JPH03288868A - Image forming device - Google Patents

Abstract

PURPOSE:To uniformize the contact of a developing surface and to realize thin layer developing without irregularity by using a conductive elastic sleeve and executing contact and pressurizing developing to a developed image forming part. CONSTITUTION:The conductive elastic sleeve 2 is used as a toner carrier at a developing time and the contact and pressurizing developing is executed to the developed image forming part. That means, the surface of a drum is formed of a dielectric body 9 and the conductive substrate 10 of the inside thereof is grounded. Then, photoner (photoconductive toner) triboelectrified by a magnetic brush of two components 1 is made into a thin layer to the sleeve 2 according to the intensity of an electric field. By the photoconductive toner (photoner) which is made the thin layer, the sleeve 2 and the drum are brought into contact with each other and a developing electric field is impressed between them. Then, photoirradiation is executed by an exposure system 3 and an image is formed. Thus, the contact between the sleeve and the developed image forming part is uniformized and the uniform thin layer developing is realized. As the result, the clear image is obtained with excellent reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus using photoconductive toner that can be applied to printers, copying machines, facsimile machines, and the like.

[Prior Art] As an image forming apparatus using conventional photoconductive toner,
Japan Display' 86 p56
As shown in Fig. B, there is a method of applying a layer of leuco dye on a conductive substrate, irradiating it with light, forming an image, and then coloring the leuco dye on clay paper. ), there is a method of transferring toner to an intermediate transfer member once, and then transferring the insulating toner to plain paper, as shown in Japanese Patent Laid-Open No. 60-138566.

In addition, as a contact pressure type developing method, Japanese Patent Application Laid-Open No. 58-214
As shown in No. 176, there was an insulating toner developing method in which microelectrodes were floating on an elastic sleeve.

[Problems to be Solved by the Invention] However, the following problems have been pointed out in conventional photoconductive toners and image forming apparatuses using photoconductive toners, and solutions are desired.

As seen in conventional technology, one layer is coated on a conductive substrate and irradiated with light to form a latent image, which is then transferred using the difference in charge, or the conductive toner is removed using an intermediate transfer member. In this method, it is difficult to separate the toner sufficiently, which causes smearing, and furthermore, in normal printing, toner is rapidly consumed, leading to high costs. Furthermore, especially in the latter process, the steps are complicated, and a method that allows printing through simple steps is desired.

The toner used in the contact-pressing development method is limited to insulating properties, and the process itself requires time and effort to form electrodes, and the process itself is mechanically similar to conventional ones.

The present invention has been made to solve the above problems, and its purpose is to make it possible to obtain clear images with good reproducibility using a simple method and regardless of the transfer recording paper. be. Furthermore, the contact between the sleeve and the image forming section is made uniform, and uniform thin layer development, which is a characteristic of conductive toner development, is made possible.

[Means for Solving the Problems] The image forming apparatus of the present invention is characterized in that a conductive elastic sleeve is used as a toner conveying member during development, and development is carried out by contact and pressure with respect to the image forming section. In addition, the conductive elastic sleeve is characterized by using a JIS hardness of 20 to 40'' and a specific resistance of 106 Ωcm or less. In the image forming process, the irradiated toner has a low resistance and is basically injected with charge from a conductive substrate.

Normally, photoconductive toner is insulative in the dark, so if the toner has a multilayer structure (such as a one-component magnetic brush), it will not be able to receive charge injection from the substrate.

Therefore, the toner is thinned into one or two layers in the form of a conductive substrate, brought into contact with a dielectric, and irradiated with light while applying a bias to inject charge into the toner, causing it to adhere to the dielectric.

At that time, an air gap exists depending on the degree of contact between the substrate and the dielectric surface, reducing the effective developing electric field applied to the toner, and making the contact uniform because a conductive path may or may not be formed. This leads to uniform development adhesion. By using the conductive elastic sleeve of the present invention, pressure is applied to the image forming surface so that the toner receives charge injection while being in uniform contact with the toner, so the charge injection is distributed to each thin layer of toner, resulting in uniform adhesion.・Development is now performed. As a result, it is possible to obtain an image forming device that can print in a simple process using photo-4-electrode toner without causing scattering or blurring during development or complicating the process as in the past. became.

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

[Example] Photoconductive toner (hereinafter referred to as FO) used in the present invention. ) is shown below. Basically, photoconductive pigments, sensitizers, binding and fixing resins, and colorants are used.

The following photoconductive pigments are used.

Zinc oxide, titanium oxide, zinc sulfide, selenium, cadmium sulfide, α-silicon.

Any dye can be selected as the sensitizer depending on the photoconductive agent and the sensitive wavelength range. For example, triphenylmethane dye, diallylmethane dye, monomethine cyanine, trimethine cyanine, pentamethine cyanine, heptamethine cyanine,
styryl dye, oxonol, merocyanine, complex cyanine, azenium dye, azo dye, anthraquinone dye,
Indigo dyes, vinylene dyes, and azomethine are used.

Examples of these types of dyes include rose bengal, acridine orange, rhodamine B, erythrosin, eosin, fluorescein, brilliant green, crystal violet, and the like.

The following can be used as the coloring agent.

Nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, pont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate,
Lambeau Lac, Oil Black, Azo Oil Black, Rose Bengal, Crystal Violet, Rhodamine B.

Known insulating thermoplastic resins can be used as the binding and fixing resin, including acrylic resins such as polyacrylate and polymethacrylate, and copolymers thereof;
Styrene resins such as polystyrene, poly-1 to methylstyrene and their copolymers, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polyvinylidene fluoride, polyester resins and their copolymers, polycarbonate resins, cellulose resins, polyarylates Resins can be used alone or in combination.

Furthermore, the following materials can be used for the conductive elastic sleeve, which is a feature of the present invention.

NBR (acrylonitrile butadiene rubber), CR (
chloroprene), silicone, urethane.

Specific examples of the present invention are shown below, but it goes without saying that the present invention is not limited thereto.

[Example 1] The composition and manufacturing method of the toner used in the process of the present invention are shown below.

Zinc oxide...40] ifi part Sensitizing dye...0.04 parts by weight Ethyl alcohol...80 parts by weight As the sensitizing dye, considering a semiconductor laser as a light source,
A cyanine dye with the following structure was used.

The above materials were mixed and uniformly dispersed and adsorbed using ultrasonic waves.

After adsorption, the solvent ethyl alcohol is removed by centrifugation to obtain dried dye-adsorbed zinc oxide.

Next, the following materials were dissolved in a toluene solvent to prepare a colored resin solution.

Acrylic resin...40 parts by weight Black dye-1...20 parts by weight Black dye-1 has the property of transmitting near infrared light and is the second
As shown in the figure, it has a naphthalene ring and an azo coupling, Me is Cr, xl, and Xs are long chain methyl groups,
The one in which x2 and XJ are long-chain ethyl groups was used.

The above-mentioned dye-adsorbed zinc oxide is added to this solution, and further subjected to ultrasonic dispersion so that it is uniformly dispersed in the resin. In this manner, a dispersed raw material solution was prepared to have a solid content of 15%, and a phototoner having a thickness of about 10 μm was prepared by spray drying.

Next, FIG. 1 schematically shows the process of an image forming apparatus using the phototoner of the present invention. The basic structure consists of a drum, a two-component developer, a conductive elastic sleeve, a writing optical system, a corona transfer device, a heat roll, and a cleaning brush.

Next, the process will be explained. The drum surface is formed of a dielectric material 9, and the inner conductive substrate 10 is grounded. The phototoner triboelectrically charged by the two-component magnetic brush 1 is formed into a thin layer on the conductive elastic sleeve 2 according to the electric field strength. This thin layered phototoner is brought into close contact with the conductive sleeve 2 and the drum, a developing electric field is applied therebetween, and an exposure system 3 irradiates the phototoner with light to form an image. The sleeve used this time is JIS
The hardness was 40', the specific resistance was 104 Ωcm, and the nip width when brought into close contact was about 2 nm. Furthermore, since the exposure system uses zinc oxide sensitized to near-infrared rays using a sensitizing dye, an inexpensive semiconductor laser can be used as the light source.

During light ablation, only the electrically conductive toner is injected with charge and further adhered to the dielectric surface. At this time, the phototoner was set to receive a positive charge from the conductive elastic sleeve 2. In the transfer section, an image is formed on the paper by normal electrostatic transfer using corona through the plain paper 8.

The transit time of the paper through the corona transfer section is approximately 0 from the process speed.
．． It was 15 seconds. Next, it is permanently fixed using a heat roll 6. The toner remaining on the drum is removed by a cleaning brush 7. When an image was actually formed through this process, a printing speed of 20 PPM was obtained at a resolution of 300 DPI. For the black solid image, O and D values of 1.5 or more were ensured. In addition, good images were obtained with good reproducibility in 10,000 printing tests. The number of light stars in the exposure system at this time is 10
Writing was performed at erg/cm2. In this method, development and exposure are performed simultaneously, increasing speed, and since only one layer is developed by charge injection, it is possible to print with clear images without background smearing. In addition, clear printing with good reproducibility indicates that the toner's fixability to plain paper and the black printing temperature are functioning as desired.

[Example 2] A phototoner was prepared using zinc oxide in the same manner as in Example 1, and process experiments were conducted using various conductive sleeves.

As a comparative example, a case using an aluminum sleeve is also shown. The results are shown in Table 1. In this case, the sleeve dimensions are: sleeve length 23cm, sleeve axis φ5mm, sleeve diameter φ20
It was done in mm.

Needless to say, if the thickness of the elastic body changes, the degree of freedom in the hardness of the rubber used changes.

As can be seen from this Table 1, the JIS hardness is 20~
When a material within the range of 40° was used, development was uniform and clear printing was possible.

When the hardness is 50° or more, the current elongation decreases, resulting in a low print density, and when an aluminum tube is used, the contact is uneven and the prints have many hollow holes.

[Example 3] Process experiments were conducted using the same photoner as in Example 1 and varying the specific resistance of the elastic sleeve. The results are shown in Table 2. The sleeve dimensions were the same as in Example 2, and the material was silicone rubber.

Table 1 Table 2 As you can see from this second table, the specific resistance is 106Ωcm
If the value exceeds 100%, charge injection cannot be done in time for the process speed, and development becomes non-uniform.

[Example 4] The process of the present invention is also applicable to color printing. The composition of each color phototoner is shown below. As for the structure, the surface has a composition with an excess of zinc oxide for photoresponsiveness, and the inner core is a double-structured microcapsule type with an excess of resin to ensure fixation.

The composition and manufacturing method of the micro-buself toner are shown below.

Basic composition Core resin: Styrene sphere Colorant Photoconductive agent: Zinc oxide sensitizing dye Outer shell binding resin: Butyral resin The colorant and sensitizer in each color toner are as follows.

Cyan toner colorant: copper phthalocyanine sensitizer: NK1870, phthalic anhydride magenta toner colorant: quinacridone sensitizer: tetrabromophenol blue phthalic anhydride yellow toner colorant: disazo Sensitizer: rose bengal, phthalic anhydride First, styrene particles with a particle size of 10 μm are dyed directly in an alcohol solution of a coloring agent to form inner core particles 11.

Next, prepare the following solution.

Zinc oxide: 75 parts by weight Sensitizer: 0.075 parts by weight Ethyl alcohol: 100 parts by weight Butyral resin: 25 parts by weight First, the above materials were mixed except for the resin, and then treated with ultrasonic waves. Uniformly dispersed and adsorbed.

Next, a resin is added to this dispersion liquid and subjected to ultrasonic dispersion in the same manner to prepare a zinc oxide dispersed resin solution. Furthermore, inner core particles are added to this resin solution and subsequently uniformly dispersed using ultrasonic waves. In this manner, the raw material solution was prepared to have a solid content of 20%, and a phototoner whose surface was coated by a spray drying method was prepared. Approximately 1 μm according to electron microscope observation
It was confirmed that the zinc oxide dispersed film 12 was coated with a thickness of . FIG. 3 shows a schematic cross-sectional view of the microcapsule type photoner produced in this example.

The outer photosensitive layer 12 of the microcapsule phototoner is not limited to the pigment-dispersed type as in this embodiment, but may also be of any type, such as a pigment-only or a resin-only photosensitive layer, such as a lever structure. Needless to say.

The above three color toners were placed in a two-component developer 1, triboelectrically charged while being mixed, and randomly formed into a thin layer on a conductive sleeve 2. A light source that has read the original is irradiated onto the sleeve, and three-color toner corresponding to R, G, and B light is developed on the dielectric surface while a developing electric field is applied. The process is basically the same as in Example 1, where only the toner made conductive by light irradiation receives charge injection and is further developed on the drum.

In the transfer section, an image is formed on the paper by normal electrostatic transfer using corona through the plain paper 8. When an image was actually formed through this process, 32 gradations and a printing speed of 5 PPM were obtained. The black solid image was secured with a D value of 1.5 or more, and good images were obtained with good reproducibility after 10,000 printing tests. The light amount of the exposure system at this time was 10erg/
Writing was done in cm2. In this way, it has become possible to easily obtain color images with good reproducibility.

Although the embodiments have been described above, the process using the photoner of the present invention is applicable not only to the above embodiments but also to all processes using photoconductive toner.

[Effects of the Invention] As stated above, according to the present invention, a conductive elastic sleeve is used as a toner transporting member during development, and contact pressure development is performed on the developing area to prevent contact on the developing surface. It became possible to achieve uniformity. In addition, by using a conductive elastic sleeve with a TIS hardness of 20 to 40'' and a specific resistance of 10'Ωcm or less, the air gap between the photo-toner on the sleeve and the image forming section is reduced, and the individual photo-toners are charged. By spreading the injection evenly, it became possible to develop a thin layer without unevenness.

If the printing process according to the present invention is used, it is possible to provide an image forming apparatus that is small, simple, and can produce clear images with good reproducibility.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a process using the image forming method of the present invention. FIG. 2 is a diagram showing the composition of the black dye used in the photoconductive toner of the present invention. FIG. 3 is a diagram showing the cross-sectional structure of the photoconductive toner of the present invention. 1. Two-component magnetic brush developer 2. Conductive elastic sleeve Exposure system Photoner Corona transfer device Heat roll Cleaning brush Plain paper drum Dielectric surface drum Conductive substrate

Claims (2)

[Claims] (1) In an image forming method using photoconductive toner, which includes a means for developing the toner by irradiating light and a means for transferring the developed toner to recording paper, a conductive elastic sleeve is used as a toner transporting body during development. . An image forming apparatus characterized in that contact pressure development is performed on a developing image forming section. (2) JIS hardness 20-40 as conductive elastic sleeve
2. The image forming apparatus according to claim 1, wherein the image forming apparatus uses an image forming apparatus having a specific resistance of 10^6 Ωcm or less.