JPS6073649A - Developing device - Google Patents

Abstract

PURPOSE:To perform development without density uneveness by using an elastic metallic plate for a coating member which contacts the surface of a movable developer carrier, separating the downstream end part of the metallic plate from the developer carrier, and passing toner between them during the period. CONSTITUTION:The nonmagnetic toner 17 is sent out of the bottom part of a hopper 16 to the developer carrier 11. The flexible coating member 13 made of elastic metal, e.g. phosphor bronze is brought into contact with the developer carrier 11, and the bias voltage is applied between the carrier 11 and coating member 13. The downstream-side front end part 13' of the coating member 13 is separated from the surface of the carrier 11 and the toner 17 is applied over the surface of the carrier 11 to uniform thickness to form a developed image having no density uneveness on the surface of the latent image holder 15. The surface of the carrier is roughened finely by a sand blast to improve the effect more. Consequently, the uniform image of high quality is obtained. Through a small-sized, lightweight device by single-component development using only the nonmagnetic toner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing device, and more specifically, in an electrophotographic device or an electrostatic recording device, an electrostatic latent image formed on a photoreceptor or a dielectric material is transferred to a non-magnetic toner. This invention relates to an improvement in a developing device that produces a visible image using a one-component developer consisting of only one component.

[Technical background of the invention and its problems]

This type of developing device has undergone technological advances, including those that use a two-component developer consisting of toner and carrier, and those that use a single-component developer that consists only of magnetic toner. Developing devices using a one-component developer made only of non-magnetic toner have been developed, which can overcome these drawbacks. However, since non-magnetic toner is used, the only major problem is that it is difficult to stably form a uniform thin layer of toner on the surface of the movable developer carrier, which makes it difficult to put it into practical use. It was blocked.

For these reasons, the present inventors have already invented a developing device (Japanese Patent Application No. 57-155934) shown in FIG. 1, and have succeeded in making it possible to form a thin layer of non-magnetic toner. In this invention, a rubber blade 2 as a flexible application member is attached to a carrier roll 1 as a movable developer carrier, and the free end thereof and the surface other than the edge located on the downstream side of the flow of developer are attached to the roll. 1, the rubber blade 2 applies non-magnetic toner 4 supplied from the toner container 3 onto the surface of the carrier roll 1 to form a thin toner layer, This is a device that develops the electrostatic latent image by opposing the photosensitive drum 5 as a latent image holder.

According to the above-mentioned developing device, it is possible to set a large contact area between the surface of the movable developer carrier and the flexible coating member, and the edge of the flexible coating member does not come into contact with the surface of the carrier. Therefore, local application of pressure contact force can be avoided. As a result, it is possible to alleviate unevenness in the pressure welding force caused by subtle defects in setting conditions or machine precision, wear, etc.
A more uniform developer layer can be formed □. In addition, since the contact area between the surface of the carrier and the coating member is large, the developer is subjected to friction under pressure for a long time when passing through this contact area, and the resulting image is The agent will be given a uniform and sufficient triboelectric charge.

Therefore, it is possible to form a uniform thin layer of developer having sufficient charge, so that the electrostatic latent image can be developed satisfactorily.

However, subsequent experiments conducted by the present inventors have revealed that the above-described developing device has the following problems.

■ The rubber blade 2 of the developing device shown in FIG. 1 is fixed to the toner container 3 with screws 6, as shown in FIG. 2
As shown in the figure, there are waves at positions corresponding to the setscrews 6, and uneven pressure contact force against the carrier roll 1 is generated. The toner thin layer is formed by repeatedly shearing the toner aggregate under the pressure of the blade 2, but if the pressure of the blade 2 is uneven, the thickness of the formed toner thin layer will be reduced. Otherwise, it will be non-uniform.

Therefore, by performing development with such a developing device facing the photoreceptor, the developed images formed will have non-uniform image density.

(2) If the developing device is left unused for a long time, the rubber blade 2 will be plastically deformed and the pressing force against the carrier roll 1 will decrease.

Therefore, the thickness of the formed toner thin layer increases, and the resulting developed image has an increased image density and degree of fogging.

(2) When an insulating or high-resistance rubber blade 2 is used, the pressure contact surface of the blade is charged with a surface charge due to frictional charging with the toner. Since the polarity of this surface charge is opposite to the polarity of the charge acquired by the toner, subsequent toner entering under the pressure force is subjected to an attractive force (Coulomb force) toward the blade. Therefore, the toner aggregate under pressure is
As the shearing force changes, the thickness of the thin toner layer formed on the surface of the carrier roll changes over time. In order to solve this problem, it is possible to prevent the blade from being charged by using a conductive rubber blade and making it the same potential as the carrier roll 6-, but the plastic deformation of the blade Significantly, variations in the thickness of the formed toner thin layer over time are still not eliminated. Conductive rubber generally has a low resistance by dispersing carbon particles in the resin, but this impairs the elasticity of the blade and makes it more likely to undergo plastic deformation.

[Purpose of the invention]

An object of the present invention is to provide a developing device that can stably form high-quality images with uniform and sufficient density using a one-component developer consisting only of non-magnetic toner.

[Summary of the invention]

The present invention applies a one-component developer containing only non-magnetic toner to the surface of a movable developer carrier by bringing a flexible coating member into contact with the carrier, and then faces the latent image carrier. In an apparatus for developing a latent image, the flexible application member is formed of an elastic metal plate, and the application member is placed on the carrier, and the surface of the application member excluding the end portion is in surface contact with the carrier. The main idea is to obtain a developing device that can stably form a high-quality image as described above by arranging the developing device in such a manner.

Hereinafter, the present invention will be explained in detail with reference to FIGS. 3 and 4.

11 in the figure is a carrier roller as a movable developer carrier supported rotatably in multiple clockwise directions, and the surface (curve) of this roll 11 is roughened by sandblasting, for example. 12 are formed.

Reference numeral 13 in the figure denotes a metal plate having elasticity as a flexible coating member, and this metal plate 13 is in surface contact and pressure contact with the carrier roll 11 at its curved belly surface. That is, the free end of the metal plate 13, the edge located on the downstream side in terms of the flow of the toner, does not contact the carrier roll 11, and the surface other than the free end is in surface contact with the roll 1. . The pressing force of the metal plate 13 against the carrier roll 11 is t O01! /crr+ to 2500 g/rn is preferable from the viewpoint of uniform triboelectrification and formation of an appropriate amount of toner thin layer. Here, the pressure contact force is the pressure that corresponds to a length of one scratch measured in a direction parallel to the central axis of the carrier roll. When the pressure contact force is less than 100 /l/cm, the metal plate 1
3, the blocking force (the force that tries to prevent the toner from passing under the pressure force) is small, so the toner aggregate passes under the pressure force without being sheared into a sufficiently thin layer, and therefore the carrier roll The thickness of the toner thin layer formed on the surface increases. As a result, although the image density increases, the amount of uncharged toner that does not participate in frictional electrification with the carrier roll or metal plate also increases, resulting in the occurrence of background fog. On the other hand, if the pressing force exceeds 25009/cm, the toner thin layer becomes extremely thin and sufficient image density cannot be obtained.

Examples of the metal plate 13 include a phosphor bronze plate and a stainless steel plate. Among these coating members, when a phosphor bronze plate is used, it is preferable to have a thickness of 0.11 to 0.4 cm, from the viewpoint of forming a thin toner layer with an appropriate thickness of 9 cm. When the thickness of the phosphor bronze plate is less than 0.1 m, the elastic modulus against bending becomes small, making it difficult to form a thin toner layer with an appropriate thickness. On the other hand, when the thickness of the phosphor bronze plate exceeds 0.4 m, the nip width between the plate and the carrier roll decreases, and the pressing force in units of v1i'st and υ increases. A sudden high pressure is applied, and the toner adheres to the surface of the carrier roll due to frictional heat. The presence of stuck toner causes non-uniformity in the thickness of the toner layer. Note that it is effective from the viewpoint of ease of assembly to polish at least the end surface of the metal plate located near the surface of the carrier roll into a gently curved surface.

Furthermore, 14 in the figure is a power source for applying a bias voltage to both the carrier roll 11 and the metal plate 13, and 15 in the figure is a counterclockwise multi-directional power source arranged opposite to the carrier roll 11. This is a selenium photosensitive drum that serves as a latent image holder that rotates.

10- Note that 16 in the figure is arranged above the carrier roll 11, and the non-magnetic toner 1 is placed between the roll 11 and the metal plate 130.
This is a toner container for supplying toner 7.

According to this configuration, when the carrier roll 1 is rotated clockwise, the non-magnetic toner 17 in the toner container 16 will move along the carrier roll 11 and exhibit its elasticity as a flexible application member. The metal plate 13 is conveyed under the pressure force of the metal plate 13 having the metal plate 13 .

At this time, the metal plate 13 has a higher elastic modulus than a rubber plate and is less deformed by the pressure of the mounting jig, etc., and also has less plastic deformation, and the curved belly portion of the metal plate 13 contacts the roll 11. Therefore, the roll 11 made of the metal plate 13
The pressing force against the toner is made uniform, and a thin toner layer of uniform thickness can be formed. Moreover, by configuring the flexible application member with a metal plate, when the metal plate 13 presses the toner 17, surface charging of the metal plate 13 due to frictional charging with the toner 17 can be prevented, and shearing that acts on the toner aggregate can be prevented. Since the force is always constant, a thin toner layer of uniform thickness can be stably formed. When forming such a thin toner layer, a bias voltage is applied to the carrier roll 11 in order to prevent the occurrence of background fog.The bias voltage source 14 is also connected to the metal plate 13 to short-circuit the roll 11 and the metal plate 13. If you do this, metal plate 1
3. Surface charging can be reliably prevented. When the photosensitive drum 15 disposed opposite to the carrier roll 11 on which such a thin toner layer is formed rotates and the electrostatic latent image formed on its surface is transferred to the thin toner layer, the negatively charged toner 1
7 adheres to the electrostatic latent image and is developed. Therefore, by using a metal plate as a flexible application member and arranging this metal plate so that its surface, excluding the edges, is in surface contact with the carrier roll, a thin toner layer of uniform thickness can be stably formed. This makes it possible to obtain high-quality developed images with uniform image density and good reproducibility. Particularly, when a phosphor bronze plate having a large elastic limit is used as the metal plate, uniform pressing force, prevention of plastic deformation, etc. are further improved, and it becomes possible to obtain a developed image with a constant image density.

Note that by forming the surface of the carrier roll 11 to have an uneven surface 12, it is possible to form a more uniform toner thin layer.

That is, the formation of the toner thin layer is carried out on the metal plate 13 as shown in FIG.
and the conveying force F1 due to the carrier roll 1.
This is done by repeatedly shearing the toner aggregate 18 under the action of , but if the surface smoothness of the carrier roll 11 is high, slippage occurs between the toner aggregate 18 and the carrier roll 1. The toner aggregate 18 remains under the pressure of the metal plate 13. As a result, subsequent toner cannot pass through this position, and streaks occur in the thin toner layer that is formed. This tendency occurs when toner with strong self-cohesive properties is used! It is clearly recognized. By making the surface of the carrier roll 11 uneven and rough 12, it is possible to prevent slippage between the toner aggregate 18 and the carrier roll 11, and it is possible to always maintain uniformity regardless of the self-cohesiveness of the toner. A thin layer of toner can be formed.

13- As described above, the developing device of the present invention exhibits particularly great effects in the non-contact developing method. The non-contact development method has many advantages such as prevention of background fog and application to color storm registration development. The developing device according to the present invention performs development by forming a thin toner layer on the surface of a carrier roll and transferring this to the latent image surface. For this reason, when applying a contact development method in which development is performed by bringing a thin toner layer into contact with the latent image surface, it is necessary to prevent damage to the photoreceptor due to contact between the carrier roll and the photoreceptor. Setting requires advanced mechanical 8 degrees. Therefore, by regulating the gap between the carrier roll and the photoreceptor to be equal to or greater than the thickness of the thin toner layer, or in other words, the thickness of the thin toner layer to be less than the above-mentioned gap, it is possible to prevent damage to the photoreceptor and prevent background fogging. Many effects can be obtained, such as prevention and application to color one-overlapping development.

[Embodiments of the invention]

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 3, which has already been described.

14- An aluminum carrier roll 11 with a diameter of 40 m and supported rotatably in a clockwise direction was used as a movable developer carrier. In addition, the surface of this roll 110 is subjected to sand blast treatment! 7 JIS 10 point average roughness display: 4
A rough surface 12 with concavities and convexities of μm is formed. In addition, a phosphor bronze plate 13 with a thickness of 0.211+++1 is used as a flexible coating member.
was used.

This phosphor bronze plate 13 is in pressure contact with the carrier roll 11 on its surface (belly surface) excluding its free end. A selenium photosensitive drum 15 was used as a latent image holder.

Further, as the non-magnetic toner 17 contained in the toner container 16, a toner containing polystyrene, carbon, a charge control agent, etc. and having an average particle size of 14 μm was used.

In the developing device configured as described above, when the carrier roll 11 was rotated clockwise, a thin toner layer was formed on the surface of the roll 11. When the thin toner layer thus formed was subjected to non-contact development on the selenium photosensitive drum 15 disposed opposite to the carrier roll 1, the phosphor bronze plate 13
The correlation shown in FIG. 5 was observed between the image density, the image density, and the fog density. However, the maximum value of the surface potential of the selenium photosensitive drum 15 is 800V, and the voltage from the bias power supply 14 is 10V.
0V, the gap between the carrier roll 11 and the photosensitive drum 15 is 25
The rotational peripheral speed of the 0 μm1 carrier roll 11 and the photosensitive drum 15 was set to 100 −8 ec. If the criteria for determining the quality of an image are image density 1.0 or more and fog density 0.1 or less, as shown in Fig. 5, a good image is obtained when the pressure contact force of the cylindrical bronze plate 13 (flexible coating member) is 10,097 cm to 2,500,717 cm. It can be seen that an image is obtained.

Also, thickness 0.05 #IIIIN Onl W, O*
Similar development was carried out using a phosphor bronze plate with a thickness of 4 tan and 0.5 tran, and in the case of a phosphor bronze plate with a thickness of 0.05 tan, the fog density was 0.2 (tan) and 0-5 van.
In the case of a phosphor bronze plate with a thickness of , the image density is 0.6,
Good images were obtained only when a phosphor bronze plate with a thickness of 0.1 to 0.4 trrm was used.

Historically, when continuous copying was performed under the above-mentioned optimum conditions, good image quality was maintained even after 5,000 copies were made, and no toner adhesion on the surface of the carrier roll was observed.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to obtain a developing device that can stably form cylinder-quality images with uniform and sufficient density using a single-component developer made only of non-magnetic toner, and furthermore, this invention It has remarkable effects such as being able to make image recording apparatuses such as copying machines incorporating a developing device smaller, lighter, and cheaper.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a conventional developing device, FIG. 2 is a schematic diagram for explaining the problems of the conventional developing device, and FIG. 3 is a schematic diagram of a developing device showing a simple embodiment of the present invention. Figure 4 is the third
FIG. 5 is a schematic diagram for explaining the operation of the developing device shown in FIG. 5, and FIG. 5 is a characteristic diagram showing the relationship between image density and resolution and the surface roughness of the uneven surface of the carrier roll. 11... carrier roll (movable developer carrier), 12...
... Uneven rough surface, 13... Elastic metal plate (flexible coating member), 15... Selenium photosensitive drum (latent image 17- holder), 17... Non-magnetic toner, 18...・Toner aggregate. Applicant's agent Patent attorney Takehiko Suzue 18- Figure 3 Figure 4

Claims (8)

[Claims] (1) By bringing a flexible coating member into contact with a movable developer carrier, a one-component developer containing only non-magnetic toner is applied to the surface of the carrier, and the developer is placed opposite the latent image carrier. In an apparatus for developing a latent image, the flexible coating member is formed of an elastic metal plate, and the coating member is placed on the carrier, and the surface of the coating member excluding the end portion is in surface contact with the carrier. A developing device characterized in that it is arranged so as to. (2) The developing device according to claim 1, wherein the pressure force of the flexible coating member against the movable developer carrier is 1009/cm 2 to 2500717 cm. (3) The developing device according to claim 1, wherein the metal plate is a phosphor bronze plate. (4) The developing device according to claim 3, wherein the phosphor bronze plate has a thickness of 0.1 to 0.4 am. (5) The developing device according to claim 1, wherein the surface of the movable developer carrier has an uneven surface. (6) A patent claim characterized in that the thickness of the developer layer on a movable developer carrier applied by a flexible coating member is regulated to a thickness equal to or less than the distance between the carrier and the latent image holder. The developing device according to item 1. (7) The developing device according to claim 1, wherein the movable developer carrier and the flexible application member are electrically connected and a bias voltage is applied to the cough carrier. (8) Among the end faces of the flexible application member, at least the end face located near the surface of the movable developer carrier is polished to form a gently curved surface. developing device.