JPH05341694A - Cleaning device - Google Patents

Abstract

PURPOSE:To obtain a cleaning device capable of achieving cleaning performance with secular stability by setting the center axis of the rotation of a recovering roller at a specified position. CONSTITUTION:The center axis 32C of the rotation of a fur brush 32 and the center axis 33C of the rotation of the recovering roller 33 are set, and the outside diameter A of the brush 32, the outside diameter B of the roller 33, and the bite amount (a) of each are set. Toner adhering to the brush 32 is flicked to fly in the direction of an arrow, and it is prevented from adhering to the brush 32 again in the case that the flying angle is toward the axis 33C side of the roller 33 further than a vertical direction. Therefore, it is desirable that the position of the center axis 33C of the roller 33 to the brush 32 is within a hatched range. In such a case, since the angle theta is expressed theta=cos<-1>[{(A+ B)(A-2a)+2a}/A(A+B-2a)] by the theorem of cosine, the angle alpha showing the position of the center axis 33C of the roller 33 to the brush 32 is theta<alpha<theta+180 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device applicable to a photoconductor fur brush cleaning system of an electrophotographic device using a dry toner.

[0002]

2. Description of the Related Art Conventionally, as a method for cleaning a photoconductor fur brush of an electrophotographic apparatus, the following methods have been used. A fur brush that rubs the photoconductor, a flicker bar that contacts the fur brush, a collecting roller that contacts the fur brush, and a scraper that abuts the collecting roller are provided. Which removes the residual toner of. A fur brush that rubs the photoconductor, a collection roller that contacts the fur brush, and a scraper that abuts the collection roller, and removes residual toner on the photoconductor by using a potential gradient. A fur brush that rubs the photoconductor, a collection roller that contacts the fur brush, and a scraper that abuts the collection roller are provided, and the potential gradient of the surface of the photoconductor, the fur brush, and the collection roller is applied to the photoconductor. There are known ones for removing the residual toner.

The outlines of the electrophotographic apparatus and the cleaning apparatus relating to the above technologies are as shown in FIGS. 7 and 8. Since these are known contents, only the main members are named.

Reference numeral 1 is a main body of the electrophotographic apparatus, reference numeral 2 is a transfer sheet, reference numeral 3 is a paper feed cassette, reference numeral 4 is a paper feed roller, reference numeral 5
Is a registration roller, 6 is a transfer charger, 7 is a separation charger, 8 is a fixing device, 9 is a paper discharge roller,
Reference numeral 10 is a paper discharge tray, reference numeral 11 is a cleaning device,
Reference numeral 12 is an optical writing device, reference numeral 13 is a charge eliminating lamp, reference numeral 1
Reference numeral 4 is a photosensitive drum, reference numeral 15 is a developing device, and reference numeral 11a is P.
CC (pre-cleaning corotron) is shown respectively.

.. Further, as a cleaning device using a fur brush, there is a technique disclosed in Japanese Patent Application Laid-Open No. 1-195485.

The first feature of this technique is that of a bias roller that removes residual toner and dust on the photoconductor by an electrically biased fiber fur brush and removes what is collected by the fur brush from the fur brush. Locating the position as close as possible to the first vibration node of the fur brush vibration that occurs when the fur brush that is in contact with the photoreceptor leaves, which facilitates toner removal from the fur brush. The second feature is that the detoning roll is arranged around the fiber fur brush and adjacent to the surface of the photoconductor to minimize the time during which the toner and dust are subjected to the triboelectric action of the fur brush fiber, thereby reducing the detoning roll. Toner is removed from the fur brush before it exceeds the optimum level for removal.

[0007]

The above-mentioned prior art has the following problems.

First, in order to increase the linear velocity ratio, the fur brush and the collecting roller are bitten and rotated in the counter direction. In this case, the collecting roller acts as a flicker for the fur brush, and the fur brush is After passing through the collecting roller, the toner and the paper dust held therein are repelled in the normal direction by the force of returning to the original state. Since the repelled toner and the like are directed toward the fur brush in the conventional positional relationship, they enter the central portion of the fur brush, cause clogging, and deteriorate cleaning performance.

Further, when printing is performed for a long time without being able to collect the toner from the fur brush, the resin component of the toner is fused to the fur brush, and the contact resistance of the image portion increases, and the image The fur brush characteristics in the image area and the non-image area change. As a result, even if a potential difference is applied between the surface of the photoconductor, the fur brush, and the collection roller, a current flows from the fur brush portion having a low resistance, and the fur brush in the image portion cannot obtain a predetermined cleaning property. ..

Therefore, an object of the present invention is to provide a cleaning device which can exhibit a stable cleaning performance with time.

[0011]

In order to achieve the above object, the present invention has any of the following configurations.

(1). Downward in the vertical direction from the plane position when the plane passing through the fur brush rotation center axis is rotated by an angle θ in the direction opposite to the brush rotation direction around the fur brush rotation center axis based on the horizontal plane passing through the center axis, The rotation center axis of the collecting roller is provided. Here, the angle θ has a value that satisfies the following condition.

[0013] θ = cos ~ ¹ [{(A + B) (A -2a) + 2a 2} / A (A
+ B-2a)] where a is the amount of the fur brush and the collecting roller, A is the outer diameter of the fur brush, and B is the outer diameter of the collecting roller.

(2). The surface resistance of the collecting roller is partially increased (claim 2).

(3). In (2), the surface resistance of the collection roller that abuts the fur brush having a width that rubs the photoconductor in the non-image area is set higher than the surface resistance of the collection roller that abuts the fur brush that rubs the photoconductor in the image area. (Claim 3).

(4). The collecting roller is swung in the thrust direction of the rotary shaft (claim 4).

[0017]

According to the first aspect, the fur brush adheres to the
Toners that have been mechanically removed by the collection roller do not reattach to the fur brush, and the dirt on the fur brush accumulates over time, reducing cleaning performance and scattering toner. , Can maintain stable performance.

According to the second and third aspects, even if the fur brush input toner adheres to the fur brush fiber over time and the electrostatic characteristics of the fur brush are uneven between the toner input portion and the non-input portion, the collecting roller Since the surface resistance has been changed in advance,
It is possible to prevent the cleaning property of the image portion from being deteriorated.

According to the present invention, since the collecting roller swings by self-rotation, it becomes easy to remove paper dust caught between the roller surface and the scraper, and the blade as a scraper has a long service life at a low cost. Can be promoted.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 3, the construction of the conductive fur brush cleaning system and the function of each part will be described.

The PCC 36 charges up the toner remaining on the photosensitive drum 31 without being transferred to give the toner its original polarity and charge amount. At the same time, the uneven surface potential of the photosensitive drum 31 is converged.

Next, a voltage is applied to the collecting roller 33 to form a potential gradient between the surface of the photoconductor drum 31, the fur brush 32 and the collecting roller 33, and the charged toner is fed from the photoconductor drum 31 to the fur. The brush 32 and the collecting roller 33 are moved.

For example, the toner is charged to (-) by the PCC 36, and the surface potential of the photosensitive drum 31 is about -8 at the same time.
If it is set to 00V, -500V is applied to the collection roller 33, and the core metal of the fur brush 32 is floated.

Then, the (-) toner is moved to a higher potential by the electrostatic force, is collected by the collecting roller 33, is scraped off by the blade 34, and is conveyed by the conveying auger 3.
It is discharged out of the unit at 5.

The flicker bar 37 is a bar that comes into contact with the fur brush 32 by biting by 0.5 to 2 mm, and serves to remove the toner and paper dust from the fur brush 32.

The fur brush 32 is in contact with the photosensitive drum 31 by 0.5 to 2 mm, and the recovery roller 33 is in contact with the fur brush 32 with the same amount of bite. Here, the conventional problem is that, as shown by an arrow YA in FIG. 3, the toner mechanically removed by the fur brush 32 again enters between the recovery roller 33 and the fur brush 32, and then the recovery roller 33. It was not possible to collect it at 33.

In particular, in the case shown in FIG. 2, the fibers of the fur brush 32 bent by the collecting roller 33 often fly the toner and the like in the arrow direction.

As a result, the scattered toner is collected by the collecting roller 3.
When the fur brush 32 enters in the direction of the core metal, enters the inside of the brush, and accumulates, the charging characteristics of the toner change,
Reattachment to the photosensitive drum 1 occurred.

[Example Corresponding to Claim 1] The present invention is characterized in that the outer diameters of the collection roller 33 and the fur brush 32 and the position of the collection roller 33 with respect to the fur brush 32 are determined from the biting amount as shown in FIG. By limiting, the toner can be collected from the brush more smoothly and without waste.

The positional relationship between the rollers for that purpose will be described with reference to FIG. 1 and 4, the fur brush 32
32C, the rotation center axis of the collecting roller 33 is indicated by 33C. Further, when the outer diameter of the fur brush 32 is indicated by reference symbol A, the outer diameter of the recovery roller 33 is indicated by reference symbol B, and the biting amounts thereof are indicated by reference symbol a, the nip end portions on the downstream side in the rotational direction thereof are indicated by There is a triangular relationship.

The tip of the brush fiber of the fur brush hits the collecting roller 33, is pushed and bent, and the position at which it returns to the original position is, to be exact, changed depending on the waist strength of the brush, the length of the bristle and the coefficient of friction. It is the nip end on the downstream side in the rotational direction.

Therefore, the toner attached to the fur brush 32 is mechanically repelled in the direction of the arrow shown in FIG.
If this angle is more toward the shaft side of the collecting roller 33 than the vertical direction, the repelled toner and the like will be removed by the fur brush 3.
It does not redeposit on 2.

Therefore, it is desirable that the position of the central axis of the collecting roller 33 with respect to the fur brush 32 be within a hatched range as shown in FIG.

[0034] Here, FIG. 1, the angle theta is the cosine theorem in FIG 4, θ = cos ~ ¹ [{(A + B) (A -2a) +2
^{a 2} / A (A +} B-2a) ] and expressed.

Therefore, the angle α indicating the position of the central axis of the collecting roller 33 with respect to the fur brush 32 is θ according to FIG.
<Α <θ + 180 °. However, θ = cos ~ ¹ [{(A
+ B) and ^{(A-2a) + 2a 2} } / A (A + B-2a) ].

For example, A = 20 mm, B = 12 mm, a
= 1 mm, θ ≈ 15.56 °, which is 15.5.
6 ° <α ° <195.56 °.

In FIG. 1, a flicker bar 37 is 0.5 to 2 mm upstream of the nip portion between the fur brush 32 and the recovery roller 33 in the rotational direction of the fur brush 32.
The paper dust on the photoconductor drum 31 is mechanically blown off.

The flicker bar 37 is electrically floated and is made of a material such as stainless steel having a diameter of 2 mm. This position must be upstream of the nip of the collecting roller 33 and vertically below the horizontal plane passing through the rotation axis of the fur brush 32 in FIG.

In this embodiment, the position of the fur brush roller is restricted by the amount of the collecting roller (bias roller) with respect to the fur brush roller and the outer diameter of the fur brush roller. It is possible to obtain stable high image quality.

[Examples Corresponding to Claims 2 and 3] Next, as another example, a case where the resistance value changes with the portion of the fur brush with time will be described with reference to FIG.

For example, with respect to the width of the photosensitive drum 31,
The fur brush 32 abuts and rubs against the image region and the non-image region in the axial lengthwise direction with a biting amount of 0.5 to 2 mm.

However, the toner is input to the fur brush 32 in the image area or the maximum paper width, and almost no toner, paper dust or the like is input outside the image area.

Therefore, when components such as toner adhere to the fur brush over time, the electrical resistance value of the fibers in that portion increases. Therefore, in this example, the surface resistance of the toner recovery roller 38 from the fur brush is changed in advance in the image area and the non-image area, or the transfer paper width and the outside thereof, so that the portion of the fur brush over time is changed. It was decided to prevent the change in static resistance.

In this example, a portion of the surface of the collecting roller 38 corresponding to the non-image area is coated with a conductive resin film containing carbon in fluororesin. This thickness is 10
The thickness is preferably 30 μm, and if it is less than 30 μm, it wears with time and the life becomes short. The volume resistance is 10 ⁸ Ω
Below.

The core metal of the collecting roller 38 may be made of any conductive metal, for example, stainless steel or the like.
Therefore, the peripheral surface of stainless steel corresponds to the image area.

The surface of the collecting roller 38 is preferably polished at the same time so as to eliminate a step with the coating film, or a fluororesin is sprayed on the polished stainless collecting roller 38 for coating.

In the present example, stable cleaning performance can be exhibited even if a difference occurs in the brush resistance value between the image area and the non-image area over time.

[Example Corresponding to Claim 4] Next, a method of maintaining the ability of removing toner and paper dust from the collecting roller with time will be described with reference to FIG. 6 showing a cross section of the cleaning device.

In FIG. 6, the fur brush 32 is supported by the unit frame 39 and is rotating. Blade 34
Has one end fixed to the holder 34 ′, and the holder 34 ′ is fixed to the unit frame 39.

The other end of the blade 34 is in contact with the collecting roller 33. The collecting roller 33 is movable in the thrust direction while rotating, and is pressed to the left side in the drawing by a spring 45.

That is, a protrusion 40 is provided on the side of the recovery roller 33 opposite to the spring 45. When the protrusion 40 slides on the peripheral surface of the receiving portion 41 protruding from the unit frame 39, the blade 34 is moved. Along the end face, the collecting roller 33 makes a swinging motion in the thrust direction indicated by the arrow in the figure. This makes it easier to remove the paper dust caught between the roller surface and the blade. The maximum stroke is preferably 5 mm or less.

In this case, only the collecting roller 33 makes the thrust motion, and the collecting roller 33 is biased through the conductive bearing 42. Therefore, the contact failure of the bias may occur due to the swinging. There is no.

[0053]

According to the present invention, it is possible to provide a cleaning device capable of exhibiting stable cleaning performance over time.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention.

FIG. 2 is a diagram illustrating a direction in which a fur brush blows off toner.

FIG. 3 is a diagram illustrating a configuration of a conductive fur brush cleaning method according to the present invention.

FIG. 4 is a diagram illustrating an angle θ according to the present invention.

FIG. 5 is a diagram illustrating an image area and a non-image area according to the present invention.

FIG. 6 is a diagram illustrating a swinging mechanism of a collecting roller according to the present invention.

FIG. 7 is a diagram illustrating an outline of an electrophotographic apparatus and a cleaning apparatus suitable for implementing the present invention.

[Explanation of symbols]

 32C Fur brush rotation center axis 32C Recovery roller rotation center axis θ Angle

Claims (4)

[Claims] 1. A fur brush that rubs a photosensitive member, a flicker bar that contacts the fur brush, a collecting roller that contacts the fur brush, and a scraper that contacts the collecting roller, and uses a potential gradient. In the cleaning device for removing the residual toner on the photoconductor, an angle in a direction opposite to the brush rotation direction is centered around the fur brush rotation center axis with respect to a plane passing through the fur brush rotation center axis and a horizontal plane passing through the center axis. A cleaning device characterized in that a rotation center shaft of a recovery roller is provided vertically below a plane position when rotated by θ. Here, the angle θ has a value that satisfies the following condition. θ = cos ~ ¹ [{(A + B) (A -2a) + 2a 2} / A (A
+ B-2a)] where a is the amount of the fur brush and the collecting roller, A is the outer diameter of the fur brush B is the outer diameter of the collecting roller 2. A fur brush for rubbing a photosensitive member, a collecting roller in contact with the fur brush, and a scraper in contact with the collecting roller, wherein residual toner on the photosensitive member is removed by utilizing a potential gradient. In a cleaning device for an electrophotographic device, the cleaning roller is characterized by partially increasing the surface resistance of the collecting roller. 3. The collecting roller according to claim 2, wherein a surface resistance of a collecting roller that abuts a fur brush having a width that rubs the photoconductor in the non-image area is brought into contact with a fur brush that rubs a photosensitive body in the image area. A cleaning device characterized by being made higher than the surface resistance. 4. A fur brush rubbing the photoconductor, a collecting roller in contact with the fur brush, and a scraper in contact with the collecting roller, and utilizing the potential gradient of the surface of the photoconductor, the fur brush, and the collecting roller. In the cleaning device for removing the residual toner on the photoconductor, the collecting roller swings in the thrust direction of the rotary shaft.