JP2008164707A - Image forming apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming method which are free from printing failure such as image deletion, a white void and white fog due to NOx and a member approaching close to an electrostatic latent image carrier in the image formation by an electrophotographic system or the like. <P>SOLUTION: The surface of a member approaching close to a photosensitive drum 2 and opposing to the photoreceptor drum 2 is composed of a surface member made of a metal element that can couple with a nitrate ion to form a metal salt or made of an alloy material essentially comprising the metal element. That is, a steel plate Ab subjected to electroless nickel plating is stuck to each of a part of a destaticizing lamp 11, a base part 4a of a LED printing head, and a support part of a pre-cleaning charger 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus and an image forming method provided with an electrostatic latent image carrier, particularly an electrostatic latent image carrier having a photosensitive layer made of an organic photosensitive material.

  As is well known, in an electrophotographic image forming apparatus, an electrostatic latent image is formed on an endlessly moving electrostatic latent image carrier by a charging and exposure process, and the electrostatic latent image is often developed by a developing process. Is a toner image, the toner image is transferred to a recording medium such as paper by a transfer process, and the toner image transferred onto the recording medium is fixed to the recording medium under the action of heat, pressure, etc. to form an image. Complete. A slight amount of toner may remain on the electrostatic latent image carrier after the transfer, but these are removed by a cleaning process, and the remaining electrostatic latent image is removed by a static elimination process. It is usual to perform image formation continuously by sequentially repeating a series of processes.

In the charging process and transfer process described above, a charger based on corona discharge is often used. As is well known, in chargers based on these corona discharges, it is known that gases such as ozone and NOx are generated along with the corona discharge. These are harmful to the human body and damage the photosensitive layer of the image forming apparatus, particularly the electrostatic latent image carrier, causing printing troubles such as image loss, white spots and white background fogging. It has been. For this reason, in the prior art, a fan, a blower, etc. are arranged in the image forming apparatus, and the charger and its nearby air are forcibly exhausted during the operation of the image forming apparatus. In many cases, ozone or NOx or the like is not stagnation for a long time in and around the inside. In the present specification, compounds composed of oxygen atoms and nitrogen atoms, such as NO, NO ₂ , N ₂ O _4, etc. are collectively referred to as NOx.

  In addition, the printing failure due to ozone, NOx, or the like may be caused not only by the operation of the image forming apparatus but also by ozone, NOx, etc. remaining in the image forming apparatus after the image forming operation is stopped. For example, when the image forming apparatus is stopped at night and the image forming operation is resumed the next morning, the above-described image flow, white spots, white background fogging, etc. are printed on a portion of the electrostatic latent image carrier facing the charger. Failure may occur. This is because the photosensitive layer is damaged by ozone, NOx, etc. remaining in the machine even after the image forming operation is stopped. The fan, blower, etc. There are cases where measures are taken such as operating for a predetermined time and forcibly continuing to exhaust ozone, NOx, and the like.

  However, the present inventors have clarified that the following printing failure, which is considered to be caused by NOx generated from the charger, occurs even when the above measures are taken.

  After the image forming operation for a considerable time is continued, the image forming apparatus is stopped, for example, the image forming apparatus is left overnight. The next morning, when the image forming operation is resumed, image flow, white spots, fogging on the white background, and the like may occur also in a specific portion of the electrostatic latent image carrier that is not opposed to the charger. . These printing failures are the same as those described in the prior art in that they occur when the operation of the image forming apparatus is resumed, but are different in the places where they occur.

  These printing faults occur at a location where the electrostatic latent image carrier and the member that is in close proximity to each other, and are not necessarily a location facing the charger.

  The occurrence mechanism of this printing failure is assumed as follows. NOx generated from the charger is combined with moisture on a member that is in close proximity to the electrostatic latent image carrier, and nitric acid is formed. The formed nitric acid or nitrate ions damage the photosensitive layer on the opposing electrostatic latent image carrier after stopping, and after resuming the image forming operation, print troubles such as image flow, white spots, and white background fogging.

  In an electrophotographic image forming apparatus, a recording medium that is a paper material is often heated at the time of fixing, and moisture is evaporated from the paper material at this time. Accordingly, it is conceivable that the humidity is higher in the image forming apparatus than outside the apparatus. In addition, it can be imagined that the moisture is condensed on the proximity member after the vehicle stops.

  In this specification, the term “close to the electrostatic latent image carrier” means that the shortest distance from the surface of the photosensitive layer is about 1 cm or less, or about 7% or less of the circumference of the electrostatic latent image carrier. Say the case of length.

  These print failures do not occur in all members adjacent to the electrostatic latent image carrier. As described above, it is considered that NOx generated from the charger is involved in this printing failure. Therefore, depending on the positional relationship of each member in the image forming apparatus and the state of airflow, NOx does not exist, or It is considered that there is a case where the density does not reach the level at which the printing failure occurs, and the printing failure does not occur.

This printing failure is particularly remarkable when the photosensitive layer is composed of an organic photosensitive layer. This is because the organic photosensitive layer is usually based on a polymer material such as polycarbonate, and is more susceptible to nitric acid or nitrate ions than a photosensitive layer made of an inorganic material such as amorphous silicon or a selenium alloy. It is thought from.

  Further, it is known that there are two types of organic photosensitive layers, a laminated type and a single layer type. The stacked type has a structure in which a charge generation layer and a charge transport layer are stacked. Usually, the charge transport layer is often formed on the upper layer, that is, on the surface side. On the other hand, the single layer type often has a structure in which a charge generation agent and a charge transport agent are dispersed in a single layer. The above-described printing troubles such as image flow, blank areas, and white background fogging may be more significant in the case of a single-layer type photosensitive layer. This is because the layer type has a charge transport layer basically having only a charge transport agent on the surface affected by nitric acid or nitrate ions, whereas the single layer type has a charge transport agent and charge transport agent. It is presumed that both exist and both are affected by nitric acid or nitrate ions.

Further, in corona discharge, it is known that positive discharge generates more NOx than negative discharge. In recent digital copying machines and digital printers, so-called reversal development, in which toner development is performed in the exposed portion, is the mainstream, and the generated NOx is more positive in the case of a positively charged photoreceptor having a positive discharge main charger. It seems that the amount is large, and this printing failure is more problematic. In particular, when a positively charged organic photosensitive layer is provided, the problem is often more pronounced.

  In an electrophotographic image forming apparatus, a charger may be used in addition to the main charger and the transfer charger. For example, a pre-transfer electrostatic latent image carrier referred to as a pre-transfer charger and the like, a charger for charging a toner image thereon, a pre-cleaning electrostatic latent image carrier prior to a cleaning process, and the like A charger or the like for charging the upper residual toner image. When a charger other than the main charger and transfer charger is used, the total amount of NOx generated naturally increases, and this printing failure may become more problematic.

  Further, this printing failure may become significant even when the image forming apparatus has a fixing device of a flash fixing system. When a fixing device using a flash fixing system is included, depending on the positional relationship between the recording medium conveyance path and each image forming unit in the image forming apparatus, a slight amount of light leaks from the flash lamp of the flash fixing device to the electrostatic latent image carrier. May be irradiated. Even if the light leaks to the extent that there is no problem under normal circumstances, it may cause a more significant printing failure if it overlaps with the location where this printing failure occurs. The leakage light may increase when the recording medium conveyance path from the transfer point to the fixing device is substantially linear, and in this case, the actual printing failure may become more significant.

  As a countermeasure against such a printing failure caused by NOx and the proximity member, as described in Patent Document 1, a technique in which the proximity member surface is a heat insulating member is known.

JP 2002-278385 A

  However, even with such a heat insulating member, the above-mentioned printing trouble may occur, and in the known technology, the heat insulating material is composed of an organic substance such as a rubber material. Depending on the use, there is a problem that these heat insulating materials are deteriorated and deteriorated due to the generated nitric acid or nitrate ions, and the desired effect cannot be obtained.

  As a result of the study by the present inventors to solve the above-described problems, at least the surface of the member adjacent to the electrostatic latent image carrier that faces the electrostatic latent image carrier is combined with nitrate ions to form a metal salt. It has been found that these obstacles can be reduced and solved by using a surface element made of a metal element capable of forming a metal or an alloy material containing them as a main component.

  According to the present invention, as means for solving the above problems, an image forming apparatus having an electrostatic latent image carrier, wherein at least the electrostatic latent image carrier of a member adjacent to the electrostatic latent image carrier is provided. There is provided an image forming apparatus characterized in that an opposing surface is constituted by a surface member made of a metal element capable of forming a metal salt by being combined with nitrate ions or an alloy material containing them as a main component.

In addition, according to the present invention, there is provided an image forming apparatus characterized in that a member adjacent to the electrostatic latent image carrier is a recording medium conveying member. Also according to the invention. An image forming apparatus is provided in which a member adjacent to the electrostatic latent image carrier is a charger for the electrostatic latent image carrier.

According to a preferred aspect of the present invention, there is provided an image forming apparatus characterized in that the surface member is provided so as to be replaceable. According to another preferred aspect of the present invention, there is provided an image forming apparatus wherein the surface member has a photosensitive layer made of an organic photosensitive material. According to another preferred aspect of the present invention, there is provided an image forming apparatus wherein the photosensitive layer is a positively charged type.

According to another preferred embodiment of the present invention, there is provided an image forming apparatus, wherein the photosensitive layer has a single layer structure. According to another preferred aspect of the present invention, the image forming apparatus has a charger for the electrostatic latent image carrier in addition to the main charger and the transfer charger. An apparatus is provided.
According to another preferred aspect of the present invention, there is provided an image forming apparatus characterized in that the image forming apparatus has a fixing device using a flash fixing system.

According to another preferred aspect of the present invention, an image is characterized in that at least a portion of the recording medium conveyance path of the image forming apparatus between the transfer position to the recording medium and the fixing position is substantially linear. A forming apparatus is provided. Further, according to another aspect of the present invention, in the image forming method, the electrostatic latent image on the electrostatic latent image carrier is developed into a toner image, and the toner image is transferred to a recording medium and fixed. A metal element capable of forming a metal salt by binding at least a surface of the member adjacent to the latent electrostatic image bearing member facing the latent electrostatic image bearing member to nitrate ions, or an alloy material containing them as a main component There is provided an image forming method characterized by comprising a surface member made of

  The mechanism that can reduce or solve this printing failure by these means is estimated as follows.

When the metal material is a material that does not form a metal salt by combining with nitrate ions, the generated nitric acid remains for a long time. On the other hand, when the metal material is a material that can form a metal salt by combining with nitrate ions, the generated nitric acid immediately combines with the metal material to form a metal salt, so that it remains as nitric acid for a long time. Nothing will happen. For this reason, it is considered that the photosensitive layer is not damaged.

The metal material suitable for the present invention may be any metal that can be combined with nitrate ions to form a metal salt (in short, a metal that dissolves in nitric acid) and alloys having these as a main component.
In addition, having as a main component means containing 20% or more by weight ratio, preferably 50% or more. Nickel, zinc, tin, lead, brass, bronze, etc. are suitable. On the other hand, examples of materials unsuitable for the present invention include various stainless steels, copper, aluminum, anodized aluminum, glass, ceramics, ceramic materials, and the like. Some metal elements can form a metal salt by combining with nitric acid, but some form a passive state with respect to nitric acid. These materials are also considered substantially insoluble in nitric acid and are not suitable for the present invention. Examples of these metals include iron, aluminum, and chromium.

In practice, at least the surface of the metal member facing the electrostatic latent image carrier may be the above-described suitable material or an alloy containing these as a main component. For example, even if it is various materials raised as unsuitable, the surface may be coated with a suitable material, plated, attached with a thin plate, or the like. Specifically, a galvanized steel plate (so-called SECC), a nickel-plated steel plate, a zinc chromate steel plate, and the like can be given.

In addition, among the members close to the electrostatic latent image carrier, it is not preferable or difficult to make the material suitable for the present invention in the image forming process. For example, there may be a case where the developing roller or the like cannot be made of a suitable material according to the present invention in terms of its mechanical strength and wear resistance. In such a case, regardless of the definition of proximity described above, even a member that is close to the electrostatic latent image carrier should not be a suitable material to be raised according to the present invention.

According to the first to eleventh aspects of the present invention, in electrophotographic image formation, it is possible to cause printing troubles such as image flow, white spots, and white background fogging caused by a member close to the NOx and the electrostatic latent image carrier. Image forming apparatus and image forming method can be provided.

Hereinafter, an embodiment according to an image forming apparatus and an image forming method of the present invention will be described in detail with reference to FIG.

  As shown in FIG. 1, the electrophotographic printer 1 has a main charger 3, an LED print head 4, a developing unit 5, a transfer charger 6, and a separation device around a photosensitive drum 2 as an electrostatic latent image carrier in a housing 1a. A charger 7, a pre-cleaning charger 8, a carrier recovery unit 9, a cleaning unit 10, and a charge removal lamp 11 are arranged, and a fixing unit 20 is arranged on the downstream side of the photosensitive drum 2 in the conveyance path through which the recording medium MRC is conveyed. . Further, the electrophotographic printer 1 includes a guide plate 13 and a tractor 14 which are one of recording medium conveying members on the upstream side of the photosensitive drum 2 in the conveying path, and a conveying unit 15 in a position facing the fixing unit 20 in the conveying path. Each is provided.

Here, in the electrophotographic printer 1, continuous paper is used as the recording medium MRC. As shown in the figure, the recording medium MRC is introduced from the inlet 1b on the right side of the housing 1a and discharged from the outlet 1c on the left side.

  In the photosensitive drum 2, a single photosensitive layer made of a positively charged organic photosensitive material is formed on the surface of a cylindrical drum, and an electrostatic latent image is formed on the surface by light emitted from the LED print head 4. . Prior to the formation of the latent image on the photosensitive drum 2 by the LED print head 4, the main charger 3 uniformly charges the surface of the photosensitive drum 2 with ions generated by discharge. The LED print head 4 exposes the surface of the photosensitive drum 2 with a light beam to form an electrostatic latent image corresponding to the recorded information.

  The developing unit 5 is disposed to face the photosensitive drum 2 and includes a toner cartridge 5b and a developing roll 5c disposed in the housing 5a. The toner cartridge 5b contains a two-component developer in which toner particles and carrier particles are mixed at an appropriate weight ratio. The developing roller 5c is a roller composed of a rotatable sleeve (metal tube) that develops the electrostatic latent image while carrying and transporting the two-component developer on the photosensitive drum 2, and a magnet that is rotatable inside. 5d. The magnet 5d is a permanent magnet that is long in the axial direction, and a plurality of poles are arranged in the circumferential direction.

  Here, as the two-component developer, toner particles and carrier particles produced as follows were used.

Toner particles:
50% by weight of polyester resin (“Tuffton” TTR-2, manufactured by Kao Corporation), 25% by weight of polyester resin (“Toughton” TTR-5, manufactured by Kao Corporation), magnetic material (EPT-1000, Toda) 20% by weight manufactured by Kogyo Co., Ltd., 2% by weight of carbon black ("Regal" 330R, manufactured by Cabot), 1% by weight of a nigrosine-based charge control agent ("Bontron" N-01, manufactured by Orient Chemical), polyethylene wax (""HighWax" 405MP, manufactured by Mitsui Petrochemical Co., Ltd.) 2% by weight, after sufficiently mixing each of the above components, it was melted and kneaded with a twin screw extruder (PCM-30, manufactured by Ikekai Steel Co., Ltd.), and then a jet mill The mixture was finely pulverized with a pulverizer (PJM-100, manufactured by Nippon Pneumatic Industry Co., Ltd.). This was classified with an air classifier (A-12, manufactured by Alpine Co., Ltd.) to obtain resin fine particles having a weight average particle diameter of 11.9 μm.

  Further, 0.4 parts by weight of hydrophobic silica fine powder (REA200, manufactured by Nippon Aerosil Co., Ltd.) and polyvinylidene fluoride particles (“KYNER” 500, manufactured by Elf Atchem Japan Co., Ltd.) are used for the resin fine particles. 0.4 parts by weight of each was added and mixed with a super mixer (SMV-20, manufactured by Kawata) to obtain toner particles. The weight average particle diameter of the obtained toner particles was 11.9 μm, and the standard deviation of the weight distribution was 3.2 μm.

Carrier particles:
Polyester resin (“Tuffton” TTR-2, manufactured by Kao Corporation) 23% by weight, Magnetic material (KBF-100SR, manufactured by Kanto Denka Kogyo Co., Ltd.) 73% by weight, Charge control agent (“Bontron” S-34, Orient Chemical Co., Ltd.) 2% by weight, Wax (LUVAX-1151, Nippon Seiwa Co., Ltd.) 2% by weight, and after sufficiently mixing each of the above components, a twin screw extruder (PCM-30, Ikegai Steel Co., Ltd.) Melt kneading was performed. The kneaded product was cooled and then coarsely pulverized using a coarse pulverizer (UG-210KGS, manufactured by Horai Iron Works) having a screen having a diameter of 2 mm. Furthermore, after this was pulverized by a medium pulverizer (“Fine Mill” FM-300N, manufactured by Nippon Pneumatic Industrial Co., Ltd.), a fine pulverizer (“Separator” DS-5UR, manufactured by Nippon Pneumatic Industrial Co., Ltd.) was used. And classified to obtain resin fine particles having a volume average particle diameter of 52 μm.

  Next, the resin fine particles were stirred at 75 ° C. for 15 minutes using a high-speed stirring type mixing granulator (ODM-25 type, manufactured by Nara Machinery Co., Ltd.), and subjected to spheronization treatment. Furthermore, 0.1 part by weight of hydrophobic silica fine powder (REA200, manufactured by Nippon Aerosil Co., Ltd.) is added to the resin fine particles, and the volume average particle size is mixed by supermixer (SMV-20, manufactured by Kawata). 53 μm carrier particles were obtained.

  The transfer charger 6 transfers the unfixed toner image developed on the photosensitive drum 2 to the recording medium MRC using ions generated by the discharge. The separation charger 7 is a charger that electrically separates the recording medium MRC from the photosensitive drum 2. For example, a corotron charger to which an alternating voltage is applied is used. The transfer charger 6 and the separation charger 7 are integrally configured with a common shield plate member S.

Here, a separation claw 12 for mechanically separating the recording medium MRC from the photosensitive drum 2 is provided between the separation charger 7 on the outer periphery of the photosensitive drum 2 and the pre-cleaning charger 8.

In this embodiment, in addition to the main charger 3 and the transfer charger 6, the pre-cleaning charger 8 is charged. The pre-cleaning charger 8 charges the surface of the photosensitive drum 2 prior to cleaning, The toner particles remaining on the surface of the photosensitive drum 2 without being transferred to the recording medium MRC are used for the purpose of facilitating recovery by the cleaning unit 10.

  The carrier recovery unit 9 is provided between the transfer charger 6 and the cleaning unit 10 when viewed in the rotation direction of the photosensitive drum 2, and is not transferred to the recording medium MRC and remains on the surface of the photosensitive drum 2. The carrier scraped off from the surface of the photosensitive drum 2 due to the brush roller 10b described later is collected. In the carrier recovery unit 9, a recovery roller 9b, which is a magnetic roller, and a blade 9c made of a resin film are housed in a housing 9a. The collection roller 9b magnetically attracts and collects the carrier particles. The blade 9c scrapes the carrier particles collected by the collection roller 9b from the surface of the collection roller 9b.

  The cleaning unit 10 mainly removes toner particles remaining on the surface of the photosensitive drum 2 without being transferred to the recording medium MRC. A brush roller 10b and a recovery roller 10c are provided in the housing 10a. The brush roller 10b is applied with a bias voltage having a polarity opposite to that of the toner particles, scrapes the toner particles remaining on the surface of the photosensitive drum 2 with a brush, and electrostatically adsorbs the toner particles for cleaning. The collection roller 10c is applied with a bias voltage higher than that of the brush roller 10b, and electrostatically collects the toner particles adsorbed on the brush roller 10b. The collected toner particles are scraped off from the collection roller 10c by a blade (not shown), and are transferred by a transfer roller 10d to a collection unit (not shown) provided in one direction on both sides of the paper surface.

  The charge removal lamp 11 is a small light bulb, and removes residual charges from the surface of the photosensitive drum 2 by light irradiation. A light emitting element such as an LED can be used instead of the light bulb. In the transport unit 15, a transport belt 15b is stretched between two transport rollers 15a, and the two transport rollers 15a are supported by a casing 15c made of a ferromagnetic material.

As shown in FIG. 1, in the electrophotographic printer 1, the toner image is fixed by the fixing unit 20 from the transfer position where the unfixed toner image developed on the photosensitive drum 2 is transferred by the transfer charger 6. The conveyance path through which the recording medium MRC is conveyed, including the period up to the fixing position, is configured to be substantially linear and substantially horizontal. In this way, when the conveyance path of the recording medium MRC is substantially linear, the recording medium is not bent when the recording medium is conveyed, and a thick paper (having a basis weight of approximately 110 g / m ² or more), a thin paper (approximately 50 g / m ² or less), synthetic paper, label paper, tack paper, plastic cards, and so-called special media can be easily transported.

On the other hand, in particular, since the transport path between the transfer position and the fixing position is substantially linear, leakage light from the fixing lamp 21 in the fixing unit 20 easily reaches the photosensitive drum 2, and the surface member Ab (described later) according to the present invention. ), Etc., printing troubles such as the above-described image flow due to NOx, white spots, and white background fogging are likely to occur.

In the fixing unit 20, two fixing lamps 21 serving as a radiant heat source, a reflection plate 22, and a heat radiation fin 23 for cooling the reflection plate 22 are provided in the housing 20 a, and a protection is provided on the front surface of the housing 20 a facing the conveyance unit 15. Glass 24 is arranged. A suction duct 26 for sucking air is provided on the downstream side of the fixing unit 20.

  For example, a xenon lamp or a halogen lamp is used as the fixing lamp 21. The reflecting plate 22 is formed by processing a metal such as aluminum having a high reflectance on the inner surface thereof. However, if the reflection plate 22 is a metal, it is difficult to be formed into an arbitrary shape because the metal plate has a low degree of freedom in shape and becomes heavy. For this reason, the reflection plate 22 may be formed of a heat-resistant resin such as polyimide deposited with metal. For example, a polyimide film having a thickness of about 0.1 to 0.5 mm is integrally formed into a desired reflector shape by vacuum forming, and a metal such as aluminum, silver, or gold is deposited on the inner surface.

  1, the suction duct 26 is arranged in the front and back direction of the housing 1a in FIG. 1, has an opening on the transport unit 15 side, and is provided with suction means such as a filter for deodorization and smoke removal and a blower. The suction duct 26 sucks air around the fixing unit 20 and discharges it to the outside of the housing 1a, thereby removing unpleasant odors and smoke of toner components mainly generated by fixing the unfixed toner image in the fixing unit 20. .

The electrophotographic printer 1 is configured as described above, and performs a desired print by fixing an unfixed toner image on the recording medium MRC by the electrophotographic method described below.

  First, the surface of the photosensitive drum 2 whose surface is cleaned by the cleaning unit 10 and rotated at a constant speed in the direction of the arrow is charged by the main charger 3 after the residual charge on the surface is removed by the charge eliminating lamp 11.

  Next, the LED print head 4 irradiates the photosensitive drum 2 with a light beam to form an electrostatic latent image corresponding to the recording information on the surface of the photosensitive drum 2. The electrostatic latent image is developed by the developing unit 5 by the rotation of the photosensitive drum 2 and becomes an unfixed toner image (visible image).

  The unfixed toner image developed on the photosensitive drum 2 is transferred by the transfer charger 6 onto the recording medium MRC conveyed along the conveyance path indicated by the arrow. The recording medium MRC to which the unfixed toner image is transferred is separated from the photosensitive drum 2 by the separation charger 7 and conveyed to the fixing unit 20 by the conveyance unit 15. In the fixing unit 20, the fixing lamp 21 emits light, and the unfixed toner image is melted by the generated heat and fixed on the recording medium MRC.

  In the electrophotographic printer 1, as described above, an image corresponding to the recording information is formed on the recording medium MRC, charged by the pre-cleaning charger 8, the carrier recovery by the carrier recovery unit 9, and the cleaning unit 10. After the surface cleaning of the photosensitive drum 2, the residual latent image on the photosensitive drum 2 is erased by the charge eliminating lamp 11 and is used for the next subsequent image formation.

Next, the proximity member and the surface member Ab according to the present invention will be described with reference to FIG. 1 and a partially enlarged view thereof. For comparison, FIGS. 3 and 4 show a conventional electrophotographic printer. In FIG. 1 (FIG. 2) and FIG. 3 (FIG. 4), the same reference numerals are assigned to the same members.

In FIG. 1 showing an embodiment according to the present invention, a surface member Ab is affixed to the neutralizing lamp 11 portion, the base portion 4a of the LED print head, and the support portion of the pre-cleaning charger 8. The surface member Ab is obtained by subjecting a 0.5 mm thick steel plate to electroless nickel plating specified by JIS-H8645. Further, the surface member Ab is attached in a replaceable manner with a screw (not shown). If the surface member Ab is provided so as to be replaceable in this way, it is preferable that the surface member Ab can be replaced even if, for example, dirt or deterioration occurs due to long-term use.

Further, in FIG. 1, the common shield plate S of the transfer charger 6 and the separation charger 7 is obtained by applying the same electroless nickel plating to a 1 mm thick steel plate, and the guide plate 13 is also 1.5 mm thick. The same electroless nickel plating treatment was applied to the steel plate.

On the other hand, in the conventional electrophotographic printer shown in FIGS. 3 and 4, the surface member Ab does not exist. The aluminum member covering the lamp is exposed in the vicinity of the photosensitive drum 2 in the portion 11 of the electric lamp. The base portion 4a of the LED print head is also made of an aluminum material, which is also close to the photosensitive drum 2. The pre-cleaning charger 6 support is also made of an aluminum drawn material and is close to the photosensitive drum 2.

The common shield plate S of the transfer charger 6 and the separation charger 7 is a stainless steel (SUS303) steel plate having a thickness of 1 mm, and the transfer guide 13 is a stainless steel (SUS303) steel plate having a thickness of 1.5 mm.

In FIG. 3, in the electrophotographic printer, an aluminum material or a stainless steel plate is exposed in proximity to the photosensitive drum 2, and in these portions, the above-described image flow due to NOx, white spots, and white background fogging. Printing failure occurs. In particular, these printing obstacles are remarkable at the opposing parts of the transfer charger 6, the separation charger 7, and the guide plate 13. This is thought to be because NOx is heavier than the atmosphere and tends to stay vertically below the photosensitive drum 2.

On the other hand, in FIGS. 1 and 2 which are the embodiments of the present invention, the surface member Ab is replaceably provided at these portions, and the shield plate S and the guide plate 13 themselves are electroless nickel. Plating is applied to effectively prevent the above-mentioned printing failure.

1 is a cross-sectional front view illustrating a schematic configuration of an electrophotographic printer according to an embodiment of the image forming apparatus and the image forming method of the present invention. FIG. 2 is an enlarged cross-sectional front view centering on a photosensitive drum in the electrophotographic printer of FIG. 1. 1 is a cross-sectional front view illustrating a schematic configuration of an electrophotographic printer according to an embodiment of an image forming apparatus and an image forming method according to a conventional technique. FIG. 4 is an enlarged cross-sectional front view centering on a photosensitive drum in the electrophotographic printer of FIG. 3.

Explanation of symbols

1. Electrophotographic printer 1d. Side plates 1e, 1f. Stay 1g, 1h. Shield plate 2. 2. Photosensitive drum Main charger 4. LED print head 5. Development unit 5c. Developing roll 5d. Magnet 6. Transfer charger 7. Separation charger 8. 8. Pre-cleaning charger Carrier recovery unit 10. Cleaning unit 10b. Brush roller 11. Static elimination lamp 12. Separation claw 13. Guide plate 14. Tractor 15. Transport unit 16. Sukaflora20. Fixing unit 21. Flash lamp 22. Reflector 23. Radiating fin 24. Protective glass 26. Suction duct Ab surface member PIF. Image forming unit Shield plate

Claims (11)

An image forming apparatus having an electrostatic latent image carrier, wherein at least a surface of a member adjacent to the electrostatic latent image carrier that faces the electrostatic latent image carrier is combined with nitrate ions to form a metal salt. An image forming apparatus comprising a surface member made of a formable metal element or an alloy material containing them as a main component.   The image forming apparatus according to claim 1, wherein the member adjacent to the electrostatic latent image carrier is a recording medium conveying member.   The image forming apparatus according to claim 1, wherein the member adjacent to the electrostatic latent image carrier is a charger for the electrostatic latent image carrier.   4. The image forming apparatus according to claim 1, wherein the surface member is provided so as to be replaceable.   The image forming apparatus according to claim 1, wherein the electrostatic latent image carrier has a photosensitive layer made of an organic photosensitive material.   The image forming apparatus according to claim 5, wherein the photosensitive layer is a positively charged type.   The image forming apparatus according to claim 5, wherein the photosensitive layer has a single layer structure.   The image forming apparatus according to claim 1, wherein the image forming apparatus includes a charger for the electrostatic latent image carrier in addition to a main charger and a transfer charger. The image forming apparatus according to claim 1, wherein the image forming apparatus includes a fixing device using a flash fixing method.   The image forming apparatus according to claim 9, wherein at least a portion of the recording medium conveyance path of the image forming apparatus between the transfer position to the recording medium and the fixing position is substantially linear. In an image forming method for developing an electrostatic latent image on an electrostatic latent image carrier into a toner image, transferring the toner image to a recording medium, and fixing the same, a member adjacent to the electrostatic latent image carrier At least the surface facing the electrostatic latent image carrier is composed of a surface member made of a metal element capable of binding to nitrate ions to form a metal salt or an alloy material containing them as a main component. Image forming method.

Images