JPH07117782B2 - Image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an electrophotographic image forming apparatus using a magnetic toner and a non-magnetic toner to form a two-color or multi-color image. In particular, the present invention relates to an image forming apparatus characterized by cleaning means for an image carrier repeatedly used.

Conventional Technology and Problems For example, in an image forming apparatus such as an electrophotographic copying apparatus,
The toner image formed on the surface of the electrophotographic photosensitive member is transferred to a transfer material such as paper to obtain a copy, but the photosensitive member is repeatedly imaged after removing the toner remaining on the surface by cleaning means having various forms. It is subjected to the forming process.

As a cleaning means of this kind, a structure using a cleaning blade made of an elastic material such as urethane rubber is generally used. Since such a structure is simple and small in size, and the residual toner removing function is excellent. It has been widely used from the past.

However, although such a cleaning blade has an excellent toner removing function, when a transfer paper is used as it is most often used as a transfer material, precipitates such as rosin and talc generated from the transfer paper are used. Alternatively, it is not sufficient to remove the corona products generated from the high-voltage member in the apparatus, and if such a substance adheres to the surface of the photoconductor, it causes image deletion under high humidity and significantly deteriorates the quality of the copy image. There was a problem.

Therefore, a magnet roller is provided as a cleaning means in order to remove the deposits on the photoconductor, a magnetic particle layer is formed on the roller, and the magnetic particles are rubbed on the surface of the photoconductor to remove the deposits. The one configured for removal has been proposed and is in actual use.

On the other hand, in recent years, for example, because the recorded image becomes clearer and the information is easier to understand, for example, the color of the format and the color of the calculated value or the value of the data are expressed in different colors, or output by CAD. It is desired to be identified by two colors or multiple colors such that a part of the drawing is output in another color, and toner of colors other than black has come to be often used.

Generally, color toners other than black are mainly non-magnetic toner at present. Therefore, when only this non-magnetic toner is used in a large amount, the surface of the magnetic particle layer on the magnet roller is covered with the non-magnetic toner. As a result, the non-magnetic toner may fall out of the container of the cleaning means, causing stains inside the machine and stains on the image.

OBJECT OF THE INVENTION An object of the present invention is to supply magnetic particles to a magnet roller portion of a cleaning means in an apparatus for forming an image using a magnetic toner and a non-magnetic toner, especially when the non-magnetic toner is used. , Magnetic toner and non-magnetic toner are mixed in the magnetic particle layer on the magnet roller to prevent the surface of the magnetic particle layer from being covered only with non-magnetic toner, and scattering of non-magnetic toner inside the machine and image contamination It is an object of the present invention to provide an image forming apparatus capable of preventing the above phenomenon and obtaining a high quality image.

Means for Solving Problems The above object is achieved by the image forming apparatus according to the present invention.
In summary, the present invention forms a latent image on an image carrier, visualizes the latent image by selectively developing it with a magnetic toner or a non-magnetic toner, and transfers the visible image to a transfer material. However, in an image forming apparatus in which the residual toner on the image bearing member is removed by a cleaning device so that the image bearing member is repeatedly used, when a non-magnetic toner is used during image formation, the cleaning device is magnetically charged. An image forming apparatus characterized in that it has means for supplying particles.

Embodiment Next, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic view showing an example of an electrophotographic apparatus capable of two-color recording which embodies the image forming apparatus according to the present invention. According to this embodiment, the drum-shaped image carrier, that is, the electrophotographic photosensitive drum 1 having a photoconductive layer such as amorphous silicon is rotatably supported in the direction of the arrow, and the image forming means is arranged around it. It Explaining further, a first charger 2, a first image exposing unit 3, a first developing unit 4, a second image exposing unit 6, and a second unit around the photosensitive drum 1.
The developing device 7, the transfer charging device 8 and the cleaning means 11 are provided. If necessary, a pre-exposure unit (not shown) may be provided between the cleaning unit 11 and the first charger.

Further, the first image exposure means 3 and the second image exposure means 6 emit a first semiconductor laser 12 that emits a first laser beam modulated by the first image signal and a second laser beam. The first and second laser beams are driven by the second semiconductor laser 13 and the motor 15 to polarize them, and the first image and the second image are transferred onto the photoconductor 1 via the imaging lens 16 and the folding mirror 17. Rotating polygon mirror 14 for raster scanning
Have and. Further, as will be described later, the first developing device 4
A second (second) charger 5 may be provided between the second image exposing unit 6 and the second image exposing unit 6.

Next, regarding the operation of the two-color electrophotographic apparatus having the above-mentioned configuration,
It will be described with reference to FIG. 3 and FIG.

The photoconductor drum 1 rotating in the direction of arrow A is provided with the first charger 2
Is uniformly charged to, for example, +460 V (Fig. 2 (a)). The first exposure means 3 forms a first latent image on the photoconductor 1 in which the surface potential of the exposed portion is, for example, + 110V (FIG. 2B). The first latent image is subjected to reversal development by applying a bias of an appropriate magnitude in the first developing device 4 having, for example, red toner (FIG. 2C).
At this time, the potential of the visible red toner image rises by about 100V due to the toner charge and becomes about + 200V.

Then, the second image signal is applied to the photoconductor 1 by the second exposure means 6, and a second latent image in which the surface potential of the exposed portion is +90 V is formed on the photoconductor 1 (second photo image). Figure (d)). At this time, as an alternative method, as described above, the second
After the charging device 5 is provided to visualize the first latent image, the photoreceptor 1
Recharging causes the first toner image potential to rise to + 420V, as shown in FIG. 3D, after which the second image exposure 6 is carried out, and the exposure portion potential becomes + 60V. It is also possible to attenuate (FIG. 3 (e)).

The second latent image formed in this manner is visualized by applying a bias of an appropriate magnitude in the second developing device 7 having black toner, for example. (FIG. 2 (e), FIG. 3 (f).
The color image is generally transferred onto the transfer material 9 by the transfer charger 8, separated from the photoconductor drum 1 by a separation charger (not shown), fixed by the fixing means 10, and then as a two-color print. It is discharged to the outside of the aircraft.

On the other hand, the photosensitive drum 1 is subjected to the next image forming process after the residual toner is removed by the cleaning device 11.

FIG. 4 shows an embodiment of the cleaning device 11.
In this embodiment, the cleaning device 11 has a container 20, and the container 20 has a cleaning blade 22 made of an elastic material such as urethane rubber and a magnet cleaning means 24. The magnetic cleaning means 24 comprises a magnetic particle layer on the outer peripheral surface, a magnetic roller 28 which can form a magnetic toner layer 26 in this embodiment, and a thickness of the magnetic toner layer 26 on the magnetic roller. And a layer thickness regulating member (30) having a predetermined thickness.

With the above configuration, the adhered matter such as the residual toner on the photosensitive drum 1 is rubbed against the magnetic toner layer 26 on the magnet roller, and is removed or the adhesion is weakened. Further, the photosensitive drum 1 is coated with the magnetic toner layer 26a by coming into contact with the magnetic toner layer 26,
Cleaning blade 22 with residual toner and residual deposits
Is removed from the surface of the photosensitive drum 1.

The residual toner and residual deposits thus removed are discharged to a collection container (not shown) by the transport screen 32.

When the non-magnetic toner is collected as the residual toner by the cleaning device 11 having the above-described configuration, the non-magnetic toner is physically or electrically adsorbed on the magnetic toner layer 26 on the magnet roller 28, and together with the magnetic toner. It is held on the magnet roller 28.

However, when a large amount of non-magnetic toner is used for image formation as compared with magnetic toner, for example, when a large number of red copies are continuously produced, a cleaning device is used.
The magnetic toner layer 26 on the magnet roller 28 of 11 is covered with the collected non-magnetic toner, and the inside of the apparatus may be contaminated due to scattering of the non-magnetic toner, dropping of the non-magnetic toner, and the like.

According to the present invention, in order to solve the above problems, when non-magnetic toner is used in image formation, the magnetic toner is forcibly supplied to the magnet roller 28 of the cleaning device 11.

That is, according to the present invention, when the non-magnetic toner, in this embodiment, the red toner is used for image formation,
Magnetic toner (black toner) is supplied to the magnet roller 28 of the cleaning device 11. To explain further, if red toner is used, black toner (magnetic toner)
However, in the non-image area of the photoconductor drum, that is, in the photoconductor area between the transfer material which does not contact each transfer material to which the photoconductor is continuously supplied, and in the post-rotation step of the photoconductor. It is sometimes developed on the photosensitive member and supplied to the magnet roller of the cleaning device without being subjected to the transfer action.

An embodiment of the operation sequence of the two-color image forming apparatus according to the present invention will be described with reference to FIG. 6 for the manner of developing the black toner on the non-image area of the photoconductor, which is performed according to the present invention.

FIG. 6 is a sequence diagram when copying one sheet. The photoconductor is driven with the copy switch ON, and the first charger 2
Is turned on and the photoconductor 1 is charged to an appropriate potential. Then
The first video signal (first laser signal) of the first image exposure means 3 and the first developing bias of the first developing device 4 are turned on,
A first latent image is formed and developed with red (non-magnetic) toner. Further, the second video signal (second laser signal) of the second image exposing means 6 and the second developing bias of the second developing device are
Turns on and develops with black (magnetic) toner.

When the image formation is completed, the first video signal of the first image exposing means 3, the first developing bias of the first developing device 4, and the second video signal of the second image exposing means 6 are turned off and the post-rotation is started.
Immediately, the second video signal of the second image exposure means 6 is turned on to form a line-shaped (band-shaped) latent image on the photoconductor. The line-shaped latent image is developed by the second developing device 7 with black (magnetic) toner.

The line image visualized with the magnetic toner is supplied to the magnet roller 28 of the cleaning device 11 without being transferred, thereby preventing the magnet roller 28 from being covered with the non-magnetic toner. You can

FIG. 7 is a sequence diagram at the time of continuous copying,
A line-shaped latent image is formed between each transfer material,
The line-shaped latent image is developed with magnetic toner.

In this way, the magnetic toner can be developed between the transfer sheets or at the time of post-rotation, that is, in the non-image area and the black toner can be supplied to the magnet roller of the cleaning device. In the example, the magnet roller is covered with the red toner, and as a result, the red toner scatters or drops off, and the inside of the device is contaminated.

In this embodiment, the line width formed between transfer sheets or during post-rotation is about 2 mm, and the length is the same as the developing sleeve. In this embodiment, the toner consumption of this line is
The amount was 0.01 g, which corresponds to the transfer residual toner of the red (non-magnetic) toner.

The present inventors conducted an image forming experiment at an image forming process speed of 440 mm / sec using an amorphous silicon photoconductor drum having a diameter of 108 mm in the apparatus having the configuration shown in FIG. When the device is operated based on the above operation sequence, a chart with an image ratio of 10% is copied only with red toner, and A4 size intermittently copies 50,000 sheets and 100,000 sheets continuously. In the copy test, the red toner did not scatter out of the container of the cleaning device, and the image did not stain and the inside of the device did not stain at all. The same was true when 500 solid red solid images were continuously copied.

In this experiment, the diameter of the magnet roller of the cleaning device is 18 mm, the surface magnetic flux density is 1000 gauss, and the number of poles is 6
The peripheral speed was 350 mm / sec, the gap between the photosensitive drum and the magnet roller was 1.0 mm, and the gap between the magnet roller and the toner layer thickness regulating member was 1.3 mm.

FIG. 8 is a schematic diagram of an analog two-color electrophotographic copying machine according to another embodiment of the present invention. According to this embodiment, the image exposing means 3A and the blank exposing means 3B are provided between the first charger 2 and the first developing device 4, and after uniform charging by the first charger 2, The image exposure means 3A is operated to form a red latent image, and then the image is visualized by the red (non-magnetic) toner of the first developing device 4, and then the photoconductor undergoes a transfer process and a cleaning process, and again. , A latent image of a black portion is formed on the photoconductor uniformly charged by the first charger 2 by the image exposure means 3A, and visualized by the black (magnetic) toner of the second developer 6. A two-color copy is obtained through the transfer process.

FIG. 9 shows a developing sequence of black (magnetic) toner to a non-image area when two red images are successively copied in this embodiment. The blank exposure means 3B is turned off for a short time between transfer materials and during post-rotation, and the second black toner
When the developing bias of the developing device 6 is turned on, the black toner is developed. Of course, the development may be performed by turning on and off the developing bias for black toner without using the blank exposing means 3B. Further, during continuous copying, the magnetic particles may be supplied not every sheet of paper but every several sheets.

Although each of the above-described embodiments has been described as being carried out by the two-color electrophotographic apparatus having the configuration shown in FIGS. 1 and 8, the present invention is not limited to these two-color electrophotographic apparatus. It goes without saying that the present invention can be applied not only to other two-color electrophotographic apparatuses but also to image forming apparatuses such as multicolor electrophotographic apparatuses. Further, although the exposure means for forming a latent image is described by laser light or analog exposure, other means, for example, an exposure means such as a liquid crystal shutter array may be used.

Further, in each of the above embodiments, the magnet cleaning means has the magnet roller, but the present invention is not limited to this, and an elastic roller or a flocking roller having a magnetic field generating means therein may be used. It can also be used, and its rotation direction is not limited to that shown in the figure.

Further, the present invention is not the cleaning device in which the magnetic toner on the magnet roller is slid on the surface of the image carrier as described in the above embodiment, but the magnetic cleaning means is simply the magnetic toner collecting member. The present invention can be suitably embodied even in a developing and forming apparatus that employs a cleaning device configured to act as.

Further, the supply of the magnetic particles to the magnet cleaning means is not performed by developing the magnetic toner in the non-image area with the developing device for magnetic toner as described in the above embodiment, but as shown in FIG. As shown in the drawing, the cleaning may be performed by providing the magnetic particle supplying means 40 in the cleaning device 11. That is, the magnetic particle supply means 40 is provided with a supply device 46 in which the magnetic particles 42 are contained and a large number of supply ports 44 are formed along the axial direction of the magnet roller 28.
The supply of magnetic particles is achieved by controlling the opening and closing of the above according to the above operation sequence. The magnetic particles may be a magnetic toner or other magnetic particles.

Furthermore, when the non-magnetic toner has a higher cohesion degree at the cleaning blade edge portion than the magnetic toner and a cleaning failure is likely to occur, an image forming apparatus equipped with a cleaning device having no magnet cleaning means is used. However, the operating sequence is valid in accordance with the principles of the present invention.

As described above, the image forming apparatus according to the present invention forcibly supplies magnetic particles such as magnetic toner to the cleaning device when the non-magnetic toner is used for image formation, and the non-magnetic toner is used. Is prevented from scattering in the cleaning device and leaking out of the container, which in turn prevents stains on the image forming apparatus.

Further, according to the present invention, residual adhered substances on the image carrier can be completely removed, image deletion under high humidity due to such adhered substances can be prevented, and high quality images can be obtained. Has the effect.

[Brief description of drawings]

FIG. 1 is a schematic view of a two-color electrophotographic apparatus which is an embodiment of the image forming apparatus according to the present invention. 2A to 2E are diagrams showing the surface potential on the photoconductor in each image forming step for explaining the image forming mode of the apparatus of FIG. FIGS. 3A to 3F are diagrams showing the surface potential on the photoconductor in each image forming process according to another embodiment for explaining the image forming mode of the apparatus of FIG. 4 and 5 are schematic sectional views of an embodiment of the cleaning device used in the image forming apparatus according to the present invention. 6 and 7 are operation sequence diagrams showing an embodiment of the operation mode of the image forming apparatus according to the present invention. FIG. 8 is a schematic view of a two-color electrophotographic apparatus which is another embodiment of the image forming apparatus according to the present invention. FIG. 9 is an operation sequence diagram showing an embodiment of the operation mode of the apparatus of FIG. 1: image carrier (photosensitive drum) 2: primary charger 3: first image exposing means 4: non-magnetic toner developing device 6: second image exposing means 7: magnetic toner developing device 8: transfer charger 11: cleaning Device 22: Cleaning blade 24: Magnet cleaning means

Claims (3)

[Claims] 1. A latent image is formed on an image carrier, and the latent image is visualized by selectively developing the latent image with a magnetic toner or a non-magnetic toner, and the visible image is transferred to a transfer material. In an image forming apparatus in which the residual toner on the image bearing member is removed by a cleaning device so that the image bearing member is repeatedly used, when non-magnetic toner is used during image formation, magnetic particles are added to the cleaning device. An image forming apparatus having a supply unit. 2. The cleaning device comprises a magnet cleaning means for cleaning the image bearing member with magnetic particles, and the magnetic particle supply means supplies magnetic particles to the magnet cleaning means. The device according to. 3. The cleaning device comprises a magnet cleaning means for cleaning the image bearing member with magnetic particles, and the magnetic particle supplying means develops the non-image area of the image bearing member with magnetic toner. An apparatus according to claim 1, wherein magnetic particles are supplied to the cleaning means.