JPH041906B2 - - Google Patents

Description

[Detailed Description of the Invention] (A) Technical Field of the Invention The present invention relates to two types of electrostatic recording devices, electrophotographic devices, etc.
The present invention relates to a color recording device, and particularly relates to a two-color recording device including a second developer having a separation device for removing developer from the first developer mixed into the second developer.

(B) Technical background In recent years, as electronic computers have become faster, output devices such as line printers are required to meet the following requirements.

(1) High-speed printing (2) Miniaturization of the device (3) Easy maintenance (4) No noise In order to meet these requirements, research on non-impact type line printers is underway.

In addition, the printed matter from the output device is not only used to confirm information processing results as in the past, but also processed, edited, tabulated, etc., and there is a tendency for the printed matter to be treated as an official document. , it is required to be able to change the colors of figures, etc. as necessary.

(C) Prior Art and Problems Figure 1 shows a schematic diagram of a conventional two-color recording device.
Further, FIG. 2 shows the potential levels of each process for two-color recording. In FIG. 1, the entire surface of the photoreceptor 1 is uniformly charged by an initial charger 2. As shown in FIG. The potential at this time is set to the initial charging potential level Vs, as shown in FIG. Next, the photoreceptor 1 is exposed to an image corresponding to a first color (hereinafter referred to as red) by the exposure section 3. At this time, the potential on the photoreceptor 1 exposed by the exposure section 3 attenuates to approximately OV as shown in FIG. Thereafter, using toner with a positive red charge, the developing bias voltage setting section 5 sets the developing bias voltage V _B1 to a value slightly lower than the initial charging potential level Vs, as shown in FIG. Developing is carried out by By performing development, toner adheres to the photoreceptor 1 in areas from which charges have been removed, as shown in FIG. 2 and 3. Next, the exposure unit 6 performs exposure of an image corresponding to a second color (hereinafter referred to as black). At this time, the potential on the photoreceptor 1 exposed by the exposure section 6 attenuates to approximately OV as shown in FIG. 2. Next, using a toner with a positive black charge, the developing bias voltage setting section 8 sets the developing bias voltage V _B2 to the second level.
As shown in FIG. 5, development is performed by the two-component developer 7 at a value slightly lower than the initial charge level Vs. By performing the development, black toner adheres to the portion from which the charge has been removed, as shown in FIG. 2, and a two-color visible image is formed on the photoreceptor 1. Next, the visible image is transferred onto the recording paper 10 by the transfer section 9 . Next, as in a normal electrophotographic process, a visible image on the recording line is heated and fixed, and a cleaning step 11 is performed.
One process is completed through the static elimination process 12. Two-color recording can be performed by sequentially repeating the above steps.

However, the above conventional method has the following problems. First, in the two-component development method, iron powder with a particle size of about 100 to 300 [μm] is used as a carrier. As shown in FIG.
An ear 14 of about d = 5 [mm] is formed on the photoreceptor 1 at a contact depth δ = 3 [mm] during development.
It is done by making contact with the degree. In this manner, in the two-component development method, development is performed while pressing the developer against the photoreceptor 1 and rubbing it. Therefore, if the contact depth δ of the ears 14 of the second developing device 7 is not set appropriately, the first developing device 4
When the red image formed is passed through the second developing device 7, it is mechanically scraped off, resulting in destruction of the red image.

Furthermore, after the red image is removed, black toner may adhere to the red image, resulting in an image that is originally red becoming a mixture of red and black. FIG. 4 shows the relationship between the contact depth δ of the second developing device 7 and the developer density when red is used as the first developer and black as the second developer. As the contact depth δ of the second developing device 7 increases, the density of the black image increases, but the density of the red image decreases. This is the second developing device 7
This is because the red color is mechanically rubbed off, and after the red color is removed, the black toner in the second developing device 7 adheres, causing color mixing.

Further, the red toner is mixed little by little into the second developing device 7 as well. Therefore, when recording is performed for a long time, the second developer, which is originally black, becomes a mixture of red and black developer.

(D) Purpose of the Invention The purpose of the present invention is to prevent the destruction of toner images and color mixing caused by the second developing device as much as possible, and to separate the developer from the first developing device mixed into the second developing device. It is an object of the present invention to provide a second developing device having functions.

(E) Structure of the Invention The above-mentioned object of the present invention is to provide two-color recording in which two-color recording is performed by developing a latent image formed on a latent image forming medium using a first developing device and a second developing device. In the apparatus, the first developing device uses a two-component developer consisting of toner and carrier, causes the toner to adhere to the carrier by electrostatic force, and moves the toner-attached carrier to a magnet placed opposite to the latent image forming medium. The second developing device is configured to develop the latent image formed on the latent image forming medium by conveying it on a rotating sleeve contained therein, and the second developing device uses a one-component developer made of magnetic toner. The latent image formed on the latent image forming medium is developed by conveying the toner over a sleeve containing a magnet disposed opposite to the latent image forming medium, and furthermore, the surface of the latent image forming medium is The mixed toner of the two-component developer is adsorbed by magnetic force by utilizing the fact that the toner of the two-component developer is non-magnetic, whereas the one-component developer is magnetic. This can be achieved by a two-color recording device characterized by further incorporating a separation device for separation.

(F) Embodiments of the Invention The present invention is characterized in that a one-component developing method is used in the second developing device.

That is, the one-component development method uses a toner in which magnetic powder is dispersed. The diameter of this toner is 10
It is about [μm], and 0.1~
Forms ears of about 0.3 [mm]. This toner originally has no charge, but during development, a charge is injected into the toner due to electrostatic induction of the latent image, and development is performed. This one-component development method does not use carriers with large particle sizes like the two-component development method.
Furthermore, since development is carried out near the point where the tip of the toner comes into contact with the photoreceptor, it can be said to be an extremely soft developing method. FIG. 5 is a diagram showing the relationship between the contact depth δ of the second developing device and the developed density when the one-component developing method is used for the second developing device. The contact depth δ of the black image is 0 [mm]
A developed density of about 1.2 can be obtained in the vicinity. At this time,
Unlike the conventional method, the density of the red image does not change even if the contact depth δ of the second developing device increases. This is because a one-component development method, which is a soft development method, is used as the second development, and the toner of the red image is mechanically scraped off by the second development.
This is because development is not performed after that, as black toner adheres and color mixture occurs.

As described above, if the one-component developing method is used as the second developing device, good records can be obtained for both red and black images.

According to the present invention, since the second development uses a soft development method, the proportion of red toner mixed into the second developing device can be significantly reduced.
However, when recording for a long time, red toner may get mixed into the second developing device. In this case, the second
Red toner needs to be removed from the developer. FIG. 6 is a diagram showing a developing device equipped with the toner separation device of the present invention.

The principle of toner separation will be described below.

Since the toner used in the one-component development method has magnetic powder dispersed inside, it is attracted by the magnetic force of the magnet 15 of the magnetic roller 17. but,
The toner used in the two-component development method does not contain magnetic powder and is not attracted by magnetic force. Therefore, the toner used in the one-component development method is transferred to the magnetic roller 1 by the magnetic force of the magnet 15 and the electrostatic force of the sleeve 13.
It is adsorbed to 7. Further, the toner used in the two-component development method is attracted to the magnetic roller 17 by the electrostatic force of the sleeve 13. In this state, air is supplied from an air supply source (not shown) (arrow indicated by symbol A in the figure).
By spraying, only the toner used in the two-component development method, which has a weak adsorption force, is blown away. Therefore, toner can be easily separated by blowing air onto a part of the magnetic roller 17 of a conventionally used developing device.

Next, another embodiment of a developing device equipped with the toner separation device of the present invention will be described.

FIG. 7 is a schematic diagram showing another embodiment of a developing device equipped with a toner separation device according to the present invention.

FIG. 8 is a schematic diagram for explaining the toner separation device in FIG. 7.

In this embodiment, a separating roller 1 is used to separate the two-component developer used in the first developing device from the developing device using the one-component developer, that is, the second developing device.
8 and a magnetic blade. This separation roller 18 uses a non-magnetic conductive sleeve 21 that encloses a magnetic roller 20.

Next, the operation of this embodiment will be explained.

First, the magnetic roller 2 in the separation roller 18
0 and the non-magnetic conductive sleeve 21 are rotated as shown in FIG.
3 is conveyed (in the direction of the arrow shown by symbol C in the figure) on the separation roller 18 in a mixed state. Among these toners 22 and 23, one-component magnetic toner 22
If the magnetic force of the magnetic blade 19 is made strong enough, it will be attracted by the magnetic blade 19 and cannot pass through the gap 24 between the non-magnetic conductive sleeve 21 and the magnetic blade 19. However, since the two-component toner 23 does not contain a magnetic material, it is not attracted to the magnetic blade 19, and since it retains an electric charge (positive charge in this case), the non-magnetic conductive sleeve 23 is moved by the image force. , and is transported through the gap 24 between the magnetic blade 19 and the magnetic blade 19 . Therefore, as shown in FIG. 8, the two-component toner 2 that has passed through the gap 24 between the magnetic blade 19 and the non-magnetic conductive sleeve 21
3 is recovered from the non-magnetic conductive sleeve 21 by means such as a blade 25, the two-component toner 23 is recovered.
can be separated.

Therefore, if a one-component developer is used in the second developer of a developing device equipped with the above-mentioned toner separation device, color mixing will not occur even if two-color recording is performed for a long time, and good two-color recording will be achieved. can be done.

(G) Effects of the Invention According to the present invention, by using a one-component development method, which is a soft development method, as the second development, not only image destruction and color mixing caused by the second development can be suppressed as much as possible, but also the second development Even if the two-component toner used for the first development in the two-component developing device gets mixed into the second developing device, it can be easily separated and removed by utilizing the toner properties of the one-component developing method and the two-component developing method. Good recording can be maintained even when recording for a long time.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional two-color recording device;
The figure shows the potential levels of each process for two-color recording, Figure 3 is a schematic diagram showing the developing method, and Figure 4 shows the case where two-component development is used for the first and second development. FIG. 5 is a diagram showing the development characteristics when a one-component development method is used for the second development. FIG. 6 is a conceptual diagram showing a developing device equipped with a toner separation device. It is. FIGS. 7 and 8 are diagrams showing other embodiments of the toner separation device according to the present invention. In the figure, 1 is a photoreceptor, 2 is an initial charger,
3 and 6 are exposure sections, 4 and 7 are developing devices, 5 and 8 are development bias voltage setting sections, 9 is a transfer section, 10 is a recording paper, 11 is a cleaning process, 12 is a static elimination process,
13 is a sleeve, 14 is an ear, 15 is a magnet,
16 is a blade, 17 is a magnetic roller, and A is air.

Claims (1)

[Scope of Claims] 1. In a two-color recording device that performs two-color recording by developing a latent image formed on a latent image forming medium using a first developing device and a second developing device, the first developing device comprises: The container consists of toner and carrier2
Using a component developer, the toner is attached to a carrier by electrostatic force, and the carrier with the toner attached is conveyed over a rotating sleeve containing a magnet disposed opposite to the latent image forming medium, thereby forming the latent image forming medium. The second developing device is configured to develop a latent image formed on the latent image forming medium, and the second developing device uses a one-component developer made of magnetic toner, and contains a magnet disposed opposite to the latent image forming medium to carry the toner. The toner of the two-component developer mixed from the surface of the latent image forming medium is transferred to the one-component developer. The two-color image forming apparatus further includes a built-in separation device that separates the one-component developer by adsorbing it by magnetic force, taking advantage of the fact that the two-component developer toner is non-magnetic while the developer is magnetic. Recording device. 2. In the two-color recording device according to claim 1, the separation device provided in the second developing device has means for blowing compressed air onto the sleeve, and the one-component developer is separated by magnetic force. A two-color recording device characterized in that the toner of the non-magnetic two-component developer is separated from the sleeve using compressed air in an adsorbed state. 3. In the two-color recording device according to claim 1, the separation device provided in the second developing device includes a non-magnetic conductive sleeve containing a magnet and provided adjacent to the sleeve. , a magnetic blade disposed with a gap between the sleeve and the sleeve is provided, and while the one-component developer is attracted by the magnetic force of the magnetic blade, only the toner of the non-magnetic two-component developer is removed. A two-color recording device characterized in that it is configured to be separated by being conveyed by a sleeve.