JPH05107997A - Cleaning device - Google Patents

Abstract

PURPOSE:To stably maintain cleaning performance over a long period by scraping toner and an external addition agent without being leaked, and preventing the toner from being melt-stuck to the brush and a toner removing member. CONSTITUTION:In this cleaning device assuming to have the brush 2 coming into contact with the surface of a toner image carrier 1 such as a photosensitive body, and rotating, and a toner removing means 3 removing the toner T stuck to the brush 2, as the toner removing means 3, plural toner scraping bars 4 and a movable supporting means 5 supporting these plural toner scraping bars 4, and circulating each toner scraping bar 4, so as to change an enchroaching quantity on the brush 2, are provided, as a feature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device for removing toner attached to a toner image carrier by a brush in an image forming apparatus such as an electrophotographic copying machine, and more particularly to a toner attached to the brush by a removing member. The present invention relates to an improvement of a cleaning device of a type that removes.

[0002]

2. Description of the Related Art Conventionally, as a cleaning device used in an electrophotographic copying machine or the like, for example, JP-A-1-31
The one described in Japanese Patent No. 2578 is already known. As shown in FIG. 11, a blade 102 made of an elastic material is elastically contacted with the photosensitive member 101, the toner is scraped off by the blade 102, and the surface of the photosensitive member 1 located upstream of the blade 102 is rotated. The surface of the photoconductor 101 is cleaned by the brush 103 in contact therewith, and then the rod-shaped toner scraping member 10 in contact with the brush 103.
4, the toner T is removed from the brush 103.

[0003]

However, in the above-described conventional cleaning device, the toner scraping member 104 only comes into contact with the surface of the brush 103 only once, and the toner adhering to the brush 103 is removed. In addition to the fact that T cannot be scraped off sufficiently, the toner T is usually added with particles having a smaller particle diameter than the toner T, which is called an external additive, for the purpose of improving powder fluidity and the like. When the bite amount of the toner scraping member 104 is uniquely set, the brush 1 of these external additives is used.
A technical problem was found that the scraping off from 03 becomes more difficult.

As a means for solving such a technical problem, for example, as shown in FIG. 12, a plurality of toner scraping members 105, 106, 107, 108 are attached to a brush 103.
In order to efficiently remove the toner T and the external additive adhering to the brush 103, it is possible to arrange them by changing the biting amount in sequence along the rotation direction of the toner (Japanese Patent Laid-Open No. Sho 56-56). (See Japanese Patent Publication No. 138769).

However, even in this type, the plurality of toner scraping members 105 to 108 are fixedly arranged, and the relative contact position between the toner scraping members 105 to 108 and the brush 103 is unique. Because
Even if a system for sucking and discarding the toner scraped by the toner suction mechanism is adopted, the toner T easily accumulates on the toner scraping members 105 to 108 during long-term use, and the accumulated toner scrapes each toner. Adhesion or heat fusion to the members 105 to 108 or the brush 103 reduces the toner scraping effect of the toner scraping members 105 to 108, and the toner T reattaches to the surface of the photoconductor 101, resulting in the result. As a result, a technical problem has been found that deterioration in copy image quality such as white streaks and white spots is brought about.

The present invention has been made in view of the above-mentioned circumstances. By scraping off the toner and the external additive adhering to the brush without leaking, and preventing the toner from adhering to the brush and the toner removing member, The purpose is to maintain the cleaning performance stably over a long period of time.

[0007]

That is, the present invention is
As shown in FIG. 1, it is assumed that the cleaning device has a brush 2 that rotates in contact with the surface of the toner image carrier 1 such as a photoconductor and a toner removing unit 3 that removes the toner T adhering to the brush 2. As the toner removing means 3, a plurality of toner scraping bars 4 and a movable supporting means for supporting the plurality of toner scraping bars 4 and circulatingly moving the respective toner scraping bars 4 so that the amount of bite into the brush 2 is changed. And 5 are provided.

In such a technical means, the plurality of toner scraping bars 4 may be arranged at regular intervals at regular intervals or may be irregularly arranged at any place. Although it may be arranged, it is necessary to arrange so that the amount of bite into the brush 2 changes when the movable supporting means 5 circulates.

Further, as the movable supporting means 5, a plurality of toner scraping bars 4 may be constantly continuously circulated, or a unit job (for example, a series of copy jobs for copying a plurality of originals or a plurality of copy jobs). A plurality of toner scraping bars 4 may be intermittently circulated and moved for each copy).

At this time, in consideration of the scraping effect of the toner T, the circulating movement direction of the plurality of toner scraping bars 4 is preferably the reverse direction of the rotation direction of the brush, but may be the forward direction. It doesn't matter. Further, in the type in which the plurality of toner scraping bars 4 are intermittently circulated and moved, from the viewpoint of improving the removal efficiency of the toner T and the external additive, at least two toner scraping members 4 are brushes. It is preferable to design so as to simultaneously bite into the two with different biting amounts, and in this case, it is necessary to select the biting amounts effective for removing the toner T and the external additive, respectively.

As the movable supporting means 5, for example, if the toner removing member 3 is moved at an extremely low speed while the machine is stopped, the bristles of the brush 2 due to the contact between the brush 2 and the toner removing member 3 for a long time are removed. It is possible to prevent deformation.

Further, the toner T on the toner scraping bar 4 is
From the viewpoint of more reliably avoiding the adherence of the toner, it is preferable to provide the cleaning means 6 for removing the toner T adhered to the toner scraping bar 4. In this case, the cleaning means 6 may be a fixed member or a movable member.

[0013]

According to the above-mentioned technical means, the movable support means 5 circulates and moves the plurality of toner scraping bars 4 so that the amount of bite into the brush 2 changes. At this time, if the amount of the toner scraping bar 4 biting into the brush 2 is optimized for removing the toner T and the external additive, the toner scraping bar 4 effectively scrapes the toner T and the external additive from the brush 2. Further, since the toner scraping bar 4 is alternately contacted with the brush 2, the brush 2 is not in contact with the same part of the toner scraping bar 4 for a long period of time, and the toner T is deposited on the toner scraping bar 4. The situation of accumulation is gone.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on the embodiments shown in the accompanying drawings. Example 1 FIG. 2 is a process block diagram of an electrophotographic copying machine including Example 1 of a cleaning device to which the present invention is applied.
In the figure, the electrophotographic copying machine includes a photoconductor 21, a charger 22, an exposing device 23, and a developing device 2 for developing with toner T.
4, a transfer device 27, a fixing device 29, and a cleaning device 10.

In this embodiment, first, the surface of the photoconductor 21 is uniformly charged by the charger 22. The exposure device 23 irradiates the light to remove the charged electric charge in the exposed portion to form an electrostatic latent image. For example, in the case of a digital electrophotographic copying machine in which an organic photoconductor is used as the photoconductor 21 and a laser beam light is used as the exposure device 23, the surface of the photoconductor 21 is negatively charged by the charger 22 and the laser beam light is applied. As a result, a dot-shaped digital latent image is formed, and toner is applied by the developing device 24 to the portion exposed to the laser beam light to form a visible image. In this case, a negative bias is applied to the developing device 24. Then, the recording paper 28 is superposed on the toner image, and the transfer device 27 applies a charge having a polarity opposite to that of the toner to the recording paper 28 from the back side of the recording paper 28, and the toner image is transferred to the recording paper 28 by electrostatic force. The transferred toner image is
Heat or pressure is applied to fuse the recording paper 28 to form a permanent image. On the other hand, the toner T remaining on the photoconductor 21 without being transferred is removed by the cleaning device 10. One cycle is completed by this series of processes from charging to cleaning.

FIG. 3 is a schematic enlarged view of the cleaning device used in the first embodiment. In FIG. 1, the cleaning device 10 includes a blade 11 made of an elastic material that elastically contacts the surface of the photoconductor 21 and an upstream side of the blade 11. The brush 12 that removes the toner T is included, and the toner removing member 13 that removes the toner T attached to the brush 12. Reference numeral 14 is an auger that conveys the toner scraped by the brush 12 and the toner dropped by the toner removing member 13 to a collection bottle (not shown).

In this embodiment, the brush 12 is
The same direction as the moving direction of the photoconductor 21 (arrow A) (arrow B)
The brush 12 is usually made of polypropylene, acrylic, or carbon-containing nylon or other conductive fiber.

Further, as shown in FIGS. 3 and 4, the toner removing member 13 includes a pair of rotating discs 31 connected to a rotating shaft that rotates in a direction (arrow D) opposite to the brush 12 at a predetermined speed, The pair of rotating discs 31 are supported by semicircular recesses formed at predetermined angular intervals (30 ° in this embodiment) around the pair of rotating discs 31, and are hung in a cage shape between the pair of rotating discs 31. A plurality of cylindrical toner scraping bars 32
And a cleaning brush 33 which is disposed on the opposite side of the contact portion with the brush 12 and contacts the toner scraping bar 32. The toner scraping bar 32 may be partially embedded around the rotary shaft.

In this embodiment, polyaser resin is usually used as the toner scraping bar 32, but in order to reduce friction with the brush 12, it is made of a conductive material such as Teflon or earth that removes the electric charge of the toner. Carbon filled plastic can also be used.

Further, as shown in FIG. 5, the toner scraping bar 32 is designed to bite into three brushes 12 at the same time. For example, the length of the bristles of the brushes is set to L, and the brushes 12 rotate. Toner scraping bar 32a located on the line connecting the center O and the rotation center O'of the rotating disk 31.
The biting amount of the brush 12 to the brush 12 is m1, and the biting amounts of the toner scraping bars 32b and 32c located above and below the toner scraping bar 32a having the biting amount m1 at this time are m2.

In this embodiment, m1 is 25% of the brush bristle length L, and m2 is 5 of the brush bristle length L.
%, Which are set to values suitable for scraping off the toner T and the external additive, respectively. That is, as a result of the inventors' studying the amount of biting of the toner scraping bar 32 into the brush 12, for example, in the case of toner having a particle size of about 7 μm, about 1 to 10% of the bristle length L of the brush 12 is good. 20 to 30% in the case of an external additive (for example, a particle size of several tens of μm)
Is confirmed to be good, and m1 and m2 are set based on these experimental data.

Further, in this embodiment, polypropylene or acrylic is used as the cleaning brush 33, but it is more effective to use conductive fibers such as carbon-containing nylon grounded.

Next, the operation of the cleaning device according to this embodiment will be described. The toner T on the photoconductor 21 is the brush 1
The toner T which is scraped off by the brush 2 and adhered to the brush 12 is sequentially scraped by the toner scraping bars 32 of the toner removing member 13 which rotates in sequence, and the scraped toner T is collected via the auger 14 in a collecting bottle. Be recovered. Further, since the toner scraping bar 32 sequentially contacts the cleaning brush 33, the toner T still attached to the toner scraping bar 32 is removed by the cleaning brush 33.

In such a cleaning process, the cleaning device according to this embodiment, the cleaning device shown in FIG. 11 (comparative example 1) and the cleaning device shown in FIG. 12 (comparative example 2) were used under the following conditions. Then, when the amount of toner attached to the brush 12 and the grade of image quality deterioration due to the attachment of the toner and the external additive to the photoconductor are compared, the results shown in FIGS.

○ Experimental conditions ・ Photoconductor: Organic photoconductor ・ Developer: Toner average particle size 7 μm External additive average particle size 40 nm ・ Process speed: 160 mm / sec ・ Brush: Material polypropylene denier / Density 17d, 50,000 lines / In
ch ² Fiber length 6.5 mm Brush outer diameter 20 mm Rotation speed Approximately 320 mm / sec Rotation direction Same direction as the photoconductor at the contact with the photoconductor Shaft earth ground ・ Toner removal member: Toner scraping bar Material Polyacetal outer diameter 1.5 mm Number of 12 Rotating disk outer diameter 9mm Rotation speed Approximately 32mm / sec Rotation direction Opposite to the brush at the contact part with the brush ・ Cleaning brush: Material BELtron B12N (trade name, manufactured by Kanebo Co., Ltd.) Denier / Density 10d, 48,000 lines / inch2 fixed Used by grounding-Photoconductor surface potential: image area -200V, non-image area -600V-Development bias: -500V

According to FIG. 6, in Comparative Examples 1 and 2,
As shown in FIG. 6, the amount of toner attached to the brush gradually increases as the number of copies increases, but in the first embodiment, even if the number of copies increases, the amount of toner adheres to the brush. It is understood that the toner amount did not increase, which proves that the toner scraping effect of Example 1 type is excellent.

According to FIG. 7, in Comparative Examples 1 and 2,
Although the image quality obviously deteriorates as the number of copies increases, it is confirmed in Example 1 that the image quality is sufficiently secured even if the number of copies increases. The grade of image quality deterioration in this embodiment uses an index of graininess, which represents roughness of image quality, and is calculated, for example, by calculating density variation data measured while scanning a micro densitometer with a formula called Wiener spectrum. Here, the relationship between the image quality deterioration grade and the graininess data is generally as follows. Image quality degradation grade Graininess data Actual image quality 1 1.0 or less White stripes can finally be confirmed with a magnifying glass. 2 1.0 to 1.2 White streaks can finally be visually confirmed. 3 to 1.5 White streaks can be visually confirmed. 4 to 2.0 White lines can be clearly seen, which is an eyesore. 5 2.0 or higher The image quality of the copy is no longer present.

Example 2 FIG. 8 shows a main part of a cleaning device according to Example 2.
In the figure, the basic configuration of the cleaning device is substantially the same as that of the first embodiment, but unlike the first embodiment, three toner scraping bars 32 (specifically 32A, 32B ... ) As a unit for step rotation.

According to the second embodiment, as shown in FIG. 5, the biting amount of the toner scraping bar 32 with respect to the brush 12 is always m1 (external additive removing optimum value) and m2 (toner removing optimum value). Can be set to
As indicated by the alternate long and short dash line in FIG. 7, the cleaning performance can be further improved as compared with the first embodiment.

In this embodiment, the three toner scraping bars 32 (specifically, 32A, 32B ...) Are rotated stepwise, but as shown in FIG. The toner scraping bar 32 may be rotated by one step for each number (for example, one).

Example 3 FIG. 10 shows a main part of a cleaning device according to Example 3. The same components as those in the above-described embodiments are designated by the same reference numerals, and detailed description thereof will be omitted here. In the figure, the cleaning device according to this embodiment has a toner removing member 13 different from the above-described embodiments. In this toner removing member 13, three toner scraping bars 32 are arranged around the rotating disk 31 at angular intervals of 30 °, and a plurality of toner removing members 13 and brushes 12 are provided on the opposite side. In this embodiment, 5 cleaning brushes 33
(Specifically 33a to 33e) are provided, and during the cleaning operation, the three toner scraping bars 32 are set to the set position where they bite into the brush 12, and when the copy job is completed, the rotating circle By rotating the plate 31 a plurality of times, the toner adhering to the toner scraping bar 32 is removed by the cleaning brush 33. Even in this type, substantially the same operation and effect as those of the above-described second embodiment can be obtained.

[0032]

As described above, according to the invention described in any one of claims 1 to 3, the plurality of toner scraping bars are circulated and moved so that the amount of bite into the brush is changed. Therefore, if the amount of bite of the toner scraping bar with respect to the brush is optimized for removing the toner and the external additive, not only the toner and the external additive can be effectively scraped from the brush by the toner scraping bar, but also the toner is removed. Since the scraping bar is alternately brought into contact with the brush, the brush does not come into contact with the same part of the toner scraping bar for a long period of time, effectively preventing the toner T from accumulating on the toner scraping bar. As a result, it is possible to prevent the toner from being fused to the toner removing member or the brush due to the contact with the brush, and to prevent the toner from being transferred to the toner image carrier. Can be prevented to effectively prevent re-adhesion of over.

Further, since the cleaning performance is improved by using the toner removing member according to the present invention, a cleaning pretreatment means (neutralizing the toner charge and carrying the toner image) for the pretreatment of the conventional cleaning device is carried out. It is not always necessary to use (making it easy for toner to be lost from the body), and the apparatus can be simplified and the cost can be reduced accordingly.

According to the second aspect of the present invention, the toner adhering to the toner removing member is surely removed by the cleaning means, so that the toner adhering to the toner removing member reattaches to the brush. It is possible to more reliably prevent the situation where the toner image is reattached to the toner image carrier.

According to the third aspect of the present invention, a plurality of toner scraping bars are simultaneously bited into the brush, and the biting amount is optimized for removing the toner and the external additive. Not only the toner but also the external additive can be removed reliably and efficiently.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a cleaning device according to the present invention.

FIG. 2 is a process configuration diagram of an electrophotographic copying machine including a cleaning device according to a first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the basic configuration of the cleaning device according to the first embodiment.

FIG. 4 is a detailed perspective view of a toner removing member used in Embodiment 1.

FIG. 5 is an explanatory diagram showing a relative positional relationship between a toner scraping bar and a brush used in the first embodiment.

FIG. 6 is a graph showing the relationship between the number of copies and the amount of toner adhered to the brush when the cleaning devices of Examples 1 and 2 and Comparative Examples 1 and 2 are used.

FIG. 7 is a graph showing the relationship between the number of copies and the grade of image quality deterioration when the cleaning devices of Examples 1 and 2 and Comparative Examples 1 and 2 are used.

FIG. 8 is an explanatory diagram showing a second embodiment of the cleaning device to which the present invention is applied.

FIG. 9 is an explanatory diagram showing a modified example thereof.

FIG. 10 is an explanatory diagram showing a cleaning device according to a third embodiment of the invention.

FIG. 11 is an explanatory diagram showing an example of a conventional cleaning device.

FIG. 12 is an explanatory diagram showing another example of a conventional cleaning device. DESCRIPTION OF SYMBOLS 1 ... Toner image carrier, 2 ... Brush, 3 ... Toner removing means, 4 ... Toner scraping bar, 5 ... Movable supporting means, 6 ...
Cleaning means

Claims (3)

[Claims] 1. A cleaning device comprising a brush (2) rotating in contact with the surface of a toner image carrier (1) and a toner removing means (3) for removing toner (T) adhering to the brush (2). The toner removing means (3) is
A plurality of toner scraping bars (4) and each toner scraping bar (4) at a predetermined toner scraping position so as to support the plurality of toner scraping bars (4) and change the amount of bite into the brush 2. And a movable supporting means (5) for circulatingly moving the cleaning device. 2. The cleaning device according to claim 1, wherein the toner removing means (3) includes a cleaning means (6) for removing the toner adhering to the toner scraping bar (4). apparatus. 3. The toner according to claim 1 or 2, wherein the movable supporting means (5) allows the at least two toner scraping bars (4) to simultaneously bite into the brush (2) with different biting amounts. A cleaning device, characterized in that the scraping bar (4) is moved intermittently.