JPH03259284A - Image forming device - Google Patents

Abstract

PURPOSE:To develop one component magnetic toner with high-resolution and high-density without having tailing and irregularities in a density by specifying the value of the ratio of the circumferential speeds of a thin film member and a latent image carrier, and the minimum magnetization inverting interval of a magnetic field generating layer. CONSTITUTION:A developing roller 9 carrying toner 8 is composed of a driving roller 10 rotatively driven and having a frictional part, etc., on an outer periph ery and a cylindrical thin film member 11 whose excess length is left and which is armored on the outer periphery of the driving roller 10, and the magnetic field generating layer 12 is disposed on the cylindrical thin film member 11. The value Vd/Vp of the ratio of the circumferential speed Vd of the thin film member 11 of the developing roller 9 and the circumferential speed Vp of the latent image carrier is set >= 1 and <= 5, and the minimum magnetization inverting interval of the magnetic field generating layer is set <= 500(mum). Thus, the one-component magnetic toner is developed with the high-resolution and high-density without having the tailing and the irregularities in the density.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image forming apparatus using a one-component magnetic toner, and more specifically, the present invention relates to an image forming apparatus that uses a one-component magnetic toner, and more specifically, the one-component magnetic toner is conveyed by a developing roller having a cylindrical thin film member. The present invention relates to an image forming apparatus that performs image development.

[Prior Art] As disclosed in Japanese Patent Application Laid-Open No. 64-65579, a conventional image forming apparatus uses an excess portion of a sleeve of a cylindrical thin film member having an excess circumference with respect to a drive roller to elastically attach it to a photoreceptor. It was also possible to transport and develop non-magnetic toner by bringing it into close contact with the toner.

[Problem M to be solved by the invention] However, in the above-mentioned conventional technology, the force for holding the toner on the developing roller is based on electrostatic mirror image force and adhesive force, so it is difficult to make the amount of toner conveyed uniform. there were. In addition, when toner is developed on a latent image carrier such as a photoconductor, uncharged toner or toner with a non-regular polarity is developed in non-image areas, resulting in an image with a significant amount of blurring on the latent image carrier. Since only toner of the correct polarity is transferred to the recording paper, an image without blurring can be obtained on the recording paper, but due to the blurring of the toner, the resolution decreases, and some toner is not transferred and is wasted unnecessarily. In many cases, not only is the resolution low and uneconomical, but also an excessive amount of space is required for the waste toner container, making the image forming apparatus larger.

The present invention is intended to solve these problems, and its purpose is to provide an image forming apparatus suitable for developing one-component magnetic toner with high resolution and high density without trailing or temperature unevenness. It's there to provide. Still another object is to provide an image forming apparatus that stably forms a thin layer of toner on a magnetic developing roller, has stable toner transport I, and has less temperature unevenness. Still another object is to provide an image forming apparatus that causes less contamination due to toner scattering and can reduce unnecessary waste toner. Still another object is to provide an image forming apparatus that is simple in structure, small in size, and low in cost.

[Means for Solving the Problems] An image forming apparatus of the present invention is an image forming apparatus in which a developing roller conveys a one-component magnetic toner and develops the one-component magnetic toner onto a latent image carrier. a thin film member and a driving roller that contacts at least a portion of the inner circumferential side of the cylindrical thin film member, the thin film member has at least a magnetic field generating layer, and the peripheral speed Vd of the thin film member of the developing roller and the latent image Ratio value Vd to the peripheral speed Vp of the carrier
/Vp is 1 or more and 5 or less, and the minimum magnetization reversal interval of the magnetic field generation layer is 500 [μm] or less.

[Function] According to the above structure of the present invention, the structure of the developing roller is simplified by conveying the toner near the surface of the thin magnetic field generating layer and constructing the developing roller with a single rotating body. However, it is possible to obtain a small, lightweight, and low-cost developing roller. In addition, by magnetizing the thin magnetic field generation layer at a minute pitch to reduce the minimum magnetization reversal interval, a uniform and thin toner layer (or a thin layer of magnetic brush at a minute pitch) is formed on the developing roller. It is possible to perform development with excellent reproducibility of fine lines and isolated dots.

Furthermore, by setting the circumferential speed ratio between the developing roller and the latent image carrier to 1 or more and 5 or less, it is possible to ensure the amount of toner conveyed to obtain sufficient image density. It is possible to reduce the adhesion of toner to the edge of the image) and tailing (adhesion of unnecessary toner to the edge of the image).

Furthermore, in addition to applying a magnetic binding force to the toner on the developing roller, the fine magnetic binding force enables stable thinning and stable development prevention during development, resulting in high-density images with less blurring. can be formed.

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

[Example] FIG. 1 is a cross-sectional schematic diagram of an image forming apparatus in an example of the present invention, in which a latent image carrier 1 has an organic or inorganic photoconductive material on a conductive support part 2. It is coated with a photosensitive layer 3 and rotates at a circumferential speed Vp. After the photosensitive layer 3 of the latent image carrier 1 is charged using a charger 4 such as a corona charger or a charging roller, light B from a laser or LED is applied.
The light emitted from the photosensitive layer 15 is selectively irradiated onto the photosensitive layer 3 according to the image through the imaging optical system 6 to obtain a potential contrast and form an electrostatic latent image. On the other hand, the developing device 7 uses magnetic toner 8.
The developing roller 9 that conveys the toner 8 is a driving roller 10 that is rotatably driven and has a friction portion on its outer periphery, and a cylindrical roller that is sheathed with an extra length left on the outer periphery of the driving roller IO. A magnetic field generating layer 12 is disposed on the cylindrical thin film member 11, and the magnetic toner 8 is held directly on the developing roller 9 by leakage magnetic flux around the outer periphery of the magnetic field generating layer 11. Thin spring-like elastic blade 1 made of non-magnetic or magnetic metal or resin
3, the thin film member 11 constituting the developing roller 9 is rotated at a circumferential speed Vd (or may be moved at a linear speed Vd) to convey the thin layer of toner 8. The developing roller 9 is pressed against the latent image carrier 1 with a predetermined pressure, and when the toner 8 on the developing roller 9 is conveyed to the pressure contact portion, the potential contrast of the latent image carrier 1 and the developing bias applying means 14 are applied. Toner 8 charged according to the developing electric field adheres to the latent image carrier 'l, and the electrostatic latent image is visualized.

Further, a toner image is transferred onto the recording paper 16 using a transfer device 15 such as a corona transfer device or a transfer roller, and the toner is fixed on the recording paper using heat or pressure to obtain a desired image on the recording paper. It is. The pressure with which the developing roller 9 is pressed against the latent image carrier is approximately 0.5 [kgf] to maintain a stable developing state.
is not limited to an elastic blade, and a known toner transport amount regulating member such as a rigid blade may be used. Using an image forming apparatus as shown in FIG. 1, using a laser beam writing head of 600 [DPI], and using a developing device having a developing roller with a minimum magnetization reversal interval of about 80 [μm] in the magnetic field generation layer, When line images, character images, and solid images were continuously formed on 10,000 sheets, 600
The [DPI] line image is stably formed without line thickening, and the resolution of the line image is sufficiently large.
It is possible to stably form a high-density solid image of ○D@1.4 or higher without any trailing or background blurring at the edges of the image, and there is no background blurring on the recording paper, as well as on the latent image carrier. There was also no soil blurring, and the amount of waste toner was significantly reduced.

In FIG. 1, the drive roller 10 has a resin or metal shaft with natural rubber, silicone rubber, urethane rubber, etc.
Butadiene rubber, chloroprene rubber, neoprene rubber,
A friction part is provided using NBR or the like, and the thin film member 1
1 is pressed against the drive roller 10 to transmit rotational driving force.

Further, the thin film member 11 can be made of a metal thin film such as phosphor bronze, stainless steel, or nickel, or a resin thin film material such as nylon, polyimide, or polyethylene terephthalate.
The thickness of the thin film member 11 varies depending on the material, but in order to obtain sufficient pressure contact with the latent image carrier, it is 10 to 500 [μm].
Furthermore, the magnetic field generation layer 12 can be made of a known magnetic recording material or magnet material, and more specifically, Fe, Ni, Co,
Magnetic materials containing at least one element among Mn, such as y-Fe203, Ba-Fe, Ni-
Co, Co-Cr, Mn-A1, etc. can be used, and the film thickness is 100 [μm] or less, preferably around 10 [μm], and the minimum magnetization reversal interval is 500 [μm] or less, preferably 100 [μm]. By using the following method (horizontal magnetization or perpendicular magnetization may be used), it is possible to uniformly thin the toner, and at the same time suppress fluctuations in the amount of toner conveyed on the developing roller due to magnetic brush formation to a minute pitch, thereby reducing temperature unevenness. , the peripheral speed Vd of the developing roller and the peripheral speed Vp of the latent image carrier
By setting the speed ratio of It eliminates image disturbances caused by the relative speed of the latent image carrier and supplied toner without supplying excessive toner to the body, and reduces trailing caused by toner adhering to the edges of text and thin line image areas, and significantly improves image quality. Even if a large amount of toner is supplied to the latent image carrier, the toner is retained on the developing roller by magnetic binding force, and an image with high area gradation can be formed with less background blur in non-image areas. Further, as the toner used in the present invention, all toners known as one-component magnetic toners can be used, and the composition of the developer may be either resin-based toner or wax-based toner, as is known in the art. It is made by adding magnetic powder, colorants, external additives, and other additives to resin, and is created by pulverization or polymerization methods.

In addition, in FIG. 1, the present invention is not limited only to the configuration in the figure, and although the arrows indicate the rotation direction of each member, the present invention is not limited to the present invention.Furthermore, the developing method is also It can be used regardless of whether it is regular development or reversal development.

FIG. 2 is a schematic cross-sectional view B of a cylindrical thin film member in an embodiment of the present invention, in which a magnetic field generation layer 22 is provided on the thin film member 21, and a conductive layer 23 is provided on the magnetic field generation layer 22. This is what I did. The minimum magnetization reversal interval of the developing roller is 500 [μm] in order to reproduce clear fine lines and isolated dots even if the minimum dot pitch in optical writing is 100 [μm] or less.
μm] or less (around 80 μm1 in the figure), toner 2
By uniformly forming the thin layer No. 4 on the surface of the developing roller, it is possible to improve the reproducibility of fine lines and isolated dots due to uneven conveyance of the toner 24, and temperature unevenness can hardly be discerned visually. However, if the minimum magnetization reversal interval is 500 [μ
When m1 or more is, for example, 1000 [μm], temperature unevenness in the solid image area is clearly confirmed even by visual inspection, and the number of area gradations by the dither matrix of 4 dots vertically and 4 dots horizontally can only be sWi scale or less, resulting in a gradation image. becomes difficult to reproduce. A minute toner chain of toner 24 is formed on the conductive layer 23 by the magnetic field generated by the magnetic field generation layer 22, resulting in a thin and stable toner layer. Moreover, by adopting such a layer configuration, a developing bias voltage can be applied to the conductive layer 23 to improve the developing electrode effect and obtain a high-resolution image. Furthermore, if such a layer structure is adopted, 6
00 [DPI] high resolution line image and OD value l.

A solid image with a high density of 4 or more can be formed. Note that the arrows in the figure indicate the direction of magnetization, and the direction of the magnetic field generation layer 22
may be a perpendicular magnetization film.

The present invention has been explained above using Examples, but regarding the layer structure of the thin film member of the developing roller, in addition to the magnetic field generation layer, a conductive layer or an insulating layer may be appropriately disposed to improve the developing electrode effect. The chargeability of the toner can be improved, and in addition, a protective layer can be provided to improve durability, and an intermediate layer can be provided to improve moldability. Furthermore, the magnetic field generation layer of the developing roller can be used in various magnetized states such as line magnetization, lattice magnetization, and spiral magnetization. A stable thin toner layer can be formed on the developing roller by magnetizing the toner so that the reversal interval is sufficiently small (for example, 100 [μm] or less). Further, the magnetization may be carried out directly on the developing roller, or a film-like magnetic field generating layer may be previously magnetized and appropriately disposed on the developing roller by means such as adhesion.

Although the embodiments have been described above, the present invention can be applied not only to the above embodiments but also to a wide range of image forming apparatuses that use magnetic toner, especially when applied to printers, copiers, facsimiles, and displays. It is valid.

[Effects of the Invention] As described above, according to the present invention, the developing roller has at least a cylindrical thin film member, the thin film member has at least a magnetic field generating layer, and the peripheral speed of the thin film member constituting the developing roller is Value of the ratio between Vd and the peripheral speed Vp of the latent image carrier Vd/V
By setting p to 1 to 5 and the minimum magnetization reversal interval of the magnetic field generation layer to 500 [μm] or less, there is no temperature unevenness, excellent reproducibility of fine lines and isolated dots, and high resolution and high quality images. This has the effect of providing an image forming apparatus that can be stably formed and is suitable for developing a one-component magnetic toner with high resolution and high density without trailing or temperature unevenness. Also,
It is possible to provide a developing device and an image forming device with a simple structure, small size, and low cost.Moreover, the amount of waste toner is reduced by the magnetic binding force of minute pitch, and the pollution caused by toner scattering is also reduced, making it possible to improve running performance during image formation. It is possible to reduce costs and reduce maintenance of the image forming apparatus.

Therefore, the image forming apparatus of the present invention has the excellent effect of providing an image forming apparatus that can obtain high-resolution images with few image defects such as soil blur and temperature unevenness in one-component magnetic development. It is.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional overview of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional overview of a thin film member according to an embodiment of the present invention. 0 1 Latent image carrier developing device Toner developing roller drive roller Thin film member 2 Magnetic field generating layer and above

Claims (1)

[Claims] (1) One-component magnetic toner is conveyed by a developing roller,
In the image forming apparatus for developing the one-component magnetic toner onto a latent image carrier, the developing roller includes at least a cylindrical thin film member and a drive roller that contacts at least a portion of an inner peripheral side surface of the cylindrical thin film member. and the thin film member has at least a magnetic field generating layer, and the ratio Vd/Vp of the peripheral speed Vd of the thin film member of the developing roller to the peripheral speed Vp of the latent image carrier is 1 or more and 5 or less, and An image forming apparatus characterized in that the minimum magnetization reversal interval of the magnetic field generation layer is 500 [μm] or less.