JP2006243657A - Image forming method and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method by which noise and shortening of life of a photoreceptor resulting from increase of friction force between the photoreceptor and a cleaning blade are prevented and consumption of toner used for image formation is also suppressed when a monochrome image is formed in a tandem type image forming apparatus. <P>SOLUTION: The image forming method is characterized that it includes two or more image formation unit and an intermediate transfer body, the image formation units have at least cleaning blades for cleaning the surface of an electrostatic latent image carrier and when formation of the monochrome image is performed at least via a process for forming a toner image only by any one of the two or more image formation units, supplies toner for lubrication on the surfaces of electrostatic latent image carriers of all the image formation units except any one of the image formation unit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming method for forming an image using electrophotography and an image forming apparatus using the image forming method.

Conventionally, as an image forming apparatus such as a copying machine or a printer that can form a full-color or black-and-white image using an electrophotographic method, a so-called tandem type that can obtain a color image at high speed and high quality Various image forming apparatuses (hereinafter sometimes referred to as “tandem machines”) have been proposed, and commercialized.
The structural feature of this tandem machine is that a plurality of image forming units that form toner images of different colors such as yellow, magenta, cyan, and black are arranged on the outer peripheral surface side of an intermediate transfer member such as an intermediate transfer belt. It is located along the rotation direction of the transfer body.

Color image formation by a tandem machine corresponds to the original color image information on the outer peripheral surface of the intermediate transfer member by using toner images of each color such as yellow, magenta, cyan, and black sequentially formed by the image forming unit corresponding to each color. The toner images (color toner images) are superimposed and primary transferred as described above, and then the superimposed toner image (color toner image) is collectively transferred from the intermediate transfer member to the surface of the recording medium, and the color toner image is fixed on the surface of the recording medium. Is done by.
In addition, the black and white image is formed in the same manner as the color image except that the black toner is formed using only the black image forming unit and then the toner image is not superimposed on the outer peripheral surface of the intermediate transfer member. Thus, primary transfer, secondary transfer, and fixing are performed.

  A typical configuration of such a tandem machine will be described with reference to the drawings. FIG. 3 is a schematic diagram showing an example of the configuration of a conventional tandem type image forming apparatus, in which 100Y, 100M, 100C, and 100K form yellow, magenta, cyan, and black toner images, respectively. An image forming unit, 101 is a photosensitive member (electrostatic latent image carrier), 102 is a contact type charging device, 103 is an exposure device, 104 is a developing device, 105 is a charger for primary transfer, 106 is an intermediate transfer belt, Reference numeral 107 denotes a cleaning device, 108, 109, 110, 111, and 112 denote rollers, 113 denotes a secondary transfer roll, and 114 denotes a recording medium.

  In the tandem machine shown in FIG. 3, four image forming units 100Y, 100M, 100C, and 100K are arranged at constant intervals in this order along the rotation direction (the direction of arrow A in the figure) on the outer peripheral surface side of the intermediate transfer belt 106. The tandem machines are arranged in parallel with each other.

  The four image forming units 100Y, 100M, 100C, and 100K are configured in the same manner except that the colors of the toner images to be formed are different. The image forming unit 100Y will be described as an example. The image forming unit 100Y includes a contact-type charging along the outer peripheral surface of the photoconductor 101 in addition to the photoconductor 101 disposed in contact with the outer peripheral surface of the intermediate transfer belt 106. The apparatus 102, the developing device 104, and the cleaning device 107 are configured in this order along the rotation direction of the photosensitive member 101.

Here, the yellow toner image is formed as follows. First, after charging the outer peripheral surface of the photoconductor 101 by the charging device 102, the outer peripheral surface of the photoconductor 101 charged by the exposure device 103 is exposed to form an electrostatic latent image. To develop a yellow toner image.
The yellow toner image is charged at a contact portion (primary transfer portion) between the image forming unit 100Y and the intermediate transfer belt 106 via the intermediate transfer belt 106, and a charger 105 disposed so as to face the photoreceptor 101. Is transferred onto the outer peripheral surface of the intermediate transfer belt 106. The toner remaining on the outer peripheral surface of the photoconductor 101 after the yellow toner image is transferred is cleaned by the cleaning device 107 to prepare for the formation of the next toner image.

  In forming a full-color image, the same process is performed in the other image forming units 100M, 100C, and 100K, and the toner images of the respective colors are sequentially formed on the outer peripheral surface of the intermediate transfer belt 106 so as to correspond to the original image information. By superimposing, a full-color toner image is formed. When forming a black and white image, only the image forming unit 100K forms a toner image and transfers it to the outer peripheral surface of the intermediate transfer belt 106.

  On the other hand, the intermediate transfer belt 106 is stretched by five rollers 108 to 112 including a driving roller disposed in contact with the inner peripheral surface of the intermediate transfer belt 106. Circulation drive at equal speed is possible. Of the five rollers 108 to 112, the roller 111 is disposed opposite to the secondary transfer roll 113 via the intermediate transfer belt 106 so as to constitute a secondary transfer portion. Here, at the time of image formation, a recording medium 114 conveyed by a conveying means (not shown) is inserted in the direction of arrow B in the drawing at the contact portion between the outer peripheral surface of the intermediate transfer belt 106 and the secondary transfer roll 113. The

  Here, the full-color toner image formed on the outer peripheral surface of the intermediate transfer belt 106 described above is transferred to the surface of the recording medium 114 at the secondary transfer portion. The recording medium 114 onto which the full-color toner image has been transferred is further conveyed in the direction of arrow B to the unillustrated fixing device, where it is fixed to form a full-color image. It is discharged outside.

  On the other hand, in a conventional image forming apparatus using electrophotography, a cleaning blade method is known as a method for removing toner remaining on the surface of a photosensitive member (electrostatic latent image carrier) after transferring a toner image. ing. In this method, the cleaning blade is formed into a plate shape with a rubber material such as urethane rubber, and the edge of the cleaning blade is brought into physical contact with the surface of the rotating photoconductor with a predetermined pressing force, so that the residual toner on the photoconductor Is to be removed. Since this cleaning blade system is very simple in construction, it is also frequently used in the tandem machine as described above.

However, in a tandem type image forming apparatus that employs a cleaning blade method for cleaning a photosensitive member, not only a color image using two or more colors but also a monochrome image or the like by switching an image forming mode. A monochrome image is also formed. In this case, there is a problem that the formation of a single-color image leads to a high-frequency noise trouble due to the generation of noise (squeal) due to the vibration of the cleaning blade, and the life of the image forming unit is shortened due to an increase in the amount of wear of the photosensitive member. .
This is because when a single color image is formed, toner is not supplied from the developing device to the surface of the photoreceptor of the image forming unit that does not form a toner image, and between the photoreceptor and the cleaning blade in contact with the photoreceptor. This is because the toner present in the toner is depleted and the frictional force increases. From such a phenomenon, it can be said that the toner present between the cleaning blade and the photoconductor also functions as a lubricant that suppresses an increase in frictional force between the two.

  A method for solving such a problem that occurs at the time of monochromatic image formation, roughly speaking, adopting a retract mechanism, or a method for forcibly forming a toner image on a photoconductor even in an image forming unit that does not contribute to image formation There is.

  As a technology that employs a retract mechanism, a mechanism in which an image forming unit including a photoreceptor is pressed / retracted (see Patent Document 1), and a mechanism in which an intermediate transfer belt is pressed / retracted (see Patent Documents 2 to 6). Has been proposed. In these techniques, since the intermediate transfer belt and the photosensitive member are physically separated at the time of creating a monochrome image, it is possible to extend the life of the photosensitive member that does not perform image formation.

Further, even in an image forming unit that does not contribute to image formation, as a technique for forcibly forming a toner image on a photoconductor, a toner is forcibly supplied from the developing device to the surface of the photoconductor, There is a technique for preventing the toner between the photoconductors to be depleted (for example, Patent Document 7). Also in this technique, as a result, the life of the photoconductor can be extended and the noise of the cleaning blade can be suppressed.
Japanese Patent Laid-Open No. 10-186774 JP-A-3-2881 JP-A-6-258914 Japanese Patent Laid-Open No. 9-292753 JP-A-10-142932 Japanese Patent Laid-Open No. 10-319664 JP 2001-356642 A

However, the retract mechanism that physically separates the intermediate transfer belt and the photosensitive member when creating a monochrome image has a complicated configuration. This leads to an increase in size and cost of the tandem machine. Furthermore, the operation of physically separating the intermediate transfer belt and the photosensitive member has a problem that it is difficult to correct color misregistration and to set transfer parameters.
In addition, a technique for forcibly forming a toner image on a photoreceptor even in an image forming unit that does not contribute to image formation has a problem that toner is wasted for purposes other than image formation. Therefore, as a result, toner replenishment / toner cartridge replacement is required at an early stage.

An object of the present invention is to solve the above problems. That is, according to the present invention, when a monochromatic image is formed in a tandem type image forming apparatus, noise due to an increase in frictional force between the photoconductor and the cleaning blade and shortening of the life of the photoconductor can be prevented. It is an object of the present invention to provide an image forming method capable of suppressing waste of toner used for image formation.
Further, the present invention can prevent noise caused by an increase in frictional force between the photoconductor and the cleaning blade and shorten the life of the photoconductor when forming a monochromatic image in a tandem type image forming apparatus. It is an object of the present invention to provide an image forming apparatus having a simpler configuration than that of a conventional tandem type image forming apparatus provided with a retract mechanism for suppressing waste of toner used for image formation.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1>
Two or more image forming units, and an intermediate transfer member in which the two or more image forming units are arranged on the outer peripheral surface side in the rotation direction,
An electrostatic latent image carrier in which the image forming unit is in contact with the outer peripheral surface of the intermediate transfer member to form a primary transfer portion; and an electrostatic latent image formed on the surface of the electrostatic latent image carrier. Developing means for forming a toner image by developing the toner image, and cleaning means comprising at least a cleaning blade for cleaning the surface of the latent electrostatic image bearing member after the toner image is primarily transferred to the outer peripheral surface of the intermediate transfer member; Including
The toner is formed on the outer peripheral surface of the intermediate transfer member between the image forming unit arranged on the most downstream side in the rotation direction of the intermediate transfer member and the image forming unit arranged on the most upstream side in the rotation direction of the intermediate transfer member. In an image forming method for forming a monochromatic image using an image forming apparatus provided with a secondary transfer portion for transferring an image to a recording medium,
When the formation of the monochromatic image is performed at least through a process of forming a toner image only by any one of the two or more image forming units.
In the image forming method, the lubricating toner is supplied to the surface of the electrostatic latent image carrier of all the image forming units other than any one of the image forming units.

<2>
The image forming method according to <1>, wherein the lubricating toner is waste toner.

<3>
An image forming apparatus that forms the monochromatic image using the image forming method according to <1> or <2>.
When supplying the monochromatic image, toner supply for supplying the lubricating toner to the surface of the electrostatic latent image carrier of all the image forming units other than the one of the image forming units via the outer peripheral surface of the intermediate transfer member An image forming apparatus comprising the means.

<4>
The image forming apparatus according to <3>, wherein any one of the image forming units is an image forming unit arranged on the most downstream side in the rotation direction of the intermediate transfer member.

<5>
Residual on the outer peripheral surface of the intermediate transfer member after the secondary transfer on the outer peripheral surface of the intermediate transfer member between the secondary transfer portion and the image forming unit disposed on the most upstream side in the rotation direction of the intermediate transfer member. The image forming apparatus according to <3> or <4>, further comprising a cleaning device that cleans and collects and accumulates toner to be collected.
The image forming apparatus is characterized in that the lubricating toner is supplied from the cleaning device.

  As described above, according to the present invention, when a monochromatic image is formed in a tandem type image forming apparatus, (1) noise caused by an increase in frictional force between the photosensitive member and the cleaning blade, An image forming method capable of preventing the life of the toner from being shortened and suppressing waste of toner used for image formation, and (2) noise caused by an increase in frictional force between the photosensitive member and the cleaning blade, and the life of the photosensitive member. It is possible to provide an image forming apparatus that can prevent the shortening of life and has a simpler configuration than a conventional tandem type image forming apparatus that includes a retract mechanism that suppresses waste of toner used for image formation.

(Image forming method)
The image forming method of the present invention includes two or more image forming units, and an intermediate transfer member in which the two or more image forming units are arranged on the outer peripheral surface side in the rotation direction. Are formed on the surface of the electrostatic latent image carrier, and an electrostatic latent image carrier (hereinafter also referred to as “photosensitive member”) that forms a primary transfer portion in contact with the outer peripheral surface of the intermediate transfer member. Developing means for developing the electrostatic latent image with a developer to form a toner image, and cleaning the surface of the electrostatic latent image carrier after the toner image is primarily transferred to the outer peripheral surface of the intermediate transfer member. An image forming unit disposed at the most downstream side in the rotation direction of the intermediate transfer member, and an image forming unit disposed at the most upstream side in the rotation direction of the intermediate transfer member. Intermediate transfer body in between In the image forming method of forming a single color image using an image forming apparatus provided with a secondary transfer portion for transferring the toner image to a recording medium on a peripheral surface, the formation of the single color image is performed by the two or more images. The electrostatic latent image carrier of all image forming units other than any one of the image forming units when the toner image is formed by at least one of the image forming units. Lubricating toner is supplied to the surface.

The image forming apparatus used in the image forming method of the present invention is a conventional tandem type image forming unit in that the image forming unit is a so-called tandem type image forming apparatus provided with a cleaning blade that causes noise during monochromatic image formation. The image forming apparatus has the same configuration.
The image forming apparatus has two image forming modes, an image forming mode for forming a monochrome image (for example, a black and white image) and an image forming mode for forming a color image. A color image can be formed.

Here, the formation of a single color image is performed through at least a process of forming a toner image by only one of the two or more image forming units. Normally, the toner image formed by the image forming unit is primarily transferred from the image forming unit to the outer peripheral surface of the intermediate transfer member at the primary transfer portion, and further, the toner image is removed from the intermediate transfer member by the secondary transfer portion. Secondary transfer from the peripheral surface to the surface of the recording medium is performed by fixing on the recording medium.
Further, the color image is formed by sequentially superimposing the respective color toner images formed by the respective image forming units on the outer peripheral surface of the intermediate transfer body so as to coincide with the original document image, and performing primary transfer. The color toner image is secondarily transferred onto the recording medium at the secondary transfer portion and then fixed on the recording medium.

  Here, in the formation of a single color image, in an image forming unit for forming a toner image (hereinafter sometimes referred to as “monochromatic image forming unit”), the surface of the photoreceptor is exposed from a developing unit for image formation. Since the supplied toner (image forming toner) is present, sufficient lubricity between the photoconductor and the cleaning blade is ensured, and noise is generated due to increased frictional force, and photosensitivity due to photoconductor wear. It is possible to prevent shortening of the body life.

  On the other hand, when forming a single color image, toner is supplied from the developing means to the surface of the photoreceptor of an image forming unit that does not form a toner image (hereinafter sometimes referred to as “non-monochromatic image forming unit”) for image formation. Therefore, in this state, sufficient lubricity between the photoconductor and the cleaning blade cannot be secured, the frictional force increases, noise is generated, and photoconductor wear is promoted, shortening its life. Resulting in. However, in the image forming method of the present invention, since the lubricating toner is supplied to the surface of the photoreceptor of the non-monochromatic image forming unit, such a problem can be prevented.

Here, the “lubricating toner” means a toner other than the image forming toner that is directly supplied from the developing means provided in the image forming unit to the surface of the photoconductor. Means a toner used mainly for securing lubricity between the photosensitive member of the non-monochromatic image forming unit and the cleaning blade.
Although details of the supply source of the lubricating toner in the image forming apparatus will be described later, it is particularly preferable to use waste toner collected by cleaning the surface of the photosensitive member and the outer peripheral surface of the intermediate transfer member as the lubricating toner. . Also, as a toner for lubrication, it cannot be used for image formation, such as a defective toner at the time of toner production or an old type toner that can no longer be used for the current image forming apparatus, and there is not much use other than disposal. Such toner can also be used.

  Therefore, the image forming method of the present invention can prevent noise caused by an increase in the frictional force between the photoconductor and the cleaning blade and shorten the life of the photoconductor, and can suppress waste of toner used for image formation. Therefore, at the time of monochromatic image formation, it is not necessary to use the image forming toner incorporated in the developing means in order to ensure lubricity between the photoreceptor and the cleaning blade of the non-monochromatic image forming unit. There is no need for toner replenishment / toner cartridge replacement as in the past.

(Image forming device)
Next, an image forming apparatus using the image forming method of the present invention will be described.
The image forming apparatus of the present invention is an image forming apparatus that forms a monochromatic image using the image forming method of the present invention, and is formed on the surface of the photoreceptor of a non-monochromatic image forming unit when forming a monochromatic image. It is characterized by comprising toner supply means for supplying lubricating toner via the outer peripheral surface of the transfer body.
Therefore, the image forming apparatus of the present invention can prevent noise caused by an increase in frictional force between the photosensitive member and the cleaning blade and shorten the life of the photosensitive member when forming a monochromatic image, and can also be used for image formation. Waste of toner to be used can also be suppressed. In addition, when forming a monochrome image, it has toner supply means for supplying lubricating toner to the surface of the photoreceptor of the non-monochromatic image forming unit via an intermediate transfer member that is in contact with the photoreceptor surface. There is no need to provide a retract mechanism that separates the photosensitive member of the unit from the intermediate transfer member, and the configuration is simple.

  The above-described “toner supply means” is a function for supplying lubricating toner to the surface of the photoreceptor of the non-monochromatic image forming unit via the outer peripheral surface of the intermediate transfer body (hereinafter referred to as “lubricating toner”). It may be referred to as a “supply function”). The configuration of the toner supply means is not particularly limited as long as the toner supply function for lubrication can be exhibited. In the present invention, basically, an existing transfer medium including an intermediate transfer member provided in a general tandem type image forming apparatus having two or more image forming units each provided with a cleaning blade as a photoconductor cleaning means is provided. The members and devices can be used almost as they are or with some modifications as required.

In this case, the toner supply means can perform the toner supply function for lubrication by using a hardware part composed of a combination of two or more of these existing members and devices and a hardware part composed of the plurality of members and devices. And a software part (control means) integrated and controlled.
Here, as the software part, an existing control circuit can be replaced with a new one or an existing program can be rewritten so that the supply of the lubricating toner can be appropriately performed according to the situation. In this case, the timing and amount of supply of the lubricating toner affect the lubrication state between the photosensitive member and the cleaning blade, such as the image formation pattern, the total number of monochromatic images formed, the temperature and humidity, and the like. Various factors can be databased and determined accordingly.
It should be noted that semi-automatic / manual control may be used, such as when a noise (squeal) increases during monochromatic image formation, a person who has noticed this presses a button to start supplying lubricant toner.

  Therefore, the image forming apparatus of the present invention has an advantage that the hardware elements of the existing tandem type image forming apparatus can be used almost as they are except for changing software elements such as a control circuit and a program. Of course, if necessary, a new member / device may be provided in the existing tandem type image forming apparatus in order to achieve the above-described function.

For example, a cleaning device for cleaning the outer peripheral surface of the intermediate transfer member after the secondary transfer is generally disposed on the outer peripheral surface side of the intermediate transfer member of the tandem type image forming apparatus. For this reason, as a hardware portion of the toner supply means, in addition to the intermediate transfer member, this cleaning device can also be used.
Specifically, the image forming apparatus according to the present invention performs secondary transfer on the outer peripheral surface side of the intermediate transfer member between the secondary transfer unit and the image forming unit disposed on the most upstream side in the rotation direction of the intermediate transfer member. When the toner remaining on the outer peripheral surface of the subsequent intermediate transfer body is equipped with a cleaning device that collects and collects and accumulates the toner, the surface of the non-monochromatic image forming unit passes through the intermediate transfer body when forming a single-color image. The supplied lubricating toner can be supplied from this cleaning device.

  Here, the cleaning device that can be used as the toner supply means has a function of accumulating the toner (waste toner) collected by the cleaning in the cleaning device and the toner remaining on the outer peripheral surface of the intermediate transfer member on the cleaning device side. It is necessary to have a function of not only collecting, but also supplying waste toner once collected and accumulated to the outer peripheral surface of the intermediate transfer member.

  As such a cleaning device, for example, a cleaning device of a type that collects toner by an electrostatic method such as a conductive brush can be used. In this cleaning device, the toner is collected by utilizing the potential difference between the cleaning member such as a conductive brush and the intermediate transfer member. Therefore, the polarity is reversed between the cleaning member and the intermediate transfer member. This is because waste toner can be easily supplied from the cleaning device to the surface of the intermediate transfer member by applying the above voltage or reversing the potential gradient between the two.

  In this case, the timing for supplying the waste toner from the cleaning device to the surface of the intermediate transfer member and the supply amount of the waste toner can be easily controlled by controlling the voltage application time and the voltage value. Therefore, the control means controls the voltage applied between the cleaning member of the cleaning device and the intermediate transfer member so that the waste toner can be supplied from the cleaning device to the intermediate transfer member at a desired timing and supply amount. A control circuit / program that has been replaced / rewritten may be used.

In the case of a cleaning device that uses a brush-like cleaning member, regardless of the presence or absence of electrical conductivity, the waste toner once attached to the brush is intermediate transferred by centrifugal force with the brush rotating speed higher than that during cleaning. It is also possible to supply to the body surface.
In addition to the brush-like cleaning member as described above, if the cleaning device is provided with a cleaning blade on the downstream side in the rotation direction of the intermediate transfer member with respect to the cleaning member, supply of lubricating toner Sometimes it is necessary to separate the cleaning blade from the intermediate transfer member. If the cleaning blade remains in contact with the surface of the intermediate transfer member, waste toner supplied to the surface of the intermediate transfer member is collected by the cleaning blade upstream of the cleaning blade in the rotation direction of the intermediate transfer member. It is.

  As described above, as the supply source of the lubricating toner, a cleaning device for the intermediate transfer member can be used. In this case, there is an advantage that the waste toner can be reused. Of course, the supply source of the lubricating toner is not limited to the cleaning device for the intermediate transfer member. For example, for the purpose of supplying lubricating toner only to the outer peripheral surface of the intermediate transfer member between the cleaning device for the intermediate transfer member and the image forming unit disposed on the most upstream side in the rotation direction of the intermediate transfer member. You may provide the apparatus of.

  If the amount of waste toner in the cleaning device is insufficient, spare toner may be filled in the cleaning device in advance. In addition, as such replenishment toner and toner when using a dedicated device, for example, waste toner collected from the image forming unit at the time of maintenance, defective products at the time of toner production, and current image forming devices can be handled. Toners that have little use other than disposal, such as old toner that has been lost, can be used as appropriate.

  On the other hand, the transfer of the toner image from the photosensitive member surface to the intermediate transfer member surface also utilizes the potential difference between the two, as described above. For this reason, the waste toner supplied from the cleaning device to the surface of the intermediate transfer member can be controlled from the surface of the intermediate transfer member by controlling the voltage applied between the photosensitive member and the intermediate transfer member in the same manner as described above. Waste toner can be supplied to the surface as lubricating toner. In this case, the control of the supply timing of waste toner from the surface of the intermediate transfer member to the surface of the photoreceptor and the control means are the same as described above.

The monochromatic image forming unit may be any of the image forming units arranged along the rotation direction of the intermediate transfer member, but is an image forming unit arranged at the most downstream side in the rotation direction of the intermediate transfer member. It is particularly preferable for practical use.
In this case, all the non-monochromatic image forming units are arranged on the upstream side in the rotation direction of the intermediate transfer member with respect to the monochromatic image forming unit. For this reason, when forming a monochrome image, the primary transfer of the toner image formed by the monochrome image forming unit located on the most downstream side in the rotation direction of the intermediate transfer member to the surface of the intermediate transfer member and the monochrome image forming unit This is because the supply of the lubricating toner via the intermediate transfer member to the photosensitive member of the non-monochromatic image forming unit disposed upstream in the rotation direction of the intermediate transfer member can be performed simultaneously. Further, as a merit that the primary transfer and the supply of the toner for lubrication can be performed at the same time, a single drive source for driving the plurality of image forming units is sufficient, so that the configuration of the image forming apparatus can be simplified.

  On the other hand, when the monochromatic image forming unit and the non-monochromatic image forming unit are not in the arrangement relationship as described above with respect to the rotation direction of the intermediate transfer member, the single color image forming unit and the non-monochromatic image forming unit are more preferable than the monochromatic image forming unit with respect to the rotation direction of the intermediate transfer member Since the supply of the lubricating toner to the non-monochromatic image forming unit located on the downstream side needs to be sewed between the timings for forming the monochromatic image, the control may be complicated.

  The color of the toner image formed by the monochromatic image forming unit is generally black, but is not limited to this, and may be a color such as cyan. The intermediate transfer member is generally belt-shaped, but may be drum-shaped.

-Specific examples of image forming apparatus-
Next, embodiments of the image forming apparatus of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing an example of an image forming apparatus of the present invention, which shows a so-called tandem type digital color printer. FIG. 2 is an enlarged view of the main part of the image forming apparatus shown in FIG.
1 and 2, 1 is a main body, 10 is an image processing system, 11K, 11C, 11M, and 11Y are image forming units, 12 is a photosensitive member, 13 is a charging roll, 14 is a developing device, 14a is a developing roll, 15 Is a primary transfer roll, 16 is a cleaning device, 20 is a transfer unit, 21 is an intermediate transfer belt, 22 is a drive roll, 23 is a tension roll, 24 is a backup roll, 25 is a cleaning device, 25a is a cleaning brush, and 25b is a cleaning blade. , 29 is a fixing unit, 30 is a ROS (Raster Output Scanner), 31 is a polygon mirror 32 is a frame, 33 is a window, 40 is a sheet conveying system, 41 is a sheet feeding device, 42 is a nudger roll, 43 is a feed roll, 44 is a conveyance path, 45 is a resist roll, 46 is a secondary transfer roller Le, the discharge roller 47, 48 is a discharge tray, duplex transport unit 49, 50 denotes an IPS (Image Processing System).

  The image forming apparatus shown in FIG. 1 includes an image processing system 10 that forms an image corresponding to gradation data of each color, a sheet conveyance system 40 that conveys recording paper (sheet), such as a personal computer or an image reader. An IPS (Image Processing System) 50, which is an image processing system that is connected to a device or the like and performs predetermined image processing on received image data, is provided.

The image processing system 10 is arranged in parallel at a certain interval in the horizontal direction along the rotation direction of the intermediate transfer belt 21, and is arranged in yellow (Y), magenta (M), cyan (C), black (K 4) image forming units 11Y, 11M, 11C, and 11K, and transfer units that multiplex-transfer toner images of respective colors formed on the photoreceptors 12 of the image forming units 11Y, 11M, 11C, and 11K onto the intermediate transfer belt 21. 20 includes a ROS (Raster Output Scanner) 30 which is an optical system unit that irradiates the image forming units 11Y, 11M, 11C, and 11K with laser light.
Further, the main body 1 is provided with a fixing device 29 for fixing the image on the recording paper (sheet) secondarily transferred by the transfer unit 20 to the recording paper using heat and pressure. Further, toner cartridges 19Y, 19M, 19C, and 19K are provided for supplying toner of each color to the image forming units 11Y, 11M, 11C, and 11K.

  The transfer unit 20 includes a drive roll 22 that drives an intermediate transfer belt 21 that is an intermediate transfer member, a tension roll 23 that applies a constant tension to the intermediate transfer belt 21, and a secondary transfer of the superimposed toner images of each color onto a recording sheet. For this purpose, a backup roll 24 and a cleaning device 25 for removing residual toner and the like existing on the intermediate transfer belt 21 are provided. The intermediate transfer belt 21 is wound around the drive roll 22, the tension roll 23, and the backup roll 24 with a constant tension, and is driven to rotate by a dedicated drive motor (not shown) having excellent constant speed. The drive roll 22 is circulated at a predetermined speed in the direction of the arrow.

As the intermediate transfer belt 21, for example, a belt whose resistance is adjusted with a belt material (rubber or resin) that does not cause charge-up is used. The cleaning device 25 includes a cleaning brush 25a and a cleaning blade 25b that are sequentially arranged along the rotation direction of the intermediate transfer belt 21. From the outer peripheral surface of the intermediate transfer belt 21 after the secondary transfer of the toner image is completed. Residual toner is removed and residual toner is collected and accumulated.
The cleaning brush 25a utilizes electrostatic force due to a potential difference generated by a voltage applied between the cleaning brush 25a and the outer peripheral surface of the intermediate transfer belt 21, and mechanical sliding due to rotation of the cleaning brush 25a. The residual toner is collected.

  The ROS 30 is a polygon mirror that deflects and scans laser light (LB-Y, LB-M, LB-C, LB-K) emitted from the laser diode (LD) in addition to a laser diode (LD) and a modulator (not shown). 31 is provided. In the example shown in FIG. 1, since the ROS 30 is provided below the image forming units 11Y, 11M, 11C, and 11K, there is a risk of contamination due to dropping of toner or the like. Therefore, the ROS 30 is provided with a rectangular parallelepiped frame 32 for sealing each constituent member, and a glass window 33 through which laser light (LB-Y, LB-M, LB-C, LB-K) passes. Is provided above the frame 32 to enhance the shielding effect together with the scanning exposure.

The sheet conveyance system 40 is loaded with a recording paper (sheet) on which an image is recorded and fed, a nudger roll 42 that picks up and feeds the recording paper from the paper feeding device 41, and is fed from the nudger roll 42. A feed roll 43 that separates and conveys the recording sheets that have been separated one by one and a conveyance path 44 that conveys the recording sheets separated one by one by the feed roll 43 toward the image transfer unit are provided.
Also, a registration roll 45 that transports the recording paper transported through the transport path 44 in a timely manner toward the secondary transfer position (a contact portion between the backup roll and the secondary transfer roll), and secondary transfer. A secondary transfer roll 46 is provided which is provided at a position and presses the backup roll 24 to secondary-transfer the image onto the recording paper. Further, a discharge roll 47 for discharging the recording paper on which the toner image is fixed by the fixing device 29 to the outside of the main body 1 and a discharge tray 48 for stacking the recording paper discharged by the discharge roll 47 are provided. In addition, a double-sided conveyance unit 49 is provided that enables double-sided recording by inverting the recording paper fixed by the fixing device 29.

  Next, the image forming units 11Y, 11M, 11C, and 11K in the image process system 10 will be described in detail with reference mainly to FIG. FIG. 2 shows a yellow (Y) image forming unit 11Y, a magenta (M) image forming unit 11M, a cyan (C) image forming unit 11C, a black (K) image forming unit 11K, and a transfer unit. It is shown.

  The image forming units 11Y, 11M, 11C, and 11K are charged by a photosensitive member 12 as an image carrier that carries a toner image, a charging roll (charger) 13 that charges the photosensitive member 12, and a charging roll 13, and ROS 30 (FIG. 2, a developing device 14 that develops an electrostatic latent image formed on the photosensitive member 12 by a developing roller 14 a by laser light (LB-Y, LB-M, LB-C, LB-K) from a not-shown image. A primary transfer roll 15 provided on the intermediate transfer belt 21 so as to be opposed to the photosensitive member 12 and transferring the toner image developed on the photosensitive member 12 onto the intermediate transfer belt 21, and remains on the photosensitive member 12 after transfer. In order to remove the residual toner, a cleaning device 16 including a cleaning blade disposed so as to come into contact with the photosensitive member is provided.

  In the present embodiment, the photosensitive member 12, the charging roll 13, and the cleaning device 16 of each of the image forming units 11Y, 11M, 11C, and 11K are integrated to form a process cartridge so that the main body 1 of the image forming apparatus can be used. Only the process cartridge can be removed, and only the process cartridge can be attached to the main body 1, and can be replaced by the user. Each of these process cartridges is equipped with a non-volatile memory unit (not shown).

In this nonvolatile memory unit, for example, when the process cartridge is mounted in a predetermined image forming unit 11Y, 11M, 11C, or 11K such as the rotational speed of the photosensitive member 12, the high voltage application time, and the number of prints. Each cartridge usage history information is stored. These process cartridges can be used by being replaced between the image forming units 11Y, 11M, 11C, and 11K.
Since each process cartridge is equipped with a non-volatile memory unit, even when the process cartridge is used in different image forming units, the process cartridge itself stores its own usage history information. can do. As a result, for example, the correct lifetime can be determined for each process cartridge.

  Next, a full color image forming operation of the image forming apparatus shown in FIG. 1 will be described. A color material reflected light image of a document read by a document reading device (not shown) and color material image data formed by a personal computer (not shown) are, for example, R (red), G (green), and B (blue). Each 8-bit reflectance data is input to the IPS 50. In the IPS 50, the input reflectance data is subjected to predetermined image processing such as various image editing such as shading correction, position shift correction, lightness / color space conversion, gamma correction, frame deletion, color editing, and moving editing. Is done. The image data that has been subjected to image processing is converted into color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K), and is output to the ROS 30.

In the ROS 30, laser light (LB-Y, LB-M, LB-C, LB-K) emitted from a laser diode (LD) (not shown) according to the input color material gradation data, The light is emitted to the polygon mirror 31 through an f-θ lens (not shown). In the polygon mirror 31, the incident laser light is modulated in accordance with gradation data of each color, deflected and scanned, and image forming units 11Y, 11M, 11C, and 11K through an imaging lens (not shown) and a plurality of mirrors. The photoconductor 12 is irradiated.
On the photoreceptor 12 of the image forming units 11Y, 11M, 11C, and 11K, the charged surface is subjected to scanning exposure to form an electrostatic latent image. The formed electrostatic latent image is supplied with a developer from the developing unit 14, so that each of the image forming units 11 </ b> Y, 11 </ b> M, 11 </ b> C, and 11 </ b> K has yellow (Y), magenta (M), and cyan (C ) And black (K) toner images.

The toner images of the respective colors formed on the photoconductors 12 of the image forming units 11Y, 11M, 11C, and 11K are multiple-transferred onto the intermediate transfer belt 21 so as to coincide with the original document image. Here, the transfer of the toner image from the surface of the photosensitive member 12 to the outer peripheral surface of the intermediate transfer belt 21 is performed between the photosensitive member 12 and the primary transfer roll 15 disposed opposite to the photosensitive member 12 with the intermediate transfer belt 21 interposed therebetween. Is controlled so that the toner charged to one polarity can be electrostatically moved (transferred) from the surface of the photoreceptor 12 to the outer peripheral surface of the intermediate transfer belt 21.
Each of the image forming units is arranged in the order of the image forming units 11Y, 11M, 11C, and 11K from the upstream side to the downstream side along the rotation direction of the intermediate transfer belt 21, and therefore the outer periphery of the intermediate transfer belt 21 The toner images of the respective colors are sequentially transferred onto the surface in the order of yellow, magenta, cyan, and black.

On the other hand, during the single color image forming operation, the image data subjected to the image processing is converted into black (K) single color material gradation data and output to the ROS 30. On the basis of the same principle as that for full-color image formation, a black (K) single-color toner image is developed only on the photoreceptor 12 of the image forming unit 11K and is primarily transferred to the intermediate transfer belt 21.
Here, since the developer is not supplied from the developing unit 14 to the photoconductor 12 of the image forming units 11Y, 11M, and 11C that are not involved in the formation of a single color image, the cleaning device 25 is interposed via the intermediate transfer belt 21. The operation of supplying the waste toner collected and accumulated therein as the lubricating toner to the surface of the photoreceptor 12 of the image forming units 11Y, 11M, and 11C is also performed.

  First, waste toner collected and accumulated in the cleaning device 25 is transferred (supplied) to the outer peripheral surface of the intermediate transfer belt 21 using the cleaning brush 25a. The supply of waste toner to the outer peripheral surface of the intermediate transfer belt 21 controls the magnitude and polarity of the voltage applied to the cleaning brush 25a so that the waste toner is transferred from the cleaning brush 25a side to the outer peripheral surface of the intermediate transfer belt 21. In addition, the rotational speed of the cleaning brush 25a is made larger than that at the time of cleaning, and a centrifugal force is applied to transfer the waste toner adhering to the brush fibers of the cleaning brush 25a to the outer peripheral surface of the intermediate transfer belt 21. .

  During this operation, the waste once supplied to the outer peripheral surface of the intermediate transfer belt 21 by the cleaning blade 25b positioned downstream of the cleaning brush 25a in the rotation direction of the intermediate transfer belt 21. The tip of the cleaning blade 25b is kept away from the outer peripheral surface of the intermediate transfer belt 21 so that the toner is not collected.

Next, the waste toner supplied from the cleaning device 25 to the outer peripheral surface of the intermediate transfer belt 21 is transferred (reversely transferred) to the surface of the photoreceptor 12 of the image forming units 11Y, 11M, and 11C. In the reverse transfer, a voltage having a reverse polarity is applied between the photosensitive member 12 and the outer peripheral surface of the intermediate transfer belt 21 or the magnitude of the applied voltage is changed between the photosensitive member 12 and the primary transfer member. This can be done by reversing the slope of the potential gradient.
A series of operations for supplying waste toner as a lubricating toner from the cleaning device 25 to the surface of the photoconductor 12 via the intermediate transfer belt 21 may be a system that is always performed at the time of monochromatic image formation. An intermittent method (hereinafter, sometimes referred to as “intermittent supply method”) may be used.
In the latter case, for example, the frictional force between the surface of the photosensitive member 12 of the three image forming units 11Y, 11M, and 11C and the cleaning blade of the cleaning device 16 increases from the start of monochromatic image formation to a predetermined level or more. This time may be estimated from the image formation pattern, the number of continuous prints of a single color image, the temperature and humidity environment, and the like, and based on this, control may be performed to automatically supply the lubricating toner.
In addition, when noise (squeal) starts to be heard, a manual mode may be provided in which a button for performing a lubricating toner supply operation can be pushed and manually supplied.

Further, it may be performed simultaneously on all of the three image forming units 11Y, 11M, and 11C. However, in order to reliably supply waste toner to the photoconductor 12 of each image forming unit, one time is shifted. It is preferable that the method is sequentially performed every time (hereinafter, sometimes referred to as “time difference supply method”).
When the latter operation is performed intermittently, for example, when the time of one cycle for maintaining the potential difference between the photoreceptor 12 and the outer peripheral surface of the intermediate transfer belt 21 so that reverse transfer can be performed is 12 seconds. , 12 seconds are assigned to each of the three image forming units 11Y, 11M, and 11C every 4 seconds, and reverse transfer is sequentially performed from the upstream side in the rotation direction of the intermediate transfer belt 21 to the downstream image forming unit every 4 seconds. Can do.

  As a supply source of the lubricating toner, instead of the cleaning device 25, a dedicated toner supply device is disposed on the outer peripheral surface side of the intermediate transfer belt 21 between the cleaning device 25 and the photoconductor 12 of the image forming unit 11Y. May be.

Example 1
-Image forming device-
A tandem type image forming apparatus (Fuji Xerox Co., Ltd., Docu Center a450) having the same configuration as the image forming apparatus shown in FIG. 1 was used, and negatively charged toner was used as the toner contained in the developer. However, this apparatus is modified so that the toner for lubrication can be supplied from the cleaning device 25 to each of the image forming units of yellow, magenta, and cyan during monochrome image formation.
Here, the supply of the lubricating toner (waste toner) is an intermittent supply method in which the cumulative number of prints is performed every predetermined number, and the supply of the lubricating toner (waste toner) to the three image forming units is a time difference supply method. The timing of intermittent supply and the timing of time difference supply can be set so as to be implemented under desired conditions.
The cleaning device 25 is provided with a retracting mechanism in which the tip of the cleaning blade 25b is separated from the outer peripheral surface of the intermediate transfer belt 21 in the lubrication toner (waste toner) supply mode.
In addition, the operating conditions of the cleaning device 25 and the reverse transfer conditions in the primary transfer unit during the supply mode of the lubricating toner (waste toner) were set as follows.

-Operating conditions of the cleaning device 25-
The potential difference between the outer peripheral surface of the intermediate transfer belt 21 and the cleaning brush 25a in the supply mode of the lubricating toner (waste toner) was set to -800V (the potential of the outer peripheral surface of the intermediate transfer belt 21: 0V, the potential of the cleaning brush 25a: -800V).
During cleaning (and when the lubricating toner (waste toner) is not supplied), the potential difference between the outer peripheral surface of the intermediate transfer belt 21 and the cleaning brush 25a is set to 1 kV (on the outer peripheral surface of the intermediate transfer belt 21). Potential: 0 V, cleaning brush 25 a potential: 1 kV).

-Reverse transfer conditions in the primary transfer section-
In the lubrication toner (waste toner) supply mode, the potential difference between the primary transfer roll 15 and the photoreceptor 12 was set to 900 V (the potential of the primary transfer roll 15: −1.5 kV, the potential of the photoreceptor 12: -600V).
Note that the potential difference between the primary transfer roll 15 and the photosensitive member 12 is set to −2.1 kV during cleaning (and including the case where lubricating toner (waste toner) is not supplied) (primary transfer roll 15). Potential: 1.5 kV, potential of photoconductor 12: -600 V).

-Image formation test-
Next, in an environment of 28 ° C. and 85%, a process speed is set to 52 mm / s, and a chart having a 1% image with respect to a size of image density A4 (210 × 297 mm) is used as a copy original, and A4 paper. (Fuji Xerox Office Supply Co., Ltd., C2) was used to print 500 black and white images continuously. At this time, the friction between the photosensitive member 12 of the image forming unit and the cleaning blade not involved in the formation of the black and white image. The noise (squeal) caused by the increased force was evaluated.
The supply condition of the lubricating toner during continuous printing of black and white images is as follows: the intermittent supply timing is 50 sheets, the intermittent supply length of one cycle is 12 seconds, and the yellow, magenta, and cyan image forming units. The photosensitive member 12 was set so as to be supplied with a time difference every 4 seconds in order from the image forming unit upstream in the rotation direction of the intermediate transfer belt. Note that approximately three prints are performed during one cycle of intermittent supply.
The results are shown in Table 1.

(Example 2)
Using the same apparatus as in Example 1, the evaluation was performed under the same conditions as in Example 1 except that the intermittent supply timing was changed every 100 sheets. The results are shown in Table 1.

(Example 3)
Evaluation was performed under the same conditions as in Example 1 except that the temperature and humidity environment during black-and-white image formation was changed to 10 ° C. and 15% using the same apparatus as in Example 1. The results are shown in Table 1.

Example 4
The same apparatus as in Example 1 was used, except that the temperature and humidity environment during black-and-white image formation was changed to 10 ° C. and 15%, and the intermittent supply timing was changed every 100 sheets. The condition was evaluated. The results are shown in Table 1.

(Comparative Example 1)
The same as in Example 1 except that the device used in Example 1 before remodeling (the device that cannot supply the toner for lubrication from the cleaning device 25 to each image forming unit of yellow, magenta, and cyan) is used. Evaluation was performed under the conditions of The results are shown in Table 1.

-Noise evaluation-
Noise evaluation during continuous black-and-white image formation is based on whether or not abnormal noise caused by the vibration of the cleaning blade can be heard from a position approximately 1 m away from the apparatus in a room without a main sound source other than the image forming apparatus. The degree of sound was sensory evaluated. The evaluation criteria are as follows.
○: No abnormal noise caused by the vibration of the cleaning blade can be heard during printing of 500 sheets.
Δ: While 500 sheets were printed, abnormal noise due to the vibration of the cleaning blade was confirmed. However, the apparatus does not have a large difference from the normal operation sound during printing, and the abnormal noise cannot be determined unless it is consciously heard.
X: During 500 sheets printing, abnormal noise caused by the vibration of the cleaning blade was clearly confirmed.

1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. FIG. 2 is an enlarged view of a main part of the image forming apparatus shown in FIG. 1. It is a schematic diagram showing an example of a configuration of a conventional tandem type image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body 10 Image process system 11K, 11C, 11M, 11Y Image forming unit 12 Photoconductor 13 Charging roll 14 Developer 14a Developing roll 15 Primary transfer roll 16 Cleaning device 19K, 19C, 19M, 19Y Toner cartridge 20 Transfer unit 21 Intermediate transfer Belt 22 Drive roll 23 Tension roll 24 Backup roll 25 Cleaning device 25a Cleaning brush 25b Cleaning blade 29 Fixing device 30 ROS (Raster Output Scanner)
31 Polygon mirror 32 Frame 33 Window 40 Sheet transport system 41 Paper feed device 42 Nudger roll 43 Feed roll 44 Transport path 45 Registration roll 46 Secondary transfer roll 47 Discharge roll 48 Discharge tray 49 Double-sided transport unit 50 IPS (Image Processing System) )
100Y, 100M, 100C, 100K Image forming unit 101 Photoconductor 102 Charging device 103 Exposure device 104 Development device 105 Charging device 106 Intermediate transfer belt 107 Cleaning device 108, 109, 110, 111, 112 Roller 113 Secondary transfer roll 114 Recording medium

Claims (5)

Two or more image forming units, and an intermediate transfer member in which the two or more image forming units are arranged on the outer peripheral surface side in the rotation direction,
An electrostatic latent image carrier in which the image forming unit is in contact with the outer peripheral surface of the intermediate transfer member to form a primary transfer portion; and an electrostatic latent image formed on the surface of the electrostatic latent image carrier. Developing means for forming a toner image by developing the toner image, and cleaning means comprising at least a cleaning blade for cleaning the surface of the latent electrostatic image bearing member after the toner image is primarily transferred to the outer peripheral surface of the intermediate transfer member; Including
The toner is formed on the outer peripheral surface of the intermediate transfer member between the image forming unit arranged on the most downstream side in the rotation direction of the intermediate transfer member and the image forming unit arranged on the most upstream side in the rotation direction of the intermediate transfer member. In an image forming method for forming a monochromatic image using an image forming apparatus provided with a secondary transfer portion for transferring an image to a recording medium,
When the formation of the monochromatic image is performed at least through a process of forming a toner image only by any one of the two or more image forming units.
An image forming method comprising supplying a lubricating toner to the surface of an electrostatic latent image carrier of all image forming units other than any one of the image forming units.   The image forming method according to claim 1, wherein the lubricating toner is waste toner. An image forming apparatus that forms the monochromatic image using the image forming method according to claim 1,
When supplying the monochromatic image, toner supply for supplying the lubricating toner to the surface of the electrostatic latent image carrier of all the image forming units other than the one of the image forming units via the outer peripheral surface of the intermediate transfer member An image forming apparatus comprising: means.   The image forming apparatus according to claim 3, wherein the one image forming unit is an image forming unit disposed on the most downstream side in the rotation direction of the intermediate transfer member. Residual on the outer peripheral surface of the intermediate transfer member after the secondary transfer on the outer peripheral surface of the intermediate transfer member between the secondary transfer portion and the image forming unit disposed on the most upstream side in the rotation direction of the intermediate transfer member. The image forming apparatus according to claim 3, further comprising a cleaning device that cleans and collects and accumulates toner to be collected.
The image forming apparatus, wherein the lubricating toner is supplied from the cleaning device.

Images