JPS5872158A - Formation of two-color toner image forming method - Google Patents

Abstract

PURPOSE:To record a two-color image well without color mixture, by charging frictionally a toner of the first color, which is mixed in a developing device for the second color, with a polarity different from that of the second latent image charge to prevent accumulation of the toner of the first color. CONSTITUTION:A positive-polarity latent image formed on a photosensitive drum 1 is developed in the first developing device 5 using a toner 4 of the first color having a positive polarity. The second positive-polarity latent image is formed on the drum 1 by exposure and is developed in the second developing device 8 using a toner 7 of the second color having a positive polarity. In this case, a part of the toner 4 on the drum 1 is peeled by a magnetic brush due to the device 8 and is mixed into the toner 7 of the device 8 and is charged frictionally by the carrier and the toner 7 of the device 8. Then, the mixed toner 4 which is charged frictionally in a prescribed order has a negative polarity and is not accumulated and is stuck to the nonimage part of the drum 1. Positive-polarity toners forming respective color images are transferred to a recording paper 9 by a negative-polarity bias voltage due to a charger 10 for transfer, and thus, good recording without color mixture is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-color toner image forming method, and in particular, a two-color toner image forming method, in which two latent charge images formed on the same photoreceptor are moderated with different color toners to form a two-color toner image, This invention relates to a method for forming a two-color toner image by transferring this toner to recording paper.

As a printer used in combi-tater terminals, etc.
As an oCO@ printer that is desired to be capable of recording with two or more multicolor toners, an electrophotographic method is practical, and a laser beam printer has been proposed. A two-color laser beam printer uniformly charges a rotating photoconductive photosensitive drum and exposes the photosensitive drum sound negative with a first laser beam modulated with first image information to create a first electrostatic latent image. An image is formed, and this first electrostatic latent gI is reversed by a first developing device to cause the toner tube of ggl to adhere to the charge emitting area. Forms a toner image of I 0 and then modulates with image information of cylinder 2 2
The photosensitive drum is negatively exposed again with the laser beam to form a second electrostatic latent image, and this 20th electrostatic latent image is reversely developed by the second developing device to develop the charge emitting area El! A second toner is deposited to form a second toner image. The two-color toner image thus formed on the surface of the photosensitive drum is transferred to recording paper and then spread.

In this two-color toner image forming method of a laser beam printer, during the process of developing the second latent charge gI, the first toner already attached to the photosensitive drum gets mixed into the developing device of the straw 2. However, when the amount of mixed toner increases, the second toner image becomes cloudy.As a regular two-color development method, when the toner from the first developing device is mixed into the 8g2 developing device, The mixed first toner is charged by friction with the carrier of the second developer, and is reversely charged to the same polarity as the second latent image charge to prevent it from adhering to the photosensitive drum, thereby preventing color mixing. Methods have been proposed to prevent this. However, in this two-color regular development method, the second toner adheres to the surrounding area of the second developer carrier, so there is less chance of friction with the first toner, and therefore the charging polarity is reduced. It takes a long time to reverse the charge, and there is a risk that it will adhere to the second charge latent scratches by then. Also, the SGL toner, whose charge polarity has been reversed, will remain in the second developer circle, so the developer In case O has a device that controls the toner mixing ratio or the amount of developer at a constant level, the second toner decreases by the amount of first toner mixed in, and the composition ability of the second developing device decreases. There was a problem.

Therefore, the target ore of the present invention is at least 2 in good quality without color mixture.
It is an object of the present invention to provide a two-color toner image forming method that can stably obtain color toner images.

To achieve this object, the present invention converts the first color toner that has entered the second color developing device into the second color latent gIt charge on the photoreceptor! In order to triboelectrically charge the I4 polarity, the toner of the second color is attached to the charge emitting area by reversal development of the second color to form a toner image of the second color, and a second 31#! The toner of the first color that has entered the imager is deposited on the gold charge unreleased area to prevent the first toner from accumulating in the developing device of the second color, and the toner of the first color that has entered the imager is then deposited on the gold charge unreleased area to prevent the first toner from accumulating in the developing device of the second color.
By electrostatically transferring the second toner image onto the recording paper using a bias electric field with a different polarity, the toner of the first color (with the same polarity as the bias electric field) attached to the charge emitting area during the reversal development of the second color. ) is not transferred to the recording paper to prevent color mixing.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an overall side view of a two-color electrophotographic apparatus for carrying out the present invention, and FIG. 2 is an enlarged view of the existing portion thereof. The surface of the photoconductive photosensitive drum 10, which is rotated in a clockwise direction, is uniformly charged by a charger 2, for example, to a positive polarity.

The surface of the ram is negatively exposed to a light beam 3 containing first image information to form a first electrostatic latent image, and this first electrostatic latent image is charged to the same positive polarity as the latent image charge. Step 1 toner 4
The first current g/! Device 5
As a result, the charge emitting area of the photosensitive drum 1 is exposed to a first tone to form an electrostatic latent image of 8g2, and this 20th electrostatic latent image has a positive polarity of the same polarity as the charge of the latent image. Area reversal development is carried out in the second developing device 8 having the toner 7 (exaggeratedly shown as a black circle) charged at @2. Since the toner 1 adheres to form the second toner image 7A, if the first toner 4 and the second toner T are different colors, a two-color toner image is formed on the hexagonal i of the photosensitive drum 1. be able to. In this way, the two-color toner image 4A,
The recording paper 9' is brought into contact with the surface of the photosensitive drum 1 on which the toner image 7A is formed, and a bias electric field having a polarity different from that of the toner image is applied from the back side of the recording paper 9 by the charger 10. Electrostatic transfer of color toner images. toner image 4
A cleaner 11 is applied to the surface of the photosensitive drum 10 after transferring A and 7A.
It is then cleaned and uniformly charged again by the charger 2.

In this electrophotographic apparatus, when the first developing device 115 uses the toner 4 together with a magnetic carrier to form a two-component developer magnetic brush on the surface of the five developing rolls, the toner 4 is charged by friction with the carrier. Positive polarity VC? J electric train is being used. The toner 7 of the second developing device 8 is also used together with the individual carrier, and is positively charged by frictional charging with the toner H carrier, and a two-component developer magnetic brush is completely formed on the surface of the developing roll 8Ac/). When the second developing device 8 develops the electrostatic latent image of the flute 2, a first toner image 4A of the first toner 4 is formed on the surface of the photosensitive drum 1. Therefore, a part of the first toner 4 is peeled off from the surface of the optical drum 1 in FIG. 1 and mixed into the developing device 8 of M2. If the number of teeth of the first toner 4B increases, if the first toner 4 continues to have a positive charge, the second electrostatic charge will be generated together with the second toner 1. The toner particles adhere to the latent image and cause the second toner image to become cloudy.

However, in this embodiment, the triboelectric charging order of the first toner 4 is different from that of the magnetic carrier used in the second developing device 15.
○ Therefore, the first toner 4 mixed into the second developing device 8 is
The charge polarity of B is quickly reversed to negative polarity due to frictional charging with the toner 7 of @2, and becomes a different polarity toner 4C. is reattached to the remaining non-image area) and transferred to the second developing device 1.
8 and is not accumulated in the second developing device t8. In addition, on the surface of the photosensitive drum 1, there are a first toner image 4A having t-4 charges of positive polarity, a second toner image 7A having charges of positive polarity, and an extra toner image 4A having charges of negative polarity. 1 toner 4C will be attached. However, since the electrophotographic copying of the toner image is carried out by applying a negative bias charge to the recording paper 9, the first toner image charged to the positive polarity. Second
The toner images 4A and 7A are attracted by this bias charge and transferred to the recording paper 9, but the negative polarity and the extra first toner images 4A and 7A are
Since the toner 4Cti is repelled and not transferred, the recording paper 9 is not stained.

For example, when the first toner 4 is black, the toner used in the present invention contains a resin made of styrene hebutyl methacrylate copolymer, carbon black, and nigrosine dye in a weight ratio of 85:10:s. When the second toner T is red, it is kneaded, solidified, and crushed in a ratio of 96:4 to a resin consisting of styrene-butyl methacrylate copolymer and watching red as a red dye. Those that were cross-wired, assimilated, or crushed were good. In addition, the magnetic carrier used with each of the toners 4.7 in the image border gI devices 5 and 8 is preferably DIP-1580 manufactured by Nippon Tetsuko Co., Ltd. The blow-off charge amount of the second toner 4.7 was 25 μc/g and 37 μc/g, respectively.

FIG. 3 shows the first developing device 5t in the electrophotographic apparatus shown in FIGS. 1 and 2, which has been changed to a developing device using component magnetic toner. , a cylindrical conductive sleeve 5B, a magnet roll 5C, and a toner regulating plate 5D.

A toner container 5Et is provided. The one-component magnetic toner 12 housed in the toner container 5E is attracted by the magnet roll 5C to form a magnetic brush around the sleeve 5B, and when the magnet roll 5Ct moves clockwise, the magnetic brush touches the toner regulating plate 5D. The sleeve surface is moved counterclockwise with the edge thickness regulated to lightly rub the surface of the photosensitive drum 10. Reversal development characteristics can be obtained by applying a bias voltage to the sleeve 5B from the tube bias power supply 13 having the same polarity as the latent image charge on the surface of the photosensitive drum. In the case of using a one-component magnetic toner, the developing conditions are such that the distance between the photosensitive drum 1 and the sleeve 5B is 0.
．． 3 to 0.5 mm to control the stiffness of the magnetic brush so that the toner 12 lightly rubs the surface of the photosensitive drum 1. It is better to apply a new full bias voltage. As the one-component magnetic toner 12, when using a high-resistance charged magnetic toner gold that contains a small amount of dye as a charge control agent in addition to magnetic powder and resin and is used in a positive polarity, the photosensitive drum 1 and the sleeve are used. The total interval of 5B is 0.2 to 0.3 mm, and the thickness of K is regulated so that the magnetic brush formed inside the sleeve surface does not come into contact with the photosensitive drum surface, and the thickness is 0.5 to 1 times the potential of the residual charge. The bias potential of sleeve 5
Excellent reversal development characteristics can be obtained for B.

The surface of the photosensitive drum on which the first toner @12A is formed by the first developing device 115 is negatively exposed to the second light l1g16, as in the previous embodiment, and is reversed again by the second developing device @8. A second toner image IA is formed by development.

In this case as well, a part of the first toner 12 gets mixed into the second developing device, but the mixed toner 12B becomes negatively charged toner 12C of a different polarity due to frictional charging with the second toner 7. , adheres to the non-charge-emitting area of the photosensitive drum surface and is removed from the second developing device.

In this embodiment, the use of the first toner (12t), a one-component magnetic toner, makes it possible to downsize and simplify the first developing device 5, and the one-component magnetic toner has a portion of magnetic powder on its surface. has been exposed to light and has a strong frictional charging property with the second toner I, which has the advantage that mixed toner can be easily charged to the opposite polarity and removed.

FIG. 4 shows that the first toner 4 in the electrophotographic apparatus shown in FIGS. 1 and 2 is made into a magnetic toner containing 10 to 50 weight of magnetic powder and mixed with a magnetic carrier. The developing device RJ17T8 of No. 2 has a gold film on the mixed toner removing means. For simplicity, FIG. 4 omits the first developing device it5.

A conductive rotating electrode gH is provided in the second developing device 8, and a full voltage of the same polarity as the charge on the surface of the photosensitive dome is applied to this (b) rotating electrode 8B from the power source 14, and the photosensitive drum is attracted to the rotating electrode 8B. The removed toner is removed by a scraping plate 8c and returned to the collection section 51).
It's like it's going to fall.

In this way, the first toner 4C that has mixed into the first developing device 8P3 and has been charged with a different polarity is reattached to the surface of the photosensitive drum 1 and removed.
It also adheres to the surface and is collected in the collection section 8D circle.

In this embodiment, since the first toner 4 contains magnetic powder, it has strong frictional electrification with the second toner 7 and is easily charged to the opposite polarity, and the first toner 4 is mixed with a carrier. The bias power source for reversal development becomes military equipment because it is used with m- charging to the same polarity as the latent image charge.

13i-1 from 1. It can also be implemented by using both the second toner as one-component magnetic toner.

In the present invention, the first toner needs to be charged to a polarity different from the latent image charge formed on the surface of the photosensitive drum by frictional charging with the second toner. It can be freely adjusted by adding charge control agents such as pigments and dyes, magnetic powder, etc. Many experimental examples have shown that when the same carrier is used, the object of the present invention can be achieved by selecting a toner material such that the amount of charge of the second toner is greater than that of the first toner. The type of carriers in the first developing device and the second developing device may be changed.

As a means for removing the first toner mixed in the grip gI device li1 of M2, it is possible to utilize the difference in scattering properties and the difference in magnetism between the two toners. Second current 4J
The charged polarity of the first toner mixed in the R device circle is reversed, but the band wLm is relatively small and easily scattered, so it can be dispersed by suction air. Since there are some toners that cannot be completely reversed, this makes it possible to remove these toners.

As described above, in the present invention, the toner of the first color mixed into the reversal developing device of the second color is frictionally charged to have a different polarity from the latent image charge of the second color on the photoreceptor, thereby removing the charge on the photoreceptor. The toner of the first color is deposited on the discharge area to prevent the toner of the first color from being drawn into the reversal developing device of the second color, and the toner of the first and second colors on the photoreceptor is then deposited with polarity opposite to these. In the Piasumi world, recording paper is charged with a different polarity to prevent the first color toner attached to the photoconductor from being transferred to the recording paper. It has the effect of stably producing high-quality two-color toner without color mixing. The present invention can also be developed as a method for forming toner images of three or more colors by changing the number of repetitions of electrostatic m-image creation and reversal development.

[Brief explanation of the drawing]

Fig. 1 is an overall side view of a two-color electrophotographic apparatus used in the present invention, Fig. 2 is an enlarged view of its developing section, Fig. 3 is a side view showing another example of the developing section, and Fig. 4 is a further Another example of the developing section is shown.
It is a first view of ilt. DESCRIPTION OF SYMBOLS 1... Photoconductive photosensitive drum, 3... Light beam containing first image information, 4... First toner, 4A... First 1 toner image, 4B...
・Contaminated first toner, 4C...First toner with different polarity, 5...1V) developing device, 6...Second image Informational exchange of light, 1...
...Second toner, /A...Second toner image, 8...Second developing device, 9...Recording paper, 10... ... 21 diagrams of Teigoki for transcription? Figure 2

Claims (1)

Claims: 1. Inversion 3j in the first moderation device with the first electrostatic latent *t-first toner! A second electrostatic latent image of the same polarity as the first electrostatic latent image formed on the photoconductive photoreceptor having the first toner gI obtained by In the method of forming a second toner having a second toner having a different color from the toner, and electrostatically transferring this two-color toner*1 onto a recording paper to form a two-color toner on the recording paper, @2 moderate By frictionally charging the first toner mixed into the device to a polarity different from the second latent charge, the second inversion IAgI! The first toner mixed in the 20th dispensing device is deposited on the electro-discharge area of the 20th toner tube to form a second toner image, and then the first toner mixed in the 20th dispensing device is deposited on the non-charge emitting area, and then A two-color toner image forming method in which toner particles are electrostatically transferred onto a recording paper using a bias electric field of a different polarity. 2. In claim 1, the first toner mixed in the second moderating device is rubbed with the second toner.
Therefore, the two-color toner image forming method is characterized in that the toner image is charged with a polarity different from that of the second latent image. 3. A method for forming a two-color toner image, characterized in that it contains magnetic powder from the first toner company, as set forth in claim 8 (1). 4. 41FF Claim i! 1. The two-color toner image forming method according to item 1, wherein the first toner is used in combination with a carrier.