JP3143136B2 - Cleaning method for untransferred 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 cleaning untransferred toner in an electrophotographic image forming apparatus such as a laser printer, a copying machine, a facsimile machine, etc., provided with a transfer medium such as a transfer roller.

[0002]

2. Description of the Related Art In an image forming apparatus such as a laser printer, a toner image formed on an image carrier is directly or indirectly transferred to a final transfer material such as transfer paper using a transfer medium such as a transfer roller. There is something like that. In such an image forming apparatus, untransferred toner remaining without being transferred to the final transfer material is cleaned by cleaning devices provided on the outer periphery of the image carrier and the transfer medium, respectively.

Incidentally, in this type of image forming apparatus, the following is a general example of an untransferred toner image which remains without being transferred to a final transfer material. A toner image left on the image carrier when the apparatus stops due to some abnormality during image formation. A toner image formed on an image carrier for process control such as toner density control.

[0004]

However, in an image forming apparatus provided with a transfer medium, good image quality cannot be maintained unless both the image carrier and the transfer medium are always kept clean. Therefore, there is a disadvantage that the image quality is inferior to that of an apparatus which only needs to clean only the untransferred toner on the image carrier. The present invention has been made in view of the above points, and has as its object to enable an image forming apparatus provided with a transfer medium to maintain good image quality for a long period of time.

[0005]

According to the present invention, a toner image formed on an image carrier is directly or indirectly transferred to a transfer paper or the like using a transfer medium such as a transfer roller. An image forming apparatus for transferring to the transfer material, following
Cleaning of untransferred toner shown in (1) to (6) below
Provide a way. (1) Untransferred toner remaining without being transferred to the final transfer material
Are provided on the outer periphery of the image carrier and the transfer medium, respectively.
Clean with a cleaning device
Clean the untransferred toner from the image carrier and transfer medium
The larger the capacity of the waste toner container provided in the
Divide.

(2) The remaining untransferred part on the final transfer material
Transfer the toner onto the outer periphery of the image carrier and the transfer medium
Cleaning with the provided cleaning device,
At this time, the untransferred toner is stored in each of the cleaning devices.
The image carrier and the image carrier are transferred according to the remaining toner amount in the waste toner container
Selectively distribute to the shooting media. (3) Untransferred toner remaining without being transferred to the final transfer material
Are provided on the outer periphery of the image carrier and the transfer medium, respectively.
Clean with a cleaning device
The image carrier is changed by changing the transfer conditions for untransferred toner.
And transfer media selectively.

(4) Cleaning of untransferred toner of (3)
In addition to the transfer method, the transfer conditions
Is the transfer current value, and the untransferred toner is transferred to the image carrier.
Transfer bias voltage value when distributing more to
When distributing the transfer current value more toward A1 and the transfer medium
When the transfer bias application voltage value or the transfer current value is A2,
The transfer bias applied voltage value when
Or when the transfer current value is A3, A1 <A3 <A2
To satisfy the relationship .

(5) The remaining untransferred part on the final transfer material
Transfer the toner onto the outer periphery of the image carrier and the transfer medium
Cleaning with the provided cleaning device,
At that time, the above untransferred toner is distributed more toward the image carrier.
When the toner is passing through the transfer area,
Separate the carrier from the transfer medium and transfer the untransferred toner.
In the case where the toner is distributed more toward the printing medium, the toner is transferred.
When the image carrier and the transfer medium are
By transferring the untransferred toner to the image carrier and the transfer medium,
Selectively distribute to the body . (6) In addition to the method (3) for cleaning untransferred toner,
Of the untransferred toner toward the image carrier.
When the toner is passing through the transfer area,
Separate the image carrier from the transfer medium and remove the untransferred toner.
If the toner is distributed more toward the transfer medium, the toner
When the image carrier and the transfer medium are passing through the transfer area.
Make contact .

[0009]

In the image forming apparatus using the untransferred toner cleaning method of the present invention, the amount of waste toner in each cleaning device and the amount of remaining toner inside the cleaning device can be adjusted.
Since the untransferred toner is selectively distributed to the image carrier and the transfer medium, the cleaning performance of each cleaning device is stabilized, and thus, it is possible to maintain good image quality for a long period of time.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be specifically described below with reference to the accompanying drawings. 1 to 3 are schematic configuration diagrams showing different examples of an image forming apparatus embodying the present invention.
Corresponding parts are denoted by the same reference numerals.

FIG. 1 shows an image forming apparatus using a transfer roller as a transfer medium. The outer peripheral surface of a photosensitive drum 1 as an image carrier is charged by a charger 2 and the charged surface is transferred from an exposure device (not shown). The electrostatic latent image is formed by exposure to light 3, and the latent image is visualized by attaching toner with a developing device 4, and then the transfer roller 5 is transferred to a transfer paper (final transfer material) conveyed by a registration roller 6. 3) The toner formed on the outer peripheral surface of the photosensitive drum 1 on the transfer paper 7 by indirectly contacting the photosensitive drum 1 via 7 and applying a transfer bias voltage from a power supply (not shown) to the transfer roller 5 Transfer the image.

Further, after the untransferred toner (hereinafter simply referred to as “untransferred toner”) remaining without being transferred onto the transfer paper is selectively distributed to the photosensitive drum 1 and the transfer roller 5 (to be described later). Cleaning is performed by cleaning blades 8a and 9a in cleaning devices 8 and 9 provided on the outer periphery of the photosensitive drum 1 and the transfer roller 5, respectively, and collected in the waste toner containers 8b and 9b. The charge remaining on the outer peripheral surface of the is removed by the charge remover 10 to prepare for the next image formation.

Reference numeral 11 denotes an optical sensor which is provided so as to face the outer peripheral surface of the photosensitive drum 1, and for example, when a toner image for process control such as toner density control is formed on the outer peripheral surface. The density is detected and a signal corresponding to the density is output to a control unit (not shown).

FIG. 2 shows an image forming apparatus using a transfer / transport belt as a transfer medium. A toner image is formed on the outer peripheral surface of the photosensitive drum 1 by the same processing as that of the above-described image forming apparatus. The transfer paper 7 is electrostatically adsorbed on the transfer belt 7 and transported to a transfer area. The transfer transport belt 12 is indirectly contacted with the photosensitive drum 1 with the transfer paper 7 interposed therebetween, and the back surface of the transfer transport belt 12 is To the transfer paper 7 by applying a corona charge from the transfer charger 13 to the transfer paper 7
To transfer the toner image on the photoconductor.

After the untransferred toner is selectively distributed to the photosensitive drum 1 and the transfer / transport belt 12, the cleaning devices 8 and 14 provided on the outer periphery of the photosensitive drum 1 and the transfer / transport belt 12, respectively. The photosensitive drum 1 is cleaned by the cleaning blades 8a and 14a, collected in the waste toner containers 8b and 14b, and the charge remaining on the outer peripheral surface of the photosensitive drum 1 is removed by the charge remover 10 to form the next image. Prepare.

FIG. 3 shows an image forming apparatus using an intermediate transfer belt and a transfer roller as a transfer medium. After forming a toner image on the outer peripheral surface of the photosensitive drum 1, the intermediate transfer belt 1
The toner image on the photosensitive drum 1 is directly transferred to the intermediate transfer belt 15 by applying a bias voltage to the intermediate transfer belt 15.

Here, assuming that the developing device 4 is composed of three developing devices respectively containing toners of cyan, magenta and yellow, among the color-separated latent images, cyan should be developed first. After forming a latent image on the photosensitive drum 1 and developing it by a developing device having cyan toner, the toner image is transferred onto the intermediate transfer belt 15.

Next, a latent image to be developed with magenta is formed on the photosensitive drum 1 and is visualized by a developing device having magenta toner. The image is transferred so as to overlap the transferred cyan toner image.

Further, a latent image to be developed in yellow is formed on the photosensitive drum 1 and visualized by a developing device having yellow toner, and the toner image is formed on the intermediate transfer belt by cyan and magenta. Are further superimposed and transferred onto the superimposed image of each color toner. As a result, a full-color toner image is formed on the intermediate transfer belt 15.

When the above steps are completed, the transfer roller 16 is moved via the transfer paper 7 to the intermediate transfer belt 15 serving as an image carrier.
To transfer the toner image on the intermediate transfer belt 15 to the transfer paper 7 by applying a bias voltage to the transfer roller 16.

After the untransferred toner is selectively distributed to the photosensitive drum 1, the intermediate transfer belt 15, and the transfer roller 16, the photosensitive drum 1, the intermediate transfer belt 15,
And cleaning blades 8 in cleaning devices 8, 17, and 18 provided on the outer circumference of the transfer roller 16, respectively.
a, 17a, and 18a, and is collected in the respective waste toner containers 8b, 17b, and 18b. Further, the charge remaining on the outer peripheral surface of the photosensitive drum 1 is removed by the charge remover 10 to form the next image. Prepare for.

As for the conventional problems in the image forming apparatus provided with the transfer medium as described above, the inventor has studied in detail how and when to distribute untransferred toner. The conclusions described in (1) and (2) above were obtained. Therefore, the contents will be specifically described.

(1) The untransferred toner is distributed so as to be increased to one of the image carrier and the transfer medium. When the image carrier and the transfer medium are formed of different materials, it has been found that it is better to allocate the untransferred toner to one of them in consideration of the following items.

The untransferred toner is distributed more to those formed of a material that is easy to clean. Since the image carrier and the transfer medium are used repeatedly, they must always be in a clean state. For this purpose, the untransferred toner must be reliably cleaned. Therefore, it may be better to distribute the untransferred toner to a material formed of a material that is easy to clean.

For example, in a cleaning device in an image forming apparatus as shown in FIGS. 1 to 3, a cleaning blade is generally used so as to have high cleaning performance and low cost. This indicates that it is better to allocate a larger amount of untransferred toner to a craning device having a cleaning blade formed of the material, since a material having a smaller size is easier to clean.

Further, it is also shown that since the paper dust generated from the transfer paper causes the deterioration of the cleaning performance, it is better to distribute a large amount of the untransferred toner to the surface to which the transfer paper does not contact. A large amount of untransferred toner is allocated to the toner formed of a material that is difficult to film.

As shown in (1), since the image carrier and the transfer medium are used repeatedly, the image carrier and the transfer medium must be always kept in a clean state. Therefore, it is desirable that there is no filming in which the toner is fused to the surface. . Therefore, it may be better to allocate a large amount of untransferred toner to a toner formed of a material that is difficult to film. Here, the material with which the toner is difficult to film means a material or the like having a large surface energy.

The untransferred toner is distributed more to the lower temperature of the cleaning device. The toner used in a normal image forming apparatus is finally fixed as a permanent image on transfer paper by heat. Therefore, it is preferable that the heat is cut off as much as possible except for fixing. For example, if a large amount of toner present in the cleaning device is heated, the toner is fused in the device or the transport path, resulting in a problem that transport failure occurs. Therefore, the temperature of the cleaning device is also one of the important criteria.

A large amount of untransferred toner is distributed to a surface that does not contact the transfer surface of the transfer paper. As a further criterion, there is a method of distributing a large amount of untransferred toner to a surface of the transfer paper that does not contact the transfer surface. This is because, if a cleaning failure occurs on the surface of the transfer paper that comes into contact with the transfer surface, it appears on the transfer surface, and the transferred image may be unsightly.

The surface of the transfer sheet which does not contact the transfer surface is, for example, a transfer roller in the image forming apparatus of FIG. 1, a transfer conveyance belt in the image forming apparatus of FIG. 2, or an outer peripheral surface of a transfer roller in the image forming apparatus of FIG. , Which means a final transfer medium. More untransferred toner is distributed to the larger capacity of the waste toner container provided in each cleaning device.

From the above, the image quality or the damage of the apparatus is used as a criterion, but in some cases it is necessary to judge from the configuration of the apparatus. The cleaning devices provided on the outer periphery of the image carrier and the transfer medium respectively have independent waste toner containers, and their capacities may differ depending on the layout of the device. Untransferred toner is basically extra toner, so in such a case, more untransferred toner is allocated to the larger side of the waste toner container.

As described above, the criterion for allocating the untransferred toner to one of the image carrier and the transfer medium so as to always increase the amount has been described. By the way, since the untransferred toner is basically an extra toner as described above, the amount thereof may be considerably increased depending on the frequency of occurrence. Therefore,
An apparatus having a sensor or the like for detecting the fullness of the waste toner container continues the operation of the apparatus when the waste toner container allocated to increase the amount of untransferred toner becomes full. Therefore, it is better to have a function of changing the distribution so that a large amount of untransferred toner is collected in the other waste toner container.

Further, in order to increase the time margin until the space is full, it is necessary to increase the capacity of the waste toner container for distributing a large amount of untransferred toner as long as there is room in the layout of the apparatus.

(2) As the distribution of the non-transferred toner, a substantially uniform distribution or a random distribution is selected. If it is not necessary to consider the inconvenience shown in (1), the following may be performed. The untransferred toner is distributed almost equally between the image carrier and the transfer medium. This is to ensure that the cleaning load and the waste toner capacity load are not biased to both.

The remaining toner capacity of each waste toner container is monitored, and a large amount of untransferred toner is distributed to the one with the larger remaining toner capacity. Detecting means such as a weight sensor is provided in each waste toner container to detect the remaining toner capacity, and based on the detected value, the untransferred toner is transferred to the waste toner container having the larger remaining toner capacity among the image carrier and the transfer medium. Sort out a lot.

Next, a method for selectively distributing the untransferred toner to the image carrier and the transfer medium will be described.
The distribution of the untransferred toner is basically performed by a transfer process. FIG. 4 shows the relationship between the transfer bias voltage value applied to the transfer roller and the transfer efficiency. Here, the reason why the transfer of the toner is performed even when the bias voltage is “0” is as follows.
This is because pressure transfer is performed by contact between the image carrier and the transfer roller serving as a transfer medium.

From this figure, it can be seen that the adjustment of the transfer toner amount can be controlled by the applied transfer bias voltage value.
As a result, the transfer bias application voltage value when distributing the untransferred toner toward the image carrier is V1 and the transfer bias application voltage value when distributing the untransferred toner toward the transfer roller is V2.
, The relationship of V1 <V2 is satisfied.

Further, when the transfer bias application voltage value when the untransferred toner is almost equally distributed to the image carrier and the transfer roller is V3, it is easy to satisfy the relationship of V1 <V3 <V2. Can understand.
Although the transfer bias voltage value applied to the transfer roller has been described above as an example of the transfer condition, the same can be said for the transfer current value when a transfer charger is used instead of the transfer roller.

That is, the transfer condition is a transfer current value,
The transfer current value when distributing the untransferred toner to the image carrier more is I1, the transfer current value when distributing more to the transfer charger is I2, and the transfer current value when distributing almost equally to both is I3. At this time, the relationship of I1 <I3 <I2 may be satisfied.

Here, in each image forming apparatus, the image carrier and the transfer medium may be damaged due to friction generated by the pressure transfer. It is configured to be able to contact and separate from the transfer medium,
Except for the transfer step, the image carrier and the transfer medium are separated from each other.

In such an image forming apparatus, when a large amount of untransferred toner is distributed to the image carrier, in order to avoid distribution of untransferred toner due to pressure transfer,
By separating the image carrier and the transfer medium while the toner is passing through the transfer area, the untransferred toner is reduced by 10%.
0% is distributed to the image carrier.

When the untransferred toner is distributed more toward the transfer medium, it is very difficult to transfer in a non-contact state. Therefore, when the toner passes through the transfer area, the image carrier and the transfer medium are separated. May be brought into contact. FIG. 5 shows a specific example of the untransferred toner processing.

[0043]

As described above, according to the present invention, the cleaning performance of each cleaning device in an image forming apparatus provided with a transfer medium is stabilized, so that good image quality can be maintained for a long period of time. it can.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus using a transfer roller as a transfer medium embodying the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of an image forming apparatus using a transfer conveyance belt as a transfer medium embodying the present invention.

FIG. 3 is a schematic configuration diagram illustrating an example of an image forming apparatus using an intermediate transfer belt and a transfer roller as a transfer medium embodying the present invention.

FIG. 4 is a diagram showing a relationship between a transfer bias voltage applied to a transfer roller and a transfer efficiency for explaining the operation of this embodiment.

FIG. 5 is a flowchart showing a specific example of an untransferred toner process in this embodiment.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photosensitive drum 2 charger 4 developing device 5 transfer roller 7 transfer paper 8 cleaning device 8a cleaning blade 8b waste toner container 9 cleaning device 9a cleaning blade 9b waste toner container 12 transfer transport belt 13 transfer charger 14 cleaning device 14a cleaning blade 14b Waste toner container 15 Intermediate transfer belt 16 Transfer roller 17 Cleaning device 17a Cleaning blade 17b Waste toner container 18 Cleaning device 18a Cleaning blade 18b Waste toner container

Continuation of the front page (56) References JP-A-2-106676 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16 G03G 21/10

Claims (6)

(57) [Claims] 1. An image forming apparatus for directly or indirectly transferring a toner image formed on an image carrier to a final transfer material such as transfer paper by using a transfer medium such as a transfer roller, wherein: Untransferred toner remaining without being transferred
Each click of the image bearing member and then cleaned by the cleaning device provided respectively on the outer periphery of the transfer medium, the image bearing member and the transfer medium on the Symbol untransferred toner case
Larger capacity of waste toner container provided in the cleaning device
A method for cleaning untransferred toner, characterized in that the toner is distributed to a large amount . 2. A method for transferring a toner image formed on an image carrier.
Direct or indirect transfer using transfer media such as rollers
In an image forming apparatus for transferring to a final transfer material such as paper, an untransferred toner remaining without being transferred to the final transfer material is
Provided on the outer periphery of the image carrier and the transfer medium, respectively.
Clean with a cleaning device
Waste toner provided with untransferred toner in each of the above cleaning devices
-The image carrier and the transfer medium according to the amount of residual toner in the container;
Cleaning method for untransferred toner, characterized in that the toner is selectively distributed to the toner. 3. Transferring a toner image formed on an image carrier
Direct or indirect transfer using transfer media such as rollers
In an image forming apparatus for transferring to a final transfer material such as paper, an untransferred toner remaining without being transferred to the final transfer material is
Provided on the outer periphery of the image carrier and the transfer medium, respectively.
Clean with a cleaning device
By changing the transfer conditions for the untransferred toner, the image
A method for cleaning untransferred toner, which is selectively distributed to a carrier and a transfer medium . 4. A method for cleaning untransferred toner in an image forming apparatus according to claim 3, wherein the transfer condition is a transfer bias application voltage or a transfer current value.
Yes, distributes the above untransferred toner more toward the image carrier
Transfer bias applied voltage value or transfer current value when
1.Transfer bias mark when distributing more to the transfer medium
Applied voltage value walking will shake the transfer current value A2, both substantially uniformly
Transfer bias applied voltage value or transfer current when separating
When the value is A3, the relationship of A1 <A3 <A2 is satisfied.
Method for cleaning untransferred toner, which comprises as the. 5. A method for transferring a toner image formed on an image carrier.
Direct or indirect transfer using transfer media such as rollers
In an image forming apparatus for transferring to a final transfer material such as paper, an untransferred toner remaining without being transferred to the final transfer material is
Provided on the outer periphery of the image carrier and the transfer medium, respectively.
Clean with a cleaning device
When distributing a large amount of untransferred toner to the image carrier
Is the image bearing member when the toner is passing through the transfer area.
The body is separated from the transfer medium, and the untransferred toner is transferred to the transfer medium.
In the case where the toner is distributed more toward the printing medium, the toner is transferred.
The image carrier and the transfer medium are contacted while passing through the area.
The untransferred toner is brought into contact with the image carrier
And a transfer medium . 6. A method for cleaning untransferred toner in an image forming apparatus according to claim 3, wherein the untransferred toner is more distributed to an image carrier.
The image bearing when the toner is passing through the transfer area.
The carrier and the transfer medium are separated from each other, and the untransferred toner is
When the toner is distributed more toward the transfer medium, the toner is transferred.
The image carrier and the transfer medium are
A method for cleaning untransferred toner, which is brought into contact .