JPH02201471A - Developing device - Google Patents

Abstract

PURPOSE:To stably obtain high image quality by a one component non-magnetic developing method by forming an insulating layer that a toner carrier satisfies specified conditions on a conductive supporting body. CONSTITUTION:The insulating layer 11 whose film thickness (d) is d > 15mum and whose electrical resistivity R is R > 10<12>OMEGAcm is formed on the conductive supporting body 10 of the toner carrier 9. By making the electrical resistivity R of the insulating layer 11 R > 10<12>OMEGAcm, electric charge can be prevented from escaping from electrostatically charged toner 8. Besides, by making the film thickness (d) of the insulating layer 11 on the toner carrier 9 d > 15mum, an impressed developing bias can be made relatively a low voltage. Then, the electrostatic charge of the toner and the regulation of the carrying quantity of the toner are executed at the same time. Thus, only the toner 8 having the prescribed electric charge can be made into a thin layer and carried to a developing part. Besides, an image whose density is changed a little is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device that performs development using non-magnetic toner.

[Prior Art] A conventional developing method or apparatus is disclosed in USP-261855.
2 and USP-2846333, and USP-3909258 and USP-412193.
1. From the one-component magnetic development method represented by JP-A-56-14264 and its improvement, to the one-component non-magnetic development method represented by JP-A-57-114163, and the one-component non-magnetic development method typified by JP-A-63-91000. Various methods have been devised, including contact development methods.

[Problem to be solved by the invention] However, in the above-mentioned conventional technology, in the case of the two-component development method,
Although clear images can be obtained due to the developing electrode effect, there are problems in that the temperature of the carrier needs to be controlled and the image is distorted due to the scraping effect of the carrier. In addition, in the case of the -component magnetic development method, although the carrier problem of the two-component development method has been solved, high positional accuracy of each component is required to obtain a clear image, and it is difficult to color the magnetic powder. Therefore, there was a problem in that it was extremely difficult to form a color image. Furthermore, in the case of the -component non-magnetic development method, not only is the cost high because the toner transport body has a special function, but also the contact development method causes toner to adhere to non-image areas, degrading the image quality. There was a problem.

SUMMARY OF THE INVENTION The present invention aims to solve these problems, and its purpose is to provide an image forming method and an image forming apparatus that can stably obtain high image quality using a one-component non-magnetic development method. be. Still another object is to provide an image forming method and an image forming apparatus that are capable of controlling the amount of charge on toner that contributes to image temperature.

[Means for Solving the Problems] The developing device of the present invention includes a latent image carrier that forms an electrostatic latent image, and a toner image forming member disposed adjacent to the latent image carrier. The toner conveying body includes a toner conveying body, a toner conveying amount regulating means disposed adjacent to the toner conveying body, and a means for applying a voltage between the toner conveying body and the toner conveying amount regulating means, In a developing device for making the electrostatic latent image visible by electrostatically adhering the toner on the toner carrier to the latent image carrier, the toner carrier has a film on the conductive support. It is characterized by forming an insulating layer having a thickness d>15 μm and a resistance value R>10'2 Ωam.

[Function] According to the above-described structure of the present invention, it is possible to apply a high electric field to the toner near the insulating layer of the toner transporting body by the electric field generating means to induce electric charge and charge the toner. The charged toner adheres to and is transported by the toner transport member due to electrostatic mirror image force with the toner transport member. At this time, by setting the resistivity R of the insulating layer constituting the surface of the toner conveying body to R>10<12 >ΩCm, it is possible to prevent the charge from escaping from the charged toner. The conveyed toner is affected by the electric field applied between the toner conveying body and the latent image bearing body at a portion where the latent image bearing body and the toner conveying body are adjacent to each other, depending on the potential contrast of the latent image bearing body. It adheres to the latent image carrier and forms an image. The developing bias applied here can be made relatively low by setting the thickness d of the insulating layer on the toner conveying member to d>15 μm. Furthermore, toner charging and toner conveyance amount are simultaneously controlled, and only toner having a predetermined electric charge can be made into a thin layer and conveyed to the developing section, making it possible to form an image with less fluctuation in hot water temperature.

Hereinafter, the present invention will be explained in detail with reference to Examples.

[Embodiment] FIG. 1 is a cross-sectional schematic diagram of an image forming apparatus in an embodiment of the present invention. In the figure, reference numeral 1 denotes a latent image carrier, which has a photoconductive layer 3 coated on a conductive support 2. After the photosensitive layer 3 is charged with a charger 4 to a predetermined potential, the light emitted from a light source 5 such as a laser is scanned using a rotating polygon mirror (not shown), and an imaging optical system 6 scans the light emitted from a light source 5 such as a laser. An electrostatic latent image is formed on the latent image carrier 1 by forming an image on the photosensitive layer 3 to obtain a potential contrast. On the other hand, 7 in the figure
1 is a developing device that charges toner 8, which is an image forming body, and transports it with a toner transport body 9. The toner conveying body 9 includes a conductive support 10 and a thin insulating layer 11 formed thereon. Adjacent to the toner transport body 9, an electrically conductive, cylindrical sleeve 12, which is a toner transport amount regulating member, and a conductive, flat blade 13, which is also a toner transport amount regulating member, are disposed, and a voltage applying means 14. are between the conductive support 10 and the sleeve 12 and between the conductive support 10 and the sleeve 12, respectively.
and the blade 13. The voltage applying means generates a high electric field in the gaps between the sleeve 12 and the toner transport body 9, and between the blade 13 and the toner transport body 9,
Charge is injected into the toner 8 from the sleeve 12 or the blade 13 while the insulation resistance of the toner 8 is lowered to charge the toner 8 to a predetermined amount of charge. The toner 8 not attached to the toner conveying body 9 but attached to the sleeve 12 is deposited in the gap.
In order to prevent the particles from agglomerating or clogging the voids, they are removed by a scraper 15. sleeve 1
The toner 8 that has passed through the toner 2 and the blade 13 is charged, is held by the toner conveying body 9 by electrostatic image force, and is conveyed, approaching the development gap (the part where the latent image bearing body 1 and the toner conveying body 9 are close to each other). A developing electric field is generated according to the potential contrast of the electrostatic latent image on the latent image carrier 1 by the voltage applied between the supporting part 2 and the conductive support 10 by the developing bias applying means 16, and the electric charge is removed. Toner 8 held
flies toward the electrostatic latent image on the latent image carrier 1 and adheres in accordance with the potential contrast to visualize the latent image. Furthermore, the toner 8 adhering to the latent image carrier 1 is electrostatically transferred onto the recording paper 18 by the transfer device 17, and the toner 8 is fixed on the recording paper 18 by means such as pressure or heating to obtain a desired image. It is.

In FIG. 1, the potential of each part is -300V for the conductive support 10, Ov for the support part 2 of the latent image carrier 1;
Sleeve 12 is -900V, blade 13 is -900V
The gap between the latent image carrier 1 and the toner transport member 9 is 0.2 mm, the gap between the toner transport member 9 and the sleeve 12 is 0.3 mm, and the gap between the toner transport member 9 and the blade 13 is set to 00 V. When the gap is set to 0°15 mm, a toner image with high contrast and high density gradation can be formed, and when a semiconductor laser is used as the light source 5, a toner image with high resolution and excellent area gradation can be formed. I was able to form an image.

Further, in FIG. 1, the arrows indicate the rotation directions of the respective members, but this does not limit the present invention, and the above-mentioned numerical values also do not limit the present invention. The method of constructing the photosensitive layer is not limited to that shown in this figure.

Example 1 In this example, a non-magnetic one-component toner having a volume average particle diameter of 10 μm and containing carbon black and a styrene-acrylic copolymer as the main components was used as toner 8. The insulating layer 11 of the toner transport body 9 is made of resin having a dielectric constant of 2 to 4. In the image forming apparatus using the developing device configured as described above, the thickness of the insulating layer 11 of the toner transport body 9 is changed,
The lowest value of the developing bias that would give an average optical density of 1.4 when printing 10 solid black sheets on plain paper was measured.

FIG. 2 is a schematic diagram of the lowest limit of developing bias with respect to film thickness. 20, 21, and 22 in FIG.
3. Measurements were made using a toner conveying body provided with an insulating layer of No. 4. In addition, the voltage indicated by v1 in the figure is 1000 (V
), and a development bias higher than this is not practical. That is, FIG. 2 shows that the optical density that can be obtained at a practical level of developing bias is 15 μm.

Example 2 Also in this example, toner 8 was a non-magnetic one-component toner containing carbon black and a styrene-acrylic copolymer as main components and having a volume average particle diameter of 10 μm. In the developing device configured as described above, toner conveying bodies 9 whose insulating layers 11 have the same dielectric constant but different resistivities are prepared, and the toner conveying bodies 9 and sleeve 12 are rotated to remove the toner adhering to the toner conveying bodies. The amount of charge was measured on the sample that had been moved to the development position. FIG. 3 is a schematic diagram of the amount of charge of the toner with respect to the resistivity of the insulating layer. 31st! l is the resistivity R
However, when R<1012 Ωcm or less, the blocking property is low and the charge of the charged toner escapes, indicating that an image with sufficient density cannot be obtained.

The present invention can be widely used as an electrophotographic developing device, and can be applied to copying machines, printers, facsimile machines, displays, etc.

[Effects of the Invention] As described above, according to the present invention, an electric field is applied to the toner by an electric field generating means between the toner transport amount regulating member and the conductive support having an insulating layer on the surface to charge the toner. By transporting and developing the toner, an image forming apparatus using a one-component non-magnetic toner can be realized which has a simple structure, low cost, and easy maintenance. By setting the thickness d of the insulating layer on the toner transport body to d>15 μm, an image can be formed with a relatively low developing bias. In addition, by setting the resistivity R of the insulating layer to R>10"9cm, it is possible to prevent the charge from escaping from the charged toner, supplying toner with a stable charge amount to the latent image carrier, and achieving high quality. This has the effect of enabling image formation.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional schematic diagram of a developing device in an embodiment of the present invention. FIG. 2 is a schematic diagram of the lowest limit of developing bias with respect to film thickness. FIG. 3 is a schematic diagram of the amount of charge of the toner with respect to the resistivity of the insulating layer. Latent image carrier Toner Toner carrier Conductive support Insulating layer Sleeve Blade Voltage application means

Claims (1)

[Claims] a latent image carrier that forms an electrostatic latent image; a toner carrier disposed adjacent to the latent image carrier that transports toner serving as an image forming body; and a toner carrier disposed adjacent to the toner carrier. and a means for applying a voltage between the toner conveying body and the toner conveying rate regulating means, and the toner on the toner conveying body is electrostatically held in the latent image. In a developing device that visualizes the electrostatic latent image by adhering it to a body, the toner conveying body is formed on a conductive support, the film thickness d is d>15 μm, and the resistivity R is R>10. ＾1＾2Ωc
A developing device characterized by forming an insulating layer of m.