JPH06149045A - One-component developing device - Google Patents

Abstract

PURPOSE:To enable developer to normally follow up an oscillating electric field caused on a developing area where a developer carrier is proximately opposed to an electrostatic latent image holding body so that good developing can be obtained by using a conductive carbon component having a specified pH as the conductive carbon component of a semiconducting resin layer. CONSTITUTION:The developer 4 whose layer is thinned and which is electrostatically charged is carried to the developing area A by the rotation of the developer carrier 6, and many developer particles having enough charge in an alternating electric field caused on a gap between the carrier 6 and the electrostatic latent image holding body 1 fly and reciprocate. The particles of the developer collide each other by the reciprocating motion so that entire developer becomes a cloud state. The cloud of the developer 4 is attracted to a latent image 2 part on the holding body 1 by the DC component of a bias voltage and developing is finished. In this case, negatively charged developer is used and the conductive carbon whose pH is >=7 is used as the conductive carbon on the semiconducting resin 6b of the holding body 6, so that sufficient charge can be accurately given to the developer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-component developing device used in an electrophotographic image forming apparatus such as a copying machine or a printer, and more particularly, it is generated between an electrostatic latent image holding member and a developer carrying member. The present invention relates to a one-component developing device that develops an electrostatic latent image by flying a one-component developer in the generated oscillating electric field.

[0002]

2. Description of the Related Art As a developing method for developing an electrostatic latent image formed on an electrostatic latent image carrier to form a visible image, various conventional developing methods have been used depending on the type of developer used. The method of is proposed. In it, for example, US Pat.
There is transfer development using a developer carrying member called a donor disclosed in Japanese Patent No. 9547. The transfer development is as follows: 1) A layer of toner, which is a developer, and a photoconductor (electrostatic latent image carrier) are in non-contact with each other with a predetermined gap, and the toner flies toward the photoconductor and flies in a gap therebetween. And 2) the toner layer is rotated and brought into contact with the photoconductor, and 3) the toner layer is brought into rotational contact with the photoconductor and the image portion is slid to be developed. In this case, it is a generic name of and is well known as a touch-down developing method.

The one-component developing device using the touch-down developing method is roughly classified into a developing device using a one-component magnetic developer and a one-component non-magnetic developing device according to the kind of the developer. A developing device that does this is conventionally known.

As a conventional one-component developing device using a magnetic developer, for example, JP-A-54-51848, JP-A-58-146249, US Pat.
Various items have been proposed in the specification No. 75, the specification No. 3426730, etc., and a typical apparatus configuration example thereof is shown in FIG. This type of developing device is generally
Hopper 33 for storing one-component magnetic developer 34
A cylindrical developer carrier 36 rotatably supported around the plurality of magnetic pole rolls 35, and the developer carrier 36.
The developer carrying member 36 is provided so as to be in pressure contact with the surface, and the developer carrying member 36 is provided at the opening of the hopper 33 facing the electrostatic latent image holding member 31. The electrostatic latent image holding member 31 has a structure in which a photoconductive layer is provided on the electrodes, and the surface of the electrostatic latent image holding member 31 is uniformly charged and then irradiated with image light to form an electrostatic latent image 32. Is what you can do. In such a developing device, first, the one-component magnetic developer 34 housed in the hopper 33 is developed by the magnetic force of the magnet roll 35.
It is held on the surface of No. 6 and rubbed on the developer carrying member 36 by the developer regulating member 37. As a result, the developer 34
Is attached in a thin layer on the developer carrying member 36 and is given a necessary charge. The thinned developer 34 is sent to the developing area A where the electrostatic latent image carrier 31 and the developer carrier 36 face each other by the rotation of the developer carrier 36. Then, a DC superimposed AC voltage is applied to the developer carrying member 36 from the high voltage AC power source 38 and the DC power source 39, and an oscillating electric field is generated in the gap between the electrostatic latent image holding member 31 and the developer carrying member 36. The oscillating electric field causes the charged developer 34 on the developer carrier 36 to fly to the electrostatic latent image 32 on the electrostatic latent image holder 31 for development.

A conventional one-component developing device using a non-magnetic developer is proposed in, for example, Japanese Patent Laid-Open No. 60-53975, and a typical device configuration example is shown in FIG. This type of developing device is generally shown in FIG.
As shown in, the one-component non-magnetic developer 44 stored in the hopper 43 is supplied to the developer carrier 46 by a supply roll 50 that rotates in the opposite direction at the same peripheral speed as the developer carrier 46. The supplied developer 44 is the developer carrier 4
6 The developer regulating member 47, which is provided so as to come into contact with the surface at a predetermined pressure, regulates the amount of attachment to the developer carrying member 46, attaches it in a uniform thin layer, and imparts a necessary electric charge, After that, it is sent to the developing area A facing the electrostatic latent image holding member 41. Then, the developer carrier 4
Since a high voltage AC power supply 48 and a DC power supply 49 apply a DC superimposing AC voltage to 6, the developer 44 is statically moved by an oscillating electric field generated in the gap between the electrostatic latent image holder 41 and the developer carrier 46. The electrostatic latent image 42 is developed by flying to the side of the electrostatic latent image holder 41.

In these one-component developing devices, a cylindrical pipe made of aluminum or stainless steel is usually machined as a developer carrying member, and then an insulating polymer material such as phenol resin is electrically conductive on its peripheral surface. A semiconductive resin layer formed by coating a semiconductive composition containing an appropriate amount of conductive carbon is provided, and the surface roughness of the semiconductive resin layer is Ra = The thickness is about 0.1 to 1.0 μm. In a developing device using a non-magnetic developer, it is not necessary to provide a magnet roll inside the developer carrier, so a cylinder (solid) form is used as the developer carrier instead of the above cylindrical pipe. It is also possible to do so.

[0007]

However, the one-component developing device using the developer carrying member provided with the semiconductive resin layer as described above has the following problems.
That is, in such a developing device, the one-component developer is rubbed between the developer control member that is pressed against the developer carrier and the surface of the developer carrier (actually, the surface of the semiconductive resin layer). Although the toner is triboelectrically charged by this, the developer is not sufficiently charged, so that the flying property of the developer in the developing region is deteriorated, and as a result, the image density is lowered or the background fog is generated. However, there is a problem in that it causes image defects.

The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to surely charge a developer sufficiently, thereby developing a high quality image without image defects. It is an object of the present invention to provide a one-component developing device capable of performing.

[0009]

Means for Solving the Problems As a result of intensive studies by the present inventors in order to achieve the above-mentioned object, the charging characteristics of the developer in a one-component developing device are found to be half that of a developer carrying member which is triboelectrically charged. It was found that the pH value of the conductive carbon contained in the material forming the conductive resin layer is greatly affected. That is, it was found that the developer cannot be sufficiently charged when the pH value of the conductive carbon contained in the semiconductive resin layer is not suitable, and the present invention has been completed.

That is, the one-component developing device of the present invention is provided so as to face the electrostatic latent image holding member, and a developer carrying member for adhering and carrying the developer on the surface thereof, and the developer carrying member. A developer regulating member that regulates the amount of the developer that is pressed and adheres to the surface of the carrier to reduce the thickness of the developer, and is formed in a developing region in which the developer carrier and the electrostatic latent image carrier closely face each other. It is premised on a one-component developing device that visualizes an electrostatic latent image on an electrostatic latent image holding member by adhering a charged developer on the electrostatic latent image holding member in an electric field generated by the developer. The surface of the carrier is
A semiconductive resin layer containing an insulating polymer material and conductive carbon as a main component, and the conductive carbon has a PH in the range of 2 to 6 when a positively charged developer is used, When a negatively charged developer is used, its PH is 7-1.
It is characterized by being in the range of 0.

In the above technical means, the semiconductive resin layer has a pH of 2 to 6 when a positively charged developer is used.
Of conductive carbon and an insulating polymer material made of a synthetic resin negatively charged with a developer such as a polyester resin as a main component. When a negatively charged developer is used, conductive carbon having a pH of 7 to 10, preferably pH 8 to 10, an acrylic resin,
It is composed of a composition material whose main component is an insulating polymer material made of a synthetic resin positively charged to a developer such as a polyamide resin. This semiconductive resin layer is formed by coating each of the above-mentioned forming materials on the base material of the developer carrying member by a conventional method, and the film thickness thereof is about 30 to 180 μm. Also,
The surface of the semiconductive resin layer is surface-treated so that the ten-point average roughness (Rz) according to JIS B 0601 is about Rz = 0.8 to 5.0 μm.

The developer regulating member has a structure such as a rubber plate alone or a SUS thin plate having a thickness of 0.05 to 0.1 mm with a rubber plate attached thereto. The rubber material is urethane or EPDM. A rubber material such as silicone is used. And, this regulating member is 10 to 150 g per unit length in the longitudinal direction with respect to the surface of the developer carrying member.
It is installed so as to come into sliding contact with a pressing force of about / cm. Further, in the above technical means, each configuration other than the semiconductive resin layer is not particularly limited, and the design can be appropriately changed as necessary.

[0013]

In the developing apparatus of the present invention, as described above, the conductive carbon component of the semiconductive resin layer formed on the surface of the developer carrier is appropriately selected to have a pH suitable for the charge polarity of the developer. Therefore, the developer regulating member imparts a sufficient and appropriate electric charge to the one-component developer rubbed on the surface of the semiconductive resin layer. Therefore, the developer, which is charged sufficiently and properly, is
The developer carrying member and the electrostatic latent image holding member can normally follow an oscillating (alternating) electric field generated in a developing area in which the developer carrying member and the electrostatic latent image holding member are closely opposed to each other, and as a result, good development is performed.

[0014]

EXAMPLES The present invention will be described more specifically below with reference to examples. Example 1 FIG. 1 is a schematic cross-sectional view of a one-component developing device using a magnetic developer, showing an example of the present invention. In the figure, 1 is an electrostatic latent image holder, 2 is an electrostatic latent image, 3 is a hopper, 4 is a magnetic one-component developer, 5 is a magnet roll, 6 is a developer carrier, 7 is a developer regulating member, Reference numeral 8 indicates an AC power supply, and 9 indicates a DC power supply. In FIG. 1A, an electrostatic latent image carrier 1 is a photoconductive drum having a surface layer made of a negatively charged organic photoconductor on the surface thereof, and is uniformly charged by a charging means (not shown). After this, the latent image 2 can be formed by irradiating the image light by the difference in electrostatic potential. The surface potential when the electrostatic latent image 2 is formed can be set to, for example, −800V in the image portion and −120V in the background portion.

The developer carrier 6 in this developing device is
It is provided so as to face the electrostatic latent image holder 1 and to have a gap of about 200 to 350 μm at a position A (developing region) which closely faces the electrostatic latent image holder 1. The developer carrier 6 is rotatably supported by the magnet roll 5 provided therein, and rotates around the magnet roll 5 to convey the developer adhering to the surface thereof. is there. The magnet roll 5 has a plurality of magnets arranged along the circumferential surface of the roll and is fixedly supported so as not to rotate. The plurality of magnets form a magnetic pattern in which S poles and N poles are arranged along the roll circumferential surface, and according to this magnetic pattern,
The magnetic developer can be adsorbed on the surface of the developer carrier 6. The developer regulating member 7 includes a soft elastic body 7a that is pressed against the surface of the developer carrying body 6 and a spring plate 7b that supports the soft elastic body 7a near one end.
The other end of the spring plate 7b is fixedly supported. The contact position of the soft elastic member 7a with respect to the developer carrying member 6 is the developer with respect to the reference line connecting the position where the developer carrying member 6 is closest to the electrostatic latent image holding member 1 and the center of the magnet roll 5. It is located at a position of 80 ° on the upstream side in the rotation direction of the carrier, and is installed so that the free end of the spring plate 7b faces the downstream side in the rotation direction of the developer carrier. The soft elastic body 7a has a width of 15 mm and a thickness of 1.00 m.
m, rubber hardness 50 °, silicone rubber, leaf spring 7
b is a 0.1 mm thick stainless steel plate (SUS3
04 CSP3 / 4 material, tensile strength 95 kgf / mm ² ,
A yield strength of 68 kgf / mm ² ) is used. Hopper 3
Stores the magnetic one-component developer 4 to be supplied to the developer carrying member 6, and substantially stores the developer carrying member 6 as well as the developer at a portion opened toward the electrostatic latent image holding member 1. The surface of the carrier 6 is partially exposed, and the developer carrier 6 and the electrostatic latent image carrier 1 are arranged so as to be close to each other.

Developer carrier 6 used in this embodiment
As shown in FIG. 1 (b), a semiconductive resin layer 6b is applied and formed on the peripheral surface of a base material 6a, which is a cylindrical member of aluminum or non-magnetic stainless steel, in a thickness of 30 μm to 180 μm. is there. The semiconductive resin layer 6b is formed of a semiconductive resin material in which an acrylic resin contains conductive carbon having a predetermined pH. The surface of the resin layer 6b has a 10-point average roughness of Rz = 0.8 to 5 μm.
It is said that. Then, the base material 6a of the developer carrying member 6
DC bias AC power, which is a bias voltage, is applied by a high voltage AC power supply 8 and a DC power supply 9 to the electrostatic latent image in the developing area A where the developer carrying member 6 and the electrostatic latent image holding member 1 are close to each other. An alternating electric field is generated between the surface of the holder 1 and the grounded electrode under the photoreceptor layer.
This bias voltage has, for example, an AC component frequency of 2.
4 KHz, the peak-to-peak voltage can be 2000V, and the DC component can be -200V.

Development by such a developing device is performed as follows. First, the developer 4 in the hopper 3 is adsorbed on the surface of the rotating developer carrier 6 and rubbed by the soft elastic body 7a of the developer regulating member 7 against the semiconductive resin layer 6b on the surface of the developer holder. It As a result, the developer 4 is thinned and charged. Thinned developer 4
Is transported to the development area A by the rotation of the developer carrier 6 and has many charges in the alternating electric field generated in the gap between the developer carrier 6 and the electrostatic latent image carrier 1. Particles fly and reciprocate. Further, due to this reciprocating motion, the particles of the developer collide with each other and the entire developer becomes cloud-like. The cloud of the developer 4 is attracted to the latent image 2 portion on the electrostatic latent image holder 1 by the DC component of the bias voltage, and the development is completed.

Next, in the developing device of this embodiment, a semi-conductive resin layer 6 of the developer carrying member 6 is used by using a negatively charged developer.
When the conductive carbon in b was used with various pH values shown in Table 1 below, the effect on image density, background fog and charge amount at that time was examined. The results are shown in the table. The image density was measured by a Macbeth densitometer, and the charge amount was measured by a charge spectrograph method. In addition, the ground fog was measured by comparison with a limit sample and evaluated based on the grade evaluation method specified by the company. This ground fog is generally considered to have no practical problem if the grade is less than 1.2.

[0019]

[Table 1]

As is clear from the results in the above table, when developing using a negatively chargeable developer, if conductive carbon having a pH of 7 or more is used, there is almost no ground fog. It was confirmed that development with a sufficient image density can be performed.

Embodiment 2 FIG. 2 is a schematic sectional view showing a one-component developing apparatus using a non-magnetic developer which is another embodiment of the present invention. In FIG.
11 is an electrostatic latent image holding member, 12 is an electrostatic latent image, 13 is a hopper, 14 is a magnetic one-component developer, 16 is a developer carrying member, 1
Reference numeral 7 is a developer regulating member, 18 is an AC power source, and 19 is a DC power source. Of these components, the components other than the developer carrier 16 are the same as those in the first embodiment. Further, in the figure, reference numeral 20 denotes a supply roll, and this supply roll 20 supplies the developer 14 in the hopper 13 to the developer carrier 16. The developer carrier 16 in this developing device is shown in FIG.
As shown in (b), a semiconductive resin layer 16b similar to that in Example 1 is provided on the aluminum or stainless steel base material 16a. Since the developer 14 does not have magnetism, it is attached to the surface of the developer carrier 16 by electrostatic force or the like. When development was performed using the one-component developing device of this embodiment and using the negatively charged non-magnetic one-component developer 14 under the same conditions as in Example 1, image density and background fog are shown in the above table. It was confirmed that almost the same effect (result) was obtained.

[0022]

As described above, according to the one-component developing apparatus of the present invention, the developer carrier has a semi-conductive surface containing a conductive carbon having a pH value suitable for the charging characteristics of the developer. Since the conductive resin layer is formed, a sufficient charge can be accurately imparted to the developer, which enables high-quality development with good image density and almost no background fog.

[Brief description of drawings]

FIG. 1A is a schematic cross-sectional view of a developing device showing an embodiment of the present invention, and b is a partially enlarged cross-sectional view showing the structure near the surface of a developer carrying member.

FIG. 2A is a schematic cross-sectional view of a developing device showing another embodiment of the present invention, and b is a partially enlarged cross-sectional view showing the structure near the surface of the developer carrier.

FIG. 3 is a schematic cross-sectional view of a conventional one-component developing device that uses a magnetic developer.

FIG. 4 is a schematic sectional view of a conventional one-component developing device using a non-magnetic developer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrostatic latent image holding body, 2 ... Electrostatic latent image, 4 ... One-component developer, 6 (16) ... Developer carrying body, 6b (16b) ... Semiconductive resin layer, 7 ... Developer controlling member , A ... Development area.

Claims (1)

[Claims] 1. A developer carrying member which is provided so as to face an electrostatic latent image holding member and which carries a developer by adhering the developer to the surface of the electrostatic latent image holding member, and a developer which is pressed against the developer carrying member and adheres to the surface of the carrying member. A developer regulating member that regulates the amount of the developer to make the layer thin, and carries the developer in an electric field formed in a developing region where the developer bearing member and the electrostatic latent image holding member closely face each other. In a one-component developing device for adhering a developer having a charge on the body to an electrostatic latent image on an electrostatic latent image carrier to visualize the developer, the surface of the developer carrier is an insulating polymer material and a conductive material. It is composed of a semiconductive resin layer containing carbon as a main component, and the conductive carbon has a PH in the range of 2 to 6 when a positively charged developer is used, and when a negatively charged developer is used, Is a one-component developing device characterized in that its PH is in the range of 7 to 10.