JPH02287576A - Manufacture of single-component developing device and its developing roller - Google Patents

Abstract

PURPOSE:To stably convey single-component nonmagnetic toner by forming the developing roller of a porous body and forming pores of foaming even in the surface part. CONSTITUTION:A paddle roller 6 is arranged in a recessed part 3a formed in the bottom part of a developing container 3. When the roller 6 rotates as shown by an arrow B, single-component nonmagnetic toner 4 at the lowest position in the container 3 is scooped up toward the developing roller 7. At this time, the roller 7 rotates as shown by an arrow C to convey the toner 4, carried by the roller 6, to the contact part of a photosensitive drum 1 while the toner is adsorbed on the surface, thereby developing an electrostatic latent image on the drum 1. Here, the roller 7 is formed of the porous body and pores of foaming are formed even in the surface part. Then, the toner 4 contacts and enter the surface of the roller 7 and is prevented from peeling off against local pressure, so that the toner 4 is stably conveyed.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Fig. 6) Problem to be solved by the invention (Figs. 7 and 8) Means for solving the problem (Fig. 1 Figure) Working Example (a) - Explanation of the component developing device (Figures 2, 3, and 4) (b) Explanation of the method for manufacturing the developing roller (Figure 5) (C
) Description of Other Embodiments Effects of the Invention [Summary] Concerning a one-component developing device that performs development using a one-component non-magnetic toner, and a method of manufacturing a developing roller in No. 7.

The purpose is to stably transport single-component non-magnetic toner even under high temperature and high humidity environments.

A developing roller that is in pressure contact with the image bearing member on which an electrostatic latent image is formed and conveys the one-component non-magnetic toner, and a developing roller that is in pressure contact with the developing roller to maintain a constant layer thickness of the one-component non-magnetic toner on the developing roller. In a one-component developing device having a toner regulating means for controlling and charging the toner, the developing roller is formed of a porous material,
In addition, the structure was such that porous foam pores were also present on the surface.

[Industrial application field]

The present invention relates to a one-component developing device that performs development using a one-component non-magnetic toner, and a method for manufacturing its developing roller.

2. Description of the Related Art In image forming devices such as electrophotographic printing devices and electrostatic recording devices, developing devices are widely used to visualize electrostatic latent images on photosensitive drums and dielectric materials that are latent image carriers.

Conventionally, such developing devices have been widely used using two-component developers consisting of carrier and toner.
In recent years, one-component developers, particularly those using one-component non-magnetic toner, have been used because they are easy to handle and the apparatus can be made compact.

In a developing device using such a one-component non-magnetic toner, one that can stably transport the toner is desired.

[Conventional technology]

FIG. 6 is an explanatory diagram of the prior art.

- The component developing device 2 is provided with a developing roller 7 in pressure contact with a photosensitive drum (image carrier) 1 that rotates in the direction of the arrow.

The developing roller 7 carries the one-component non-magnetic toner 4 in the developing device 2.
1I (= is a bias blade (toner regulating blade) provided to convey and supply the toner 4 to the photosensitive drum 1, and is provided upstream from the developing section 1I (= is a bias blade (toner regulating A means) 8 is provided in pressure contact with the developing roller 7.

In the one-component developing device 2, the toner 4 is transported by the developing roller 7.
This is carried out by supporting the toner 4 of.

For this reason, conventionally, the surface of the developing roller 7, which has a solid surface, is provided with unevenness of about 1h to 115 toner particle diameter, and the toner is conveyed by fitting it into the recessed part.
Publication No. 6, etc.) are known.

[Problem to be solved by the invention]

7 and 8 are diagrams illustrating the problems of the prior art. By the way, the bias blade 8 is in pressure contact with the developing roller rough, and the one-component non-magnetic toner on the developing roller 7 is transferred to the blade 8.
The material is allowed to pass through the gaps to form a thin layer and become electrically charged.

That is, as shown in Figure 7 (:, the toner 4 slips between the developing roller 7 and the blade 8 and gets stuck in the recessed part of the developing roller 7.

Toner transport is performed.

However, in a high temperature environment (for example, 32° C., 80%), the friction coefficient of the toner 4 increases.

For this reason, as shown in FIG. 70, the toner 4 does not slip on the blade 8, but is instead bounced off the blade 8.
A problem occurred in that excessive scraping of the toner 4 occurred, resulting in a shortage of toner 4 on the developing roller 7, making it impossible to print.

This same problem occurs even if the hardness of the rubber constituting the developing roller 7 is low.

The cause of this is a problem peculiar to solid surfaces. As shown in Figure 8:2, when pressure is applied to the toner 4 with the blade 8 in the direction of the arrow, the toner 4 sinks into the developing roller 7, but the surface 1 Since it is a continuous surface, tension acts as shown in FIG. 8 (5), and the developing roller 7 cannot take in the toner 4 because it is in close contact with the developing roller 7.

This is because the blade 8 peels off the film.

In order to solve this problem, it is conceivable to increase the unevenness of the continuous surface of the developing roller 7, but if the unevenness is increased, the adhesion with the photosensitive drum 1 will deteriorate.

Print density becomes uneven.

For this reason, the range of unevenness that satisfies both the requirements of adhesion and prevention of toner peeling is extremely limited and must be uniformly dispersed, making it virtually difficult to manufacture and raising costs. .

Therefore, it is an object of the present invention to provide a one-component developing device that can stably transport one-component non-magnetic toner even in a high temperature and high humidity environment.

Another object of the present invention is to provide a method for manufacturing a developing roller for a one-component developing device, which can manufacture a developing roller for stably transporting one-component non-magnetic toner.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

As shown in the first rotation, the one-component developing device according to the present invention includes a developing roller 7 that is in pressure contact with the image carrier 1 on which an electrostatic latent image is formed and conveys the one-component non-magnetic toner 4. , a toner regulating means 8 that is in pressure contact with the developing roller rough and keeps the layer thickness of the one-component non-magnetic toner 4 on the developing roller 7 constant and charges it.
In this one-component developing device, the developing roller 7 is formed of a porous material and is configured such that porous foam pores are also present in the surface portion.

Further, in the second aspect of the present invention, the pore diameter of the porous foam of the developing roller 7 is set to be twice or less the average particle diameter of the one-component non-magnetic toner 4.

Further, there are two methods for manufacturing a developing roller according to the present invention.

As shown in FIG. 1(B), by pressure contact of the toner regulating means 8, charged one-component non-magnetic toner 4 having a constant thickness is conveyed to the image carrier 1 on which an electrostatic latent image is formed. In the method for manufacturing a developing roller of a one-component developing device that develops the electrostatic latent image by pressing against the image carrier L, the method includes a step of molding a porous roller 7a from a raw material, and a step of molding the molded roller 7a from a raw material. The method includes a step of polishing the surface of the roller 7a and removing the skin layer of the roller 7a.

[Effect]

In the present invention, the developing roller 7 is formed of a porous material.

Since the structure is such that the pores of the porous foam are also present on the surface portion, a network of continuous pores exists on one surface portion.

Therefore, in response to the local pressure generated when the toner is pressed by the blade 8, the toner sticks closely to the surface of the developing roller rough and sinks in, and peeling does not occur at the blade 8 portion.

This is because, since it has a net-like structure, tension from all directions does not work as with a solid surface, and the toner sinks into areas where the tension of the net is weak, and the toner is held in close contact with the net.

This makes it possible to perform development with stable print quality without fluctuations in conveyance characteristics due to the environment.

Furthermore, in the present invention, by making the pore diameter twice or less than the average particle diameter of the toner, excessive regulation by the blade 8 can be prevented while maintaining close contact with the image carrier 1.

Furthermore, in the present invention, when the porous developing roller is molded, a continuous skin layer is formed on the surface of the porous developing roller.
The skin layer on the surface is removed to expose pores on the second surface.

As a result, such a developing roller can be manufactured easily.

〔Example〕

(a) - Description of Component Developing Apparatus FIG. 2 is a block diagram of an embodiment of the one-component developing apparatus according to the present invention.

In the figure, 1 is the above-mentioned OPC photosensitive drum, which has a diameter of 60-2 and a surface velocity of 70 m1/s, and whose surface is charged with 1,650 volts by a corona discharger (not shown), and then by a laser (not shown). A scanning optical system, an LED exposure optical system, etc. (2) An electrostatic latent image is formed by irradiating light according to the information to be recorded.

Reference numeral 2 denotes the aforementioned one-component developing device, which has the following configuration in order to visualize an electrostatic latent image by supplying a one-component non-magnetic toner onto the OPC photosensitive drum 1. be.

That is, the developer container 3 stores a one-component non-magnetic toner (polyester toner) 4 having an average particle size of about 10 μm, and the agitator 5 rotates in the direction of the arrow inside the developer container 3 to collect one-component non-magnetic toner (polyester toner). By causing friction with the non-magnetic toner 4, the one-component non-magnetic toner 4 is negatively charged (-).

The paddle roller 6 is a first roller formed at the bottom of the developer container 3.
By rotating in the direction of arrow B, the one-component non-magnetic toner 4 present at the lowest position of the developing container 3 is pumped up and supplied in the direction of a developing roller 7, which will be described later.

The aforementioned developer q-27 rotates in the direction of arrow C.

The OPC photosensitive drum 1 has the one-component non-magnetic toner 4 conveyed by the paddle roller 6 adsorbed on its surface.
This developing roller 7 has a diameter of, for example, 20 mm, a volume resistivity of 104 to 10 x 10 am ( Optimal 1 = 10SΩam
).

Polymer foam polyurethane (open cell state) with a hardness of 10 to 35° (measured with an Asker-C hardness meter: optimal; : is 10°)
The developing bias voltage (-aoov) is applied via the central axis of conductivity, which is made of a single layer 7b and a rigid body (not shown).

Further, the developing roller 7 is pressed by a biasing means such as a spring (not shown) on the entire developing container 3 in the direction of the OPC photosensitive drum 1 (in the direction of arrow Y), so that a linear pressure of 22 to s o g/ is applied to the developing roller 7 . ls (optimal:: is 43 g/
am ) and is pressed against the OPC photosensitive drum 1 rotating in the direction of the arrow so that the nip width is 1 to 3.5 mm.

The aforementioned layer thickness regulating bias blade 8 is made of aluminum or stainless steel, and is rotatable around a shaft 8a; it is bifurcated and biased against the developing roller 7 by biasing means such as a spring (not shown).

It is pressed in the direction of arrow X with a linear pressure of 26 g/■.

The thickness of the toner layer on the developing roller 7 is regulated to a constant value, and a voltage of -400V is applied, and one component of the non-magnetic toner 4 is charged to a negative polarity in this embodiment by frictional charging, and a voltage is applied. Thing: It is designed to prevent charge from leaking.

The collection roller 9 has a volume resistivity of 10, similar to the developing roller 7.
It is made of polymeric foamed polyurethane having a hardness of about 10 to 70[Omega]m, and is arranged in the second recess 3b of the developer container 3.

This collection roller 9 has a diameter of 11 mm and a circumferential speed of 70 mm/cm.
' t is provided so that the nip thickness is 1 mm, and further: 2. A collection bias voltage (-aoov ~
-250 V) is applied to mechanically and electrically collect the one-component non-magnetic toner 4 from the surface of the developing roller rough, and eliminate mechanical and electrical history from the developing roller 7.

In the above configuration, in this embodiment, the pore diameter is 4 to 15
The developing roller 7 was made of porous polyurethane, which is a thermoplastic polycarbonate polyurethane with a micrometer diameter.

FIG. 3 is a detailed explanatory diagram of the present invention.

The third part is pore 1: A cross-sectional view of toner support, Figure 3 (
6) is its top view, and FIG. 3 (Q is a model diagram of toner support by pores, and FIG. 3 is its top view.

As shown in FIGS. 3(5) and 3(c), continuous pores exist in a net shape on the surface of the developing roller 7, so that the toner 4
For the local pressure that occurs when you press .

The toner 4 adheres closely to the surface of the developing roller 7, sinks in, and is not peeled off by the blade 8.

Because of this network structure, tension from all directions does not work like a solid, and as shown in Figure 3 (model diagram of q, 0), the toner 4 is pushed away to the area where the tension of the network is weak. The toner 4 sinks in, and the toner 4 is closely attached and held by the net.

Therefore, even if the friction coefficient of the toner 4 becomes large in a high temperature and high humidity environment, the regulating force of the blade 8 as shown in FIG.

The blade 8 is pushed into the pores on the surface of the developing roller 7.
pass through.

Since the surface of the developing roller 7 is mesh-like, the toner 4 can easily slip through it.

Therefore, the conveyance characteristics of the developing roller (r) 7 do not change with respect to the environment, and development can be performed without fluctuations in print quality.

From the above, it is possible to obtain the best print quality when the pore diameter of the porous body constituting the developing roller 7 is approximately the same as the average particle diameter of the toner 4.

We conducted an experiment to find out to what extent this pore size can be tolerated. FIG. 4 is an explanatory diagram of pore diameters in one embodiment of the present invention.

As shown in Fig. 4, when the pore size exceeds twice the average particle size of the toner 4, the adhesion between the latent image carrier (photosensitive drum) 1 and the developing roller (toner carrier) 7 decreases. As shown by the arrow, areas where the developing electric field is weak occur where the pore diameter is more than double, and the developing electric field is insufficient.

Uneven shading occurred.

Therefore, it is desirable that the pore diameter is twice or less the average particle diameter of the toner.

On the other hand, when the pore size is smaller than 1/4 of the average particle size of the toner, the toner is no longer supported, the penetration effect of the blade 8 is reduced, and the above-mentioned excessive restriction by the blade 8 occurs at high temperature and high humidity.

Therefore, when the pore diameter of the developing roller rough is not more than twice the average particle diameter of the toner and not less than 0.25 times, the adhesion to the photosensitive drum 1 is excellent and the toner carrying ability is also excellent.

Further, the volume resistivity of the porous body of the developing roller 7 is 10
The range of 4 to 10<10 >[Omega] is preferable; if the electrical resistance value is higher than this, the potential difference between the developing roller 7 and the surface of the photosensitive drum 1 becomes large, causing ground force blurring.

Conversely, if the electrical resistance value decreases below this value, the blade 8
A large current flows into the developing roller 7, generating Joule heat and burning out the developing roller 7.

Furthermore, the surface phosphorosity of the developing roller 7 is 35 on the Asker-C hardness scale.
″ or less.

(b) Description of method for manufacturing developing roller FIG. 5 is an explanatory view of an embodiment of the manufacturing method according to the present invention.

As shown in FIG. 5(5), the heated and melted polyurethane foam material 7a in the tank 10b is pressurized by the plunger 10a and extruded through the die 11.

The molded product 7b extruded through the die 11 has a roller shape and forms a porous body (see FIG. 5).
As shown in the enlarged cross-sectional view of the roller surface, a skin layer SK of 3 to 5 μm is formed on the surface of the porous portion.

If used as is, surface tension will act like conventional solid rubber, resulting in excessive toner regulation. Therefore, in the step shown in FIG. 5, the surface of the forming roller 7b is polished to form a skin layer SK. Remove.

Surface:; exposing continuous pores.

That is, while the forming roller 7b is rotated by a rotation mechanism 12 such as a motor, the whetstone 13 is pressed against the forming roller 7b,
The surface of the forming roller 7b is polished by moving the abrasive 13 in the longitudinal direction (twice) of the forming roller 7b.

By simply polishing the molded product in this way, a porous developing roller with pores up to the desired surface area can be easily obtained.

(C) Description of other embodiments In the above embodiments, the image bearing member 1 was explained as an OPC photosensitive drum, but it may be any other well-known photosensitive member such as a selenium photosensitive member, or it may be a dielectric material. Good too.

Furthermore, although the developing roller 7 has been described as being made of porous polyurethane, it may be made of other porous elastic materials.

Although the present invention has been described above using examples, the present invention can be modified in various ways according to the gist of the present invention.

These are not excluded from the present invention.

It has the effect of

(Effect of the invention〕 As explained above, according to the present invention.

■ In the device of the present invention, the developing roller 7 is made of a porous material and the porous foam pores are also present on the surface. This has the effect that the toner adheres closely to the surface of the developing roller rough, prevents the toner from peeling off, and ensures stable toner transport and, in turn, stable 0111 quality development.

In addition, since the pore size is less than twice the average particle size of the toner, it is possible to maintain good adhesion with the image bearing member 1 while preventing excessive regulation of the toner by the blade 80. Furthermore, in the manufacturing method of the present invention, after creating the porous molding roller, one surface is polished to remove the surface skin layer that repels insects from the molding. I hope we can manufacture rollers.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention. FIG. 2 is a configuration diagram of an embodiment of the developing device of the present invention. FIG. 3 is a detailed explanatory diagram of the present invention. FIG. 4 is a detailed explanatory diagram of the present invention. FIG. 5 is an explanatory diagram of an embodiment of the manufacturing method of the present invention. FIG. 6 is an explanatory diagram of the prior art. FIGS. 7 and 8 are explanatory diagrams of problems in the prior art. In the figures, 1... image carrier (photosensitive drum). 4... One-component non-magnetic toner 7... Developing roller. 8...Bias blade (toner regulating means) 0ヰApplicant Fujitsu Limited

Claims (3)

[Claims] (1) A developing roller (7) that is in pressure contact with the image carrier (1) on which an electrostatic latent image is formed and conveys the one-component non-magnetic toner (4).
); and a toner regulating means (8) that is in pressure contact with the developing roller (7) and keeps the layer thickness of the mono-component non-magnetic toner (4) constant and electrically charged on the developing roller (7). A one-component developing device, characterized in that the developing roller (7) is made of a porous material, and porous foam pores are also present on the surface. (2) Item (1) characterized in that the pore size of the porous foam of the developing roller (7) is set to not more than twice the average particle size of the one-component non-magnetic toner (4). The one-component developing device described. (3) By pressure contact of the toner regulating means (8), charged one-component non-magnetic toner (4) having a constant thickness is conveyed to the image carrier (1) on which an electrostatic latent image is formed, and Image carrier (1
) in a method for manufacturing a developing roller of a one-component developing device that develops the electrostatic latent image by contacting the roller (7a) with pressure, comprising: forming a porous roller (7a) from a raw material; A method for manufacturing a developing roller for a one-component developing device, comprising the steps of polishing the surface and removing the skin layer of the roller (7a).