JPH06214489A - Cleaning device for image forming device - Google Patents

Abstract

PURPOSE:To always interpose a proper quantity of toner, etc., to reduce friction between the edge of a cleaning blade and an image carrier, to always maintain a stable state and to always attain excellent cleaning by specifying an angle between the edge of the cleaning blade and the image carrier. CONSTITUTION:The direction of the blade is set so as to obtain alpha<=x<=90 deg.+alpha, when an angle formed by a tangent (a) to the image carrier a point (D) where the blade edge is abutted on the image carrier 1 and the extending direction of the blade 3 is defined as (alpha) and an angle with respect to a vertical line at the point D is defined as (x). When (alpha) is made small, the blade 3 goes down on the left and toner tends to slide in the direction of gravity (g). In this constitution, the toner existing on the abutting edge of the cleaning blade 3 on the image carrier 1 is sequentially replaced with fresh one, a lubricant grain added to the toner can be always supplied to an edge part as well and stable cleaning can be attained over a long period.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine and a printer.
In particular, it relates to the cleaning device.

[0002]

2. Description of the Related Art In a known image forming apparatus that repeats the process of transferring a toner image formed on the surface of an image carrier to a transfer material such as paper, the transfer material is Residual toner that has not been transferred needs to be thoroughly cleaned after each transfer.

As such a cleaning means, a cleaning blade made of an elastic material such as rubber is used to press one edge of the cleaning blade into pressure contact with the image carrier to scrape off the residual toner generated, which is simple in construction. It is well known that it is practically used because of its small size and excellent toner removing function.

The typical construction of such a cleaning means will be briefly described with reference to FIG. 8. Normally, the cleaning device 12 is provided close to the image carrier 11 formed in the shape of a rotary cylinder and traveling in the direction of arrow A. Are arranged in parallel, and one end of the elastic cleaning blade 1 is attached to the elastic cleaning blade 1.
One of the free edges 3 is pressed against the surface of the image carrier 11 in the counter direction.

When the residual toner generated at a transfer portion (not shown) reaches the position of the blade 13 as the image carrier 11 rotates, the residual toner is scraped off and reaches the toner storage portion in the cleaning device. It is assumed that the conveying screw 15 guides the toner to the toner storage portion outside the apparatus.

As shown in the figure, a magnet roller 14 is disposed upstream of the cleaning blade 13 as viewed in the running direction of the image carrier 11, and as a result, it is generated from paper that is often used as a transfer material. To remove substances that are difficult to remove with a cleaning blade, such as fine paper powder, rosin and talc deposits, corona products caused by the action of high-pressure members inside the device, etc. Has become.

With the cleaning device having such a structure, a certain effect can be expected in obtaining a high quality image.
In this type of cleaning means, the edge of the cleaning blade is normally brought into contact with the image carrier in the so-called counter direction as shown in the drawing, and the blade and the image carrier made of urethane rubber or the like are used. Due to the frictional force generated between the surfaces, a frictional force that tries to reverse this in the running direction of the image bearing member acts on the pressure contact edge to the image bearing member, so as shown in FIG. When it is flexed as shown by the dotted line, the elasticity of the blade itself causes it to return to its original position, which causes so-called chattering.

Particularly in recent years, a toner having a smaller particle diameter has been used in order to improve the image quality, and a toner having a volume average particle diameter of 9 μm or less is suitable. When the volume average particle diameter of the toner is M and the particle diameter of the toner particle is r, the toner has a toner volume distribution of (M / 2) <r <(3/2) × M within a range of 9
It is perforated that 0 volume 5 or more is contained and 99 volume% or more is contained in the range of 0 <r <2M. The developer preferably contains toner and magnetic particles.

In such a situation, if the blade edge is strongly pressed against the image carrier in order to prevent the toner from slipping through the cleaning blade, the above-mentioned chattering is likely to occur. If the toner slips from the inside to cause cleaning failure, and if the toner becomes finer as described above, the occurrence of chattering becomes more and more noticeable.

Further, when chattering frequently occurs and the amplitude thereof becomes large, the bending of the image carrier becomes larger than the restoring force due to the elasticity of the blade, and the blade is turned up to make cleaning impossible. It may reach the state.

The present invention has been made to cope with such a situation, and in a cleaning device of an image forming apparatus using a cleaning blade, an appropriate amount of toner is always provided between the edge of the cleaning blade and the image carrier. It is an object of the present invention to provide a cleaning device in which the friction between the two is minimized and the stable state is maintained at all times by the interposition of the above-mentioned factors, and the good cleaning can be always performed.

[0011]

[Constitution of the invention]

In order to achieve the above object, the present invention provides a cleaning device equipped with a cleaning blade having an edge abutting against the image bearing member, wherein the cleaning blade is attached to the image bearing member. When the angle between the normal to the contact position and the vertical direction is x, and the angle between the tangent to the image carrier and the mounting direction of the cleaning blade at the contact position is α, α ≦ x ≦ 90 °
It is characterized in that the angle α and the angle x are determined so as to be + α.

With this structure, the toner existing at the contact edge of the cleaning blade with respect to the image bearing member is sequentially replaced with a new toner, and the lubricating particles added to the toner are always kept at this edge. It can be supplied to the site and enables stable cleaning over a long period of time.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS "FIG. 1" is a side sectional view of an embodiment of a cleaning device to which the present invention is applied, and has a cylindrical shape having an axis extending in the direction perpendicular to the plane of the drawing and rotating in the direction of arrow A in the drawing. The cleaning device 2 is arranged in parallel with the image carrier 1 of FIG.
The cleaning blade 3 made of an elastic material such as urethane rubber adjusts the contact pressure of the SU on the image carrier.
It is attached by a supporting member 8 together with a back plate 7 made of an elastic material such as S or phosphor bronze, and one edge of the blade 3 on the free edge side is in pressure contact with the surface of the image carrier 1.

When the residual toner generated at a transfer portion (not shown) on the upstream side of the cleaning blade 3 as viewed in the running direction of the image carrier 1 reaches the position of the cleaning blade 3, this toner is transferred to the cleaning blade 3. The foreign matter is scraped off by the edges, and the various foreign matters as described above are removed by the magnet roller 4, and the toner and the like are conveyed by the magnet roller, and then discharged by the conveying screw 5 to the outside of the apparatus.

Although not shown in the drawing, a primary charging device, an image signal applying means, a developing device, a transfer means and other members necessary for image formation are arranged around the image carrier 1. Of course there is.

Particles 9 having a diameter smaller than that of the toner are applied to the surface of the cleaning blade 3, particularly the blade edge portion. The particle size of the small-diameter particles is preferably about 0.5 to 8 μm in view of reducing the particle size of the toner.

Further, when the small-diameter particles pass through the blade edge and are temporarily charged, when the particles become a dielectric and induce charges of opposite polarity to leave a memory, the image quality is affected. Small particles have a dielectric constant of 2.0-
A material in the range of 5.5 is preferred.

Examples of such substances include (C
F) Graphite fluoride such as Cefbon CMA and CMF (manufactured by Central Glass Co.) having a molecular formula of _n ) is suitable, and (C ₂ F) _n type Cefbon DM (manufactured by Central Glass Co., Ltd.), fluorine Carbonized carbon # 2065, # 1030,
# 1000 (manufactured by Asahi Glass Co., Ltd.), and (CF) _n type fluorocarbons # 2028 and # 2010 (manufactured by Asahi Glass Co., Ltd.) having different fluorination rates can be preferably used.

Such a substance does not leave a memory in the image carrier unlike the particles of PVdF, for example, because the dielectric constant of the image carrier is 3.05 and that of PVdF is 6. 43, whereas the dielectric constant of fluorinated graphite (A) is 3.41, and that of fluorinated graphite (B) is 3.45.
This is due to the difference in dielectric constant between (both F / m) and the image bearing member.

The adhesion of such small-sized particles to the blade edge can be carried out by directly applying fluorinated graphite powder thereto or by dipping the solvent in a fluorocarbon solvent and then evaporating the solvent. By thus forming the cleaning blade, particularly the blade edge, the small-diameter particles 9 are present between the blade edge and the surface of the image carrier as shown in FIG.

Next, the angle when the cleaning blade comes into contact with the surface of the image bearing member will be described. In the cleaning device shown in FIG. 1, as shown in FIG. 2, the angle formed by the tangent to the image carrier and the extending direction of the blade at the point P where the blade edge contacts the image carrier is α. , Where x is the angle formed by the vertical line at point P,
The blades are oriented so that α ≦ x ≦ 90 ° + α.

As can be seen by changing the angle α, the 3C plane of the blade 3 becomes horizontal when x = α, and if α is made smaller, the blade 3 will fall to the left as seen in FIG. The toner tends to slide down in the direction of gravity g. x =
In the case of 90 ° + α, the tip surface 3B of the blade 3 becomes horizontal, and as x> 90 ° + α, the toner also tends to slide down in the direction of gravity g in this case.

Looking at the state of the toner at the portion where the tip of the cleaning blade 3 abuts on the image carrier 1, as shown in FIG. 4 only for the tip, there is a gap between the blade tip surface and the image carrier surface. In the space S (hatched portion in the figure), particles 10 having the same particle size as the small diameter particles 9 such as silica added as a lubricant together with the toner are present, and these particles pass through the blade. It has been found that a smooth cleaning is performed by.

Therefore, when the toner stored in the space S stays as it is and the small particles for lubrication contained therein pass through the blade and disappear, the lubricating action of the stored toner deteriorates and a chattering phenomenon occurs. Will come to do.

In order to prevent such toner accumulation,
When the thickness of the cleaning blade is reduced to reduce the space S'as shown in FIG. 5, the amount of toner staying in this portion decreases, and the newly scraped toner is successively supplied to the space S '. Therefore, the lubricant can be applied to the blade edge portion without running short, and stable cleaning can be always performed.

If the blade thickness shown in FIG. 4 is 3 mm, a blade thickness of 2 mm or less is suitable for small-diameter toner. On the other hand, if the thickness is too thin, the specified pressure contact force against the image bearing member cannot be obtained, so the blade thickness is 0.8 to 2 mm.
It is good to set the degree. Further, the angle α is 15 ° ≦
Good results were obtained when α ≦ 40 °.

FIG. 6 is a side view showing another embodiment, in which parts corresponding to those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Omit it.

In the illustrated apparatus, only the tip of the cleaning blade 3 and the vicinity of the portion in contact with the image carrier 1 are formed thin. By forming in this way, it is possible to reduce the toner retention space S described above to prevent the retention of toner and to press the blade 3 against the image carrier 1 with a strong pressing force.

FIG. 7 shows still another embodiment. In this apparatus, the fur brush 13 is disposed near the portion where the tip of the cleaning blade 3 contacts the image carrier 1 and is always provided. Is in a retracted position so that it does not come into contact with the blade 3, the image carrier 1, etc., so that the toner in the space S is wiped off by taking an operating position in which it comes close to the abutting portion of the two for each sheet passing. I am doing it. Although the one shown in the drawing uses a fur brush, it is not limited to this, and if a mylar sheet is attached to the rotary shaft, it is not necessary to bring it close to the vicinity of the blade edge during operation, which is preferable. is there.

[0030]

As described above, according to the present invention, in the cleaning device for removing the residual toner,
Since the toner staying at the blade edge portion of the cleaning blade can be sequentially replaced with the newly arrived toner, there is no shortage of the small-diameter lubricating particles added to the toner at the edge portion, Good cleaning can always be performed stably.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a cleaning device showing an embodiment of the present invention.

FIG. 2 is an enlarged side view showing a portion in the vicinity of a contact edge of the cleaning blade with the image carrier according to the same.

FIG. 3 and

FIG. 4 is an explanatory view showing a state of small-diameter particles and toner applied to the cleaning blade in the vicinity of a contact edge of the cleaning blade with the image carrier.

FIG. 5 is an explanatory diagram showing states of small-diameter particles, toner, and added lubricant in the vicinity of a contact edge of a cleaning blade formed according to the present invention with an image carrier.

FIG. 6 and

FIG. 7 is a side view of a cleaning device showing another embodiment, respectively.

FIG. 8 is a side view showing the configuration and operation of a known cleaning device.

FIG. 9 is an explanatory view showing the behavior of the contact edge of the cleaning blade with the image carrier according to the above.

[Explanation of symbols]

 1 Image Carrier 2 Cleaning Device 3 Cleaning Blade 4 Magnet Roller 5 Conveying Screw 6 Toner

Claims (3)

[Claims] 1. A cleaning device having a cleaning blade whose edge is brought into contact with an image carrier, wherein an angle formed by a normal line and a vertical direction at a position where the cleaning blade is brought into contact with the image carrier is x. The angle α and the angle x are determined so that α ≦ x ≦ 90 ° + α, where α is the angle between the tangent to the image carrier at the contact position and the mounting direction of the cleaning blade. And a cleaning device for the image forming apparatus. 2. When the volume average particle diameter of the toner is M and the toner particle diameter is r, 90% by volume or more of the toner is in the range of (1/2) M <r <(3/2) M. The cleaning device according to claim 1, wherein the cleaning device is included. 3. The cleaning device according to claim 1, wherein the average toner particle size is 9 μm or less.