JPH0695424A - Developing method - Google Patents

Abstract

PURPOSE:To provide a developing method for always obtaining a sharp and uniform image of a high density without base fogging. CONSTITUTION:In the developing method for forming the thin layer of one- component toner 1 supplied to the surface of a toner carrier 3 arranged near a latent image holder from a toner container 2 and supplying the toner thin layer to an electrostatic latent image held on the latent image holder, to make the electrostatic latent image visualizable, an electrifying member 14 coexists with the one-component toner 1 in the toner container 2 or at least on the surface of a toner supplying member supplying the one-component toner 1 from the toner container 2 to the surface of the toner carrier 3. At this time, it is preferable that the grain diameter of the electrifying member 14 is larger than that of toner and simultaneously, a gap between the toner carrier 3 and a toner layer forming member and moreover, the bulk density of the electrifying member 14 is preferably lower than that of the toner.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method for converting an electrostatic latent image into a visible image in an electrophotographic apparatus or an electrostatic recording apparatus, and more specifically to a single component formed on a toner carrier. The present invention relates to a developing method for developing by supplying a thin layer of toner to a latent image.

[0003]

2. Description of the Related Art A pressure developing method is known as one of developing methods using a one-component toner (developer) (US Pat.
No. 754,963, No. 3,731,146, Japanese Patent Publication No. 51-3
6070 and 52-36414). This method is elastic,
Form a thin layer of one-component developer consisting of only non-magnetic toner on the surface of toner carrier having conductivity and surface roughness, and contact this toner layer with the electrostatic latent image so that the relative speed is zero. And has many advantages such as simplification of the device and easy colorization. However, as a result of the additional test experiment by the present inventors, it was found that the above-mentioned developing method includes the following problems.

As an important feature of the above pressure developing method, it is specified that the surface of the toner layer and the electrostatic latent image are moved at a relative peripheral velocity of substantially zero. However, as a result of experiments, it was found that the developed image obtained under these conditions was poor in sharpness and was a poor image with conspicuous background fog and uneven density. On the other hand, when a speed difference is provided, rolling and slippage of toner particles occur at the contact position between the toner layer and the electrostatic latent image, which promotes charging of the toner particles and uniform image unevenness. Therefore, it is extremely sharp,
A uniform and high-density developed image was obtained without background fog.

[0005]

With respect to the above problems,
JP-B-60-12627 and JP-A-53-23638 disclose that moving the toner carrier faster than the electrostatic latent image brings about improvement in image quality. In this case, rolling and slippage of the toner particles occur at the contact position between the toner and the electrostatic latent image, which promotes charging of the toner particles and uniform image unevenness. However, the toner layer is often defective before it reaches the contact position with the electrostatic latent image.

For example, if the toner supply to the toner carrier is uneven or insufficient, or if the toner layer formed by the toner layer forming member is uneven on the surface of the toner carrier, the image quality is deteriorated, which is caused by development. There is a problem of inviting. Further, when there is no contact between the toner layer and the electrostatic latent image, rolling or slippage of toner particles does not occur, and there is a problem that an ugly image is likely to be formed. The reason for this is that in the case of a developing method using two-component toner,
While the carrier uniformly charges the toner,
It is considered that the uniform charging is difficult in the case of the developing method using the one-component toner.

The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a developing method capable of obtaining a uniform and high-density image which is always sharp and free of background fog.

[0008]

[Constitution of the invention]

[0009]

SUMMARY OF THE INVENTION According to the present invention, a thin layer of one-component toner supplied from a toner container is formed on the surface of a toner carrier disposed in the vicinity of a latent image carrier, and this thin toner layer is formed. In a developing method for converting an electrostatic latent image into a visible image by supplying the electrostatic latent image held by the latent image holding member, is a charging member mixed with one-component toner in the toner container? Alternatively, a thin layer of one-component toner supplied from a toner container by a toner supply member is formed by pressing a toner layer forming member against the surface of the toner carrying member disposed in the vicinity of the latent image holding member. Then, in the developing method in which the electrostatic latent image is visualized by supplying the thin toner layer to the electrostatic latent image held by the latent image holding member, a charging member is provided on at least the surface of the toner supplying member. And mix If necessary, the developing method is characterized in that the charging member is mixed with the one-component toner in the toner container.

In the above description, the particle size of the charging member mixed in the one-component toner in the toner container is larger than the particle size of the toner and larger than the gap between the toner carrier and the toner layer forming member. Is desirable. The bulk specific gravity of the charging member is also preferably smaller than the bulk specific gravity of the toner.

[0011]

According to the developing method of the present invention, the one-component toner is easily, surely and uniformly charged by the one-component toner in the toner container or the charging member particles mixed on at least the surface of the toner supply member. Therefore, it is possible to always obtain a sharp, uniform, high-density, high-quality image without background fog. That is, the charging member particles mixed in the one-component toner in the toner container and the charging member particles mixed in at least the surface of the toner supply member effectively play the role of the carrier in the case of the development with the so-called two-component toner. Since the one-component toner that is in contact with the electrostatic latent image and is involved in the development is positively and uniformly charged, it is possible to develop a high-quality image in a stable state.

[0012]

EXAMPLES Before describing specific examples of the developing method according to the present invention, the basic functions and effects of the present invention will be described below.
A supplementary explanation will be given.

First, when a charging member having a particle size larger than the toner particle size and larger than the gap between the toner carrier and the toner layer forming member is mixed in the one-component toner in the toner container, and / or When the bulk specific gravity of the charging member is smaller than the bulk specific gravity of the toner, it is possible to easily prevent the toner from being clogged in the gap or the pressure contact portion between the toner carrier and the toner layer forming member.

That is, in the gap or pressure contact portion between the toner carrier and the toner layer forming member, the pressure is increased by the toner, and the toner flow is separated, and the toner convection flows in the toner container. Is occurring. At this time, the particle size of the charging member is larger than the particle size of the toner and larger than the gap between the toner carrier and the toner layer forming member, and / or the bulk specific gravity of the charging member is larger than the bulk specific gravity of the toner. Is also small. For this reason, the charging member flows along with the toner flow, and the return flow becomes the main flow in the gap or pressure contact portion between the toner carrier and the toner layer forming member, and the toner carrier and the toner. It is possible to prevent the toner from being clogged at the gap or the pressure contact portion with the layer forming member.

On the other hand, when the bulk specific gravity of the charging member is smaller than the bulk specific gravity of the toner and the particle size of the charging member is smaller than the particle size of the toner, the toner carrier and the toner layer forming member are separated from each other. Although it may pass through a gap or a pressure contact portion, such a charging member having a small particle size has a large charge amount and adheres strongly to the toner carrier due to the image force, and even if it is developed on a white background portion, it is recorded. Since it hardly appears on paper, there is no problem in practical use.

If at least the surface of the toner supply member contains a charging member, the charging member is supplied to and mixed with the one-component toner in the toner container. However, it is stable even after long-term use, and it is always sharp and free from background fog, and it is possible to obtain a uniform, high-density, high-quality image. For example, the toner supply member is formed of a foam in which a charging member is impregnated or dispersed, and the impregnated or dispersed charging member is gradually separated during use and supplied / mixed with the one-component toner in the toner container. By doing so, the charge amount of the toner can be easily, reliably and uniformly maintained.

FIG. 1 is a partial cross-sectional view of a developing device used for carrying out the developing method according to the present invention. This developing device includes a toner container 2 containing a one-component toner 1 and the one-component toner 1. A toner supply member (toner supply roller) 4 that supplies toner to a toner carrier (developing roller) 3, a toner layer thickness regulating member 5 that forms a substantially uniform toner layer on the surface of the toner carrier (developing roller) 3, and the toner layer. A photosensitive drum 6 that is close to the toner carrier 3 that supports and rotates and that visualizes the electrostatic latent image carried on the surface, and a recovery plate for collecting the undeveloped toner in the toner container 2. 7, a stirrer 8 for stirring the toner 1 in the toner container 2, a spring 9 for pressing the toner layer thickness regulating member 5 against the surface of the toner carrier 3 with a constant load, the visible image Paper A transfer device 10 for transferring the support,
Charger 1 for applying a required electrostatic charge to the surface of the photosensitive drum 6
1. exposure means (not shown) for forming an electrostatic latent image,
The toner carrier 3 and the toner supply member 4 are composed of a DC power supply 12 for supplying a required current, a protection resistor 13, and the like.

The toner carrier 3 in the developing device having the above-mentioned structure is made of metal such as aluminum or stainless steel, phenol resin, acrylic resin, urethane resin, fluororesin,
A hard resin or a soft resin such as a polyamide resin, a silicone resin, a melamine resin, a polystyrene resin, a polyester resin, an epoxy resin, or a composite of these can be used, and a magnetic pole is provided inside. You may use things like a magnet roller. In this embodiment, a non-magnetic (or non-magnetized) toner carrier 3 having elasticity and conductivity will be exemplified.

As the toner carrier 3, a conductive rubber layer (for example, urethane rubber, silicone) is provided around the shaft.
Rubber, ethylene propylene rubber, NBR, chloroprene rubber, butyl rubber, etc., having conductive carbon particles, metal particles, metal fibers or the like dispersed therein to have a resistance value of 10 ⁵ Ω · m ² or less). Or its surface coated with silicone resin, urethane resin, fluororesin, etc., high resistance or insulating rubber roller surface coated with conductive resin,
Alternatively, a semi-conductive (10 ⁵ Ω · m ² or less) rubber roller provided with a conductive layer on its surface can be said to be suitable, but here, in particular, a conductive urethane is formed on the surface of an EPDM rubber roller having a hardness of 30 degrees (JIS A type). A case will be described in which an elastic conductive roller coated with a paint and adjusted so that the resistance value between the metal shaft and the coating film surface is 10 ⁵ Ω · m ² or less is used. The outer diameter of the metal shaft was 8 mm, the thickness of the conductive urethane paint was 20 to 200 μm, and the outer diameter was 18 mm.

In the above description, the toner supply member 4 is preferably a conductive sponge roller in consideration of the toner transporting ability, and is preferably, for example, urethane foam which is abrasion resistant and does not solidify when the toner enters. Such urethane foam has a density of 0.03 ~
0.06g / cm ³ , hardness 15-25kgf / cm ³ (measured by JIS K 6401 because it is 10 degrees or less for A type), tensile strength as foam 0.8-1.5kgf / cm ² , elongation rate as foam 200
~ 350%, 100 cells / 25mm or less, resistance value 10 ³ to 10 ⁶ Ωc
About m is good.

Further, the conductivity of the urethane foam or the like may be, for example, itself conductive, or a conductive agent may be added to impart conductivity, and uniform conductivity is obtained by foaming these. A foam having excellent conductivity and flexibility can be formed. Alternatively, the foam may be formed and then impregnated with conductive carbon powder or the like. Further, the toner supply member 4 does not have to be a roller type, and may be a type that applies magnetic force, for example.

Further, in the toner container 2, a one-component toner 1 and a particulate charging member 14 made of urethane foam having good abrasion resistance are contained. The urethane foam charging member 14 has a bulk specific gravity of 0.03 to 0.06.
(Toner 1 has a bulk specific gravity of 0.33 to 0.44) and hardness of 15 to 25 kgf /
cm ³ (measured by JIS K 6401 because it is 10 degrees or less for A type), tensile strength as foam 0.8 to 1.5 kgf / cm
² , foam elongation rate 200 ~ 350%, cell number 100
Pieces / 25 mm or less, resistance value of 10 ³ to 10 ⁶ Ωcm or so is preferable. The conductivity and chargeability of the charging member may be, for example, conductivity and chargeability per se, or may be added with a conductive agent and a chargeable material to impart conductivity and chargeability. Well, by foaming these, a foam having uniform conductivity, flexibility and chargeability can be formed. Alternatively, the foam may be formed and then the conductive carbon powder and the charging material powder may be impregnated. However, it is sufficient to use the charging member in an amount of about 0.5 to 50% by weight, preferably about 0.1 to 25% by weight, of the one component type toner having a size of about 0.1 to 1 mm.

Examples of the charge imparting agent include electron donating dyes (eg, azine type nigrosine, nigrosine bases, nigrosine derivatives, organic quaternary ammonium salts such as benzomethyl-hexyldecyl ammonium chloride), acrylic resins, styrene resins. And so on,
Further, an acrylic compound-organic ammonium compound copolymer may be used. These are per 100 g of the foam
About 8 g (generally 5 to 50 g) should be mixed.

As a method of developing a latent image, the latent image surface and the surface of the toner carrier 3 are brought into non-contact with each other, and the toner particles 1 are caused to fly by the developing electric field to develop the toner. Alternatively, there is a method of developing by sliding. In the case of the present invention, any method can be applied, but in the present embodiment, the case where the toner carrier 14 is brought into contact with the latent image surface will be described.

The toner layer thickness regulating member 5 is made of a plate-like polymer body having a rubber hardness of 30 to 100 degrees, the tip of which is processed into a cylindrical surface shape or a curved surface shape (cylindrical surface shape or curved surface shape). The tip end contacts the surface of the toner carrier 3 by the pressing force of the spring 9. When the tip end of the regulating member 5 has a circular arc or curve, a desired toner thin layer can be formed with a relatively low pressing force, and the toner particles 1 can be surely charged by friction. The radius of curvature of the cylindrical surface or curved surface at the tip is 0.1 mm or 20 mm, preferably 0.5 mm.
Good results are obtained at 10 mm.

In this embodiment, the case where the surface potential (unexposed portion) V ₀ of the photoconductor 6 is -500 V and the exposed portion potential V ₁ is -50 V is developed by the reversal development method. That is, background potential (white background potential) -500 V, image portion potential -5
0 V, the output of the developing bias power source 12 is applied to the conductor layer of the toner carrier 3 by -200 V, and the value of the protective resistor 13 is 10 M.
Ω, and the electric resistance value R of the toner carrier 3 is the electric field applied to the toner carrier 3 (average 0 at the minimum, 60 V / m at the maximum).
m) is 10 ⁵ Ω m ² or less, the surface speed of the toner carrier 3 is 80 mm / sec, the surface speed of the photosensitive drum 6 is 40 mm / sec, and the contact width between the toner carrier 3 and the photosensitive drum 6 is 1 to 3 mm. The toner carrier 3 and the toner layer were developed by using a negative charge type one-component non-magnetic toner composed of styrene acrylic resin, carbon black, charge control agent, wax and hydrophobic silica as the toner. Toner and the like did not become clogged in the gap or pressure contact with the thickness regulating member 5, and a sharp and uniform image having a very high density and free of background fog was obtained. Even when the environmental conditions were changed, extremely good images were similarly obtained under the developing conditions set as described above. In this case, in the toner 1 in the toner container 2, the mixing amount of the charging member is 0 with respect to the amount of the toner 1.
It was about 1 to 25% by weight.

Further, as the toner carrier 3 in the developing device, a toner carrier formed of the urethane foam having the charging property and the conductivity is used, and the negative charging type one-component non-magnetic toner is used in the initial stage. When the development was carried out under the same conditions as described above, without mixing the charging member, a uniform and extremely high-quality image free of background fog was obtained. Further, even if the environmental conditions change, under the developing conditions set as described above, the toner or the like does not become clogged in the gap or the pressure contact between the toner carrier 3 and the toner layer thickness regulating member 5, and similarly it is extremely good. An image was obtained. In this developing process, the amount of the charging member supplied to the toner is 0.05 to 1,000 per 1000 A4 size recording and printing sheets.
0.12g was supplied. Further, in this case, the same result was observed when the charging member was mixed in advance in the negative charging type one-component non-magnetic toner in the initial stage.

In the examples, the case where the non-magnetic one-component toner is used is exemplified, but the present invention can be applied to the developing method using the magnetic toner, and the elastic roller is exemplified as the developing roller. Of course, even when a hard developing roller made of resin or the like is used, a great effect is exhibited.

[0029]

As described above, according to the present invention, even if a developing device which is small, low-priced and light-weight can be used, it is possible to always obtain a good image having a uniform sharpness and no background fog, and a high density. be able to.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a developing device used for carrying out the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... One-component toner 2 ... Toner container 3 ... Toner carrier (development roller) 4 ... Toner supply member 5 ...
Toner layer thickness regulating member 6 ... Photosensitive drum 7 ... Recovery plate 8 ... Toner agitator 9 ...
Spring 10 ... Transfer device 11 ... Charging device 12 ... Development bias power supply 13 ... Protective resistance 4 Charging member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsunori Saito, 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Research Institute Co., Ltd. (72) Inventor Shuichi Sato, Komukai Toshiba Town No. 1 Incorporated company Toshiba Research Institute (72) Inventor Hiroki Takano Komukai Toshiba Town No. 1, Komukai-ku, Kawasaki City, Kanagawa Prefecture Incorporated Toshiba Research Institute (72) Inventor Yoshimitsu Otaka Nakameguro, Meguro-ku, Tokyo 2-6-13 Tokyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A thin layer of one-component toner supplied from a toner container is formed on the surface of a toner carrier disposed in the vicinity of the latent image carrier, and the toner thin layer is retained by the latent image carrier. In the developing method for converting the electrostatic latent image into a visible image by supplying the electrostatic latent image, a charging member is mixed with one-component toner in the toner container. 2. A thin toner containing one-component toner supplied from a toner container by a toner supply member when a toner layer forming member is in pressure contact with the surface of the toner carrier which is disposed in the vicinity of the latent image carrier. At least the surface of the toner supply member in a developing method for forming a layer, and supplying the thin toner layer to the electrostatic latent image held by the latent image carrier to make the electrostatic latent image visible. A developing method characterized in that a charging member is mixed in.