JPS6261149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing method for visualizing an electrostatic latent image on an electrostatic latent image carrier by bringing it into contact with toner in a cloud state.

The powder cloud development method is patented in the U.S. Patent No.
As known from No. 2725304, extremely fine powder particles are blown out of a small diameter metal tube,
Forming a cloud of powder particles. At this time, the powder particles are charged to a predetermined polarity by mutual contact friction. In this method, the method of generating a powder cloud is complicated and very expensive.Furthermore, there are toners that are positively and negatively charged due to mutual frictional charging between the toners, making it extremely difficult to handle them. The drawback was that it was difficult to obtain.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such drawbacks and to provide a developing method that is free from background stains, is inexpensive, and has excellent developing efficiency while utilizing a toner cloud.

First, the principle of the present invention will be explained. The applicant is Japanese Patent Application No. 53-165160 (Japanese Unexamined Patent Publication No. 55-93160)
proposed a developing method that forms a uniform toner cloud in a simple manner. In this method, a toner layer with a high toner filling degree is formed on a toner layer with a low toner filling degree using a shearing member, and a toner cloud is generated by colliding the toner layers with different toner filling degrees with each other. It was hot. However, this method has problems such as restrictions on the relative position of the magnetic pole and the shearing member, the magnet must be large, and the toner carrier must be rotated at a fairly high speed. It was hot. The present invention is basically the same as the prior application, but uses a rotating body instead of a toner layer with a high packing density, and causes the toner layer on the toner carrier to collide with the rotating body to generate an impact force. This is what you get.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

In the figure, reference numeral 1 indicates a photosensitive drum as an electrostatic latent image carrier, which rotates in the direction of the arrow. As the photoreceptor, an organic photoconductor is used, but laminated photoreceptors of zinc oxide, Se, Se-Te, CdS, Se-PVK, etc. can also be used. A negative electrostatic latent image is formed on the organic photoconductive photosensitive drum 1. A toner carrying roller 2 is provided at a predetermined distance from the photosensitive drum 1.
The toner carrying roller 2 includes a non-magnetic sleeve 3,
It consists of a magnet 4 provided inside. The nonmagnetic sleeve 3 is rotating in the direction of the arrow a, and the magnet 4 is stationary. Magnet 4 has north and south poles
The magnetic roller is a magnetic roller whose poles are alternately magnetized, and the magnetic force of the magnet 4 causes magnetic toner to adhere to the surface of the sleeve 3, thereby forming a magnetic brush 5. As is already known, this magnetic brush 5 has toner lines in which magnetic toner is formed along the lines of magnetic force of a magnet. A toner hopper 6 is provided above the toner carrying roller 2, and contains magnetic toner therein. Magnetic toner can be divided into low-resistance types and medium- and high-resistance types, and since the specific toner charging methods are different for each type, they will be distinguished and described later. The amount of toner on the sleeve 3 is regulated by the outlet wall 6a of the toner hopper 6. Of course, the toner amount regulating member can also be installed separately from the toner hopper.
A scattering roller 7 that rotates in the direction of arrow b is provided between the photosensitive drum 1 and the toner carrying roller 2 and at a position in contact with the magnetic brush 5 (toner layer) on the toner carrying roller 2. The spreading roller 7 is moving in the opposite direction to the movement of the magnetic brush 5 and its contact position. That is, the toner layer and the dispersing roller 7 are moving relative to each other. If the dispersion roller 7 is made of a rigid body, the impact force with the toner layer will be strong, which is convenient for generating the toner cloud 8. That is, when the magnetic brush 5 as a toner layer collides with the scattering roller 7 at a constant speed difference, the toner chain is broken and the toner present on the outside is ejected in the direction of the photoreceptor drum 1. This is further promoted by the centrifugal force caused by the rotation of the dispersion roller 7, and the magnetic toner overcomes the magnetic attraction force of the magnet 4 to form a toner cloud 8.
Note that when the relative speed difference between the toner layer and the dispersion roller 7 was small, no toner cloud was observed to occur. Furthermore, if the speed difference is large,
It was possible to generate a toner cloud even when the dispersion roller 7 was placed in a position facing the magnetic pole. In this way, the toner is ejected with the sum of the speeds of the toner carrying roller and the scattering roller, and a toner airflow is easily generated, making it possible to develop an efficient toner cloud, and at the same time, it is not necessary to rotate the toner carrying roller at a very high speed. Nor. Now, when a low-resistance magnetic toner is used, an electrostatic latent image is developed in the following manner. The toner is composed of a magnetic material, resin, carbon, etc., the content of the magnetic material is 20 wt% to 70 wt%, and the volume resistivity value is 10 ² Ωcm to ^{10 10} Ωcm. Further, the toner particle size is 5 μ to 30 μ. Although this toner itself does not have an electric charge, the cloud-like toner separated from the sleeve 3 by the scattering roller 7 approaches the photoreceptor drum 1 in the development area, and is formed on the photoreceptor drum 1 at that time. In the developing electric field created by the electrostatic latent image (negative polarity), each toner appears to behave positively charged. This charging of the toner is considered to be an electrostatic polarization phenomenon caused by the developing electric field. In this way, the toner charged to the opposite polarity to the charge of the electrostatic latent image is attracted to the charge of the electrostatic latent image against the magnetic attraction force of the magnet 4, or in a place where there is not much influence of magnetic force, and this is visible. Visualize.

On the other hand, when the magnetic toner has a volume resistivity of 10 ¹² Ωcm or more (based on a known measurement method), it is possible to charge the toner in advance. By charging the toner in advance, it is possible to eliminate image defects caused by fringing fields of electrostatic latent images, such as fogging around solid areas of images and characters. For example, in a first method of charging toner, the outlet wall 6a of the toner hopper is made of a material that separates the toner in the order of triboelectrification, and the toner is positively charged by triboelectrification. At this time, instead of the toner hopper wall 6a,
Separately, a member for toner frictional charging may be provided separately so as to be in contact with the magnetic brush 5 on the sleeve 3.
The scattering roller 7 may be made of an electrically insulating material in order to prevent the toner charge from escaping.
The spreading roller 7 may be made of a conductive material and a voltage of the same polarity as the toner may be applied thereto as shown in FIG. voltage. Further, as shown in FIG. 2b, the outer surface of the dispersion roller 7 may be provided with a coating 10 made of a material that is separated from the toner in the triboelectrification order. Since the toner layer and the dispersing roller 7 have sufficient relative motion, it is possible to triboelectrically charge the toner. Of course, the entire scattering roller 7 can also be made of the above-mentioned materials. Another toner charging method is to charge the toner by providing a discharger between the toner hopper 6 and the scattering roller 7 that performs positive corona discharge on the toner supplied from the toner hopper 6 onto the sleeve 3. , the charge injection method proposed by the applicant (Japanese Patent Application Laid-Open No.
50-117432)), the toner can also be charged. In addition, known toner charging methods can also be used. In this way, when the toner is charged in advance, the dispersion roller 7 must be devised so as not to leak the charged charges as described above.

FIG. 2c shows the surface 7a of the dispersion roller 7 which has been roughened. This is to generate a toner cloud by using the toner pumping up by the dispersion roller 7 in addition to the toner cloud generated by the collision, and it is possible to obtain a larger amount of toner cloud. Other methods for obtaining such a large amount of toner cloud include coating the scattering roller 7 with a magnetic material or using a roller made of a weakly magnetic material to increase the pumping effect. In this case, the toner adhering to the spreading roller 7 as a lifting roller is separated therefrom by the centrifugal force of the spreading roller 7.

Further, in the above example, the case where there is only one scattering roller 7 has been described, but if two or more scattering rollers are used, more toner clouds can be generated, which is effective for high-speed development.

FIG. 3 is a sectional view of a developing device showing another embodiment of the present invention. Components in the figure that perform the same functions and operations as those in the first embodiment will be described using the same reference numerals. The electrostatic latent image carrier 1 is moving to the right, a toner carrying roller 11 is provided above, and the magnetic brush 5 on the sleeve 3 is brought into contact with the electrostatic latent image carrier 1. The sleeve 3 is made of a conductive material, and a voltage V _A having the same polarity as the electrostatic latent image is applied by a power source 12 . The sleeve 3 is supplied with magnetic toner from a toner hopper 6, and a magnetic brush 5 is formed thereon. An electrode 13 is provided in contact with the magnetic brush 5, to which a voltage V _B having a polarity opposite to that of the electrostatic latent image is applied by a power source 14. Therefore, there is a potential difference between the electrode 13 and the sleeve 3 |V _A −V _B |
This determines the amount of charge of the toner passing between the electrode 13 and the sleeve 3. Charging is performed by injecting charge from the electrode 13. The charging polarity of the toner is determined to be positive when V _B > _VA , and negative when V _B < _VA . In this embodiment, the toner is positively charged. Before the magnetic brush 5 comes into contact with the electrostatic latent image carrier 1, the dispersing roller 7
is provided so as to be in contact with the magnetic brush 5. A toner cloud 8 is created by the scattering roller 7 and brought into contact with the electrostatic latent image carrier 1 .
By the way, the seal electrode 15 extends from the vicinity of the electrode 13 to the vicinity of the electrostatic latent image carrier 1, and the seal electrode 15 and the magnetic brush 5 in contact with the electrostatic latent image carrier 1 are used to spread the image by the dispersing roller 7. It surrounds the toner cloud 8 that is generated. A voltage having the same polarity as the charging polarity of the toner is applied to the seal electrode 15 by a power source 16. Therefore, the configuration is such that toner is prevented from adhering to the seal electrode 15 and the toner cloud 8 is directed toward the electrostatic latent image carrier 1 . Furthermore, the seal electrode 15
By reducing the distance between the lower end of the electrostatic latent image carrier 1 and the electrostatic latent image carrier 1, the toner cloud 8 is scattered outside from the seal electrode 15 by the air flow generated on the surface of the electrostatic latent image carrier 1 in the moving direction. It is possible to prevent this from happening. In this way, a toner cloud 8 is formed, and the charged toner is attracted to the charge of the electrostatic latent image, making it a visible image. However, if a residual potential exists in the background portion of the electrostatic latent image carrier 1, toner will also adhere thereto, so the unnecessary toner is removed by bringing it into contact with the magnetic brush 5. Here, the contact of the magnetic brush 5 is much lighter than that in normal magnetic brush development, and it is thought that almost no development is performed in this area.
Since the toner present in the background area is originally attached to the electrostatic latent image carrier 1 with a weak holding force, it can be sufficiently removed with such a light rubbing force and magnetic attraction force. Since a voltage V _A having a polarity opposite to that of the toner is applied to the sleeve 3, the toner adhering to the background is attracted toward the sleeve 3 by electrostatic attraction.

Although the above-mentioned embodiment is a combination of a magnetic toner and a toner carrying roller having a magnetic field generating means, the toner can also be produced by a combination with a known toner carrying roller that carries magnetic toner or non-magnetic toner by other methods. It is also possible to generate a cloud.

Further, as the electrostatic latent image carrier, a dielectric material used in an electrostatic recording device or the like other than the photoreceptor may be used, and the image is developed by the same method.

As described above, according to the present invention, not only can a toner cloud be efficiently generated using an extremely simple method, but also the processing is simple because the toner is charged to the same polarity, resulting in high quality. In addition to being able to obtain images, there is no need to rotate the toner carrying roller at high speed.

Furthermore, since development is carried out using only toner, there is no need for a complicated toner concentration detection device, and there is no need for a carrier or other device for collecting unnecessary particles.

In addition, after the toner cloud is developed, the same toner layer is brought into contact with the developed static image surface, so not only can a good image with no background stains be obtained, but the collected toner can be reused, and the device is simple. It is.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a toner cloud developing device showing an embodiment of the present invention, FIGS. 2 a, b, and c are views showing modified examples of the dispersion roller used in the present invention, and FIG. 3 is a cross-sectional view of a toner cloud developing device showing an embodiment of the present invention. FIG. 3 is a cross-sectional view of a toner cloud developing device showing another embodiment of the present invention. 1... Photosensitive drum (electrostatic latent image carrier), 2,
11...toner carrying roller, 3...sleeve,
4... Magnet, 5... Magnetic brush (toner layer), 7
...Scatter roller, 8...Toner cloud, 13
……electrode.

Claims (1)

[Claims] 1. A toner carrier having an electrostatic latent image carrier and a toner carrier carrying a toner layer on its surface that moves a certain distance from the toner carrier, wherein the toner layer and the electrostatic latent image carrier are connected to each other. A toner cloud developing method in which a toner cloud is generated by a rotating body that moves relatively in contact with the toner layer during the toner layer to develop an electrostatic latent image on an electrostatic latent image carrier. 2. A toner carrier having an electrostatic latent image carrier and a toner carrier carrying a toner layer on its surface having a portion that moves a certain distance away from the electrostatic latent image carrier and a portion that comes into contact with the electrostatic latent image carrier, and A toner cloud is formed between a toner layer that moves a certain distance from the electrostatic latent image carrier and a rotating body that moves relatively in contact with the toner layer. 1. A toner cloud development method in which the electrostatic latent image is generated and supplied with toner to the electrostatic latent image, and then the electrostatic latent image is brought into contact with the toner layer to develop the electrostatic latent image on the electrostatic latent image carrier.