JP2021192078A - Image forming apparatus and image forming method - Google Patents

Abstract

To provide an image forming apparatus that does not need to use toner to remove a discharge product and can prevent an abnormal image and a blurred image.SOLUTION: An image forming apparatus has: a photoreceptor 40; electrifying means 60 that electrifies the photoreceptor in a non-contact manner; lubricant application means 65 that applies lubricant to the photoreceptor; and alkaline material application means 64 that applies alkaline material to the photoreceptor. The alkaline material application means can be brought into contact with and separated from the photoreceptor, and applies the alkaline material when brought into contact with the photoreceptor.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus and an image forming method.

In recent years, the development of information processing system machines using the electrophotographic method has been remarkable. In particular, laser printers and digital copiers that convert information into digital signals and record information by light have significantly improved print quality and reliability. In addition, these have been applied to laser printers or digital copiers capable of full-color printing by fusing with high-speed technology.

In recent years, as a charging means for charging a photoconductor (sometimes referred to as an "electrophotographic photosensitive member"), color image formation using a roller charging type charging means that saves power, generates a small amount of ozone, and can be made compact. Equipment is the mainstream. On the other hand, in order to further increase the durability and speed of the image forming apparatus, the conventional non-contact corona discharge type charging means has been reviewed. However, in the corona discharge type charging means, there is a concern that the amount of discharge products (ozone, NOx, etc.) generated by the discharge will be larger than that in the roller charging method.

Further, for the purpose of improving the cleaning property of the toner by the cleaning blade, a technique of applying a lubricant to the photoconductor by using a lubricant applying means to lower the friction coefficient of the photoconductor is known. In the image forming apparatus provided with such a lubricant applying means, the amount of wear of the photoconductor and the filming of the photoconductor are reduced as another merit, and the life of the photoconductor can be expected to be extended.

As described above, as an electrophotographic image forming apparatus, an apparatus configuration including a non-contact charging means such as a corona discharge method and a lubricant applying means is known. However, in such an apparatus configuration, there is a problem that the lubricant deposited on the surface of the photoconductor and the discharge product generated by the corona discharge absorb moisture, and the electric resistance on the surface of the photoconductor is lowered. When the surface electrical resistance of the photoconductor is lowered, image blurring occurs and a good image cannot be obtained.

On the other hand, when trying to remove the discharge product with a cleaning blade, the friction coefficient of the surface of the photoconductor is low due to the action of the lubricant, and the high hardness of the photoconductor makes it difficult to scrape and adheres to the surface of the photoconductor. The discharged product is difficult to remove. Therefore, in order to remove the discharge product, toner is adhered to the surface of the photoconductor, the coefficient of friction of the surface is increased, the surface of the photoconductor is easily scraped, and the discharge product adhering to the surface of the photoconductor is scratched with a cleaning blade. To be done. However, in this case, the toner is adhered to the surface of the photoconductor in order to remove the discharge product, so that wasteful toner other than printing is consumed.

On the other hand, in order to remove the discharge product, a technique other than the method of adhering the toner to the photoconductor and polishing it has been proposed. For example, Patent Document 1 discloses a technique for neutralizing and removing a discharge product by allowing an alkaline substance having an action of reacting with an acidic substance (discharge product) to neutralize the surface of the photoconductor. As its device configuration, a means for applying an alkaline substance to the surface of the photoconductor is provided so as to face the photoconductor. According to this, in order to remove the discharge product adhering to the surface of the photoconductor, it is expected that image blurring can be prevented without consuming wasteful toner.

However, in Patent Document 1, since the alkaline substance-imparting means is always in pressure contact with the photoconductor, the alkaline substance-imparting means continues to be applied even when the discharge product is not attached to the surface of the photoconductor. Therefore, there is a problem that an abnormal image is generated due to an influence on the electrical characteristics of the photoconductor and a change in the surface resistance of the photoconductor.

Therefore, an object of the present invention is to provide an image forming apparatus capable of suppressing an abnormal image or a blurred image without using a toner to remove a discharge product.

In order to solve the above problems, the image forming apparatus of the present invention includes a photoconductor, a charging means for non-contactly charging the photoconductor, a lubricant applying means for applying a lubricant to the photoconductor, and the photosensitizer. It has an alkaline substance-imparting means for imparting an alkaline substance to the body, and the alkaline substance-imparting means is capable of abutting and separating from the photoconductor, and when abutting on the photoconductor, the alkaline substance is applied. It is characterized by giving.

According to the present invention, it is not necessary to use toner to remove the discharge product, and it is possible to provide an image forming apparatus capable of suppressing an abnormal image or a blurred image.

It is a schematic diagram which shows an example of an image forming apparatus. It is a schematic diagram which shows an example of the peripheral part of a photoconductor. It is a schematic diagram which shows an example of the contact and separation of an alkaline substance addition means. It is a flowchart which shows an example of the control of a control means.

Hereinafter, the image forming apparatus and the image forming method according to the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments shown below, and can be modified within the range conceivable by those skilled in the art, such as other embodiments, additions, modifications, and deletions. However, as long as the action and effect of the present invention are exhibited, it is included in the scope of the present invention.

The image forming apparatus of the present invention includes a photoconductor, a charging means for non-contactly charging the photoconductor, a lubricant applying means for applying a lubricant to the photoconductor, and an alkaline substance for applying an alkaline substance to the photoconductor. It has a substance-imparting means, and the alkaline substance-imparting means is capable of contacting and separating from the photoconductor, and is characterized in that the alkaline substance is applied when the photoconductor is in contact with the photoconductor.

FIG. 1 is a schematic view showing an embodiment of an image forming apparatus according to the present invention. In this embodiment, the image forming apparatus is applied to a copier that performs color printing, but the present invention is not limited to this, and may be applied to a copier that performs monochrome printing.

This copier is a tandem type electrophotographic copier that employs an intermediate transfer method. In addition to the copying machine, the image forming apparatus may be applied to a printer device, a facsimile device, a multifunction device having a copying function and a facsimile communication function, and the like.

First, the configuration will be described. As shown in FIG. 1, the copying machine is a copying machine main body 100, a paper feeding unit 200, a scanner 300 mounted on the copying machine main body 100, and an automatic document transporting device (hereinafter referred to as ADF) mounted on the scanner 300. 400, a control circuit for controlling the operation of each device in the copying machine and the like are provided.

The copying machine main body 100 is provided with an intermediate transfer belt 10 (also referred to as a transfer body) composed of an annular belt in the center thereof. The intermediate transfer belt 10 is hung on three support rollers 14, 15 and 16 from the first to the third. Of these three support rollers, the third support roller 16 is a drive roller, and the intermediate transfer belt 10 is rotationally moved in the clockwise direction in the figure by the driving force thereof. As the intermediate transfer belt 10, a known one can be used.

The wide belt horizontal portion of the intermediate transfer belt 10 is configured to be stretched between the first support roller 14 and the second support roller 15 among the three support rollers. As shown in FIG. 1, a tandem image forming portion 20 is arranged to face the horizontal portion of the belt. The tandem image forming unit 20 has four sets of image forming units 18Y, 18M, 18C, yellow (Y), magenta (M), cyan (C), and black (K) along the belt moving direction in the belt horizontal portion. 18K (hereinafter, four sets are collectively referred to as an image forming unit 18) are arranged side by side. These four sets of image forming units 18 are configured to form a color image.

The exposure apparatus 21 is provided above the tandem image forming unit 20 and constitutes an exposure means. Further, the secondary transfer device 22 is provided on the opposite side of the tandem image forming unit 20 with an intermediate transfer belt 10 interposed therebetween, and constitutes a secondary transfer means. The secondary transfer device 22 transfers the toner image transferred on the intermediate transfer body to the transfer sheet. The transfer sheet means a printable sheet such as ordinary recording paper and copy paper.

The secondary transfer device 22 transfers the toner image on the intermediate transfer belt 10 to the transfer sheet S, which is a transfer material. The secondary transfer device 22 also has a sheet transfer function of transferring the transfer sheet S after the toner image is transferred from the intermediate transfer belt 10 to the fixing device 25.

Further, in the secondary transfer device 22, an annular secondary transfer belt 24 is hung between two rollers 231 and 232 as a transfer sheet transport member. The secondary transfer belt 24 is provided so as to be pressed against the third support roller 16 via the intermediate transfer belt 10.

The fixing device 25 is provided on the left side in the drawing of the secondary transfer device 22, and the pressure roller 27 is pressed against the annular fixing belt 26 to form a nip portion. The nip portion is configured such that the transfer sheet S is sandwiched between the fixing belt 26 and the pressure roller 27, which are appropriately heated, and is conveyed while being heated. In this nip portion, the toner image transferred on the transfer sheet S is fixed by heat and nip pressure.

Further, the sheet reversing device 28 is provided at a position parallel to the tandem image forming unit 20 under the secondary transfer device 22 and the fixing device 25. The sheet reversing device 28 is configured to invert the transfer sheet S and record an image on both sides of the transfer sheet S.

Hereinafter, the usage and internal operation of the above-mentioned copying machine will be briefly described. When copying using this copier, the original is set on the platen 30 of the ADF400. Alternatively, the ADF 400 is opened, the original is set on the contact glass 32 of the scanner 300, the ADF 400 is closed, and the document is pressed by the contact glass 32. After that, when the start switch is pressed, when the original is set in the ADF400, the original is conveyed and moved onto the contact glass 32.

On the other hand, when the original is set on the contact glass 32, the scanner 300 is immediately driven. Then, the first traveling body 33 and the second traveling body 34 are made to travel. Then, light is emitted from the light source of the first traveling body 33 toward the document. The reflected light from the document surface is received by the first traveling body 33, and is reflected toward the second traveling body 34 by the mirror arranged there. The light received by the second traveling body 34 is reflected by the mirror arranged therein, passes through the imaging lens 35, and is irradiated to the reading sensor 36. The reading sensor 36 converts the reflected light from the document surface received in this way into an electric signal and reads the content of the document.

In parallel with reading the document, the drive motor rotates the drive roller 16. As a result, the intermediate transfer belt 10 rotates in the clockwise direction in the drawing, so that the remaining two support rollers 14 and 15 are also driven and rotated. Since these support rollers 14 and 15 are driven, they are also referred to as driven rollers 14 and 15.

Further, at the same time as the rotation of the intermediate transfer belt 10, the photosensitive drums 40Y, 40M, 40C, 40K (hereinafter collectively referred to as the photosensitive drum 40) as the photoconductors are also rotated in the individual image forming portions 18. Then, each of the photosensitive drums 40Y, 40M, 40C, and 40K is exposed and developed on the outer periphery of the drums by using the color-coded information of yellow, magenta, cyan, and black, respectively. That is, a monochromatic toner image (visual image, visible image) is formed on each photosensitive drum 40.

Then, the toner image developed on the outer periphery of the drum of each photosensitive drum 40 is sequentially superimposed and transferred on the intermediate transfer belt 10. A color toner image in which four colors are combined is formed on the intermediate transfer belt 10. The photosensitive drum 40 and the intermediate transfer belt 10 according to the present embodiment correspond to the intermediate transfer body and the primary transfer means, respectively. Further, it is preferable that the primary transfer bias applied to the primary transfer means is controlled by a constant current.

In parallel with such image formation, the transfer sheet S is fed out from one of the paper cassettes 44. Specifically, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the transfer sheet S is fed out from one of the paper feed cassettes 44 provided in the paper bank 43 in multiple stages. The transferred transfer sheet S is separated one by one by the separation roller 45 and moved to the paper feed path 46. The transfer sheet S in the paper feed path 46 is guided to the paper feed path in the copying machine main body 100 by the transport roller 47, and is temporarily stopped at a position abutted by the resist roller 49.

Alternatively, the transfer sheet S can be supplied from the manual feed tray 51 instead of the paper cassette 44. That is, the transfer sheet S placed on the manual feed tray 51 is introduced into the paper feed path in the copying machine main body 100 by rotating the paper feed roller 50, and is temporarily stopped at a position abutted by the resist roller 49. Specifically, the transfer sheet S on the manual feed tray 51 is fed by the rotation of the paper feed roller 50, separated one by one by the separation roller 52, introduced to the manual paper feed path 53, and abutted against the resist roller 49 to stop. ..

The transfer sheet S, which is temporarily stopped at the position abutted against the resist roller 49, is fed between the intermediate transfer belt 10 and the secondary transfer device 22 while being restricted at a predetermined timing. That is, the secondary transfer device 22 rotates the resist roller 49 in time with the movement of the intermediate transfer belt 10 so that the synthetic color toner image on the intermediate transfer belt 10 can be transferred to an appropriate position on the transfer sheet S. By doing so, the color toner image is transferred onto the transfer sheet S. The secondary transfer device 22 corresponds to the secondary transfer means.

After transferring the toner image, the transfer sheet S is transferred to the fixing device 25 by the secondary transfer belt 24. The transfer sheet S is subjected to heat and pressure by the fixing belt 26 and the pressure roller 27 in the fixing device 25 to fix the transfer toner image. That is, printing is completed.

The printed transfer sheet S is sorted by the switching claw 55 at the sorting destination of either the output tray 57 or the sheet reversing device 28. When the paper is sorted to the output tray 57 side, the transfer sheet S is ejected by the ejection roller 56 and stacked on the output tray 57. On the other hand, when the sheets are sorted to the sheet reversing device 28 side, the printed transfer sheet S is guided to the sheet reversing device 28 by the switching claw 55, is inverted there, and is guided to the transfer position again, and the image is also displayed on the back surface. After recording, the paper is discharged onto the paper discharge tray 57 by the discharge roller 56.

After the toner image is transferred to the intermediate transfer belt 10, the residual toner remaining on the intermediate transfer belt 10 is removed by the intermediate transfer belt cleaning device 17. After being cleaned in this way, the intermediate transfer belt 10 stands by in the tandem image forming unit 20 in preparation for another image formation.

At this stage, the resist roller 49 is generally electrically grounded. However, it is also possible to remove paper dust and the like from the transfer sheet S by releasing the resist roller 49 from the electrical grounding and applying a predetermined bias voltage.

Next, the image forming unit 18 of the tandem image forming unit 20 described above will be described with reference to FIG. FIG. 2 is a schematic view showing a peripheral portion of a photosensitive drum of the image forming apparatus according to the embodiment. Although only the K-color image forming unit 18K will be described here, the image forming units 18Y, 18M, and 18C can also have the same configuration.

As shown in FIG. 2, the image forming unit 18K has a charging device 60K, a temperature / humidity sensor 70K, a developing device 61K, a photosensitive drum cleaning device 63K, an alkaline substance applying means 64K, and a lubricant applying means 65K around the photosensitive drum 40K. , Equipped with a static elimination device (not shown).

It is not necessary to color-code these four sets of K, Y, M, and C, which mean each color, and when they are described together, the image forming unit 18, the photosensitive drum 40, the charging device 60, the temperature / humidity sensor 70, and the development are described. The device 61, the photosensitive drum cleaning device 63, the alkaline substance applying means, the lubricant applying means, and the like may be described by removing the reference numerals meaning each color.

At the time of image formation, the photosensitive drum 40K is rotationally driven in the direction of the arrow by the drive motor. Then, the surface of the photosensitive drum 40K is uniformly charged by the charging device 60K, and then the image information of the above-mentioned original document or the like is exposed from the exposure device 21 by the writing exposure L to form an electrostatic latent image. .. The charging device 60 according to the present embodiment is a charging means according to the present invention.

The charging device 60K is a non-contact charging means such as a charging charger, and charges the photoconductor in a non-contact manner. Non-contact charging means include, for example, a non-contact charging device using corona discharge, a needle electrode device, a solid discharge element, and a conductive or semi-conductive charging roller arranged with a minute gap with respect to a photoconductor. And so on. Of these, corona discharge is particularly preferred.

The corona discharge is a non-contact charging method that gives positive or negative ions generated by the corona discharge in the air to the surface of the photoconductor, and is a Coroton charger having a property of giving a constant amount of charge to the photoconductor. There is a scorotron charger that has the property of giving a constant potential. The Coroton charger is composed of a casing electrode that occupies a half space around the discharge wire and a discharge wire placed substantially in the center thereof. The scorotron charger is obtained by adding a grid electrode to the corotron charger, and the grid electrode is provided at a position, for example, 1.0 to 2.0 mm away from the surface of the photoconductor.

The color image signal based on the image information from the scanner 300 is subjected to image processing such as color conversion processing in the image processing unit, and is output to the exposure device 21 as an image signal of each color of K, Y, M, and C. The exposure apparatus 21 converts an image signal of only K generated by the image processing unit, that is, a K image signal into an optical signal. Then, by exposing the surface of the photosensitive drum 40K, which is uniformly charged in advance, while scanning with the K optical signal converted based on the K image signal, an electrostatic latent image of only K, that is, K static image is exposed. Form an electro-latent image.

The developing device 61K is provided with a developing roller 61a in a positional relationship that is parallel to the photosensitive drum 40K and is in contact with each other on the outer peripheral surfaces. A development bias voltage is applied to the developing roller 61a. The developing roller 61a is formed with a potential difference between the K electrostatic latent image on the outer peripheral surface of the photosensitive drum 40K and the developing roller 61a, that is, a developing potential. Due to this development potential, the toner on the outer peripheral surface of the developing roller 61a is transferred from the developing roller 61a to the electrostatic latent image of the photosensitive drum 40K. As a result, the electrostatic latent image is developed to form a toner image.

The developing device 61K is provided with a supply roller 61b that supplies toner to the developing roller 61a. Further, the developing device 61K may be provided with a toner concentration sensor.

The K toner image formed on the outer peripheral surface of the photosensitive drum 40K is primarily transferred onto the outer peripheral surface of the intermediate transfer belt 10 by the primary transfer roller 62K. A primary transfer bias by constant current control is applied to the primary transfer roller 62K.

After the toner image is transferred, the residual toner in the photosensitive drum 40K is cleaned by the photosensitive drum cleaning device 63K. The photosensitive drum cleaning device 63K can be appropriately changed, and may include, for example, a cleaning blade 63a, a transport screw 63b for transporting the recovered toner, and the like.

Next, static elimination is performed by a static elimination device (not shown). The order of static elimination can be changed as appropriate after transfer.

Next, the alkaline substance is applied to the photosensitive drum 40K by the alkaline substance applying means 64K. The alkaline substance applying means in the present embodiment can abut and separate from the photoconductor, and applies the alkaline substance when it comes into contact with the photoconductor. By applying an alkaline substance to the photoconductor, it chemically reacts with a discharge product (also referred to as a conductive substance) generated by a charger charging type corona discharge or the like to reduce the concentration of the discharge product adhering to the photoconductor. be able to. As a result, it is possible to suppress a decrease in the electrical resistance of the surface of the photoconductor.

In the present embodiment, examples of the discharge product include nitrogen oxides (NOx), which are acidic substances and therefore undergo a neutralization reaction with an alkaline substance. This can reduce the concentration of the discharge product.

As the alkaline substance, sodium hydroxide and potassium hydroxide are preferable. In this case, the concentration can be satisfactorily reduced by chemically reacting with nitrogen oxides (NOx) (neutralization reaction). In addition to the above, it can be used as an alkaline substance.

The method of applying the alkaline substance can be appropriately changed. For example, it may be applied to the photoconductor in the form of a solid such as powder. In the case of a solid, it can be applied using, for example, a roller, a brush, a belt (belt-shaped member), etc., and an alkaline substance is retained on the surface of, for example, a roller, a brush, a belt, or the like. The retained alkaline substance is imparted to the photoconductor by coming into contact with the photoconductor. Note that in the case of a solid, the film thickness due to coating may increase, which may affect the photoconductor sensitivity.
In addition to the above, for example, an alkaline substance may be dissolved in a solvent to form a solution, which may be impregnated into a member such as a roller, a brush, or a belt.

Among these, it is preferable to apply using a roller. That is, the alkaline substance applying means has a roller having an alkaline substance on the surface, and the roller comes into contact with the photoconductor to apply the alkaline substance. In this case, the roller may be referred to as a coating roller or the like. When applied using a roller, there is an advantage that it is easy to form a form in which the photoconductor is brought into contact with and separated from the photoconductor.

FIG. 2 shows an example in which a rotatable coating roller 64a is used, and the contact / detachment mechanism 64b allows the photosensitive drum 40K to be brought into contact with and separated from the photosensitive drum 40K as shown by an arrow. When the coating roller 64a comes into contact with the photosensitive drum 40K, it goes around with the photosensitive drum 40K and imparts an alkaline substance having an alkaline substance on the roller surface to the photosensitive drum 40K.

When an alkaline substance is applied using a roller, the roller has a surface layer made of a sponge, and the durometer hardness of the surface layer is preferably 20 ° or less. In this case, a sponge roller having a low hardness can be used, damage to the photoconductor can be suppressed, and the life of the photoconductor can be improved. Further, when the surface layer made of a sponge is provided, it is possible to impregnate the surface layer with an alkaline substance in the form of a solution, which can be preferably applied.

Further, when the alkaline substance applying means has a roller provided with a surface layer made of a sponge, at least a part of the surface layer may be impregnated with an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide as an alkaline substance. In this case, when the surface layer impregnated with the aqueous solution of sodium hydroxide or the aqueous solution of potassium hydroxide comes into contact with the photoconductor, the aqueous solution of sodium hydroxide or the aqueous solution of potassium hydroxide is immersed in the photoconductor, and an alkaline substance is preferably imparted. Can be done.

FIG. 3 shows a schematic diagram for explaining an example of contact and separation of the alkaline substance applying means. FIG. 3 is a diagram showing an example when a coating roller is used, and is a diagram when FIG. 2 is viewed from the upper surface. In FIG. 3, a photosensitive drum 40K, a coating roller 64a, a contact / detachment bracket 81, a cam 82, a home position sensor 83, and a contact / detachment motor 84 are shown. The figure shows an example in which the coating roller 64a is in contact with the photosensitive drum 40K. The broken line in the figure is the axial direction of the coating roller 64a.

For example, a signal is sent from the control means to the home position sensor 83, and the position of the coating roller 64a is detected by the home position sensor 83. Based on this, drive control is performed for the contact / detachment motor 84. When the coating roller 64a is brought into contact with the photosensitive drum 40K, the cam 82 is driven by the contact / detachment motor 84 and pressed against the contact / detachment bracket 81. Similarly, when the coating roller 64a is separated from the photosensitive drum 40K, the cam 82 is driven by the contact / detachment motor 84 to be separated from the contact / detachment bracket 81.

In this way, the coating roller 64 can be brought into contact with and detached from each other. Further, the contact pressure of the coating roller 64a with respect to the photosensitive drum 40K can be appropriately adjusted by appropriately changing the configurations of the contact / detachment bracket 81, the cam 82, and the like.

The contact coating time is determined by, for example, a control means, and the coating roller 64a abuts on the photosensitive drum 40K during the determined contact coating time. The contact coating time can be changed as appropriate, and an example will be described below.

As described above, in the present embodiment, the alkaline substance applying means can be brought into contact with and separated from the photoconductor, and the alkaline substance can be applied to the photoconductor when necessary. Therefore, it is possible to prevent the alkaline substance from being continuously applied to the photoconductor, and it is possible to suppress the influence of the alkaline substance on the electrical characteristics of the photoconductor. As a result, it is possible to suppress the occurrence of abnormal images and image blur due to changes in the surface resistance of the photoconductor.

Next, the lubricant is applied to the photosensitive drum 40K by the lubricant applying means 65K. It is preferable that the lubricant applying means 65K is provided downstream of the cleaning device 63K and the alkaline substance applying means 64K in the rotation direction of the photosensitive drum 40K.

The lubricant applying means 65K preferably has a lubricant coating blade 65a. The material of the lubricant-coated blade 65a is not particularly limited and may be appropriately selected from known materials for cleaning blades according to the purpose. For example, urethane rubber, hydrin rubber, silicone rubber, fluororubber and the like can be selected. Can be mentioned.

The lubricant-coated blade 65a is fixed to the blade support by an arbitrary method such as adhesion or fusion so that the tip portion can press and contact the surface of the photoconductor. The thickness of the blade cannot be unambiguously defined in consideration of the force applied by pressing, but is preferably 0.5 to 5 mm, more preferably 1 to 3 mm. Further, the length of the blade that can be projected from the support and have a deflection, that is, the so-called free length, cannot be uniquely defined in consideration of the force applied by pressing, but 1 to 15 mm is preferable. 2 to 10 mm is more preferable.

As another configuration of the blade, a method such as coating or dipping a coating layer of a resin, rubber, elastomer or the like on the surface of an elastic metal blade such as a spring plate via a coupling agent, a primer component or the like, if necessary. It may be formed in the above form, heat-cured if necessary, and surface-polished if necessary.

The lubricant applying means 65K preferably has a brush-shaped roller 65b that rotates in contact with the photosensitive drum 40K as the lubricant supplying means. It is preferable that the brush-shaped roller scrapes off the lubricant to supply the lubricant onto the photoconductor. In this case, the brush fibers are preferably flexible in order to suppress mechanical stress on the surface of the photoconductor. The material of the flexible brush fiber is not particularly limited and may be appropriately selected depending on the intended purpose.

As the support of the brush-shaped roller 65b, a fixed type and a rotatable roll-shaped one can be used. Examples of the roll-shaped supply member include a roll brush made by spirally winding a tape made of a pile of brush fibers around a metal core metal. The brush fibers as the fiber diameter 10~500μm about the length of the fibers of the brush 1 to 15 mm, brush density per square inch 10,000 to 300,000 present (per square meter 1.5 × ¹⁰ 7 ~ 4.5 × 10 ⁸ pieces) is suitable.

From the viewpoint of supply uniformity and supply stability, it is preferable to use a lubricant supply means having a high brush density, and one fiber is produced from several to several hundred fine fibers. Is preferable. For example, 50 fine fibers of 6.7 denier (6 denier) such as 333 decitex = 6.7 decitex x 50 filaments (300 denier = 6 denier x 50 filaments) are bundled and flocked as one fiber. Is preferable.

As the lubricant, metal soap is suitable. Examples of the metal soap include zinc stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate, and the like. Zinc oleate, manganese oleate, iron oleate, cobalt oleate, lead oleate, magnesium oleate, copper oleate, partimic acid, cobalt zinc pultimate, copper partimate, magnesium paltimate, aluminum paltimate, paltimic acid Calcium, lead caprylate, lead caproate, zinc linolenate, cobalt linolenate, calcium linolenate, cadmium licolinolenate, candelilla wax, carnauba wax, rice wax, wood wax, oba oil, honey wax, lanolin, etc. .. These may be used alone or in combination of two or more.

The support member 65c that supports the brush-shaped roller 65b can be appropriately changed. Both ends of the shaft member forming the rotation shaft of the brush-shaped roller 65b may be supported. Further, the support member 65c may have a urging means such as a spring member, and the pressing force of the brush-shaped roller 65b may be adjusted.

Next, the same step is performed in the other image forming unit. The image forming units 18Y, 18M, and 18C are also provided with similar devices around the photosensitive drums 40Y, 40M, and 40C, respectively. Then, toner images of Y, M, and C are formed on the photosensitive drums 40Y, 40M, and 40C, respectively, and these are superposed on the outer peripheral surface of the intermediate transfer belt 10 to be primary transferred in full color.

The image forming apparatus may be configured to have, for example, a full color mode and a monochrome mode. For example, in the full color mode, when the color of the image to be formed is full color, all the photosensitive drums 40Y, 40M, 40C, 40K are brought into contact with the outer peripheral surface of the intermediate transfer belt 10. On the other hand, in the monochrome mode, when the black color is monochromatic, the photosensitive drums 40Y, 40M, 40C for color other than 40K for K color are separated from the outer peripheral surface of the intermediate transfer belt 10.

An input unit for manual operation may be provided on an operation panel (also referred to as an input panel) (not shown). The user can appropriately switch between the monochrome mode and the full color mode for input. In addition, the user may give other instructions by using the operation panel.

As described above, according to the present embodiment, there is provided an image forming method capable of suppressing an abnormal image or a blurred image without using toner to remove the discharge product. The image forming method of the present embodiment includes a charging step of charging the photoconductor in a non-contact manner, a developing step of forming a toner image on the photoconductor, a transfer step of transferring the toner image to a transfer body, and an addition of an alkaline substance. The photoconductor-imparting means comprises an alkaline substance-imparting step of imparting an alkaline substance to the photoconductor and a lubricant-imparting step of imparting a lubricant to the photoconductor, and the alkaline substance-imparting means abuts on the photoconductor and The separation is possible, and the alkaline substance is applied when the photoconductor comes into contact with the photoconductor.

Next, an example of control for abutting and separating the alkaline substance applying means from the photoconductor will be described. In this embodiment, an example of controlling contact and separation using a control means will be described.

If the control means has a measuring means for measuring at least one of the temperature and humidity around the photoconductor, the control means abuts and abuts the alkaline substance imparting means based on at least one of the temperature and humidity measured by the measuring means. Control the separation.

Examples of the measuring means include the above-mentioned temperature / humidity sensor 70K. The arrangement of the temperature / humidity sensor 70K can be changed as appropriate. As the measuring means, the means for measuring the temperature and the means for measuring the humidity may be separated, or the temperature and the humidity may be measured by one means. Further, a measuring means may be provided for each photosensitive drum, or one measuring means may be used for a plurality of drums.

In this way, the temperature and humidity around the photoconductor are taken into consideration because it is considered that the water contained in the air around the photoconductor affects the electrical resistance of the surface of the photoconductor, and the amount of water in the air is This is because it is also affected by the temperature. When the lubricant is applied to the photoconductor, the discharge product generated by the charging means is adsorbed on the lubricant, and the surface of the photoconductor is lowered in resistance due to the influence of moisture in the air, and image blurring is likely to occur. It is thought that there are many cases. Therefore, by considering the temperature and humidity around the photoconductor, it is possible to further suppress the occurrence of abnormal images and image blur. As the humidity, both relative humidity and absolute humidity can be used, but in this embodiment, it is preferable to use absolute humidity.

When the image forming apparatus starts to start, the control means obtains the time from when the image forming apparatus stops the previous start to when the image forming apparatus starts to start this time as the leaving time, and the alkaline substance applying means is based on the leaving time. It is preferable to control the contact and separation. In the present embodiment, examples of the start-up start include the following (1) to (3).

(1) When the power of the image forming apparatus is turned off and then turned on after a while, the time when the power of this image forming apparatus is turned on.
(2) The time when the power of the image forming apparatus is turned on and the current printing is started after the previous printing is completed. Examples of the time when printing is completed include the time when the transfer sheet is subjected to the fixing step and the fixing step is completed. The time point at which printing is started can be changed as appropriate, and examples thereof include a time point when the start switch is pressed after setting the original on the contact glass, a time point when the transfer sheet is fed out from the paper feed cassette, and the like.
(3) When the power of the image forming apparatus is ON, a predetermined time has elapsed without performing any processing since the last printing was completed, and after shifting to the hibernation mode, the automatic re-printing is performed. When it started. The trigger for automatic restart includes, for example, when the user operates the input panel, when an instruction from the user is received, and when a predetermined time has elapsed.

The reason for determining the standing time is that the discharge product generated by the charging means is adsorbed on the coated lubricant, and the amount of the discharge product adhering to the photoconductor increases with the passage of time. Further, when the charging means is a non-contact charging method such as a corona discharge method, the discharge product adheres to or accumulates inside the corona charging means, and the discharge product falls on the photoconductor while the photoconductor is stopped. , It is thought that the amount of adhesion will increase. Therefore, it is possible to further suppress the occurrence of abnormal images and image blur by performing control in consideration of the leaving time.

Further, when the image forming apparatus starts to start, the control means obtains the time from when the image forming apparatus stops the previous activation to when the image forming apparatus starts to start this time as the leaving time, and the leaving time exceeds a predetermined threshold value. If the humidity measured by the measuring means exceeds a predetermined threshold value, it is preferable to bring the alkaline substance-imparting means into contact with the photoconductor. That is, it is preferable to determine the contact of the alkaline substance applying means in consideration of the leaving time and humidity. As a result, it is possible to more accurately determine whether or not the state requires blur removal, and it is possible to further suppress the occurrence of abnormal images and image blur.

Further, when the leaving time exceeds a predetermined threshold value and the humidity measured by the measuring means exceeds a predetermined threshold value, the control means further determines that the temperature measured by the measuring means exceeds a predetermined threshold value. When the temperature measured by the measuring means exceeds a predetermined threshold value, the time for contacting the alkaline substance applying means with the photoconductor is set when the temperature does not exceed the predetermined threshold value. It is preferable to make it larger than that. As described above, when the temperature is high, the amount of water in the air increases, and it is considered that the influence of the discharge product on the electrical resistance of the surface of the photoconductor is increased. Therefore, when the temperature is high, the electric resistance of the surface of the photoconductor can be made more preferable by applying the alkaline substance for a longer time.

Further, it is preferable that the control means controls the amount of the alkaline substance applied according to the temperature or humidity value measured by the measuring means. That is, the amount of the discharge product adhered on the surface of the photoconductor is predicted from the temperature and humidity values measured by the measuring means, and the amount of the alkaline substance applied is controlled (adjusted) according to the amount of the discharge product adhered. change. As a result, it is possible to prevent excessive application of alkaline substances, and it is possible to keep the electrical resistance of the surface of the photoconductor in a better state.

The method for controlling the amount of the alkaline substance applied can be appropriately selected. For example, when a coating roller having a surface layer made of a sponge is used, a method of adjusting the amount of a solution of an alkaline substance impregnated in the surface layer, a method of changing the contact force for abutting the coating roller, and the like can be mentioned. In addition to this, as a method of controlling the amount of the alkaline substance applied, a method of varying the rotation speed of the coating roller and the like can be mentioned.

As described above, according to the present embodiment, it is possible to control the alkaline substance applying means to come into contact with the photoconductor when it is predicted that an abnormal image or image blurring will occur and it is determined that a countermeasure is necessary. .. Therefore, the addition of an alkaline substance can be minimized, and the electrical resistance of the surface of the photoconductor can be easily maintained in a good state. In addition, by adopting a configuration that allows contact and detachment according to the conditions, the time for the alkaline substance applying means to come into contact with the photoconductor can be appropriately changed according to the conditions such as the leaving time and the temperature and humidity around the photoconductor. Alkaline substances can be added only when necessary.

Next, an example of control of the control means will be described with reference to the drawings. FIG. 4 is a flowchart showing an example of control of the control means.

(S101) corresponds to the time when the image forming apparatus starts to start (start to start). The above-mentioned time points can be mentioned as the start of startup.
Next, when the image forming apparatus starts to start, the time from the previous stop of the image forming apparatus to the start of the current activation is obtained as the neglected time (S102). The start time of this time and the start stop time of the previous time are changed as appropriate as described above.

Next, the above-determined leaving time is compared with the execution determination threshold value (S103). The execution determination threshold can be changed as appropriate. The execution determination threshold value is appropriately changed depending on, for example, the configuration of the photoconductor, the type of charging method, the usage environment (humidity, temperature, etc.) of the image forming apparatus.

As a result of comparison in S103 as described above, if the leaving time is equal to or less than the threshold value, the treatment of bringing the alkaline substance-imparting means into contact with the photoconductor is not performed (S104). In the example of the flowchart shown here, the time during which the alkaline substance applying means is brought into contact with the photoconductor is referred to as the contact coating time. Therefore, in S104, the contact coating time is set to 0 [sec], and the image is formed without adding an alkaline substance. If the leaving time is equal to or less than the threshold value, it is considered that the discharge product does not adhere to the photoconductor, or even if it adheres to the photoconductor, it is at an acceptable level. It also applies when it has not been so long since the last application of the alkaline substance.

As a result of comparison in S103 as described above, when the leaving time exceeds the threshold value, temperature / humidity detection is performed (S105). The temperature / humidity detection can be performed by using a measuring means for measuring the temperature and humidity around the photoconductor, and can be performed by using, for example, the temperature / humidity sensor 70K described above.

Next, the humidity obtained in S105 is compared with the execution determination threshold value (S106).
When the humidity is equal to or less than the threshold value, the contact coating time is set to 0 [sec] (S108).

The reason why the determination is made by giving priority to the humidity over the temperature is that, as described above, it is considered that the moisture contained in the air around the photoconductor has a large influence on the electric resistance of the surface of the photoconductor. When the lubricant is applied to the photoconductor, the discharge product generated by the charging means is adsorbed on the lubricant, and the surface of the photoconductor is lowered in resistance due to the influence of moisture in the air, and image blurring is likely to occur. It is thought that there are many cases.

As a result of the comparison in S105 as described above, when the humidity exceeds the execution determination threshold value, the temperature is further compared with the execution determination threshold value (S107). The reason for comparing the temperature is that the amount of water in the air is also affected by the temperature.

As a result of comparison in S107 as described above, when the temperature is equal to or lower than the threshold value, the contact coating time is set to, for example, 120 [sec] (S108). On the other hand, as a result of comparison in S107, when the temperature exceeds the threshold value, the contact coating time is set to, for example, 240 [sec] (S109).

As described above, when the temperature measured by the measuring means exceeds a predetermined threshold value, the temperature does not exceed the predetermined threshold value for the time for bringing the alkaline substance-imparting means into contact with the photoconductor (contact coating time). It is preferable to make it larger than the case. This is because when the temperature around the photoconductor is high, the amount of water content increases, and it is considered that the influence on the electrical resistance of the surface of the photoconductor is increased. By doing so, it is possible to further suppress abnormal images and image blurring.

Next, the contact / detachment operation of the alkaline substance applying means is performed according to the contact coating time obtained as described above (S111). As the contact / detachment operation, for example, a control means sends a signal to the above-mentioned home position sensor, confirms that the alkaline substance applying means is not in contact with the photoconductor, and drives the contact / detachment motor to expose the alkaline substance applying means. Bring it into contact with the body. In the case of contacting, the alkaline substance applying means is brought into contact with the photoconductor during the contact coating time, but printing (charging, exposure, development, transfer, etc.) is performed after the contact coating time has elapsed. Or you may print in the state of being in contact with each other.

As the contacting / separating operation, for example, when the contact coating time> 0 [sec] and the alkaline substance applying means are separated, the contacting operation may be performed. Further, when the contact coating time = 0 [sec] and the alkaline substance applying means is in contact, the operation may be such that the separation operation is performed. It should be noted that the case where the contact coating time = 0 [sec] and the alkaline substance applying means is in contact is assumed to be, for example, when the power is turned off during the execution of the contact coating.

In the above example, the temperature and humidity are detected after S103 to obtain the contact coating time, but the present embodiment is not limited to this, and if the leaving time is equal to or longer than the threshold value in the comparison of S103, the present invention is not limited to this. The contact coating time may be set to a predetermined value.

10 Intermediate transfer belt 18 Image forming part 40 Photosensitive drum 60 Charging device 61 Developing device 61a Developing roller 61b Supply roller 63 Photosensitive drum cleaning device 64 Alkaline substance applying means 64a Coating roller 64b Contact / detachment mechanism 65 Lubricant applying means 65a Lubricant coating blade 65b Brush-shaped roller 65c Support member 70 Temperature / humidity sensor

Japanese Unexamined Patent Publication No. 02-079069

Claims (11)

Photoreceptor and
A charging means that charges the photoconductor in a non-contact manner,
A lubricant applying means for applying a lubricant to the photoconductor, and
It has an alkaline substance imparting means for imparting an alkaline substance to the photoconductor.
The image forming apparatus is characterized in that the alkaline substance applying means can be brought into contact with and separated from the photoconductor, and the alkaline substance is applied when the photoconductor is brought into contact with the photoconductor. The image forming apparatus according to claim 1, wherein the alkaline substance contains at least one selected from sodium hydroxide and potassium hydroxide. The image forming apparatus according to claim 1, wherein the alkaline substance applying means has a roller having the alkaline substance on the surface, and the roller comes into contact with the photoconductor to apply the alkaline substance. .. The image forming apparatus according to any one of claims 1 to 3, wherein the roller has a surface layer made of a sponge, and the durometer hardness of the surface layer is 20 ° or less. The alkaline substance applying means has a roller provided with a surface layer made of a sponge, and is characterized in that at least a part of the surface layer is impregnated with an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide as the alkaline substance. The image forming apparatus according to any one of claims 1 to 4. A control means for controlling the contact and separation of the alkaline substance applying means, and
It has a measuring means for measuring at least one of the temperature and humidity around the photoconductor.
The control means according to any one of claims 1 to 5, wherein the control means controls the contact and separation of the alkaline substance applying means based on at least one of the temperature and the humidity measured by the measuring means. Image forming device. It has a control means for controlling the contact and separation of the alkaline substance applying means, and has
When the image forming apparatus starts to start, the control means determines the time from when the image forming apparatus stops the previous activation to when the image forming apparatus starts to start this time as a leaving time, and based on the leaving time, said. The image forming apparatus according to any one of claims 1 to 6, wherein the contact and separation of the alkaline substance applying means are controlled. A control means for controlling the contact and separation of the alkaline substance applying means, and
It has a measuring means for measuring the temperature and humidity around the photoconductor.
When the image forming apparatus starts to start, the control means obtains the time from the previous stop of the image forming apparatus to the start of the current activation as the leaving time, and the leaving time is a predetermined threshold value. 1 to 7, wherein when the humidity measured by the measuring means exceeds a predetermined threshold value, the alkaline substance applying means is brought into contact with the photoconductor. The image forming apparatus described in the above. When the leaving time exceeds a predetermined threshold value and the humidity measured by the measuring means exceeds a predetermined threshold value, the control means further determines the temperature measured by the measuring means. If the temperature measured by the measuring means exceeds a predetermined threshold value, the time for which the alkaline substance applying means is brought into contact with the photoconductor is set to a predetermined threshold value. The image forming apparatus according to claim 8, wherein the image forming apparatus is made larger than the case where the temperature is not exceeded. It has a control means for controlling the contact and separation of the alkaline substance applying means, and has
The image forming apparatus according to any one of claims 1 to 9, wherein the control means controls an amount of the alkaline substance applied according to a temperature or humidity value measured by the measuring means. A charging process that charges the photoconductor in a non-contact manner,
The developing process of forming a toner image on the photoconductor and
A transfer step of transferring the toner image to a transfer body, and
An alkaline substance imparting step of imparting an alkaline substance to the photoconductor by an alkaline substance imparting means,
It has a lubricant applying step of applying a lubricant to the photoconductor.
The image forming method, characterized in that the alkaline substance applying means can be brought into contact with and separated from the photoconductor, and the alkaline substance is applied when the photoconductor is in contact with the photoconductor.

Images