JPH08101528A - Image forming method - Google Patents

Abstract

PURPOSE: To obtain a uniform and thick solid black image without fogging at a background part by forming a uniform developer layer on a developer carrier after regulating it by a regulating member. CONSTITUTION: In this image forming method, an electrostatic latent image is formed on an electrified electrostatic latent image holding body, the thin layer of one-component developer is formed on the developer carrier by allowing the regulating member to abut on the developer carrier, and the thin layer of developer is supplied to the electrostatic latent image on the electrostatic latent image holding body, thereby developing the image. The electrostatic latent image holding body is electrostatically charged to -150 to -800V, and the developer which is prepared by pulverization and classification and satisfies relation shown by a following expression d75 /d25 <=d50 /40+1.2[in the expression, d25 , d50 and d75 express particle diameters in the case volume or weight percentage to all the particles becomes 25%, 50% and 75% when the particles of the developer are integrated from small ones.], and also d50 is within 7 to 14μm is used as the one-component developer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for visualizing an electrostatic latent image. More specifically, in the present invention, the one-component developer supplied onto the developer carrying member is used as a developer layer having a predetermined thickness and charge amount by a regulating member, and this developer layer is provided on the electrostatic latent image holding member. The present invention relates to an image forming method in which an electrostatic latent image is conveyed and visualized.

[0002]

2. Description of the Related Art As a dry developing device for developing an electrostatic latent image formed on an electrostatic latent image holding member, a two-component developer composed of toner and carrier has been used, and friction charging with the carrier has been conventionally used. Thus, a two-component developer that applies an electric charge to the toner and electrostatically attracts the charged toner to the electrostatic latent image has been developed and put into practical use. As described above, a developing device using a two-component developer composed of a toner and a carrier can sufficiently withstand practical use, but recently, from the viewpoint of preventing deterioration of the developer, a one-component developer composed of only a toner is used. Image forming methods used have come to be proposed.

As an image forming method using such a one-component developer, a method using a magnetic developer, a method using a non-magnetic developer, or a method in which the developer is brought into direct contact with the electrostatic latent image carrier is used. Some are developed or some are developed without contact.

As a one-component developing device, for example, Japanese Patent Laid-Open No. Sho 60
The one disclosed in −53975 is known. An example of this is shown in FIG. That is, reference numeral 1 in the drawing denotes an electrostatic latent image holder, which holds an electrostatic latent image 2 having a surface potential of about 200 to 900 V on its surface. A thickness of 1 mm and a specific resistance of 1 × 10 ¹⁰ Ωcm on the developing electrode 3 toward the electrostatic latent image carrier 1.
A phenol developer carrier 4 to which carbon having a relative permittivity ε = 30 and glass fiber or the like is added is provided at an interval of 10
0 to 400 μ are placed to face each other. The surface of the developer carrying member 4 is polished in the axial direction (direction perpendicular to the developer conveying direction) by sandpaper or the like, and the surface thereof has a roughness (Rz, JIS standard, ten-point average roughness) 1 -10
μm.

A supply member 6 for supplying the developer 5 stored in the hopper 10 onto the developer carrying member 4 is pressed against the developer carrying member 4 at a depth of about 1 mm to develop in the direction of the arrow in the figure. It rotates at the same peripheral speed as the agent carrier 4. As the supply member 6, in order to reduce the load applied to the developer carrier 4 during pressure contact, a foam 9 such as urethane is wound around the shaft 8 and the surface is covered with EPDM rubber or the like having a thickness of 0.5 to 1 mm. Is used. The surface of the rubber is about 200 μm in height and 15 °
Concavities and convexities are provided at equal intervals, and the developer 5 filled in the convex portions is sent onto the developer carrier 4. The sent developer 5 is sent to the regulating member 7 by the rotation of the developer carrier 4 (in the direction of the arrow in the figure), and the developer 5 is given a desired charge by frictional charging and is developed on the developer carrier 4. A uniform layer of Agent 5 (0.3-1.0 mg / cm ² ) is formed and transferred to the electrostatic latent image 2.

The regulating member 7 is made of SUS304 having a thickness of 0.1 mm.
It is composed of a CSP3 / 4H spring material and a silicone rubber material with a thickness of 1 mm and a rubber hardness of 50 ° on it.
Fillers of silicon dioxide and titanium dioxide are added to the silicone rubber material. Regulation member 7 and developer carrier 4
The contact pressure between and is set to 50-300 g / cm.

DC voltage of 200 to 400 V is applied to the developing electrode 3.
, With a frequency of 1 to 10 KHz and Vpp of 400 to
A high frequency alternating voltage of 4500 V is applied to form a peripheral electric field in the electrostatic latent image portion 2 on the electrostatic latent image holder 1 to move the developer 5 to perform development.

The developer 5 is a non-magnetic one-component type developer, in which a pigment such as carbon black or a polarity control agent such as a metal-containing dye is dispersed in various thermoplastic resins such as styrene resin and acrylic resin, and pulverized. The particle size is 5 to 20 μm depending on the classification, but depending on the case, in order to improve the mobility of the developer 5 from the developer carrying member 4 to the electrostatic latent image 2, it is 0.1 to 2.0 with respect to 5 particles of the developer. You may add hydrophobic silica in the range of weight%.

In the image forming method using the conventional one-component developer as described above, the uniformity of the layer of the developer 5 after passing through the regulating member 7 greatly affects the image quality. That is, when a uniform layer of the developer 5 is obtained, a solid black image is uniform and dark, and a clear image without fog on the background portion is obtained, whereas when the layer of the developer 5 is uneven. Is a non-uniform solid black image, and only a terrible image with a light background fog can be obtained.

Conventionally, even if the developer 5 of the same material is used, the layer of the developer 5 may be uniform or non-uniform, and a stable and uniform layer of the developer 5 cannot be obtained, so that a solid black image is formed. Only a non-uniform image with low density and severe fogging was obtained.

[0011]

The object of the present invention is to solve the above-mentioned problems of the developing method, and the developer is always obtained as a uniform layer on the developer carrier, and a solid black image without any background fog. Another object of the present invention is to provide an image forming method capable of obtaining a uniform copy image of

[0012]

As a result of various studies on the above-mentioned conventional problems, the inventors of the present invention have found that the toner on the developer carrying member is required to have good uniformity. As a result, it was found that a toner satisfying the condition that the particle size distribution is constant should be used.

That is, according to the present invention, an electrostatic latent image is formed on a charged electrostatic latent image holding member, a regulating member is brought into contact with the developer carrying member, and a thin layer of a one-component developer is formed on the developer carrying member. In the image forming method, in which the developer of the thin layer is formed and is supplied to the electrostatic latent image on the electrostatic latent image holding member to visualize it. It is charged to 800 V and is prepared as a one-component developer by pulverization and classification, and the following formula d ₇₅ / d ₂₅ ≦ d ₅₀ /40+1.2 is used, where d ₂₅ , d ₅₀ and d ₇₅ are developer particles. It represents the particle size when the volume or weight percentage with respect to all particles becomes 25%, 50% and 75%, respectively, when integrated from the smaller side. Satisfies the relationship represented by, and is an image forming method characterized by the use of what d ₅₀ of in the range of 7～14Myuemu.

By using the positively chargeable developers (A to Q) having various particle size distributions shown in Table 1 below, the uniformity of the developer layer on the developer carrying member after being regulated by the regulating member is controlled. It was visually observed. The results are shown in Table 1 and FIG. If it obtained from a uniform developer layer (○) and when uniformity is bad (×) and the horizontal axis d ₅₀ a, there is a clear correlation was plotted on the vertical axis the d ₇₅ / d ₂₅ This correlation d ₇₅ / d ₂₅ = d
_A uniform toner layer was formed in the lower area of this straight line, which is indicated by 50/40 + 1.2.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

Examples of the present invention will be described below. It should be noted that this example is merely an example and does not limit the scope of the present invention.

Example 1 In a developing device in which the diameter of the developer carrier 4 shown in FIG. 1 was 20 mm, carbon black was added to styrene acrylic resin having d ₇₅ / d ₂₅ = 1.2 and d ₅₀ = 10 (μm). 8 parts by weight,
When a developer prepared by containing 2 parts by weight of a metal-containing dye was added and tested, a uniform layer of the developer 5 was obtained and a good copy image was obtained. As a comparative example, using the same developing device, a developer having the above composition with d ₇₅ / d ₂₅ = 1.7 and d ₅₀ = 10 (μm) was tested, and the developer layer was non-uniform and good copy images were obtained. I couldn't do it.

Example 2 The developer carrier 4 shown in FIG. 1 has a diameter of 15 μm, and 1% by weight of vanadium pentoxide on a SUS spring material as a regulating member.
Silicone rubber material contained in the developing device d ₇₅ / d ₂₅
= 1.3, d ₅₀ = 12 (μm), a developer prepared by containing 4 parts by weight of a phthalocyanine blue pigment and 1 part by weight of a quaternary ammonium salt in a styrene acrylic resin, and containing -150 to -800 V. As a result of a test for developing the electrostatic latent image formed on the electrostatic latent image carrier charged in the above, a uniform layer of the developer 5 was obtained, and a good blue copy image was obtained.

Example 3 As shown in FIG. 3, d ₇₅ / d ₂₅ = 1.2 and d ₅₀ = 1 in a magnetic developing device having a magnet inside the developer carrying member 24.
When a magnetic developing device prepared by containing 2 parts by weight of carbon black and 40 parts by weight of magnetite in a styrene acrylic resin of 1 (μm) was put and tested, a uniform developer layer was obtained and a good copy was obtained. It was Using the same developing device as a comparative example, d ₇₅ / d ₂₅ = 2.0 and d ₅₀ = 1
As a result of testing using the developer having the above composition of 1 (μm), the developer layer was non-uniform and a good copy image was not obtained.

[0021]

According to the present invention, a thin layer of a one-component developer is formed on a developer carrying body by forming an electrostatic latent image on a charged electrostatic latent image carrying body and bringing a regulating member into contact with the developer carrying body. In the image forming method, in which the developer of the thin layer is formed and is supplied to the electrostatic latent image on the electrostatic latent image holding member to visualize it. It is charged to 800 V and is prepared as a one-component developer by pulverization and classification, and the following formula d ₇₅ / d ₂₅ ≦ d ₅₀ /40+1.2 is used, where d ₂₅ , d ₅₀ and d ₇₅ are the developer particles. It represents the particle size when the volume or weight percentage with respect to all particles becomes 25%, 50% and 75%, respectively, when integrated from the smaller side. ] The image forming method which uses the one satisfying the relationship represented by [4] and having d ₅₀ in the range of 7 to 14 μm. After being regulated by the regulating member, a uniform developer layer is formed on the developer carrying member. Therefore, a uniform and dark solid black image can be obtained, and no fog is generated in the background portion.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a non-magnetic one-component developing device.

FIG. 2 is a graph showing a relationship between a toner particle size distribution and a developing layer on a developer carrying member.

FIG. 3 is a schematic view of an example of a magnetic one-component developing device.

[Explanation of symbols]

 1 Electrostatic Latent Image Holder 2 Electrostatic Latent Image 3 Developing Electrode 4,24 Developer Carrier 5 Developer 6 Supplying Member 7,27 Restricting Member 8 Shaft 9 Foam 10,30 Hopper

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatsugu Kajimoto 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Works (72) Inventor Kazuhiko Tsukoshi 2274 Hongo, Ebina City, Kanagawa Fuji Xerox Co., Ltd.Ebina Business In-house

Claims (3)

[Claims] 1. A latent electrostatic image is formed on a charged electrostatic latent image holder, and a regulating member is brought into contact with the developer carrying member to form a thin layer of a one-component developer on the developer carrying member. In the image forming method of supplying the thin layer of developer to the electrostatic latent image on the electrostatic latent image carrier to visualize the electrostatic latent image carrier, the electrostatic latent image carrier is -1.
Charged to _{50 to} -800 V, prepared as a one-component developer by pulverization and classification, and represented by the following formula: d ₇₅ / d ₂₅ ≤d ₅₀ /40+1.2 [wherein d ₂₅ , d ₅₀ and d ₇₅ are It represents the particle diameter when the volume or weight percentage of all the particles is 25%, 50% and 75%, respectively, when the agent particles are integrated from the smaller side. Satisfies the relationship represented by, and an image forming method comprising the use of what d ₅₀ of in the range of 7～14Myuemu. 2. A non-magnetic one-component developer is used.
The image forming method described in 1 .. 3. The image forming method according to claim 1, wherein a magnetic one-component developer is used.