JP3099924B2 - Method for collecting toner in image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering toner, which conveys toner collected by a cleaning device of an image forming apparatus to a developing device and reuses the toner.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a printer, and a facsimile, an electrostatic latent image is formed on an image carrier.
In an image forming apparatus in which the electrostatic latent image is developed as a toner image by a developing device and the toner image is transferred to a predetermined transfer sheet, toner that has not contributed to the transfer (hereinafter referred to as “transfer residual toner”) ) Remains on the surface of the image carrier, and is collected while being removed by a cleaning device.

Also, in order to maintain the toner concentration of the developer in the developing device constant, even in an image forming apparatus which forms a pattern visualized image with toner on an image carrier, the toner of the pattern visualized image is cleaned by a cleaning device. Removed and recovered.

The transfer residual toner and the toner of the pattern image are gradually stored in the toner collecting section of the cleaning device. However, since the amount is large, it is necessary to increase the toner collecting capacity. If it does so, a cleaning apparatus will become large easily. In addition, a toner collection container is provided detachably with respect to the cleaning device, the toner is put in the container, and the container is disposed of for each toner.
When the container is attached, the size of the cleaning device is easily increased. Further, if such a large amount of toner is discarded and left, the consumption of the used toner increases and the running cost increases.

Therefore, various techniques have been proposed in which the toner collected in the cleaning device is returned to the developing device via the image carrier, and the returned toner is reused for development (Japanese Patent Application Laid-Open No. H10-163,837). See JP-A-56-74285 and JP-A-60-88977. According to such a toner recovery method, the toner can be reused, and a complicated and expensive toner transport device for transporting the toner from the cleaning device to the developing device is not required, so that the cost of the image forming apparatus can be reduced. Also have.

However, in general, if a toner removing member such as a scraping plate is used to collect the toner adhered to the image carrier toward the developing device, the surface of the image carrier is easily damaged. In addition, the developing device requires a dedicated toner removing member. Further, if the developer carrying / conveying rotary member composed of the developing sleeve or the like is rotated in the rotation direction at the time of development and the toner is collected and adhered to the developing sleeve, it is expected that the collecting effect is not so much expected. Can not.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cleaning device in which a toner of a cleaning device is provided on a side of the developing device without providing a dedicated toner removing member or the like to the developing device.
An object of the present invention is to provide a toner collecting method in an image forming apparatus, which enables smooth and reliable collection.

[0008]

According to the present invention, a developing device for developing an electrostatic latent image formed on an image carrier and a toner to be recovered are removed from the image carrier. A cleaning device, wherein the developing device includes a developer that is rotationally driven in a first rotation direction such that a surface facing the image carrier moves in the same direction as a moving direction of the surface of the image carrier. A rotating member for carrying the developer, which is rotated in a first rotation direction during development, and the electrostatic latent image is transported by the toner of the developer carried on the rotating member for carrying the developer. In an image forming apparatus designed to develop an image, the toner collected on the side of the cleaning device is adhered to the image carrier, and the adhered toner is rotated while rotating the image carrier, facing the developer carrying and transporting rotating member. Leading to the site and front While rotating the developer-carrying / conveying rotary member in a second rotation direction opposite to the first rotation direction, the toner guided to the opposite portion of the developer-carrying / conveying rotation member is carried on the developer-carrying / conveying rotating member. Thus, a toner collecting method for collecting toner on the side of the developing device is proposed.

At this time, it is effective to increase the rotation speed of the developer-carrying and transporting rotary member at the time of toner recovery from that at the time of development.

In addition, a magnet body including a main pole is arranged inside the developer-carrying / conveying rotary member, and the main pole approaches the image carrier at the time of toner recovery so that the main pole faces the image carrier. It is effective to make the position variable.

Further, at the time of toner collection, it is effective to apply a bias voltage to the developer-carrying / transporting rotating member such that the toner on the image carrier electrostatically transfers to the developer-carrying / transporting rotating member.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing only a main part of an image forming apparatus embodying the present invention. The image forming apparatus exemplified here is of a digital type, and a drum-shaped negatively chargeable organic photoreceptor 1 is a main component of the image carrier. The image forming apparatus of this embodiment employs a reversal developing system using a two-component developer containing a negatively charged toner as a developer.

The photosensitive member 1 is driven to rotate in the direction of the arrow, and its surface is uniformly charged by the charger 2. Next, the surface of the photoconductor 1 is main-scanned in the axial direction by the laser beam 3 modulated according to the image information, whereby a predetermined electrostatic latent image is formed on the photoconductor. This electrostatic latent image is developed by the developing device 4 and is visualized as a toner image. This toner image is transferred to the transfer paper 7 under the action of the transfer charger 5.

After the transfer, the transfer paper is separated from the photoreceptor 1 by the action of the separation charger 6, and then discharged out of the image forming apparatus as copy paper through a fixing device (not shown). On the other hand, after the transfer step, the toner remaining on the surface of the photoconductor 1 is removed by the cleaning device 8. Thereafter, the charge remaining on the photoconductor is removed by static elimination light emitted from the quenching lamp 9, and the photoconductor 1 is prepared for the next image formation.

The cleaning device 8 illustrated in FIG. 1 has a cleaning blade 8a pressed against the photosensitive member 1 and a brush roller 8b driven to rotate while sliding on the photosensitive member 1. 1 is removed. The cleaning blade 8a can be moved toward and away from the photoconductor 1 (FIG. 2).
reference).

Here, as described above, the developing device 4 contains a two-component developer having a toner and a carrier, but when the concentration of the toner in the developer decreases, As a result, the image density decreases. In view of this, a pattern visible image 10 made of toner is formed in a non-image forming area on the surface of the photoreceptor 1, and the density of the pattern visible image is detected by a reflection type density sensor 12. When the sensor detects a decrease in the density, the toner is supplied from the toner supply unit 13 of the developing device 4, and the concentration of the toner in the developer is kept constant.

The toner of the pattern image formed on the photosensitive member as described above is also removed by the cleaning device 8. As described above, the cleaning device 8 removes toner to be collected from the photoconductor, such as the toner of the pattern visualized image and the previous transfer residual toner.

The developing device 4 is provided with a developer-carrying / transporting rotary member so as to face the photoconductor 1. In this embodiment, the developer-carrying / transporting rotary member has a small gap with the photoconductor 1. It is configured as a non-magnetic developing sleeve 15 opposed to the developing sleeve. A magnet 16 including a main pole P is arranged inside the developing sleeve 15.
6 is normally immovably held in the position shown in FIG.

During development, the developing sleeve 15 is rotated counterclockwise in the drawing so that the surface facing the photoconductor 1 is in the same direction as the surface of the photoconductor 1 moves. This rotation direction is hereinafter referred to as “first rotation direction”. The developer is carried and conveyed on the developing sleeve 15 rotating in this direction, the amount of the conveyed developer is regulated by the doctor blade 14, and a predetermined amount of the developer is conveyed to the developing area 11. Then, in the developing area 11, the previous electrostatic latent image is visualized as a toner image by the toner in the developer.

Here, the surface of the photoreceptor 1 is charged to, for example, -800 V by the charger 2. That is, the surface potential of the photoconductor at the time of development has a background potential (dark potential) of about -800 V. On the other hand, the image portion potential (bright portion potential) irradiated with the laser beam 3 becomes, for example, about -100V.

A developing bias voltage of, for example, about −600 V is applied to the developing sleeve 15 by a DC bias voltage power supply device 18, and an image portion (a bright portion, a portion to which laser light is applied) on the photosensitive member 1 and a developing portion are developed. Due to the potential difference between the toner and the sleeve 15, the negatively charged toner on the developing sleeve 15 is electrostatically transferred onto the photoconductor, and the electrostatic latent image on the photoconductor is visualized as a toner image.

The brush roller 8 of the cleaning device 8
To b, a voltage (for example, +300 V) having a polarity opposite to the charging polarity (in this example, minus) of the toner is applied, and the toner to be collected adhered on the photoconductor 1 is scraped by the rotating brush roller 8b. While being electrostatically attracted to the roller 8 side. The cleaning blade 8a scrapes and removes the toner on the photoconductor 1 that has not been completely removed by the brush roller 8b.

The image forming operation is performed as described above.
In this example, when the image forming operation is not performed,
The toner collected in the cleaning device 8 is adhered onto the photoreceptor 1, and the rotation of the photoreceptor 1 causes the toner to be
It is configured to be conveyed to.

That is, first, the cleaning blade 8a
Is separated from the surface of the photoconductor 1 as shown in FIG. 2, and the photoconductor 1 is rotated in the same direction as when a normal image forming operation is performed. At this time, the charger 2 does not operate, the laser beam 3 is not exposed, and the surface potential of the photoconductor 1 becomes almost 0 V.
b is driven to rotate, and a bias voltage (for example, -300 V) having the same polarity as the charging polarity (minus in this example) of the toner is applied to the brush roller 8b. As a result, the toner collected on the side of the cleaning device 8 electrostatically adheres to the photoreceptor 1, and the toner T adhered to the photoreceptor 1 becomes
To the region of the development region 11 opposite to. When the toner is collected from the cleaning device 8, the photoconductor 1 is charged to a polarity opposite to that of the toner.
May be made to adhere to the photoconductor 1.

The toner guided in this manner is collected toward the developing device 4. At the time of toner collection, the developing sleeve 15 is moved in the second rotation direction opposite to the first rotation direction, that is, in the second rotation direction. In FIG. 2, it is driven to rotate in the direction of the dashed arrow.

When the developing sleeve 15 is driven to rotate in the first rotation direction at the time of toner collection, the toner on the photosensitive member 1 passes between the photosensitive member 1 and the developing sleeve 15 as it is. May be left on the photoreceptor 1. On the other hand, the developing sleeve 15
When the photoconductor 1 and the developing sleeve 1 are rotated in the rotation direction of
5 and the toner on the photoconductor 1 comes into strong contact with the magnetic brush made of the developer on the developing sleeve 15, and the magnetic brush The upper toner is smooth and
The toner is reliably scraped off, carried on the developing sleeve 15, and collected on the developing device 4 side.

At the time of toner collection, a bias voltage is applied to the developing sleeve 15 so that the toner adhered on the photosensitive member 1 is electrostatically transferred to the developing sleeve 15. That is, in this example, since the toner is negatively charged,
When collecting the toner in the developing device 4, the developing sleeve 1
5, a positive bias voltage is applied, and the toner adhering to the photoreceptor 1 is electrostatically attracted to the developing sleeve 15 side to efficiently collect the toner.

As described above, the toner collecting effect can be greatly improved. Further, in the toner collecting method of the present embodiment, the existing developing sleeve 15 performs the function of removing and collecting the toner, so that a dedicated toner removing member such as a scraping plate is not required, which is advantageous in cost. Become. Further, the surface of the photoconductor is not damaged. In this manner, the toner collected from the cleaning device 8 can be reused in the developing device 4 again, so that a problem of wasteful consumption of toner can be prevented.

It is known that the collected toner is conveyed from the cleaning device 8 to the developing device 4 by a mechanical toner conveying means. However, in the present method, such a mechanical toner conveying means is not required. It is.

The developing sleeve 15 is rotated at a speed of, for example, about 360 mm / sec at the time of development. At the time of toner collection, the developing sleeve 15 is rotated at a higher speed of about 450 mm / sec. If you try to
The force for scraping the toner on the photoreceptor is increased, and the toner collecting effect can be further enhanced. Assuming that the rotation speed of the developing sleeve at the time of development is 360 mm / sec, the rotation speed ratio between the developing sleeve 15 and the photosensitive member 1 is, for example, 2.0, but the rotation speed ratio is 450 mm / sec. Is 2.5
Becomes In any case, by increasing such a rotational speed ratio (linear speed ratio), the recoverability of the toner is improved.

By the way, at the time of development, as shown in FIG.
The main pole P of the magnet body 16 is located at a position upstream of the center line connecting the center of the photoconductor 1 and the center of the developing sleeve 15 in the rotation direction of the developing sleeve 15. That is, the angle θ between the center line and the main pole is set to about 10 °. When the main pole P is at such a position, the developer is transferred in such a manner that the ears of the developer on the developing sleeve 15 are pressed against the surface of the photoconductor.

On the other hand, when the toner is collected in the developing device 4, as shown in FIG. The developer becomes spikes at the wedge-shaped portions shown in FIG. 2, and the spikes strongly rub against the toner on the photoreceptor 1, thereby further improving the toner collecting property. As described above, it is advantageous to change the position of the main pole P between the time of development and the time of toner collection because the toner collecting property can be particularly improved.

When the developer carried on the developing sleeve 15 rotating clockwise and conveyed when the toner is collected in the developing device 4 is likely to be obstructed by the doctor blade 14, The doctor blade 14 may be retracted to a position far away from the developing sleeve 15.

In the above-described example, the toner of the cleaning device 8 is supplied to the developing device 4 at a time other than the time of the image forming operation.
, And the toner can be transported to the developing device 4 while performing the image forming operation. In this case, the toner of the cleaning device 8 is made to adhere to the non-image area on the photoconductor 1 in the same manner as described above, and the toner is transported to the developing device 4 and collected.

For example, the toner of the cleaning device is attached to the non-image forming area between the image forming areas in the circumferential direction of the photoreceptor 1. Also in this case, the non-image forming area is charged to a polarity opposite to that of the toner of the cleaning device 8, or when the non-image forming area passes through the brush roller 8b of the cleaning device 8, the toner is applied to the brush 8b. A bias voltage having the same polarity as the charging polarity is applied to cause the toner to adhere to the non-image forming area. When the attached toner passes through the developing sleeve 15 of the developing device 4, the toner is removed in exactly the same manner as described above. Developing sleeve 15
Collect to the side.

It is also possible to apply the toner of the cleaning device 8 to the non-image forming region at the axial end portion of the photosensitive member 1 and transport the toner to the developing device 4 to collect the toner. As described above, when the toner of the cleaning device 8 is collected during the image forming operation, the toner can be efficiently collected in time.

The above-described configurations for changing the rotation speed of the developing sleeve, the main pole position, the developing bias voltage and the like are as follows.
It is not always necessary to carry out each of these individually, and it is also possible to carry out these in various combinations, and in this case, the toner collecting effect can be further enhanced.

In the present invention, the developer is not limited to a two-component developer, but can be applied to a developer using a one-component developer not containing a carrier. The present invention is not limited to the photoreceptor, but can be applied to a photoreceptor using an endless belt or other components.

[0040]

According to the toner collecting method of the present invention, when collecting the toner from the cleaning device via the image carrier to the developing device, the recoverability can be greatly improved. Also, there is no need to provide a dedicated toner removing member on the side of the developing device, and the surface of the image carrier is not damaged by the toner removing member.

According to the toner collecting method of the present invention, the scraping property of the toner on the image carrier is improved, and the toner collecting effect can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing only a main part of an image forming apparatus embodying the present invention.

FIG. 2 is a diagram illustrating a pattern in which toner is collected toward a developing device in the image forming apparatus.

[Explanation of symbols]

 4 Developing device 8 Cleaning device 15 Developing sleeve 16 Magnet P Main pole T Toner

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinji Kato 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (56) References JP-A-62-279383 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 15/08-15/095 G03G 21/10-21/12

Claims (4)

(57) [Claims] A developing device for developing an electrostatic latent image formed on the image carrier; and a cleaning device for removing toner to be collected from the image carrier, wherein the developing device includes an image carrier. A developer-carrying / transporting rotating member that is driven to rotate in the first rotation direction is provided so that the surface facing the image carrier moves in the same direction as the direction of movement of the surface.
In the image forming apparatus, the developer carrying / transporting rotating member is rotated in a first rotation direction, and the electrostatic latent image is developed by toner of the developer carried / transported on the developer carrying / transporting rotating member. Adhering the toner collected on the side of the cleaning device onto the image carrier, guiding the adhered toner to a portion opposed to the developer carrying and rotating member while rotating the image carrier, and While rotating the member in a second rotation direction opposite to the first rotation direction, the toner guided to the opposite portion of the developer-carrying / transporting rotating member is carried by the developer-carrying / transporting rotating member. A toner collecting method that is collected on the side. 2. The toner collecting method according to claim 1, wherein a rotation speed of the developer-carrying / conveying rotary member is set to be higher at the time of toner collection than at the time of development. 3. A magnet body including a main pole is disposed inside the developer-carrying / conveying rotary member, and the main pole approaches the image carrier at the time of toner recovery so that the main pole faces the image carrier. 3. The toner collecting method according to claim 1, wherein the position is variable. 4. The developer carrying transport member according to claim 1, wherein at the time of toner collection, a bias voltage is applied to the developer carrying transport member so that the toner on the image carrier is electrostatically transferred to the developer carrying transport member. A toner collection method in the image forming apparatus according to any one of the first to third aspects.