JPH03103885A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the flow of an image caused by defective electrification resulting from the sticking of powder to an electrifying member brought into contact with an image carrier by applying powder of <= a 10<10>OMEGA.cm volume resistivity to the contact surface of the cleaning member of a cleaning device with the image carrier. CONSTITUTION:Conductive powder of <= a 10<10>OMEGA.cm volume resistivity smaller than the grain size of toner is applied to the contact surface of the cleaning blade 13a with the photosensitive body 1. For the powder, ground conductive material such as metal and metallic oxide can be used. Consequently, the flocculated body of the powder applied to the blade 13a falls down to the photosensitive body 1, and is carried to an electrifying roller 2a. Even if the flocculated body is stuck to the surface of the roller 2a, it does not adversely affect the electrifying processing of the photosensitive body by the roller 2a since the powder itself is conductive, and the photosensitive body 1 is uniformly electrified all the time. Thus, the occurrence of the flaw of the image caused by the sticking of the powder to the electrifying roller 2a can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus. More specifically, the image forming process means includes a charging device that charges the surface of the image carrier by bringing a charging member into contact with the surface of the image carrier, and a charging device that charges the surface of the image carrier by bringing a cleaning member into contact with the surface of the image carrier after image formation. The present invention relates to an image forming apparatus including a cleaning device that cleans the surface of the image carrier and enables repeated use of the image carrier.

(Prior Art) In the above, the image forming process means is conventionally known, such as electrophotographic process means, electrostatic recording process means, etc. The image carrier is, for example, an electrophotographic photoreceptor, an electrostatic recording dielectric, etc., and is used in the form of a rotating drum, a rotating belt, or a running web. A charging device that charges the surface of the image carrier by bringing a charging member into contact with the surface of the image carrier includes, for example, a contact (direct) charging device, a friction charging device, and the like.

Here, the contact Teiden device is a roller-shaped or blade-shaped device in which a voltage (for example, a DC voltage of about 1 to 2 KV, or a superimposed voltage of a DC voltage and an AC voltage, etc.) is applied to the surface of an image carrier as a charged body. ●By contacting a conductive member (charging member) such as a brush, charge is transferred (injected) directly to the image carrier surface to charge the image carrier surface to a predetermined potential. Compared to corona dischargers, which are commonly used as devices, corona dischargers have the following advantages: the voltage of the charging system can be lowered, the amount of ozone generated is extremely small, and the configuration is simple. It is being put into practical use as an alternative charging processing device. A cleaning device that enables repeated use of the image carrier by bringing a cleaning member into contact with the surface of the image carrier to clean the surface of the image carrier after image formation uses a blade member made of rubber or the like as a cleaning member to clean the surface of the image carrier after image formation. There are blade cleaning devices that clean the surface of the image carrier by wiping it in contact with the surface of the image carrier, as well as devices that clean the surface of the image carrier by pressing a cleaning member in the form of a rotating roller, a running web, or a pad body against the surface of the image carrier. .

Note that the image forming apparatus of the present invention includes a transfer type copying machine, a laser beam printer, a recording device, etc., in which a target image information image formed and carried on an image carrier surface is transferred to a copying material, and after the image transfer, In addition to cleaning the surface of the image carrier with a cleaning device and using it for image formation repeatedly, it is also possible to use an image display device, display device, etc., in which a desired image information image formed and carried on the surface of the image carrier is placed on a part of the monitor. It also includes an image forming apparatus in which the image bearing member is used for display and viewing, and then the formed and carried image is cleaned and erased by a cleaning device, and the image bearing member is repeatedly used to form a display image. FIG. 1 shows a schematic configuration of an example of an image forming apparatus to which the present invention is applied. It's a printer. Reference numeral 1 denotes a rotating drum-type electrophotographic photosensitive member as an image carrier, which is rotated clockwise as indicated by arrow A at a predetermined circumferential speed (process speed).

Reference numeral 2 denotes a charging device that charges the surface of the photoreceptor to a predetermined potential, and the wooden example is a contact charging device using a roller-type charging member (hereinafter referred to as a charging roller) 2a. The charging roller 2 is brought into contact with the surface of the photoreceptor 1 with a predetermined pressure by a pressure mechanism (not shown), and in the case of a wooden example, it rotates as the photoreceptor 1 rotates. By applying a DC bias or DC+AC bias from a power source 3 to the charging roller 2a, the surface of the rotating photoreceptor 1 is uniformly charged to a predetermined potential. Next, image exposure L of the target image information is performed on the surface of the charged photoreceptor by an exposure means 10 (slit exposure in 100 steps, laser beam scanning exposure means, etc.) in the exposure section C, so that the portion of the photoreceptor surface that is exposed to light is exposed. The charge is erased and an electrostatic latent image corresponding to the image exposure pattern is formed on the photoreceptor surface. The formed latent image is then subjected to toner development 15 by the developing means 1l, and the toner developed image is transferred to the transfer section between the photoreceptor 1 and the transfer means 12 from a paper feed section (not shown) at an appropriate timing. Transfer material l4 that has been transported
The image is transferred to 15a.

The transfer means 12 in the wooden example is a transfer roller to which a transfer bias is applied by a power source 12a, and the transfer roller charges the back side of the transfer material 14 with a polarity opposite to that of the toner 15, thereby causing the transfer material 14 to come into contact with and face the photoreceptor 1. The toner developed image l5 on the first side of the photoconductor 15 is transferred onto the surface of the photoreceptor 14. The transfer material 14 that has passed through the transfer section and received the image transfer is transferred to the photoreceptor 1.
It is separated from the surface and introduced into an image fixing device (not shown). Further, the surface of the photoreceptor 1 after the image transfer is cleaned by a cleaning device 13 to remove residual toner 15b and other contaminants adhering to the surface of the photoreceptor, and is used repeatedly for image formation.
The unprecedented cleaning device 13 is a blade cleaning device, in which a cleaning blade 13a made of rubber or the like is brought into contact in one direction counter to the rotation of the photoconductor 1, and the edge of the blade wipes the surface of the photoconductor 1. By letting
Transfer residual toner 15b on the surface of the photoconductor is scraped off and removed.

(Problems to be Solved by the Invention) In order to improve cleaning efficiency, the cleaning blade 13a is brought into contact with the counter in one direction with respect to the rotation of the photoreceptor 1, so that the cleaning blade 13a contacts the photoreceptor 1 in one direction, especially when the photoreceptor 1 starts rotating in four directions. The blade edge portion that is in contact with the body surface is likely to be caught in the rotating photoreceptor and be turned over in the forward direction of the rotation direction of the photoreceptor (so-called blade turning). In order to prevent this blade turning-up development, there is a conventional technique in which a slippery powder such as PVdF is applied to the contact surface of the blade 13a with the photoreceptor 1 to lower the coefficient of friction.

In this case, when applying the powder to the above-mentioned required surface portion of the blade 13a, in many cases, the powder is also applied to the back surface B side of the blade l3 (the blade surface on the side of the wedge space formed by the blade l3 and the surface of the photoreceptor 1). I end up. Moreover, the applied powder on the back side B of the blade often forms aggregates. Particularly, when a method is used in which powder is dispersed in a solution and applied to the blade in order to prevent the powder from scattering when the powder is applied to the blade, agglomeration of the powder tends to occur.

Then, the powder aggregates on the back side of the blade separate from the back side of the blade due to device vibration, etc., fall and adhere to the surface of the photoreceptor 1 after passing through the blade, and are conveyed to the position of the charging roller 2a as the photoreceptor l rotates, and a part of it is It adheres to the surface of the Teiden roller 2a. This adhered powder does not easily separate from the surface of the charging roller 2a and becomes stuck. As a result, the portion of the photoreceptor surface that comes into contact with the charging roller surface portion to which the powder has adhered is not charged or is insufficiently charged, and that portion appears as a black dot or white dot on the output image.

Furthermore, even in cases where the cleaning means is not a blade, and the cleaning roller is rotated in the opposite direction to the photoreceptor, the above problem will occur if powder is applied to the surface of the cleaning roller to reduce the coefficient of friction. .

Note that the above problem does not occur in an image forming apparatus using a corona discharger that does not contact the photoreceptor as a charging device. This is because most of the powder aggregates applied to the cleaning member fall onto the photoreceptor when the photoreceptor starts rotating, and the image quality on the photoreceptor is normally determined by the falling powder aggregates on the photoreceptor. This is because the attachment surface portion starts after passing through the exposure section C. In the present invention, a lubricating powder is applied to the contact portion of the cleaning member of the same cleaning device with the image carrier in order to lower the coefficient of friction with the image carrier surface. To always produce a good image quality by preventing an adverse effect on charging performance even if a toner falls onto the surface of an image carrier and is transported and stuck to a charging member of a charging device that is in contact with the surface of the image carrier. An object of the present invention is to provide an image forming apparatus of this type that can perform the following operations.

(Means for Solving the Problems) The present invention provides an image forming process means with a charging device that charges the surface of the image carrier by bringing a charging member into contact with the surface of the image carrier; An image forming apparatus including a cleaning device that makes it possible to repeatedly use the image carrier by bringing a cleaning member into contact with the surface of the image carrier after image formation, the cleaning member of the cleaning device coming into contact with the image carrier. This image forming apparatus is characterized in that a powder having a volume resistance of 10 Ω·cm or less is coated on the surface.

Further, in the image forming apparatus described above, the powder application is performed by applying a dispersion liquid in which the powder is dispersed in a solution. (Function) That is, by using a powder having a volume resistivity of 10 Ω·Cm or less, that is, a powder having electrical conductivity, the friction coefficient of the cleaning member against the image carrier can be lowered as in the past due to the lubricity of the powder. If the cleaning member is a blade, the problem of the blade turning over is prevented, and the agglomerates of the applied powder from the cleaning member are detached from the charging device that is in contact with the image carrier surface. Even if the adhering powder is transferred to the electrical member and adheres to the electrical member, since the adhering powder has a conductivity with a volume resistance of 10 Ω cm or less, it does not adversely affect the charging properties of the image carrier of the charging member and is uniform. Chargeability is maintained. Therefore, image defects such as black spots and white spots caused by powder stains on the charging member do not occur.

In addition, as mentioned above, there is no problem even if powder aggregates exist, so the powder dispersion coating method, which is effective in preventing powder scattering during powder coating, is used as a powder coating method for cleaning members. It becomes possible to adopt a method of applying and drying a dispersion liquid in which a liquid is dispersed without any problems, improving the work environment and work efficiency.

(Example) In the device shown in FIG. 1 described above, the cleaning blade 13
A conductive powder (volume resistance of 10 Ω cm or more) smaller than the toner particle size is applied to the contact surface with the photoreceptor l of a. The powder was dispersed in a solvent and the dispersion was applied.

As a powder, polystyrene/polyethylene ●PMMA-
Resin such as PVdF dispersed and pulverized with conductive substances such as carbon, metal, metal oxide, etc., or resin particles coated with conductive substances such as carbon, metal, metal oxide, etc. on the surface of resin particles, or carbon ●Pulverized conductive substances such as metals and metal oxides can be used.

In this way, the aggregate of the coating powder on the blade 13a falls onto the photoreceptor l and is conveyed to the charging roller 2a, and even if it adheres to the surface of the charging roller 2a, since the powder itself is conductive, the charging roller The photoreceptor l can always be uniformly charged without adversely affecting the charging performance of the photoreceptor 2a, and the charging roller 2a
Image defects such as black spots and white spots caused by powder adhesion do not occur.

Next, an experimental example will be shown. The image forming apparatus shown in FIG. 1 uses reversal development, and the power source 3 supplies the charging roller 2a with an AC frequency of 150 Hz. AC peak-to-peak voltage 2KV. DC voltage 700
The relationship between the volume resistance of the l1 powder applied to the cleaning blade 13a and the occurrence of a black spot image was investigated by applying a voltage of V and setting the process speed (rotational peripheral speed of the photoreceptor l) to 25 m/sec.

As a powder, carbon is dispersed in boristyrene, and after measuring the volume resistance, it is pulverized to produce particles with a particle size of 0.5 ILm, which is dispersed in methanol, and after drying the dispersion, the film thickness is about 500 g.
It was applied to the blade 13a so that the coating amount was m.

Table 1 shows the results. From now on, the volume resistance of the powder is 1
If the agglomerated powder particles are 0Ω・Cm or less, the charging roller 2
It can be seen that even if it adheres to a, it does not produce a sunspot image. In Table 1, the O mark indicates that there is no black spot image, and the x mark indicates that there is a black spot image.

Table 1 12 In this embodiment, the charging roller 2a is used as a contact charging device.
In addition, {1} electrified blade, electrified brush,
Similar results can be obtained with charging belts and the like.

The same applies when a cleaning roller is used instead of a blade as a cleaning means and powder is applied to the surface of the cleaning roller.

(Effects of the Invention) As described above, according to the present invention, when a lubricating powder is applied to the contact surface portion of the cleaning member of the cleaning device with respect to the image carrier surface in order to lower the coefficient of friction with the image carrier, By using the powder and /Q with a volume resistivity of 10Ω・Cm or less,
It is possible to prevent the occurrence of image defects such as black dots and white dots due to charging failure caused by powder adhesion stains on the charging member brought into contact with the image carrier.

Further, there is no problem even if the powder is dispersed in a solution and applied as a means for applying the powder to the cleaning member. There is no powder scattering during coating, which improves the working environment, and furthermore, since no scattering prevention measures are required, work efficiency is improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of an image-based precept device. l is a rotating drum-type electrophotographic photoreceptor as an image carrier;
2 is a contact charging device, 2a is a charging roller as its charging member, 3 is a bias application power source, 10 is an exposure means, 11 is a developing means, 12 is a transfer roller, 13 is a cleaning means, 13a is a cleaning blade, 14 is a transfer Material. l6

Claims (2)

[Claims] (1) The image forming process means includes a charging device that charges the surface of the image carrier by bringing a charging member into contact with the surface of the image carrier, and an image formed by bringing a cleaning member into contact with the surface of the image carrier. An image forming apparatus including a cleaning device that cleans the surface of the carrier and enables repeated use of the image carrier, and a powder having a volume resistance of 10 Ω·cm or less is applied to the contact surface of the cleaning member of the cleaning device with the image carrier. An image forming apparatus characterized by: (2) The image forming apparatus according to claim 1, wherein the powder application is performed by applying a dispersion liquid in which the powder is dispersed in a solution.