a sparse state. Therefore, the effect of removing the discharge products may be different, and the characteristics of the surface of the photoconductor after wiping may become non-uniform.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus of the type described at the beginning that avoids the drawbacks of the conventional proposals and reduces the occurrence of abnormal images even more effectively. To provide.

[0006]

In order to achieve the above-mentioned object, the present invention provides an image forming apparatus of the type described at the beginning with a polar adsorbent for adsorbing discharge products adhering to the surface of a photoreceptor. A product removal preventing means is provided, and a product adhesion preventing means that makes it difficult for the discharge product to adhere to the surface of the photoconductor, and a resistance lowering preventing means that prevents the discharge product adhered to the surface of the photoconductor from having a low resistance. An image forming apparatus is provided, which is provided with at least one of product generation preventing means for reducing the amount of discharge products generated near the surface of the photoconductor (claim 1).

In order to achieve the above-mentioned object, the present invention also provides, in an image forming apparatus of the type described at the beginning, a product removing means provided with a polar adsorbent for adsorbing the discharge products adhering to the surface of the photoconductor. An image forming apparatus is provided in which at least a part of the charger is arranged in a dry atmosphere so that the charger is charged in a dry atmosphere.

Further, in order to achieve the above object, the present invention provides an image forming apparatus of the type described at the beginning with a product removing means provided with a polar adsorbent for adsorbing the discharge product adhering to the surface of the photoreceptor. And a dry air applying unit for applying dry air to the surface of the photoconductor, and the charger is arranged so that the charger charges the surface of the photoconductor to which the dry air is applied. An image forming apparatus is proposed (claim 3).

Further, in order to achieve the above object, the present invention provides, in an image forming apparatus of the type described at the beginning, a product removing means including a polar adsorbent for adsorbing a discharge product adhering to the surface of a photoconductor. According to another aspect of the present invention, there is provided an image forming apparatus, characterized in that a heat ray irradiation unit that irradiates a heat ray is provided between the charger and the photoconductor.

In order to achieve the above-mentioned object, the present invention further comprises, in the image forming apparatus of the type described at the beginning, a product removing means provided with a polar adsorbent for adsorbing the discharge product adhering to the surface of the photoconductor. According to another aspect of the present invention, there is provided an image forming apparatus, characterized in that the image forming apparatus is provided between the charger and the photoconductor and provided with a product adsorbing unit that adsorbs a discharge product by a polar adsorbent (claim 5).

Further, in order to achieve the above-mentioned object, the present invention further comprises, in the image forming apparatus of the type described at the beginning, a product removing means provided with a polar adsorbent for adsorbing the discharge product adhering to the surface of the photoreceptor. An air blowing unit that blows dry air to a portion of the surface of the photoconductor that is downstream of the charging position of the charger and upstream of the exposure position of the exposing unit with respect to the moving direction of the photoconductor surface. An image forming apparatus characterized by being provided is proposed (claim 6).

Further, in the image forming apparatus according to any one of claims 1 to 6, the surface of the photoconductor is set to a value in the range of -500V to -600V or +5 by the charger.
It is advantageous to configure it to charge to a value in the range 00V to + 600V (claim 7).

Further, in the image forming apparatus according to any one of claims 1 to 7, in the moving direction of the surface of the photoconductor, it is located downstream of the charging position by the charger and is exposed by the exposing means. A leveling charger that contacts the surface of the photoconductor on the upstream side of the position to level the surface potential of the photoconductor is provided, and a polar adsorbent is carried on the part of the leveling charger that contacts the photoconductor surface. However, it is advantageous that the leveling charger is configured to serve as the product removing means (claim 8).

Further, in the image forming apparatus described in claim 8, it is advantageous that the leveling charger is composed of a roller which rotates while contacting with the surface of the photoconductor (claim 9).

Further, in the image forming apparatus according to claim 8 or 9, it is advantageous to provide a cleaning means for cleaning the leveling charger (claim 10).

Further, in the image forming apparatus according to any one of claims 8 to 10, in the moving direction of the surface of the photoconductor, the exposure means is located downstream of the leveling position by the leveling charger. And a second sensor for detecting the surface potential of the surface of the photoconductor on the upstream side of the exposure position, and a second sensor for detecting the surface potential of the leveling charger. Advantageously, the value of the voltage or current applied to the leveling charger is controlled based on the detection result of the sensor (claim 11).

Further, in the image forming apparatus according to any one of claims 1 to 11, the polar adsorbent is at least one of zeolite, silica-alumina adsorbent, silica gel, alumina gel, activated alumina, and activated clay. Advantageously, it consists of one (claim 12).

Further, in the image forming apparatus according to any one of claims 1 to 11, it is advantageous that the polar adsorbent is made of zeolite and the oxygen ring of the molecular structure of the zeolite is a 6-membered ring or more. (Claim 13).

Further, in the image forming apparatus according to any one of claims 1 to 11, the polar adsorbent is made of zeolite, and the molecular structure of the zeolite has 8 oxygen rings.
Advantageously, it is more than a member ring (claim 14).

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 are schematic partial cross-sectional views showing respective embodiments of the image forming apparatus. First, the common structure and operation of these illustrated image forming apparatuses will be clarified. The image forming apparatus has a drum-shaped photoconductor 1 provided in its main body, and the photoconductor 1 is rotationally driven in the clockwise direction (the direction of arrow A) in these figures with the start of the image forming operation. It At this time, the surface potential of the photoconductor 1 is initialized by the charge eliminating means. In the illustrated example, a charge eliminating means having a charge eliminating lamp 2 is provided, and the surface of the photoconductor 1 is irradiated with light from the charge eliminating lamp 2 to undergo a charge eliminating action to initialize the surface potential thereof. It on the other hand,
A DC voltage or a charging voltage obtained by superimposing an AC voltage on a DC voltage is applied to the charger 3 arranged to face the photoconductor 1,
The discharge generated thereby uniformly charges the initialized surface of the photoconductor to a predetermined polarity, for example, −900V.

Instead of the drum-shaped photosensitive member, an endless belt-shaped photosensitive member which is wound around a plurality of rollers and driven to run can be used. In either case, the surface of the photosensitive member moves. To be supported. Further, in the illustrated example, a scorotron type charger 3 having a corona wire to which a charging voltage is applied and arranged apart from the surface of the photoconductor is used. It is also possible to use a charging roller that is arranged separately, a charging brush or a charging blade that comes into contact with the surface of the photosensitive member, and in the case of these charging devices as well, a predetermined charging voltage is applied. The surface of the photoconductor is charged by the generated discharge.

The surface of the photoconductor charged as described above is irradiated with the light-modulated laser beam L emitted from the laser writing device 5 which is an example of the exposure means, whereby an image signal is formed on the surface of the photoconductor. A corresponding electrostatic latent image is formed. The potential of the surface of the photoconductor that is irradiated with the laser light is, for example, −150 V, this becomes an electrostatic latent image, that is, an image portion, and the potential of the surface of the photoconductor that is not irradiated with the laser light is maintained at approximately −900 V. Is the skin part. In this way, the surface of the photoreceptor after charging is exposed to form an electrostatic latent image.

The electrostatic latent image is visualized as a toner image by the developing device 6 as it passes through the developing device 6. The developing device 6 shown here as an example has a developing case 7 containing a dry two-component developer D having a toner and a carrier, and a developing roller 8 arranged facing the photoconductor 1 and rotating. Is charged to a predetermined polarity by the friction with the carrier, in the example shown in the figure, a negative polarity, and the developer D containing such toner is carried on the peripheral surface of the developing roller 8 and conveyed to the developing roller 8 and the photoconductor 1. To the development area between. At this time, a predetermined developing bias (for example, a voltage of −600 V) is applied to the developing roller 8, and thereby the toner in the developer which is carried to the developing area and becomes a magnetic brush is formed on the photoconductor 1. Electrostatic latent image, that is, electrostatically transferred to the image portion, and the electrostatic latent image is visualized as a toner image. In this way, the electrostatic latent image is visualized as a toner image to form an image. It is also possible to employ a developing device using a powdery one-component developer containing no carrier, a liquid developer, or the like.

A transfer device 11 is placed opposite to the photosensitive member 1. The transfer device 11 exemplified here has a transfer belt 9 which is rotationally driven in the direction of the arrow and a transfer charger 10, and the transfer belt 9 is provided. And the photoconductor 1 are fed from a paper feed unit (not shown), and the arrow B
The transfer material P sent in the direction passes. At this time, the transfer charger 10 is applied with a transfer voltage having a polarity opposite to that of the toner of the toner image on the photoconductor, that is, a positive transfer voltage in this example.
As a result, the toner image is transferred onto the transfer material P sent out at a timing that can be aligned with the toner image formed on the surface of the photoconductor. Next, the transfer material P is separated from the photoconductor 1 and passes through the fixing device 12. At this time, the transferred toner image is fixed on the transfer material by the action of heat and pressure. Next, the transfer material P is discharged outside the main body of the image forming apparatus. Transfer roller, transfer brush, transfer blade,
Alternatively, a transfer device having these and a transfer belt may be used.

In the image forming apparatus shown in FIG. 1, a recording medium such as paper, a resin sheet or a resin film is used as the transfer material P, but a transfer material composed of a belt-shaped or drum-shaped intermediate transfer member is used. , The toner image on the photoconductor is primarily transferred to a transfer material composed of the intermediate transfer body, then the toner image on the intermediate transfer body is secondarily transferred to a recording medium composed of paper or a resin sheet, and the secondary transfer is performed. The formed toner image may be fixed by a fixing device. In this way, the toner image formed on the photoconductor is transferred to a transfer medium composed of a recording medium or an intermediate transfer body to form an image.

The transfer residual toner adhering to the surface of the photoconductor which has passed the transfer position where the toner image is transferred as described above is removed by the cleaning device 14. The cleaning device 14 shown as an example here has a cleaning case 16 and a base end supported by the case 16.
It has a cleaning blade 17 made of an elastic material such as rubber whose front edge portion is pressed against the surface of the photoconductor, and a toner discharge screw 18. The cleaning blade 17 scrapes off and removes the toner on the photoconductor. The removed toner is discharged to the outside of the cleaning case by the rotating toner discharging screw 18. In this way, the untransferred toner remaining on the surface of the photoconductor without being transferred to the transfer material is removed from the surface of the photoconductor.

As described above, the image forming apparatus of this embodiment forms the electrostatic latent image on the photoconductor by exposing the photoconductor, the charger for charging the photoconductor, and the photoconductor after the charging. Exposure means, a developing device that visualizes the electrostatic latent image as a toner image, a transfer device that transfers the toner image onto a transfer material, and a photoconductor surface that has passed a transfer position where the toner image is transferred. A cleaning device for removing the transfer residual toner adhering to the recording medium and a fixing device for fixing the toner image transferred to the transfer material made of a recording medium are provided. It is also possible to omit the cleaning device and remove the transfer residual toner from the surface of the photoconductor by, for example, a developing device. Also, image-expose the charged surface of the photoconductor, the area where the absolute value of the surface potential has decreased is the background area, and the area where the absolute value is maintained high is the electrostatic latent image. The image forming apparatus can also be configured to form a toner image.

In the image forming apparatus of the above-mentioned type,
Although a predetermined charging voltage is applied to the charger 3 and the surface of the photoconductor is charged by the discharge at this time, a discharge product is generated during the discharge. The same applies when a charging roller, a charging blade or the like is used as the charging device. Ozone and NOx are generally known as discharge products, and ammonia gas, SOx, and the like are also present in the atmosphere, although the amount is very small. If such a discharge product or a discharge product generated by the reaction of moisture in the air with the components in the air adheres to the surface of the photoconductor, the potential of the surface of the photoconductor decreases, and an abnormal image such as image blur may occur. There is.

The inventor of the present invention found that ammonium nitrate was the main component as a result of various efforts to identify the discharge product attached to the surface of the photoconductor. The discharge produces ozone and nitrogen oxides (NOx), which combine with substances in the air to form ammonium nitrate,
Such a discharge product adheres to the surface of the photoconductor, and ammonium nitrate adhering to the photoconductor is water-soluble, so it absorbs moisture in the air at high humidity and reduces the resistance value of the surface of the photoconductor. It is considered that an abnormal image is generated on the photoconductor. If the cleaning blade is configured to wear the surface of the photoconductor in a relatively large amount, the discharge products are also removed from the photoconductor, so that the occurrence of an abnormal image can be prevented. Life is shortened.

Therefore, in the image forming apparatus shown in FIGS. 1 to 5, first, in order to prevent an abnormal image from occurring even when the abrasion amount of the photoconductor is suppressed or the photoconductor is not scraped, The product removing means 13 is provided with a polar adsorbent that adsorbs the discharge products adhering to the surface of the photoconductor. Product removal means 13 shown as an example in the figure
6 has a product removing member 30 carrying a polar adsorbent on its surface, as shown in an enlarged scale in FIG. 6 and FIG. The adsorbent is brought into contact with the surface of the photoconductor to remove the discharge product attached to the surface of the photoconductor.

The product removing member can be constructed in various forms, but the product removing member 30 shown in FIGS. 6 and 7 has a core shaft 31 made of a rigid body such as metal and a sponge fixed to the outer peripheral surface thereof. And an elastic body 32 composed of
A sheet 33 made of rubber, paper, cloth, resin sheet or the like wound around the outer peripheral surface of the sheet, and the sheet 33 carries a polar adsorbent. FIG. 8 is a diagram schematically showing a state in which a paper is used as the sheet 33, and a polar adsorbent made of crystallized zeolite 135 is fixed to the cellulose fibers 34 of the paper.

As described above, the product removing member 30 of this example is formed in a roller shape, and each end of the core shaft 31 in the longitudinal direction is provided with a bearing 35 as shown in FIG. The product removing member 30 is rotatably supported by a supporting member 37 composed of a side plate of the apparatus main body, and the outer peripheral surface of the product removing member 30 is a photosensitive member 1.
Of the polar adsorbent is brought into contact with the surface of the photoconductor. The product removing member 30 can be provided at an appropriate position around the photoconductor. However, the product removing member 30 of the examples shown in FIGS. 1 to 5 is better than the cleaning device 14 in the moving direction of the photoconductor surface. It is arranged on the downstream side so as to come into contact with the surface portion of the photoconductor on the upstream side of the charger 3.

When the photosensitive member 1 rotates, the product removing member 30 abutting on the surface of the photosensitive member 1 is driven to rotate in the direction indicated by the arrow E in FIG. 6, or is rotationally driven in the direction indicated by the arrow E by a driving device (not shown). To be done. A discharge product made of, for example, ammonium nitrate adheres to the surface of the photoconductor in the discharge region, and the discharge product enters the contact portion between the photoconductor 1 and the product removing member 30 as the photoconductor rotates. At this time,
The discharge product is adsorbed by the polar adsorbent carried by the product removing member 30 and removed from the surface of the photoconductor. In this way, the surface of the photoconductor, which has no discharge products or has a very small amount of adhesion, is charged and exposed, so that the amount of wear on the surface of the photoconductor is small or the surface is not scraped at all. Even when configured as described above, it is possible to prevent the occurrence of an abnormal image. Eliminating the sheet 33, the elastic body 3
The polar adsorbent may be supported on the second member 2, and the elastic body 32 may be brought into contact with the surface of the photoconductor to bring the polar adsorbent into contact with the photoconductor.

As the polar adsorbent, silica alumina adsorbent, silica gel, alumina gel, activated alumina, activated clay, etc. can be used in addition to zeolite. Zeolite is used as in the example shown in FIG. Is particularly preferred.

The action of removing the discharge products adhering to the surface of the photoreceptor by using zeolite will be described below.

In general, a zeolite crystal contains a water molecule and an exchangeable cation in a large cavity of a condensed anion having a three-dimensional framework structure of aluminosilicate. It has various structures depending on the type and number of cations. Therefore, as the properties of zeolite, the molecular sieving action by the cavity of the cyclic structure due to oxygen in the crystal, a reversible ion exchange action, further, depending on the shape and size of the molecule by the action of the molecular sieving or cation, Alternatively, it exhibits an action of adsorbing and separating a dipole, a quadrupole, a substance having an unsaturated bond, a substance having strong polarization, and the like (adsorption separation action). Also,
A substance can move in an electron potential energy field in a cavity that constitutes a crystal (intracavity diffusion). Even the smallest 3A-type zeolite in the crystal at the present time (about 3Å diameter) has a drying action by absorbing water (drying action) and also adsorbs ammonia, hydrogen, methanol, etc. . Zeolite 1
Since the molecular sieve (trade name), which is a seed, has a cation in the crystal, it has a stronger affinity for polar molecules due to electrostatic attraction with this cation than for activated alumina or silica gel (ion affinity action). . Furthermore, it also exhibits a catalytic action that causes various chemical reactions (catalytic action).

Zeolite having the above-mentioned general performance is supported on paper, cloth, felt, plastics, rubber, etc., and formed into a sheet shape, a roller shape, a plate shape, a stick shape, a honeycomb shape or the like. By contacting the surface of the photoconductor, the discharge product which is the causative substance of the abnormal image can be effectively removed.

The reason why zeolite is effective in removing the causative substance of the abnormal image is not clear, but it is considered as follows.

Ammonium nitrate, which has absorbed moisture in the air, is ionized (this ionization causes the resistance of the surface of the photoconductor to become low and causes image blurring). When the zeolite comes into contact with ammonium nitrate ionized with water, the ammonium cations are adsorbed on the zeolite due to the ion exchange action of the zeolite, the adsorption separation action, the diffusion in the cavity, etc., and the remaining nitrate ions become nitric acid together with the water. However, the nitric acid is dehydrated by the drying action of the zeolite. Dehydrated nitric acid has a property of decomposing by light and heat, and it is considered that it eventually decomposes into nitrogen dioxide and scatters in the air, or nitric acid containing water is adsorbed by the zeolite carrier. To be In any case, the ammonium nitrate is removed by the combined action of the zeolite and the discharge product, which is the causative agent of the image blur, on the surface of the photoconductor.

Examples of the zeolite carrier include porous fibrous substances such as paper and cloth, and porous materials. Examples of the porous material include urethane rubber, silicon rubber, ethylene propylene rubber, butadiene rubber, styrene rubber, chloroprene rubber, butylene rubber, elastomer, sponge, polyethylene, polystyrene, polypropylene, polyurethane, and further vinyl chloride, epoxy, phenol, urea, Examples thereof include, but are not limited to, foams such as resins such as vinylon and various thermoplastic resins, and foams subjected to hydrophilic treatment. The shape of the carrier is preferably a roller shape, a sheet shape, a honeycomb shape or the like, but a roller shape is the most preferable from the viewpoint of workability. From this point of view, in the image forming apparatus shown in FIGS. 1 to 7, the roller-shaped product removing member 30 carrying the polar adsorbent is used.

Although non-polar adsorbents such as activated carbon also have the ability to absorb molecules, such non-polar adsorbents cannot electrostatically adsorb discharge products and thus adsorb the discharge products. Not suitable for. By bringing a polar adsorbent such as zeolite into contact with the surface of the photoconductor, the discharge products can be efficiently adsorbed and the effect of removing the discharge products from the surface of the photoconductor can be enhanced.

As the polar adsorbent for adsorbing the discharge product, for example, at least one of zeolite, silica-alumina-based adsorbent, silica gel, alumina gel, activated alumina, and activated clay can be used, and especially zeolite. As described above, the discharge product can be electrostatically adsorbed in the cavity, and the removal effect can be enhanced. The oxygen ring of the molecular structure of zeolite is 3, 4, 5, 6, 8,
There are eight kinds of 10, 12, and 18, and any oxygen ring zeolite can be adopted, but the oxygen ring has 6 or more member rings,
In particular, if it is an 8-membered ring or more, since the inlet diameter of the cavity is large, the discharge product can be effectively adsorbed.

By contacting the product removing member 30 carrying the polar adsorbent as described above with the surface of the photoconductor, the discharge product adhering to the photoconductor can be removed. At that time, the polar adsorbent is used. Since the discharge products are removed, it is not necessary to use water for removing the discharge products, which can prevent the problem that the characteristics of the surface of the photoconductor after removing the discharge products become non-uniform.

The structure and operation common to the image forming apparatus shown in FIGS. 1 to 5 are as described above. According to such an image forming apparatus, since the discharge product attached to the surface of the photoconductor can be removed by the product removing unit 13, the occurrence of an abnormal image can be suppressed, but the product removing unit 13 is possible.
Occasionally, it may not be possible to completely prevent the occurrence of abnormal images. Therefore, with the provision of this product removing means, it is difficult to attach the discharge product to the surface of the photoconductor, and it is possible to prevent the resistance of the discharge product attached to the surface of the photoconductor from being lowered. It is preferable that the amount can be reduced. Product adhesion prevention means that makes it difficult for discharge products to adhere to the surface of the photosensitive belt, and resistance reduction that prevents the resistance of discharge products that adhere to the surface of the photoconductor from decreasing. At least one of the prevention means and the product generation prevention means for reducing the generation amount of the discharge products near the surface of the photoconductor is provided. According to this structure, it is possible to more effectively prevent the abnormal image from being generated by the discharge product attached to the photoconductor 1, and to further enhance the effect of the product removing unit 13.

Here, before explaining the concrete constitutional examples of the above-mentioned respective means, the nature of ammonium nitrate which causes an abnormal image will be explained. Ammonium nitrate is a fine particle in a low temperature and high humidity condition such as at night. In the state, it floats in the atmosphere, and the suspended matter aggregates and deposits on a solid. On the other hand, under high temperature and low humidity conditions such as daytime, it decomposes into ammonia gas and nitric acid gas. Therefore, when corona discharge is performed to charge the photoconductor, ozone, NOx and moisture,
Fine particles of ammonium nitrate are formed by ammonia gas, etc., and the fine particles are deposited on the surface of the photoconductor at low temperature and high humidity, for example, at night, and absorb water to reduce the surface potential of the photoconductor. Blurring phenomenon occurs. Therefore, in order to make it difficult for the discharge products that cause image blurring to adhere to the surface of the photoconductor, or to prevent the occurrence of abnormal images due to the adhered discharge products, it is best to remove water, that is, dry. It can be said to be the preferred method.

Based on such knowledge, in the image forming apparatus shown in FIG. 1, the charger 3 is arranged in the drying box 20 having an opening on the side facing the surface of the photoconductor, and the blowing box 21 is provided in the drying box 20. , 22, a dry gas, in this example air, is sent, and the sent air is discharged from the drying box 20 by an air blower 23. Air that has been dried by a drying device (not shown) is supplied into the drying box 20 by the blowers 21 and 22. In this way, the charger 3
It is placed in a dry atmosphere, and the surface of the photoconductor 1 is charged in this state. In the example shown in FIG. 1, the entire charging device 3 is arranged in the dry atmosphere of the drying box 20, but if the charging device 3 can perform charging in the dry atmosphere, only a part of the charging device 3 can be used. It may be arranged to be placed in a dry atmosphere.

As described above, in the image forming apparatus shown in FIG. 1, at least part of the charger 3 is arranged in the dry atmosphere so that the charger 3 charges in the dry atmosphere. . According to this structure, ammonium nitrate is less likely to be produced, and the produced ammonium nitrate can be decomposed into ammonia gas and nitric acid gas, so that the discharge product is less likely to adhere to the surface of the photoreceptor. Therefore, this configuration is mainly used as a product adhesion preventing means that makes it difficult for the discharge products to adhere to the surface of the photoconductor, but with this configuration, the discharge products adhered to the surface of the photoconductor are dried. Therefore, it also has a function of preventing the discharge product from lowering the resistance, and also has a function of reducing the amount of the discharge product generated near the surface of the photoconductor.

In the image forming apparatus shown in FIG. 1, the air blowers 21 and 22 blow dry air onto the surface of the photoconductor to attach the dry air to the surface of the photoconductor. Ozone, NOx, or ammonium nitrate existing in the vicinity of the surface is also blown off by air, and it also has a function of suppressing the problem that the discharge product adheres to the surface of the photoconductor. The charger 3 charges the surface of the photoconductor that has been blown with dry air. In this way, the blowers 21, 22
Constitutes an example of a dry air applying means for applying dry air to the surface of the photoconductor, and the charger is arranged so that the charger charges the surface of the photoconductor to which the dry air has been applied.

With the above-mentioned respective structures, it is possible to make it difficult for the discharge products to adhere to the surface of the photoconductor, and by the cooperation of such structures and the aforementioned product removing means, it is possible to reliably prevent the occurrence of abnormal images. can do.

In the image forming apparatus shown in FIG. 2, a heat ray irradiation means 24 for irradiating the heat ray BE is provided between the charger 3 and the photoconductor 1, and the heat ray is irradiated between the charger 3 and the photoconductor 1. The photoconductor is charged by the charger 3 while being irradiated with. As a result, the air between the charger 3 and the photoconductor 1 can be heated and dried, and the charger 3
Generation of ammonium nitrate in the space between the photosensitive member 1 and the photosensitive member 1 can be suppressed, and the generated ammonium nitrate can be decomposed, so that the discharge products can be less likely to adhere to the surface of the photosensitive member. Thus, the heat ray irradiation means 2 shown in FIG.
4 is also mainly used as a product adhesion preventing means for making it difficult for the discharge product to adhere to the surface of the photoconductor, but prevents the resistance of the discharge product from decreasing and suppresses the decrease in the resistance of the photoconductor. It also serves to reduce the amount of discharge products generated near the surface of the photoconductor. Due to the cooperative action of the heat ray irradiating means 24 and the product removing means 13, it is possible to effectively prevent the occurrence of an abnormal image.

Further, the heat ray BE is not irradiated to the photoconductor 1, and only the atmosphere in the gap between the charger 3 and the photoconductor 1 is heated to reduce the humidity thereof, and the heat ray BE is used to expose the light. It is preferable that the body 1 is not heated. By irradiating a beam of heat rays, the photoconductor 1
The heat ray can be irradiated even in a small gap between the charging device 3 and the charging device 3, and the photoreceptor 1 and the charging device 3 can be prevented from being excessively heated.

Further, the image forming apparatus shown in FIG. 3 is provided with a product adsorbing means 25 which is disposed between the charger 3 and the photoconductor 1 and absorbs the discharge product by the polar adsorbent. . The product adsorption means 25 is, for example,
As shown in FIG. 9, the adsorbent carrier 26 formed in a lattice shape (or a honeycomb shape or a net shape) and the carrier 2
6 and a polar adsorbent adhered to the surface of the adsorbent 6. The adsorbent carrier 26 is disposed in the lower opening of the case of the discharger 3. As the polar adsorbent, the same polar adsorbent as that used in the above-mentioned product removing means 13 can be used, and particularly zeolite can be advantageously used.

Nitrogen oxides, ammonia, etc. generated by the discharge from the charger 3 are adsorbed by the polar adsorbent of the product adsorbing means 25. As a result, the amount of discharge products attached to the surface of the photoconductor is reduced, and the generation of an abnormal image can be prevented by the cooperation of the product removing unit 13. As described above, the product adsorbing unit 25 constitutes an example of a product generation preventing unit that reduces the amount of discharge products generated.

Further, in the image forming apparatus shown in FIG. 4, with respect to the moving direction of the surface of the photosensitive member, the exposure is performed by the laser writing device 5 which is on the downstream side of the charging position by the charger 3 and which is an example of the exposing means. Air blowing means 27 for blowing dry air is provided on the surface of the photosensitive member on the upstream side of the position. The air blowing means 27 shown in FIG. 4 sends a case 28 whose side facing the surface of the photoconductor is open and a gas dried by a drying device (not shown), in the illustrated example, air into the case 28. The air blower 29 and the air blower 40 for discharging the air inside the case 28 to the outside of the case 28 are provided, and the dry air sent to the case 28 dries the ammonium nitrate adhering to the surface of the photoconductor. As a result, it is possible to prevent ammonium nitrate adhering to the surface of the photoconductor from becoming an aqueous solution and lowering the resistance, thereby reducing the resistance of the surface of the photoconductor, and an abnormal image is generated by the cooperation with the product removing means 13 described above. Can be stopped. Since the photoconductor is dried immediately before exposing the photoconductor, it is possible to effectively prevent the occurrence of an abnormal image.

As described above, the air blowing means 27 prevents or suppresses the resistance of the discharge products attached to the surface of the photoconductor to be lowered, thereby preventing the resistance from being lowered. However, it also suppresses the generation of ammonium nitrate and also makes it difficult for the discharge products thereof to adhere to the surface of the photoconductor.

By the way, in the image forming apparatus shown in FIGS. 1 to 5, the surface of the photoconductor is charged to about -900 V by the charger 3 as described above. In order to be charged to a high electric potential with an absolute value, it is necessary to apply a high voltage to the charger 3, which results in an ozone generation amount of, for example, about 1 to 10 ppm, and a nitrogen oxide generation amount of, for example, 0.05 ppm. To 0.5p
It becomes pm and a lot of ozone and nitrogen oxides are generated. When a charging roller is used as the charging device and the surface of the photoconductor is charged to an equivalent value, the amount of nitrogen oxides is extremely reduced, but the amount of ozone generated is, for example, 0.02 to 0.5 ppm.
And the amount of generation is quite high. As a result, the amount of discharge products attached to the surface of the photoconductor may increase. On the other hand, if the absolute value of the charging potential on the surface of the photoconductor is set to be small, the discharge energy will be small and the amounts of ozone and nitrogen oxides generated will both be small.

Therefore, when the surface of the photoconductor is charged by the charger 3 to a value in the range of -500V to -600V, and when the surface of the photoconductor is positively charged, it is + 500V to + 500V.
If it is configured to be charged to a value in the range of 600 V, it is possible to suppress the generation amounts of ozone and nitrogen oxides, and it is possible to further secure the effects of the above-described configurations.

By the way, as described above, the product removing means can be configured in various forms other than the forms shown in FIGS. For example, in the product removing means 13 shown in FIG. 10, a product removing member 30 including a core shaft 31 and a brush roller provided on the outer peripheral surface thereof and having a brush fiber 36 carrying a polar adsorbent is used. While rotating the brush roller, the brush fiber 36 is brought into contact with the surface of the image carrier 1, and the polar adsorbent carried by the brush fiber 36 is brought into contact with the surface of the photoconductor to remove the discharge products. ing.

The product removing member is constructed so as not to rotate, and the product removing member is supported so that it can be brought into contact with and separated from the surface of the photoconductor, and the product removing member is removed only when the discharge products are removed. You may make it contact | abut on a photoreceptor surface. Further, the product removing member can be swung in the longitudinal direction. As described above, the product removing member can be configured in an appropriate form.

Further, the polar adsorbent is adhered to the product removing member so that the polar adsorbent is supported on the product removing member, and the polar adsorbent in the form of particles is attached to the product removing member so that the polar adsorbent is adhered to the product removing member. The agent can be supported on the product removing member. Alternatively, the particulate polar adsorbent may be held by, for example, the cleaning blade 17, and the polar adsorbent may be brought into contact with the surface of the photoconductor to remove the discharge products attached to the surface of the photoconductor. As the polar adsorbent used in these configurations, the same polar adsorbent used in the above-mentioned product removing means 13 can be adopted.

A polar adsorbent is carried on the surface of a member required for an image forming apparatus such as a charging roller or a transfer roller to form a product removing means, and the polar adsorbent is brought into contact with the surface of the photoconductor. It is also possible to remove the discharge products attached to the surface of the photoconductor. At that time, as shown in FIG.
With respect to the moving direction of the surface of the photosensitive member, the photosensitive member is brought into contact with a surface portion of the photosensitive member on the downstream side of the charging position by the charger 3 and on the upstream side of the exposure position by the laser writing device 5, which is an example of the exposing unit, and is exposed Leveling charger 4 for leveling body surface potential
1 may be provided, and a polar adsorbent may be carried on a portion of the leveling charger 41 that comes into contact with the surface of the photoconductor, and the leveling charger 41 may be used as a product removing means. A voltage is applied to the leveling charger 41 by a power source (not shown), so that the charging unit 3 is charged.
When the surface potential of the photoconductor charged by is uneven, the surface potential is made uniform, and the above-mentioned polar adsorbent, preferably zeolite, is carried on the surface of the leveling charger 41, The discharge products attached to the body surface are removed.

The leveling charger 41 can be constructed in an appropriate form, but the leveling charger 41 shown in FIG. 5 is composed of a roller that rotates while contacting the surface of the photoconductor, and has an outer peripheral surface. The polar adsorbent is stuck. This allows
The pressure with which the leveling charger 41 contacts the surface of the photoconductor can be kept low, wear on the surface of the photoconductor can be suppressed, and discharge products can be uniformly removed from the surface of the photoconductor.

Further, cleaning means for cleaning the surface of the even charger 41 can be provided, and the cleaning means shown in FIG. 5 is constituted by the cleaning blade 42 which is in contact with the surface of the even charger 41. . The cleaning blade 42 can remove the discharge products attached to the leveling charger 41, and the function of removing the discharge products by the leveling charger 41 can be maintained for a long period of time. The leveling charger 41 includes, for example, rubber, metal,
Alternatively, the cleaning blade 42 can be made of, for example, metal or resin, but the cleaning blade 42 with respect to the leveling charger 41 can be configured so that the polar adsorbent carried by the leveling charger 41 does not come off. It is preferable to set the contact pressure.

Further, as shown in FIG. 5, with respect to the moving direction of the surface of the photosensitive member, the surface of the photosensitive member is located downstream of the leveling position of the leveling charger 41 and upstream of the position of exposure by the exposing means. A first sensor 43 for detecting the electric potential of the portion;
Second sensor 44 for detecting the surface potential of the leveling charger 41
It is desirable to provide and to control the value of the voltage or current applied to the leveling charger 41 based on the detection results of the first and second sensors 43 and 44. With this configuration, the discharge products attached to the surface of the photoconductor are not completely removed by the leveling charger 41, and the resistance of the surface of the photoconductor is locally reduced, or the discharge products are deposited on the surface of the leveling charger 41. Even if a large amount is attached, the first and second sensors 43, 44
Thus, the surface potentials of the photoconductor 1 and the leveling charger 41 are detected, and the voltage or current value applied to the leveling charger 41 is adjusted based on the detection result so that the potential of the surface of the photoconductor becomes uniform. Since it can be controlled, the uniformity of the potential on the surface of the photoconductor can be kept high. Further, even when the surface of the even charger 41 is slightly worn, the value of the voltage or current applied to the even charger 41 is adjusted based on the detection results of the first and second sensors 43 and 44. The uniformity of the potential on the surface of the photoconductor can be improved. Further, only when the decrease in the potential on the surface of the photoconductor is detected due to the adhesion of the discharge product, the leveling charger 41 is brought into contact with the surface of the photoconductor to remove the discharge product which is the causative substance of the decrease in potential. It can also be configured.

In the image forming apparatus shown in FIG. 5, the product removing member 30 and the leveling charger 41 are used to remove the discharge products adhering to the surface of the photoreceptor.
The discharge products may be removed by only one of them. FIG. 5 shows an image forming apparatus in which the configuration of the leveling charger 41 is added to the image forming apparatus shown in FIG. 3. The leveling charger 41 and the configuration related thereto are as follows.
The invention can be applied to any of the image forming apparatuses shown in FIGS. Further, the image forming apparatus can be configured by appropriately combining the configurations described above.

[0067]

According to the present invention, the discharge products adhering to the surface of the photoreceptor are removed by the product removing means, and
Since the amount of discharge products attached to the surface of the photoconductor can be reduced, it is possible to effectively prevent the occurrence of abnormal images.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an image forming apparatus.

FIG. 2 is a schematic cross-sectional view showing another example of the image forming apparatus.

FIG. 3 is a schematic sectional view showing still another example of the image forming apparatus.

FIG. 4 is a schematic sectional view showing still another example of the image forming apparatus.

FIG. 5 is a schematic sectional view showing still another example of the image forming apparatus.

6 is an enlarged cross-sectional view of the product removing member shown in FIG.

FIG. 7 is a vertical cross-sectional view of a product removing member.

FIG. 8 is a schematic enlarged perspective view showing zeolite fixed to cellulose fibers.

FIG. 9 is an enlarged perspective view of a product adsorption means.

FIG. 10 is a cross-sectional view showing another example of the product removing member.

[Explanation of symbols]

1 photoconductor 3 charger 6 Development device 13 Product removal means 24 Heat ray irradiation means 25 Product Adsorption Means 27 Air blowing means 41 Leveling charger 43 First sensor 44 Second sensor 135 Zeolite

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Aino Noguchi             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Toru Nakano             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F term (reference) 2H027 DA02 DA06 DE05 EA01 JA01                       JA02 JA16 JB05 JB06 JB07                       JB14 JB15 JB16 JC01 JC02                 2H134 GA01 GB02 GB06 GB08 HA01                       HB01 HF00 HF01 KG01 KG08                       KH01 KH06                 2H200 FA07 FA08 GA23 GA45 GA46                       GA49 GB12 HA02 HA12 HA29                       HB03 HB04 HB12 HB22 HB26                       HB28 HB41 HB45 HB46 HB48                       JA02 JB06 LB02 LB09 LB13                       LB21 LB24 LB25 LB27 LB28                       LB35 MA01 MA03 MA04 MB06                       NA02 NA09

Claims (14)

[Claims] 1. A charging device for charging a photoconductor, an exposing means for exposing the photoconductor after charging to form an electrostatic latent image on the photoconductor, and a visible image using the electrostatic latent image as a toner image. In an image forming apparatus having a developing device that changes into a solid state, a product removing unit including a polar adsorbent that adsorbs discharge products adhering to the surface of the photoconductor is provided, and the discharge products are made difficult to adhere to the surface of the photoconductor. Product adhesion preventing means, resistance lowering preventing means for preventing discharge products adhering to the surface of the photoconductor from lowering resistance, and product generation for reducing the amount of discharge products near the surface of the photoconductor An image forming apparatus comprising at least one of prevention means. 2. A charging device for charging a photoconductor, an exposing unit for exposing the photoconductor after charging to form an electrostatic latent image on the photoconductor, and a visible image using the electrostatic latent image as a toner image. In an image forming apparatus having a developing device, the product removing means including a polar adsorbent for adsorbing the discharge product adhering to the surface of the photoconductor is provided, and the charging device performs charging in a dry atmosphere. In the image forming apparatus, at least a part of the charger is arranged in a dry atmosphere. 3. A charging device for charging a photosensitive member, an exposing unit for exposing the charged photosensitive member to form an electrostatic latent image on the photosensitive member, and a visible image as the electrostatic latent image as a toner image. In an image forming apparatus having a developing device for converting into a product, a product removing unit including a polar adsorbent that adsorbs a discharge product adhering to the surface of the photoconductor, and a dry air applying unit for applying dry air to the surface of the photoconductor. And the charging device is arranged such that the charging device charges the surface of the photoconductor to which the dry air is applied. 4. A charging device for charging a photoconductor, an exposing means for exposing the photoconductor after charging to form an electrostatic latent image on the photoconductor, and a visible image using the electrostatic latent image as a toner image. In an image forming apparatus having a developing device that turns into a charge, a heat ray is irradiated between the product removing unit including a polar adsorbent that adsorbs a discharge product adhering to the surface of the photoconductor and the charger and the photoconductor. An image forming apparatus comprising: a heat ray irradiation unit. 5. A charging device for charging a photoconductor, an exposing unit for exposing the photoconductor after charging to form an electrostatic latent image on the photoconductor, and a visible image using the electrostatic latent image as a toner image. In an image forming apparatus having a developing device that turns into a charge, a product removing unit having a polar adsorbent that adsorbs a discharge product adhering to the surface of the photoconductor, and a polar member disposed between the charger and the photoconductor. An image forming apparatus comprising: a product adsorbing unit that adsorbs a discharge product by an adsorbent. 6. A charging device for charging a photoconductor, an exposing means for exposing the photoconductor after charging to form an electrostatic latent image on the photoconductor, and a visible image as the toner image. In an image forming apparatus having a developing device that turns into a charge, a product removing unit including a polar adsorbent that adsorbs a discharge product adhering to the surface of the photoconductor, and a charging direction by the charger with respect to a moving direction of the surface of the photoconductor. An image forming apparatus comprising: an air blowing unit that blows dry air to a surface portion of the photoconductor downstream of the position and upstream of the exposure position of the exposure unit. 7. The surface of the photoconductor is -5 by the charger.
7. The image forming apparatus according to claim 1, which is charged to a value in the range of 00V to −600V, or a value in the range of + 500V to + 600V. 8. The photosensitive member is brought into contact with a photosensitive member surface portion on the downstream side of the charging position of the charger and upstream of the exposing position of the exposing unit with respect to the moving direction of the photosensitive member surface. Is provided with a leveling charger for leveling the surface potential, and a polar adsorbent is carried on the part of the leveling charger that contacts the surface of the photoconductor, and the leveling charger is used as the product removing means. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: 9. The image forming apparatus according to claim 8, wherein the leveling charger comprises a roller that rotates while being in contact with the surface of the photoconductor. 10. The image forming apparatus according to claim 8, further comprising a cleaning unit that cleans the leveling charger. 11. A potential of a surface portion of the photoconductor, which is downstream of a leveling position of the leveling charger and upstream of an exposure position of the exposing unit, is detected in a moving direction of the photoconductor surface. A voltage that has a first sensor and a second sensor that detects the surface potential of the leveling charger, and that is applied to the leveling charger based on the detection results of the first and second sensors. Alternatively, the image forming apparatus according to any one of claims 8 to 10, which controls a current value. 12. The image forming according to claim 1, wherein the polar adsorbent comprises at least one of zeolite, silica-alumina-based adsorbent, silica gel, alumina gel, activated alumina, and activated clay. apparatus. 13. The image forming apparatus according to claim 1, wherein the polar adsorbent is made of zeolite, and an oxygen ring of a molecular structure of the zeolite has a 6-membered ring or more. 14. The image forming apparatus according to claim 1, wherein the polar adsorbent is made of zeolite, and an oxygen ring of a molecular structure of the zeolite is an 8-membered ring or more.