JPH0365980A - Cleaning device for image forming device - Google Patents

Abstract

PURPOSE:To perform stable cleaning for a long period by providing a cleaning blade which is allowed to press-contact with an image carrier in a reverse direction and a cleaning member which is allowed to press-contact to rub the surface of the image carrier. CONSTITUTION:The cleaning device is provided with the cleaning blade 2 which is allowed to press-contact with the image carrier 9 in the reverse direction and the cleaning member 1 which is allowed to press-contact to rub the surface of the image carrier 9. Therefore, urethane rubber having 2mm thickness and urethane rubber having 1.7mm thickness are arranged with line pressure 10g/cm and 8g/cm as the cleaning blade 1 and the cleaning blade 2 respectively. Thus, fine-grain toner whose average volume grain diameter is <=7mum is easily removed and the high-quality image is stably obtained for a long period.

Description

Detailed Description of the Invention (L) Object of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus that utilizes an electrostatic transfer process, such as an electrostatic copying machine or a printer, and particularly to a cleaning device thereof. It is.

(Prior art and issues to be solved) In a well-known image forming apparatus that repeats the process of transferring a transferable toner image formed on the surface of an image carrier onto a transfer material such as paper, the transferable toner image is transferred to the transfer material each time it is transferred. It is essential to sufficiently remove the residual toner that remains on the image bearing member without removing the toner from the image carrier.

Various methods have been proposed as means for removing residual toner for this purpose. For example, a method in which a web made of nonwoven fabric or the like is rubbed on the surface of the image carrier is a method in which the web is moved in the running direction of the image carrier. Cleaning performance is good because the web can be brought into contact with an appropriate length, but the web is likely to be contaminated when a large amount of toner arrives, making it difficult to maintain stable cleaning performance. Therefore, a cleaning blade made of an elastic material such as rubber is usually used in the normal direction of the rotating cylindrical image bearing member because it is small, simple in structure, and has an excellent toner removal function. For,
It is well known that cleaning means in which pressure is applied while tilting in the forward direction or in the counter direction are widely used.

In addition, as for the toner used for image formation, in the case of black images, carbon is dispersed in a resin such as polyethylene or polypropylene, and this is pulverized (a charge control agent may be added to this). In many cases, the volume average particle size is about 8 to 20 μm, especially 12 to 15 μm.
μ■ ones are often used.

However, in this type of image forming apparatus, from the viewpoint of improving image quality, particles with a volume average particle diameter of about 10 LLm are being used, and in the case of forming color images, Even one with a diameter of 8μ has been proposed.

As described above, the tendency for the particle size of the toner used to gradually become smaller cannot be avoided from the perspective of improving image quality, and it is highly likely that toner with even smaller diameter will be used in the future. .

By the way, as mentioned above, it is well known that there are two ways to bring the cleaning blade into contact with the edge, and another way to bring the cleaning blade into contact with the edge while tilting it in the opposite direction. As is well known, the latter method, the counter method, is often used because, although damage to the image carrier is less likely to occur, toner can easily get into the gap between the blade and the image carrier, resulting in poor cleaning. It is.

However, as described above, the toner tends to become smaller in diameter, even if the counter method described above is used, there is a tendency for the toner to slip through the blade. It is necessary to increase the pressure applied to the surface.

For example, when using toner with a volume average particle size of 15 μm, the linear pressure of the blade was adjusted to 8 gr/Cal, but when using toner with a particle size of 12 μm, the linear pressure of the blade was adjusted to 20 gr/Cal.
gr/cm is required, and for this reason, especially when an organic photoconductive layer is used as the photosensitive layer on the surface of the image carrier, the amount of abrasion of the photosensitive layer by the blade increases, causing damage to the image carrier. Durability will be impaired.

The present invention has been made to deal with this situation, and by using a well-known cleaning blade arranged in the counter direction together with other cleaning means, small-diameter toner particles with a particle size of 7 μm or less can be removed. It is an object of the present invention to provide a cleaning device that can perform good cleaning with light pressure, reduce abrasion of the photosensitive layer, and perform stable cleaning over a long period of time.

(2) Structure of the invention (technical means for solving the problem, and its operation) In order to achieve the above object, the present invention provides a cleaning device for an image forming apparatus in which an image bearing member is placed in pressure contact with the image carrier in the opposite direction. It is characterized by comprising a cleaning blade and a cleaning member disposed in pressure contact so as to rub and clean the surface of the image carrier.

With this configuration, by pressing a cleaning member such as a cleaning blade against the image carrier with light pressure, it is possible to easily remove even fine toner particles with a volume average particle diameter of 7 μm or less. Then,
Contributes to obtaining high quality images.

(Description of Embodiments) FIG. 1 is a schematic side view of an image forming apparatus showing an embodiment of the present invention, in which a cylindrical image carrier (
After the surface of the photoreceptor (hereinafter referred to as photoreceptor) 9 is uniformly charged by the primary charger 3, an image signal such as reflected light from the original or an image-modulated laser beam is projected onto the charged surface to increase the electrostatic potential. An image is formed.

Next, toner is supplied to the latent image by the developing device 5, and the latent image becomes a toner image. Further, as the photoreceptor 9 rotates, this toner image reaches a transfer site equipped with a transfer charger 6, and the transfer material is The toner image on the photoreceptor side is transferred to the transfer material by the transfer bias applied at this time.

Next, the transfer material carrying the toner image is conveyed to a fixing site (not shown), and after the toner image is fixed and fixed on the transfer material, it is discharged from the apparatus.

On the other hand, at the transfer site, the residual toner remaining on the photoconductor without being transferred to the transfer material reaches the cleaning device 7 and is removed therefrom. 9 is assumed to be ready for the next image forming process.

In the illustrated apparatus, the cleaning device 7 includes a cleaning blade l which is pressed against the photoreceptor in the forward direction, and a cleaning blade l which is in pressure contact with the photoreceptor in the downstream side of the blade 1 in the opposite direction when viewed from the direction of travel of the photoreceptor. It is characterized by having a cleaning blade 2 that is pressed into contact with the cleaning blade 2.

Next, an experimental example using such a leaning device will be explained.

[Experiment Example-1] The cleaning blade 1 arranged in the forward direction has a thickness of 2
11II+ urethane rubber is installed at a linear pressure of 10 gr/cm, and as the cleaning blade 2 arranged in the opposite direction, 1.7++ m thick urethane rubber is installed at a linear pressure of 8 gr/cm.
gr/cm.

The toner used was one made of polypropylene with a volume average particle diameter of 6 μm.

Here, I would like to say a few words about the method for measuring the volume average particle diameter.

A Coulter Counter TA-n type (manufactured by Coulter Co., Ltd.) was used as a particle size distribution measuring device, an interface for outputting the volume average distribution, and a CX-1 personal computer were connected, and primary sodium chloride was used as the electrolyte. A 1% NaCff aqueous solution was prepared.

A surfactant as a dispersant, preferably an alkylbenzenesulfonate O1l to 5mf2, is added to the above electrolyte aqueous solution of 100 to 150mj2, and a measurement sample is further added to 0.5 to 5mf2.
Add 011Ig.

The electrolytic solution in which the sample was suspended was dispersed for about 1 to 3 minutes using an ultrasonic disperser, and then dispersed using a 100 μ aperture as an aperture using the Coulter Counter TA-n type.
The particle size distribution of particles of ~40μ was measured to determine the volume average distribution, and the volume average particle size was obtained from this.

As a photoreceptor, the outer diameter is 8011! I+, length 360+1
An undercoat layer of copolymerized nylon resin is formed on a 11O aluminum cylinder by dipping coating, and on top of that a polyvinylbenzal resin with titanyl phthalocyanate dispersed is applied by dipping coating, and on top of that, CTL as shown below is applied. A photoreceptor was formed by dissolving a styryl compound of the structural formula and a polycarbonate resin in a mixed solvent of dichloromethane/monochlorobenzene (40:20) and forming a film to a thickness of 20 μm by dipping coating.

Using the photoreceptor and toner as described above, images were inspected initially and after passing 100,000 sheets using a copying machine as shown in the first figure.

Comparative Example 11 An experiment similar to Experimental Example 1 was conducted with the exception that the forward blade 1 was removed from the above apparatus.

[Comparative Example-2] In the above-mentioned apparatus, an experiment was conducted under the same conditions as in Experimental Example-1, except that the reverse direction blade 2 was removed.

[Comparative Example-3] The same equipment was used last time, except that the forward direction blade 1 was removed and the linear pressure of the reverse direction blade was set to 25 gr/cm.
The experiment was conducted under the same conditions as in Experimental Example-1.

[Comparative Example-4] The same device as before was used, except that the reverse direction blade 2 was removed and the linear pressure of the forward direction blade L was set to 30 gr/cm.
The experiment was conducted under the same conditions as in Experimental Example-1.

[Comparative Example-5] Using the same equipment as in Experimental Example-1, the forward direction blade was removed and the linear pressure of the reverse direction blade was 22gr/c.
Further, the toner was changed from a polypropylene resin toner having a volume average particle diameter of 6 .mu.m to a polyethylene resin toner having a volume average particle diameter of 8 .mu.m, and an experiment was conducted under the same conditions as in the above experimental example.

The above experimental results are shown in Table 1.

[Experiment Example-2] A polyethylene resin toner with a volume average particle size of 7 u was used as the toner, and the linear pressure of the forward blade was 12 gr.
/ca+, and the linear pressure of the reverse direction blade was 10 gr/cm, and a paper passing experiment was conducted under the same conditions as in Experimental Example-1.

[Experiment Example 3] A reverse blade having the configuration shown in Figure 2 was used, and the linear pressure of the forward blade was adjusted to 11 gr/c and that of the reverse blade to 9 gr/co. Furthermore, a paper feeding experiment was conducted under the same conditions as in Experimental Example 1, except that a polypropylene resin toner having a volume average particle diameter of 5 μm was used as the toner.

[Comparative Example-6] The forward direction blade in Experimental Example-1 was changed to the reverse direction as shown in Figure 3, and the linear pressure of this blade was increased to 10
The experiment was conducted under the same conditions as in Experimental Example-■ except for gr/C0IL/ta.

The above results are shown in Table 2.

Next, as mentioned earlier, cleaning means such as a cleaning web and a sheet-like cleaning means have basically good cleaning properties, so a cleaning device that uses both this and a cleaning blade will be described.

FIG. 4 is a schematic side view of an image forming apparatus equipped with such leaning means, and since its basic configuration is the same as that shown in FIG. 1, corresponding parts have the same reference numerals. , and their explanation will be omitted.

In this image forming apparatus, the cleaning device 7 includes:
Cleaning blade 2 and photoreceptor 9 arranged in opposite directions
A sheet-like member is disposed on the downstream side of the photoreceptor 9 when viewed in the running direction, and is formed in a winding manner so as to be wound up sequentially by an appropriate driving source, and the sheet material sequentially slides against the surface of the photoreceptor 9. A cleaning member configured to
O is arranged.

With this configuration, the drawbacks of the sheet-like cleaning member can be eliminated, and the cleaning blade can be made to have a particle size of 8.
It is possible to sufficiently remove toner particles of micrometers or less, and stable cleaning can be performed over a long period of time.

Experimental examples will be explained below.

[Experimental Example-4] In the apparatus shown in Fig. 4, a nylon woven fabric with a wire diameter of 60 uIm was used as a sheet-like cleaning member, and urethane rubber with a thickness of 9 mm was used as a cleaning blade at a linear pressure of 9
It was used by setting it to gr/Cot.

The toner used was a polyethylene resin toner having a volume average particle diameter of 7 μm.

The means for measuring the particle size and the like are the same as in Experimental Example-1 described above.

A leaning device like this was arranged in an image forming apparatus as shown in FIG. 4, and an experiment was conducted to pass 100,000 sheets to check the images.

[Comparative Example-7] The cleaning blade in Experimental Example-4 was removed and an experiment was conducted under the same conditions.

[Comparative Example-81 The sheet-like cleaning member 10 in Experimental Example-4 was removed and an experiment was conducted under the same conditions.

[Comparative Example-9] The sheet-like cleaning member 10 in Experimental Example-4 was removed, and the linear pressure of the cleaning blade 2 was reduced to 28 gr/
An experiment was conducted under similar conditions with the setting of cra.

The above results are shown in Table 3.

(Left below) [Experimental example-5] Polyethylene resin toner with a volume average particle diameter of 5 μm was used, and the linear pressure of the cleaning blade 2 was set to l Ogr/
The experiment was conducted under the same conditions as Experimental Example 4, except that the distance was set to cm.

Comparative Example 101 An experiment was conducted under the same conditions as Experimental Example 4, except that a polyethylene resin toner with a volume average particle diameter of 8 μm was used as the toner, and the sheet-like cleaning member 10 was removed.

The above results are shown in Table 4.

(Leaving space below) [Experiment Example 61 A urethane rubber blade with a thickness of 1.5 mm was used as a cleaning blade, and as shown in Figure 5, this was pressed in the forward direction with a linear pressure of 12 gr/cta to clean the sheet. The cleaning member 11 was constructed by forming a polyester woven fabric having a wire diameter of 50 LLm into the shape of an endless belt so as to rub the surface of the photoreceptor 9.

A polypropylene resin toner having a volume average particle size of 6 μm was used as the toner, and a paper feeding experiment was conducted under the same conditions as in Experimental Example 4 above.

[Comparative Example-11] The cleaning blade in Experimental Example-6 was removed and an experiment was conducted under the same conditions as those in Experimental Example-6.

[Comparative Example-123 The endless belt-like sheet-like cleaning member in Experimental Example-6 was removed, and the linear pressure of the cleaning blade 2 was set to 32
The experiment was conducted under the same conditions as in Experimental Example 6, except that it was set to gr/cm.

The above results are shown in Table 5.

(3) As described in detail of the invention, according to the present invention, the cleaning blade is disposed in the opposite direction to the image carrier and presses against the image carrier, and the cleaning blade is cleaned by rubbing the surface of the image carrier. By sharing the same cleaning member with a cleaning member arranged so as to perform cleaning, even when using fine toner particles with a particle size of 7 LLm or less, a good cleaning function can be achieved without increasing the linear pressure of the cleaning blade too much. This makes it possible to realize extremely high-quality images, and
By reducing the wear of the cleaning blade and the amount of abrasion of the photosensitive layer on the surface of the image carrier, stable cleaning can be performed over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of the main parts of an image forming apparatus showing an embodiment of the present invention; FIGS. 2 and 3 are side views showing other embodiments in which a part of the above is modified; FIG. 4 is a side view showing still another embodiment, and FIG. 5 is a side view showing another embodiment partially modified from the above. l, 2...Cleaning blade, 3...-time charger, 4...Image exposure section, 5...Developer, 6...Transfer charger, 7...Cleaning device, 9... ... Image carrier, 10.11... Sheet-like cleaning member.

Claims (4)

[Claims] (1) A cleaning device for an image forming apparatus comprising a cleaning blade placed in pressure contact with the image carrier in the opposite direction and a cleaning member placed in pressure contact so as to rub and clean the surface of the image carrier. (2) The cleaning device according to claim 1, wherein the member for rubbing and cleaning the surface of the image carrier is a cleaning blade disposed in pressure contact with the image carrier in a forward direction. (3) The cleaning device according to claim 1, wherein the member for rubbing and cleaning the surface of the image carrier is a winding type web that comes into pressure contact with the surface. (4) The cleaning device according to claim 1, wherein the member for rubbing and cleaning the surface of the image carrier is an endless belt-like member that comes into pressure contact with the surface.