JPH08115031A - Cleaning mechanism for image forming device - Google Patents

Abstract

PURPOSE: To surely clean up residual toner on a photoreceptor by applying a tip force which is equal to or exceeding the sticking force of the residual toner to an image forming body to the residual toner as a scraping force. CONSTITUTION: A brush 3 formed in a columnar shape as a whole is arranged close to the photoreceptor drum (image forming body) 1 in parallel to the photoreceptor drum 1. The brush 3 is obtained by radially flocking a large number of fibrous bristle materials 5 around a columnar brush shaft 4, and the cleaning mechanism 2 is constituted of the brush 3 and a driving source for rotary-driving the brush shaft 4. The brush 3 is arranged so that the tip of 0.5 to 2.0mm may interfere with the photoreceptor drum 1. The brush 3 is actuated so that the tip force equal to or exceeding the sticking force of the capsule toner remaining on the surface of the drum 1 to the drum 1 may be applied to the residual toner in a scraping direction as the scraping force.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a copying machine, a fax machine,
The present invention relates to a cleaning mechanism for an image forming apparatus that uses an electrophotographic system such as a printer.

[0002]

2. Description of the Related Art As a toner used in a conventional image forming apparatus using an electrophotographic method, a heat-fusion toner is generally used in terms of image quality and fixability, and such toner is removed from a photoconductor. Various cleaning mechanisms have been proposed as means for achieving this. For example, Japanese Patent Publication No.
What is disclosed in Japanese Patent No. 6590, Japanese Patent Publication No. 56-40349, etc. is the basic one of such a cleaning mechanism. The ones disclosed in these publications are those in which a pretreatment corotron is added in order to make the charge amount of the toner as the toner to be cleaned constant, and the conductive resin fiber or animal hair material is formed into a roll shape. A bias having a polarity opposite to that of the toner is applied to the rotatable brush, and this is rubbed against the photoconductor to remove the toner. Further, in such a cleaning mechanism, various studies have been made and disclosed regarding improvement of the material, density, resistance value, applied bias value, control method thereof, etc. of the bristles constituting the brush.

Here, the toner is removed from the photoconductor by the following mechanism. That is, by rubbing the rotating brush against the photoconductor, a force stronger than the image force or the Van der Waals force that causes the toner to adhere to the photoconductor is applied to the toner, which causes the toner to adhere to the photoconductor. The toner is disturbed from the surface of the photoconductor to weaken the adhesive force. Then, after that, the toner whose adhesion is weakened is attracted to the rotating brush by using static electricity and moved to be removed. Incidentally, as a means for attracting and moving the toner having the weakened adhesive force to the rotating brush, as a means to which a magnetic force is applied, for example, Japanese Patent Publication No. 2-4.
No. 910 publication, Jikken 1-92668 publication, Jikken 1
-77673, Jpn. Pat. Appln. KOKAI Publication No. 1-43728, and the like, these are configured by arranging permanent magnets inside the rotating brush.

In any of the methods, it is important to disturb the toner adhering to the photoconductor from the surface of the photoconductor as the first step in order to obtain a good cleaning property. In order to disturb from the surface of the body, it is necessary to apply a certain amount of force to the toner from the outside. And as a technique related to this, for example, JP-A-59-87483,
Various proposals have been made in Japanese Utility Model Publication No. 55-57571.

On the other hand, various types of capsule toners that can be fixed only by pressure have been proposed in addition to the above-mentioned general heat fixing type toners (for example, Japanese Patent Laid-Open No. 57-57).
179860, JP-A-58-66948,
JP-A-59-148066, JP-A-59-162
562 publication). This capsule toner is obtained by encapsulating a core agent in which a polymer is dissolved in a solvent inside a shell, and by destroying the core by pressure and fixing the core agent inside to a recording paper, etc. There is an advantage that fixing strength can be obtained and labor can be saved because heat is not required in the fixing process.

However, since the capsule toner as described above has a low mechanical strength, if the scraping force of the brush at the time of cleaning is large, the shell is broken and the core agent flows out. As a result, the core material that has flowed out adheres to the surface of the photoconductor and causes image deterioration. The mechanism of destruction of the shell of the capsule toner will be described with reference to FIG. 6. The capsule toner 21 adhered to the surface of the photoconductor 20 by a force F1 such as a mirror image force or a van der Waals force causes the brush 22 of the brush The force F2 from the material 23 acts. This force F2
Has a component force F3 for scraping off the capsule toner 21 and a component force F4 for pushing toward the surface of the photoconductor 20, and when the component force F4 becomes larger than the breaking strength of the capsule toner 21. Then, the capsule toner 21 is destroyed.

[0007]

By the way, in order to prevent abrasion of the surface layer of the photoconductor which causes deterioration of image quality, and also to prevent breakage of the shell in the capsule toner, the residual toner adhered to the photoconductor is removed. It is necessary to set the power of the brush of as small as possible. However, if this force is too small, the residual toner cannot be sufficiently disturbed from the surface of the photoconductor, so that sufficient cleaning performance cannot be obtained.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a cleaning mechanism for an image forming apparatus that can reliably clean residual toner on a photoconductor.

[0009]

The cleaning mechanism of the image forming apparatus of the present invention cleans the residual toner on the image forming body by contacting the moving image forming body while a large number of hairs are planted. A brush is provided, and the brush acts as a scraping force in a scraping direction on the residual toner with a tip force equal to or greater than the adhesive force between the residual toner to be cleaned and the image forming body. There is.

[0010]

According to the present invention, since the brush acts as a scraping force in the direction of scraping the residual toner, a tip force equal to or greater than the adhesive force between the residual toner to be cleaned and the image forming body is applied. The residual toner adhering to the body can be sufficiently disturbed from the surface of the image forming body.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus to which the present invention is applied. In FIG. 1, reference numeral 1 is a cylindrical photosensitive drum (image forming body) 1 that is uniformly charged, and reference numeral 2 is a cleaning mechanism that removes and cleans residual toner remaining on the photosensitive drum 1. In addition to the above configuration, the image forming apparatus includes an exposing unit that forms an electrostatic latent image on the photosensitive drum 1, a developing unit that develops the electrostatic latent image into a toner image that is a visible image, and a developing unit that develops the toner image. And a fixing device for fixing the transferred toner image onto the image support to form a fixed image (each not shown).

The photoconductor drum 1 is made of a cylindrical organic photoconductor and has a diameter of 84 mm and a peripheral speed of 160 mm / sec. It can be rotated in the direction of the arrow at the process speed of. Then, a brush 3 having a cylindrical shape as a whole is arranged in parallel with the photoconductor drum 1 in the vicinity of the photoconductor drum 1. This brush 3 has a large number of fiber-shaped bristle materials 5 radially planted around a cylindrical brush shaft 4.
The cleaning mechanism 2 is configured with a drive source (not shown) that rotationally drives the brush shaft 4.

The brush shaft 4 has a diameter of 6 mm, the brush 3 has a diameter of 10 to 50 mm, and in the present embodiment, the diameter is 19 mm.
In addition, the brush 3 is adapted to rotate at a peripheral speed equal to or higher than the peripheral speed of the photosensitive drum 1, and in this embodiment, 160 to 700 mm / sec. It has been. Further, although the brush 3 is capable of rotating in the forward and reverse directions, in the present embodiment, the brush 3 rotates in the same direction as the photosensitive drum 1, that is, the contact portion thereof moves in the opposite direction to the photosensitive drum 1. Further, the brush 3 has a tip of about 0.
5 to 2.0 mm is arranged so as to interfere with the photosensitive drum (hereinafter, this amount of interference is referred to as BPI). That is, when the contour lines of the photoconductor drum 1 and the brush 3 are drawn in the actual size with the arrangement of the embodiment, the contour lines are 0.
It is designed to overlap at a depth of 5 to 2.0 mm.

Further, the bristle material 5 of the brush 3 is made of a material which has a small load on the toner and the photosensitive drum 1 and therefore can maintain the cleaning performance for a long period of time. Specifically, polypropylene, acrylic, rayon, nylon, polyethylene,
It is made of material such as polyester.

Next, in order to optimize the scraping force of the brush 3 for scraping off the residual toner, the following experiment was conducted. The scraping force is a force that acts on the residual toner from the brush 3 in the direction of scraping the residual toner (the tangential direction of the photosensitive drum 1 with the residual toner as a contact point). Further, in the following experiments, a relatively fragile and weakly mechanically-encapsulated toner capable of fixing only by pressure without using heat at the time of fixing was used as the toner.

First, the tip force as a characteristic value representing the scraping force was measured as follows. The tip force is
Denier which is a weight per one specified length of the bristle material 5 which is a constituent parameter of the brush 3, flock density of the bristle material 5, pile height of the bristle material 5, P. I. And the material of the hair material 5.

As shown in FIG. 2, width (length in the direction orthogonal to the paper surface in FIG. 2) 100 mm, depth (horizontal length in FIG. 2) 55 mm, thickness (vertical length in FIG. 2) 1 mm The aluminum plate 7 is rotatably supported with the end portion on the opposite side of the brush 3 as a fulcrum 8, and the load cell 9 is arranged on the lower surface side thereof while maintaining the state orthogonal to the tangent line at the contact point of the brush 3. did.

And B. P. I. The brush 3 is made to interfere with the aluminum plate 7 at = 1 mm, and the brush 3 is moved to 256 mm /
sec. The load was detected by the load cell 9 when rotated at the peripheral speed of. And, this load is 100
A value divided by mm, that is, a value per unit length in the width direction was defined as the tip force.

Further, B. P. I. When the brush 3 is brought into contact with the photosensitive drum 1 and rotated so that = 1 mm, the turbulence can be generated in the pressure fixing capsule toner adhered to the surface of the photosensitive drum 1. The value of the tip force was taken as the adhesive force between the capsulated toner remaining on the photosensitive drum 1 and the photosensitive drum 1. Note that this adhesion force can also be detected by applying an electric field in a direction in which the photosensitive drum and the capsule toner are separated in a vacuum, and obtaining the force of the electric field when the capsule toner releases the sticking to the photosensitive drum. You can

Then, the constituent parameters shown in Table 1 (denier which is the weight per one specified length of the bristle material 5, flock density of the bristle material 5, pile height of the bristle material 5, BP I And 14 types of brushes A to N).
The relationship between each tip force and the state of disturbance of the toner image against the tip force was experimentally obtained, and the result is shown in FIG.
In FIG. 3, the disturbance state of the capsule toner on the photosensitive drum 1 is shown as G1 in which the capsule toner is not disturbed, G2 in which the disturbance of the capsule toner is small, G3 in which the disturbance of the capsule toner is medium and G4 in which the disturbance of the capsule toner is large. Are divided into four ranks, and each rank shows which rank the brush 3 has.

[0021]

[Table 1]

From FIG. 3, the larger the tip force of the brush 3, the larger the disturbance of the capsule toner, and the further 0.05 gf / m.
Below m (the adhesive force between the residual capsule toner and the photosensitive drum 1 in this case), the scraping force by the brush 3 becomes extremely low so that the toner image after passing through the brush 3 is not disturbed. I understand.

From the above experimental results, in this embodiment, the tip force of the brush 3 was set to 0.05 gf / mm or more. In order to set the tip force, the constituent parameters shown in Table 1 (denier which is the weight per one specified length of the bristle 5, densification density of the bristle 5, pile height of the bristle 5,
B. P. I. And the material of the bristle material 5 was appropriately selected.

As a result, as the first step of cleaning, the residual toner adhering to the photosensitive drum 1 can be sufficiently disturbed from the surface of the photosensitive drum 1 to weaken its adhering force. Therefore, as the next second step, it is possible to favorably remove the residual toner by the rotating brush 3 by using the static electricity or the like.

With respect to the similar brushes A to N, the load per tip of each bristle material 5, that is, the tip force, and the filming of the capsule toner against it (the core material which has been broken out of the shell to flow out the photoconductor drum) The relationship between the occurrence of a film on one surface) and the state of occurrence was experimentally determined, and the results are shown in FIG. In FIG. 4, the brush 3 is divided into four ranks, namely, a rank in which filming does not occur, a rank in which filming does not occur, a rank in which filming occurs in medium, and a rank in which filming occurs largely.
It shows which rank it will be according to the tip power of.

From FIG. 4, filming occurs moderately when the load per tip of the bristle material 5 of the brush 3, that is, the tip force is up to 0.2 mN, but when it exceeds 0.2 mN, filming occurs. It turns out that it grows rapidly. Here, FIG. 5 is a graph showing the breaking strength per capsule toner used in the examples, which is the result of measurement using a Φ50 μm head with MCTM-500 manufactured by Shimadzu Corporation. As shown in FIG. 5, the tip force is 0.2
When it was less than mN, the capsule toner was not destroyed as long as the frequency was 100.

From the above experimental results, in this embodiment,
The load per one of the bristle materials 5 of the brush 3, that is, the tip force is set to be equal to or less than the breaking load per one capsule toner, and the set tip force acts on the residual toner as a scraping force. Set the configuration parameters. Specifically, 0.2 per hair 5 of the brush 3
It was set so that a load of less than mN, that is, a tip force acts on the residual toner as a scraping force. As a result, even in the case of a capsule toner having low mechanical strength, the shell is prevented from being broken by the mechanical force acting on the capsule toner during cleaning, and the core agent adheres to the surface of the photoconductor drum and is generated. Filming can be prevented.

As described above, according to the cleaning mechanism of this embodiment, the brush 3 having the tip force set as described above is used.
Since the toner on the photoconductor drum 1 can be disturbed to weaken the adhesive force with the photoconductor drum 1, the toner remaining on the photoconductor drum 1 can be reliably cleaned. Further, since the tip force of the brush 3 is set so that the capsule toner is not broken, it is possible to prevent filming and form a high-quality image.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, the preferable range of the tip force of the brush is 0.05 gf / mm or more, but it may be 0.05 gf / mm depending on the type of toner.
May be less than. Further, in the above embodiment, the pressure fixing capsule toner is used, but the same effect can be obtained by using the heat fixing toner. Further, although the brush 3 is formed in a cylindrical shape in the above embodiment, it may be formed in a flat plate shape.

[0030]

As described above, according to the present invention, since the residual toner adhering to the photoconductor can be sufficiently disturbed from the surface of the photoconductor, static electricity or the like due to the rotating brush is used thereafter. The residual toner can be satisfactorily attracted and removed, and the residual toner can be reliably cleaned.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a main part of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a side sectional view illustrating a device for measuring a tip force of a brush.

FIG. 3 is a graph showing the state of disturbance of the toner on the photoconductor with respect to the tip force of the brush.

FIG. 4 is a graph showing a state of occurrence of filming of capsule toner with respect to a load per brush bristle material, that is, a tip force.

FIG. 5 is a graph showing the breaking load per capsule toner and its frequency.

FIG. 6 is a diagram for explaining the force of the brush that acts on the capsule toner on the photosensitive drum.

[Explanation of symbols]

1 ... Photosensitive drum (image forming body), 2 ... Cleaning mechanism, 3 ... Brush, 5 ... Bristles.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaka Yakabe 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (3)

[Claims] 1. A brush for cleaning a residual toner on the image forming body by contacting a moving image forming body with a large number of hairs implanted, the brush having the residual toner to be cleaned. A cleaning mechanism for an image forming apparatus, wherein a tip force equal to or greater than an adhesion force between the image forming member and the image forming body is applied to the residual toner as a scraping force in a scraping direction. 2. The brush contains 0.0% of the residual toner.
The cleaning mechanism for an image forming apparatus according to claim 1, wherein a tip force of 5 gf / mm or more is applied as the scraping force. 3. The residual toner is a capsule toner that can be fixed only by mechanical pressure without using heat at the time of fixing, and the brush is less than 0.2 mN per hair material in the residual toner. 3. The cleaning mechanism for an image forming apparatus according to claim 1, wherein the tip force of the blade acts as the scraping force.