JPH05289485A - Developing device - Google Patents

Abstract

PURPOSE:To obtain an excellent image without sleeve ghost or the like by the development using toner by excellently electrostatically charging the toner as one-component developer carried on a developer carrier even when pulverized toner layer is formed on the surface of the developer carrier. CONSTITUTION:By forming an elastic blade 2 of a conductive layer 2a being an elastic blade main body layer served also as an electrode and a high resistance layer 2b provided on a conductive developing sleeve 12 side of the conductive layer 2a, and impressing bias voltage having the same polarity as the toner 7 on the conductive layer 2a by a power source 13, charge is supplied to the toner layer on the sleeve 12. Even when the pulverized toner layer is formed on the surface of the sleeve 12, the charge is supplied from the upper layer of the toner layer, so that the toner 7 is excellently electrostatically charged all over the image of the toner layer in cooperation with the triboelectrification with the sleeve 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device using a one-component developer used in an image forming apparatus such as an electrophotographic copying machine or a printer.

[0002]

2. Description of the Related Art Conventionally, in a developing device using a dry toner as a one-component developer, a conductive developing sleeve as a developer carrying member is coated with toner and held in non-contact with an image carrying member. Then, a bias voltage is applied to the developing sleeve to fly the toner onto the image bearing member and attach it to the electrostatic latent image formed on the image bearing member to develop and visualize the latent image as a toner image. It is like this.

Alternatively, toner is applied on a developing sleeve having a high-resistance or medium-resistance surface layer, the developing sleeve is rotated in contact with the image carrier, and a bias voltage is applied to the developing sleeve to apply the toner on the image carrier. There is also known one that transfers an image to an electrostatic latent image on an image carrier. At this time, a developing device in which various modifications such as applying a bias voltage to the toner applying blade is further proposed and implemented.

[0004]

However, in the above-described conventional developing device, when the toner is carried on the developing sleeve and conveyed, fine toner particles having a small particle diameter are triboelectrically charged per volume. Since the charge amount becomes too large, the phenomenon that the fine powder toner accumulates on the surface of the developing sleeve due to the mirroring force of the fine powder toner to form a fine powder toner layer gradually occurs to some extent.

From the above, the majority of toner particles having an amount of electrification charge suitable for the developing conditions and having a central and decisive role in developing a latent image are in the vicinity of the average particle size. Friction electrification between the surface of the developing sleeve and the surface of the developing sleeve is hindered by the fine powder toner layer, resulting in deterioration of developability.

This decrease in developability causes a decrease in image density, or the history of the previously developed image on the rotation cycle of the developing sleeve affects the development in the next cycle, so-called sleeve ghost. It causes a phenomenon.

In the non-contact development, when a fine latent image of 600 dpi or more is developed and an image is reproduced, the distance (SD gap) between the image carrier and the developing sleeve is reduced. In this case, the latent image can be reproduced more faithfully, but if the SD gap is made smaller, the fog increases, and the developing bias leaks more easily in a low humidity environment. When the AC voltage value of the developing bias applied to the developing sleeve is lowered, the density becomes low, which causes a problem.

An object of the present invention is to provide a toner as a one-component developer carried on a developer carrying member with good charge even if a fine powder toner layer is formed on the surface of the developer carrying member. It is an object of the present invention to provide a developing device capable of obtaining a good image without a sleeve ghost or the like by the development using.

[0009]

The above object can be achieved by the developing device according to the present invention. In summary, the present invention regulates a one-component developer carried on a developer carrier by a developer regulating member abutting on the developer carrier to form a thin layer of the developer, In the developing device, which conveys the agent to the developing unit facing the image carrier by the developer carrier, develops the latent image formed on the image carrier by the developer in the developing unit to visualize the latent image, The developer carrying member is formed of a conductive member, and the restricting member is formed of a restricting member main body layer made of a conductive layer, and a high resistance layer provided on the side of the main body layer facing the developer carrying member. In addition, the developing device further comprises a power source for applying a voltage to the main body layer. Preferably, the volume average particle size of the developer is 4 to 9 μm.
The range is m.

According to another aspect of the present invention, the regulating member includes a regulating member body, a high resistance layer on a side facing the developer carrying member, and an electrode layer provided between the regulating member body and the body. And a power supply for applying a voltage to the electrode layer is provided. Preferably, the voltage is applied by the power source while constant current control is performed so that the flowing current is constant or while constant voltage control is performed so that the applied voltage is constant.

[0011]

【Example】

Embodiment 1 FIG. 1 is a sectional view showing a main part of an embodiment of a developing device of the present invention. As shown in FIG. 1, the developing device includes a developing container 4 whose interior is divided into substantially upper and lower parts, and a toner containing chamber 4a in the upper half of the developing container 4 serves as a one-component developer housed therein. A stirring rod 5 for stirring the insulating magnetic toner 7 is installed, and a stirring blade 6 made of a urethane sheet is attached to the tip of the stirring rod 5. In the opening at the lower end of the toner storage chamber 4a, a replenishment roller 8 composed of a magnet roller having N poles and S poles alternately formed in the circumferential direction is installed. The replenishment roller 8 rotates in the arrow direction and is stored in the storage chamber 4a. Toner 7 is replenished into the developing chamber 4b. A magnetic metal plate 9 for scraping off the toner 7 supplemented by the replenishing roller 8 is installed in proximity to the replenishing roller 8.

In the developing chamber 4b in the lower half of the developing container 4, a developing member carrier rotating in the direction of the arrow is provided at an opening portion facing the photosensitive drum 1 serving as an image carrying member of the image forming apparatus. A sleeve 12 is installed. Inside the developing sleeve 12, a magnet roller 11 that holds the toner 7 in the developing chamber 4b on the developing sleeve 12 by magnetic force is installed immovably with respect to the rotation of the developing sleeve 12. The magnet roller 11 moves from the position substantially above the top to N ₁ , S in the rotation direction of the developing sleeve 12 indicated by the arrow.
_It has four magnetic poles of ₁ , N _2, and S ₂ . Further, a power supply 10 for applying a developing bias to the developing sleeve 12 is connected to the developing sleeve 12.

An elastic blade 2 serving as a developer regulating member is installed above the developing sleeve 12 in the developing chamber 4b, and the elastic blade 2 extends freely in the direction opposite to the rotation direction of the developing sleeve 12 shown by the arrow. The abdomen of the end portion elastically abuts on the developing sleeve 12.

With the above-described structure of the developing device, the toner 7 carried on the developing sleeve 12 by the magnetic force of the magnet roller 11 is regulated by the elastic blade 2 to form a uniform thin toner layer. , Is conveyed to the developing section facing the photosensitive drum 1 as the developing sleeve 11 rotates,
Therefore, the developing bias applied to the developing sleeve 11 causes the toner 7 to fly onto the photosensitive drum 1 and the photosensitive drum 1
It adheres to the latent image formed above, and the latent image is visualized and developed as a toner image.

In the present invention, in order to favorably charge the toner 7 carried on the developing sleeve 12, a conductive layer is provided on the elastic blade 2 and a voltage is applied to the conductive layer to develop the developing sleeve 12. A major feature is that an electric charge is supplied to and applied to the upper toner 7 to assist the charging of the toner 7.

In this embodiment, the elastic blade 2 has a two-layer structure comprising a conductive layer 2a constituting the blade main body layer and a surface high resistance layer 2b provided on the side of the conductive layer 2a facing the developing sleeve 12. Is formed on the high resistance layer 2b.
Is in contact with the developing sleeve 12. The conductive layer 2a of the elastic blade 2 is formed by using a conductive rubber or a metal sheet in which carbon black is dispersed, thereby forming a blade body which also serves as an electrode for applying a voltage, and has a volume resistivity of 10 ³ Ωcm or less. on the other hand,
The high resistance layer 2b has a thickness of 20 to 100 μm and a volume resistivity of 10
⁸ Ωcm or more, preferably 3 × 10 ⁸ to 1 × 10 ¹⁰ Ωc
It has a high resistance of m, and in this embodiment, it is formed using hydrin rubber or urethane elastomer to have a thickness of 50 μm and a volume resistivity of 3 × 10 ⁸ to 1 × 10 ¹⁰ Ωcm. Conductive layer 2
A bias power supply 13 applied to the blade 3 is connected to a.

Further, in this embodiment, the surface of the developing sleeve 12 is sandblasted with an amorphous alundum,
Rz (10-point average roughness) is formed on a rough surface of about 3 to 5 μm. This is because the amount of the toner layer formed on the developing sleeve 12 is determined by the surface roughness of the developing sleeve 12 and the contact pressure of the elastic blade 2 on the surface of the developing sleeve 12. In this embodiment, the contact pressure of the elastic blade 2 is set to be 20 to 30 g / cm in linear pressure with respect to the surface roughness of the developing sleeve 12 so that the particle size of the toner 7 is 4 times. A toner layer is formed with a thickness of up to 8 times, and such a toner layer is conveyed to the developing section by the rotation of the developing sleeve 12.

According to this embodiment, a bias voltage having a DC component of −750 V, an AC component of 1500 V at Vpp and a frequency of 3000 Hz is applied to the elastic blade 2 by the power source 13, and the toner on the developing sleeve 2 is applied. Charge is supplied to the layer from the upper layer. As a result, the developing sleeve 1
Even if a fine powder toner layer is formed on the surface of No. 2, a stable charge is given to the toner 7 over the entire toner layer on the developing sleeve 12 in combination with the frictional charging by the elastic blade 2 and the developing sleeve 12. To be done.

When a bias voltage is applied to the elastic blade 2, the high-resistance layer 2b having a thickness of 50 μm is formed on the surface layer of the elastic blade 2, so that the developing sleeve 12 is used.
Even if the elastic blade 2 and the elastic blade 2 come into contact with each other without the toner 7, the excessive current does not flow between the developing sleeve 12 and the power source 13 of the elastic blade 2.

The toner 7 thus formed on the toner layer and having the electric charge is rotated while supporting the developing sleeve 12 with respect to the photosensitive drum 1 in a non-contact state with a space of about 300 μm. Then, the DC component is transferred to the developing sleeve 12 by the power source 10 by the power source 10.
450V, AC component is 1000V at Vpp, frequency is 1
By applying a developing bias of 800 Hz, the toner 7 adheres to the electrostatic latent image on the photosensitive drum 1 in the developing section to develop the latent image.

The photosensitive drum 1 is uniformly charged to -700 V by a charging device (not shown), and then exposed to light from a laser beam or a light source such as a halogen lamp to form an electrostatic latent image on the photosensitive drum 1. It

As described above, according to the present invention, the problem caused by the formation of the fine powder toner layer on the surface of the developing sleeve 12 is improved, and a good image without sleeve ghost can be obtained.

Embodiment 2 FIG. 2 is a sectional view showing the main part of another embodiment of the developing device of the invention. In this embodiment, a conductive layer 14 containing graphite as a main component is provided on the surface layer of the developing sleeve 12 in an amount of 8 to 12 μm.
The feature is that it is formed to a thickness of. The other structure of the developing device of this embodiment is basically the same as that of the developing device of FIG.
2, the same reference numerals as those shown in FIG. 1 denote the same members.

The above-mentioned graphite has a low contact resistance because it does not form an oxide film on the surface like general metals, and has excellent releasability because it has a cleavable crystal face.
It is also resistant to contamination by resin components such as ultrafine powder in the toner 7 and external additives. Therefore, when the conductive layer 14 containing graphite as a main component is formed on the surface layer of the developing sleeve 12, a bias voltage is applied to the elastic blade 2 on which the high resistance layer 2b having high resistance is formed, so that the toner 7 on the developing sleeve 12 is formed. The effect of uniformly charging and stabilizing the amount of charged electric charge of the toner 7 is exerted more effectively, and the effect of preventing density decrease and sleeve ghost in image formation on a large number of sheets is improved.

Embodiment 3 FIG. 3 is a cross-sectional view showing the main part of still another embodiment of the developing device of the present invention. This embodiment is characterized in that the insulating nonmagnetic toner 7 is used as the one-component developer. In this embodiment, since the non-magnetic toner 7 is used, a replenishing roller 16 made of a sponge roller is installed in the opening at the lower end of the toner storage chamber 4a of the developing container 4, and the toner 7 supplemented by this is scraped. The scraper 17 is brought into contact with the supply roller 16 in order to drop it. Further, the developing sleeve 12 has
Supply roller 18 made of a sponge roller that is in contact with this
Thus, the toner 7 is supplied and carried on the developing sleeve 12.

Also in this embodiment, the elastic blade 2 is
The blade main body layer also serving as an electrode is formed of the conductive layer 2a, and the high resistance layer 2b is provided on the side facing the developing sleeve 12, so that the blade has a two-layer structure.
With respect to the insulating non-magnetic toner 7 carried and carried on the upper surface, the toner is regulated by the conductive elastic blade 2 whose surface has been made highly resistant, and the bias voltage is applied to the elastic blade 2. The effect of the present invention, in which the charge is applied to the toner 7 by means of the toner, the charge of the toner 7 is made uniform, the density is stabilized, and the sleeve ghost is reduced, is achieved even when developing using the non-magnetic toner 7. It is fully utilized, and excellent development can be performed as compared with the conventional one.

As described above, in the present invention,
It is apparent that the effect of imparting the electric charge to the toner 7 increases when the potential difference between the developing sleeve 12 and the elastic blade 2 is large, and decreases when the potential difference is small. Therefore, the developing bias and the bias voltage applied to the elastic blade 3 are not limited to the values described in the above embodiments, but the characteristics of the toner 7, the conveying speed, and the peripheral speed ratio between the developing sleeve 12 and the photosensitive drum 1 are used. It goes without saying that appropriate values should be used in consideration of the above. Further, the bias voltage applied to the elastic blade 2 may be only the DC component, and the effect of the present invention can be obtained as long as the alternating bias voltage is applied to the developing sleeve 12.

Embodiment 4 FIG. 4 shows a case where the developing device of the present invention is applied to a process cartridge. The photosensitive drum 1 protected by a shutter 41 is disposed on one side of the cartridge box body 30. The shutter 41 is opened by incorporating the cartridge into the main body of the image forming apparatus, and the photosensitive drum 31 is opened.
An image transfer portion is formed in the opening facing the.

The developing device is formed by being incorporated in the lower half of the box body 30 of the process cartridge.
Has a developing chamber 33a provided with a developing sleeve 32, and a toner containing chamber 33b containing a non-magnetic toner 7 as a one-component developer in a lateral direction of the developing chamber 33a.

The toner 7 in the accommodating chamber 33b is conveyed from the accommodating chamber 33b to the developing chamber 33a through the opening 36 by the stirring rod 35 installed therein, and is supplied and carried on the developing sleeve 12. .. The toner 7 carried on the developing sleeve 12 is conveyed to a developing section facing the photosensitive drum 31 as the developing sleeve 12 rotates while the layer thickness is regulated by the elastic blade 37, and is developed by a power source (not shown) in the developing section. The toner 7 flies onto the photosensitive drum 1 by the developing bias applied to the sleeve 12, and the latent image formed on the photosensitive drum 1 is developed and visualized as a toner image.

In the photosensitive drum 31, after the transfer residual toner is cleaned by the cleaning blade 38 which is in contact with the photosensitive drum 31 (the toner removed by this cleaning is stored in the waste toner chamber 42), the primary charging roller 39 is used. A latent image is formed by being charged and exposed to the laser light 40, and thereafter, development is performed with the toner 7 in the developing portion facing the developing sleeve 12 as described above. The toner image obtained by the development is transferred onto the transfer material conveyed to the photosensitive drum 31 at the image transfer portion provided at the opening where the shutter 41 is opened by incorporating the cartridge into the main body of the image forming apparatus. It is transferred by a transfer charger (both not shown).

Also in this embodiment, the elastic blade 2 is
A conductive layer 2a and a high resistance layer 2b of the first embodiment shown in FIG. 1 are formed in the same manner as the elastic blade having a two-layer structure, and a bias voltage is applied to the elastic blade 2 by a power source (not shown) to be carried on the developing sleeve 32. By supplying and applying the electric charge to the toner 7 thus formed, it is possible to apply the electric charge evenly and stably to the toner 7 on the developing sleeve 32 over the entire toner layer. A good image free from sleeve ghosts and the like can be obtained by the development.

Example 5 In this example, in the developing device of Example 1 described with reference to FIG. 1, an insulating magnetic toner 7 as a one-component developer was used, and a toner having a volume average particle diameter of 4 to 9 μm. It is characterized by using. The other points of the present embodiment are that the distance between the developing sleeve 12 and the photosensitive drum 1 is 150 μm, and the high resistance layer 2b of the surface layer of the elastic blade 2 is 30 μm (volume resistivity 3 × 10 ⁸ to 1 × 10 ¹⁰ Ωcm). ) The same as Example 1 except that it was formed to a thickness of.

In this embodiment, as described above, the toner 7 having a volume average particle diameter of 4 to 9 μm was used. However, when the toner 7 has a volume average particle diameter of more than 9 μm, it is 600 dpi ( This is because when the latent image of 23.6 pel) or more is developed and reproduced, the sharpness is hardly improved, and when the volume average particle diameter is less than 4 μm, the magnetite is contained in the resin forming the toner 7. This is because it becomes difficult to stably contain the toner, and the cost for pulverization and classification during toner production becomes too high.

In the method of the present invention, not only the triboelectric charging between the toner 7 and the developing sleeve 12 but also the triboelectric charging only is applied from the elastic blade 2 side by applying the bias voltage to the toner 7, so that only the triboelectric charging is performed. The amount of so-called reversal toner charged to the opposite polarity is smaller than that in the above case. Further, in the known jumping development, if the voltage of the alternating bias applied to the developing sleeve 12 is reduced for the purpose of preventing discharge and reducing fog, the density is lowered, but the voltage difference between the bias applied to the elastic blade 2 and the developing sleeve 12 is decreased. Is increased, the charge amount of the toner 7 is increased, whereby the developability of the toner 7 can be improved and the density can be increased.

That is, for example, when the SD gap between the developing sleeve 12 and the photosensitive drum 1 is reduced, the developability of the toner 7 can be changed independently of the strength of the alternating electric field even if the alternating electric field is reduced. Therefore, in the developing device as in this embodiment, in order to improve the reproducibility of the fine latent image, the particle size of the toner 7 is set to about 6 μm, which is about half that of the conventional toner, and the SD gap is set to about 150 μm, which is about half the conventional value. However, it is possible to perform development with stable density, less sleeve ghost, and less fog.

Sixth Embodiment This embodiment is applied to the developing device of the second embodiment described with reference to FIG. 2, and the developing sleeve 12 has a conductive layer 14 containing graphite as a main component on its surface layer. 8-12
It is formed to a thickness of μm. In this embodiment, in the developing device of the second embodiment, as in the case of the fifth embodiment, the insulating magnetic toner 7 as the one-component developer has the volume average particle diameter of 4
-9 μm toner was used. The other points of this embodiment are similar to those of the fifth embodiment.

In this embodiment, since the conductive layer 14 containing graphite as a main component is provided on the surface layer of the developing sleeve 12, the toner on the developing sleeve 12 is applied by applying a bias to the conductive layer 2a of the elastic blade 2. The effect of giving an electric charge to No. 7 to make the amount of electric charge of the toner 7 uniform and stable was exhibited more effectively than in Example 5.

Example 7 This example is applied to the developing device of Example 3 described with reference to FIG. 3, and the insulating non-magnetic toner 7 is used as a one-component developer. In this embodiment, the volume average particle diameter of the toner 7 is 4 to 9 as in the case of the fifth embodiment.
μm.

Even when the non-magnetic toner 7 is used as in this embodiment, the effect of the present invention is sufficiently obtained, and the toner 7 on the developing sleeve 12 is charged to make the toner 7 uniform in charge amount. And the stabilizing effect was effectively exhibited.

Embodiment 8 This embodiment is applied to the developing device of the process cartridge of Embodiment 4 described with reference to FIG. As the non-magnetic toner 7 of the one-component developer of the developing device, a toner having a volume average particle diameter of 4 to 9 μm was used as in the case of Example 5. Others were the same as in Example 4, and similarly excellent effects were obtained.

In each of the above embodiments, the elastic blade 2 is formed of the conductive layer 2a constituting the blade body layer which also serves as an electrode and the high resistance layer 2b on the side of the developing sleeve 12 thereof. Examples 9 to 16 are characterized in that the blade body layer of the elastic blade was formed from two layers of the blade body and the electrode layer. This will be described below.

Embodiment 9 FIG. 5 is a sectional view showing still another embodiment of the developing device of the present invention, and FIG. 6 is a schematic configuration diagram showing an image forming apparatus incorporating the developing device of FIG.

First, the image forming apparatus of FIG. 6 will be described. The photosensitive drum 51, which is an image carrier, is made of OPC (induced photoconductive pair) or the like, and is a charging roller 52 that is a charging member.
The surface is uniformly charged by. Then, exposure is performed by irradiating the laser beam 59 modulated according to the image signal,
An electrostatic latent image is formed. This electrostatic latent image is visualized as a toner image by developing it with a magnetic toner as a one-component developer in a developing device having a developing sleeve 53.

Then, in time with the toner image on the photosensitive drum 51, the transfer material 58 such as paper is fed to the transfer portion formed at the nip between the photosensitive drum 51 and the transfer roller 54. A bias having a polarity opposite to that of the toner is applied to the transfer roller 54, so that the toner image on the photosensitive drum 51 is transferred onto the transfer material 58. After that, transfer material 5
8 is separated from the photosensitive drum 51 and conveyed to a fixing device 55, where it is thermally fixed and then discharged to the outside of the main body of the image forming apparatus.

On the other hand, on the photosensitive drum 51, the toner remaining on the photosensitive drum 51 is removed by the cleaning device 56, the charging is performed again, and the same image forming process is repeated.

Next, the developing device of the present invention will be described. The present developing device uses a magnetic toner 6 as a one-component developer.
6 is provided with a developing container containing 1 and a non-magnetic developing sleeve 53 made of aluminum or the like.
It is rotatably installed at a position facing the photosensitive drum 51. In the developing sleeve 53, a magnet (not shown) in which a plurality of magnetic poles N and S are alternately formed is installed immovably with respect to the rotation of the developing sleeve 53. An elastic blade 60 made of urethane rubber or the like as a developer regulating member is in contact with the developing sleeve 53 at the abdomen of the free end portion of the developing sleeve 53, which extends in the direction opposite to the rotation direction indicated by the arrow.

The toner 61 carried on the developing sleeve 53 by the action of the magnet is the elastic blade 60 and the developing sleeve 5.
When passing through the nip portion where 3 and 3 are in contact, the layer thickness is regulated and a uniform toner layer is formed. Toner 61
The frictional charge is applied by friction with the developing sleeve 53, but the frictional charge is also applied when the elastic blade 60 regulates.

According to this embodiment, the elastic blade 6
0 is an electrode layer 60 on the blade body 60a of urethane rubber.
b is provided, and a high resistance layer 60c is provided to prevent leakage. The high resistance layer 60c is provided to the developing sleeve 53.
The side is abutted. Electrode layer 6 of elastic blade 60
A bias having the same polarity as that of the toner is applied to 0b by the power supply 64 connected thereto. Further according to this embodiment,
The power source 64 is a constant current source and controls the constant current so that the value of the current flowing between the elastic blade 60 and the developing sleeve 53 becomes 3 to 5 μA when a bias is applied. By performing this constant current control, even if the resistance of the high resistance layer 60c on the surface layer of the elastic blade 60 changes due to environmental changes, problems such as leakage do not occur.

In this embodiment, as the developing sleeve 53, an aluminum pipe having a diameter of 20 mm, which is roughened with No. 100 mesh alundum abrasive grains and coated with carbon, is used.
A magnet having 4 poles of 0 gauss was incorporated.

As the magnetic toner 61, a negative polarity magnetic toner in which 100 parts by weight of magnetite is kneaded with styrene-acrylic resin and pulverized so that the center of particle size distribution is 5 to 8 μm is used. Was used by adding 1.2% by weight of silica.

As the main body 60a of the elastic blade 60,
A polyurethane rubber having a thickness of 1.3 mm and a hardness of 65 degrees (JIS-A) was used. The electrode layer 60b is polymerized on the blade body 60a with aluminum, and the electrode layer 6
0b is a resin with a resistance of 10 ⁵ to 10 ¹² Ωcm and a thickness of 3
A high resistance layer 60c having a thickness of 0 to 50 μm was formed. This elastic blade 60 was elastically deformed and brought into contact with the developing sleeve 53 with the high resistance layer 60c on the developing sleeve 53 side.

The developing device of this embodiment is configured as described above. According to this, even when the number of times of friction of the toner 61 with the developing sleeve 53 is small at the initial stage of use of the developing device and a sufficient triboelectric charge amount is not supplied, the toner 61
When the toner passes through the contact portion between the elastic blade 60 and the developing sleeve 53, a sufficient bias is applied to the upper layer portion of the toner layer by the bias applied to the electrode layer 60b of the elastic blade 60. The development used gives good images with high density and without sleeve ghosts. Further, since the current flowing from the elastic blade 60 to the developing sleeve 53 is constant, the charge is stably supplied from the elastic blade 60 to the toner, and it is possible to always obtain a high density and uniform image.

Embodiment 10 FIG. 7 is a sectional view showing still another embodiment of the developing device of the invention. This embodiment is characterized in that the non-magnetic toner 61 is used as the one-component developer.

As the developing sleeve 53, one having a diameter of 20 mm, which is obtained by similarly roughening an aluminum pipe and coating a conductive resin layer containing conductive fine particles such as carbon, is used. A polyurethane foam coating roller 65 having an outer diameter of 8 μm is pressed against the developing sleeve 53, the coating roller 65 is rotated in the same direction as the developing sleeve 53, and the residual toner on the developing sleeve 53 is peeled off by the coating roller 65. While taking it, new toner was supplied and carried on the developing sleeve 53.

As the non-magnetic toner 61, a non-magnetic toner in which a red azo pigment is internally added to a styrene-acrylic resin and the center of the particle size distribution is 7 to 10 μm is used.

The elastic blade 60 has a thickness of 1.3 mm and a hardness of 65 degrees (JIS-A) as in the case of the ninth embodiment.
An aluminum electrode layer 60b is superposed on a polyurethane rubber main body 60a, and a resin high resistance layer 60c is provided thereon.

Also in this embodiment, when the toner 61 carried on the developing sleeve 53 is regulated, the elastic blade 60 is used.
A bias was applied to the electrode layer 60b so that the current value was 3 to 5 μA, and electric charge was supplied to the upper layer portion of the toner layer of the toner 61.

Even when a large amount of toner does not have a sufficient amount of triboelectric charge in the initial stage of use of the developing device,
Since the electric charge is supplied when the toner passes through the contact portion between the elastic blade 60 and the developing sleeve 53, a good image having a sufficiently high density and free from sleeve ghost can be obtained.

Also, when the resistance value of the high resistance layer 60c provided to prevent the leak from the electrode layer 60b of the elastic blade 60 to the developing sleeve 53 changes due to environmental changes such as high humidity and low humidity. Since the constant current control is performed, the charge supply to the toner is always stable, so that the density does not decrease and a uniform high density image without unevenness can be obtained.

Further, as in the present embodiment, the non-magnetic toner of the one-component developer is different from the magnetic toner in that it does not contain a high melting point substance therein, so that it is fused at the contact portion between the developing sleeve 53 and the elastic blade 60. It is easy to cause streak-like unevenness on the image due to development. However, according to the invention, the elastic blade 6
Since the bias is applied to the electrode layer 60b of 0 to supply the electric charge, the toner 61 can be sufficiently charged without increasing the contact pressure of the elastic blade 60, and the streaky unevenness can be prevented. Occurrence can also be prevented.

Embodiment 11 FIG. 8 is a sectional view showing still another embodiment of the developing device of the invention. In this embodiment, the electrode layer 6 of the elastic blade 60 is
A switch SW is provided between the bias power source 14 and the electrode layer 60b so that the bias applied to 0b can be turned on / off depending on the number of continuous prints.

As a result, when the developing device is continuously used in a low humidity environment, the triboelectric charge amount of the toner 61 becomes excessive, the toner 61 is less likely to fly from the developing sleeve 53 to the photosensitive drum, and the image density is lowered. The problem can be prevented.

At the start of printing, the toner 61 in the developing container
The number of times that the toner rubs against the developing sleeve 53 is small, and a sufficient amount of triboelectric charge cannot be obtained. Therefore, problems such as a decrease in image density and sleeve ghost easily occur. 60b is provided to apply a bias so that electric charges are supplied to the upper layer portion of the toner layer on the developing sleeve 53 at the start of printing.

However, as the number of prints increases from the start of printing, the amount of triboelectric charge increases, and especially when the toner 61 is a toner having a high resistance value or is used in a low humidity environment, the toner 61 is excessively charged. There is a tendency to become easier. As a result, it becomes difficult for the toner 61 to fly from the developing sleeve 53 to the photosensitive drum, and the image density increased by applying the bias to the electrode layer 60b of the elastic blade 60 may decrease again.

Therefore, in the present embodiment, when a certain number of sheets are printed from the start of printing during continuous printing, the bias applied to the electrode layer 60b of the elastic blade 60 is turned off by the switch SW so that the toner 61 can be prevented from being excessively charged. did.

Specifically, it depends on the structure of the elastic blade 60, the resistance value and particle size of the toner 61, the surface roughness of the developing sleeve 53, and the contact pressure of the elastic blade 60 to the developing sleeve 53, but in a low humidity environment. Then, after printing about 1000 to 1500 sheets, the application of the bias to the electrode layer 60b may be turned off.

As a result, when the developing device is continuously used in a low-humidity environment, the triboelectric charge amount of the toner 61 becomes excessive, and the toner 61 does not easily fly from the developing sleeve 53 to the photosensitive drum. It is possible to prevent a decrease in concentration.

Embodiment 12 FIG. 9 shows a case in which the developing device of the present invention is applied to a process cartridge. The structure of this embodiment is basically the same as that of Embodiment 4 shown in FIG. The elastic blade 60 of the device is the same as that in the ninth embodiment.
a, the electrode layer 60b and the high resistance layer 60c, the elastic blade 2 of the developing device in the fourth embodiment.
Is a conductive layer 2a forming a blade body layer which also serves as an electrode
And the point of being formed from the high resistance layer 2b. Figure 9
4, the same reference numerals as those shown in FIG. 4 denote the same members.

Also in this embodiment, by applying a bias to the electrode layer 60b of the elastic blade 60 and controlling the flowing current thereof at a constant current, the toner 61 on the developing sleeve 32 is sufficiently charged, and a high density toner 61 is obtained. Images can be obtained and sleeve ghosts can be prevented.

By incorporating the developing device in such a process cartridge, there is an advantage that the photosensitive drum 31 can be easily replaced and the toner 61 can be easily replenished.

Example 13 In this example, in the developing device of Example 9 described with reference to FIG. 5, voltage application to the electrode layer 60b of the elastic blade 60 by the power source 64 is performed while constant voltage control is performed. It is a feature. The developing sleeve 53 of this embodiment is
The rotation speed is variable.

When it is desired to obtain high density and high contrast image quality such as a character image, the developing sleeve 5
The rotation number of the developing sleeve 53 is changed according to the type of the image such that the rotation number of the developing sleeve 53 is decreased and the rotation number of the developing sleeve 53 is decreased in the case of a graphic image in which the gradation is emphasized. There is a way. This is a method utilizing the fact that the developing efficiency changes by changing the amount of developer replenished per short time.

As described above, in the developing device or the image forming apparatus in which the rotation speed of the developing sleeve 53 can be switched, the elastic blade 60 and the developing sleeve 5 can be changed in a short time.
The amount of toner passing between the elastic blade 60 and the developing roller 53 changes, but if a bias voltage is applied to the elastic blade 60 so that the voltage between the elastic blade 60 and the developing sleeve 53 becomes constant by constant voltage control at this time The electric charge supplied from the elastic blade 60 to the toner 61 on the developing sleeve 53 is sufficiently supplied even when the developing sleeve 53 is rotated at a high speed, as in the case where the developing sleeve 53 is rotated at a high speed, and therefore, sufficient density can be obtained. In the present embodiment, the power supply 64 is a constant voltage source, which allows a bias of the same polarity as the toner 61 on the developing sleeve 53 to be generated at a voltage of -600 to -8.
The voltage was controlled to a constant voltage of 00 V and applied.

In this embodiment, the photosensitive drum 51 of FIG. 6 has a surface potential of −55 due to the charging roller 52.
The developing sleeve 53 is charged so as to be 0 to -650V.
Has a DC component of -350 to -550V and an AC component of V
A developing bias with a pp of 1600 V and a frequency of 1800 Hz was applied. Developing sleeve 53 and elastic blade 60
And the negatively chargeable magnetic toner 61 are the same as those in Example 9.
Same as.

In this embodiment, since the bias is applied to the electrode layer 60b of the elastic blade 60 by controlling the constant voltage as described above, the toner 61 on the developing sleeve 53 is applied to the toner 61 even when the developing sleeve 53 rotates rapidly. Sufficient charges can be supplied, and a good image with high density without sleeve ghost can be obtained.

Embodiment 14 In this embodiment, the developing device of Embodiment 10 described with reference to FIG. 7 is applied, and like Embodiment 13,
The only difference from the tenth embodiment is that the power supply 64 is a constant voltage power supply and the rotation speed of the developing sleeve 52 is variable.

Even when the non-magnetic toner 61 is used as the one-component developer as in this embodiment, a bias having the same polarity as that of the toner 61 is applied to the electrode layer 60b of the elastic blade 60 by constant voltage control as in the thirteenth embodiment. By applying the voltage as described above, sufficient charge can be supplied to the toner 61 on the developing sleeve 53 even when the developing sleeve 53 rotates rapidly, and a good image with high density and no sleeve ghost can be obtained.

Fifteenth Embodiment This embodiment is applied to the developing device of the eleventh embodiment described with reference to FIG. 8, and like the thirteenth embodiment,
The only difference from the eleventh embodiment is that the power source 64 is a constant voltage power source and the rotation speed of the developing sleeve 52 is variable.

In this embodiment, a switch SW provided between the constant voltage power source 64 and the elastic blade 60 is used to print a certain number of sheets from the start of printing during continuous printing.
Since the bias applied to the electrode layer 60b of the elastic blade 60 can be turned off to prevent the toner 61 from being excessively charged,
Even when the developing sleeve 53 rotates rapidly, the effect of supplying a sufficient charge to the toner 61 on the developing sleeve 53 and obtaining a good image with high density without sleeve ghost is further improved.

Example 16 In this example, the developing device of the process cartridge of Example 12 described with reference to FIG. 9 was applied. By applying a constant-voltage-controlled bias to the electrode layer 60b of the elastic blade 60 of the developing device in the same manner as in Example 13, a high-density image without sleeve ghost was similarly obtained.

[0082]

As described above, according to the developing device of the present invention, even if the fine toner layer is formed on the surface of the developer carrying member, the regulating member is provided with the conductive layer or the electrode layer to form one component. A bias voltage having the same polarity as that of the toner of the developer is applied to supply the electric charge to the toner carried on the developer carrier, so that the toner is distributed over all layers of the toner layer on the developer carrier. The toner can be favorably charged in combination with frictional charging with the developer carrying member, and therefore, a good image without sleeve ghost can be obtained by the development using this toner.

Further, when the bias applied to the regulating member is controlled by a constant current, even if the resistance value of the leakage preventing high resistance layer formed on the regulating member changes due to environmental changes, the bias is controlled by a constant voltage. In this case, even if the rotation speed of the developer carrying member changes, the toner can be similarly charged well and a good image without sleeve ghost can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a developing device of the present invention.

FIG. 2 is a sectional view showing another embodiment of the developing device of the invention.

FIG. 3 is a sectional view showing still another embodiment of the developing device of the present invention.

FIG. 4 is a sectional view showing a process cartridge to which the developing device of the present invention is applied.

FIG. 5 is a sectional view showing still another embodiment of the developing device of the present invention.

FIG. 6 is a schematic configuration diagram showing an image forming apparatus including the developing device of FIG.

FIG. 7 is a sectional view showing still another embodiment of the developing device of the present invention.

FIG. 8 is a sectional view showing still another embodiment of the developing device of the present invention.

FIG. 9 is a sectional view showing a process cartridge to which the developing device of the present invention is applied.

[Explanation of symbols]

 1, 51 Photosensitive drum 2, 60 Elastic blade 2a Conductive layers 2b, 60c High resistance layer 7, 61 Toner 12, 53 Developing sleeve 13, 64 Power supply 60a Blade body 60b Electrode layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroki Kisu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] 1. A one-component developer carried on a developer carrier is regulated by a developer regulating member abutting on the developer carrier to form a thin layer of the developer, A developing device that conveys the latent image formed on the image carrier by the developer to the developing unit that is conveyed to the developing unit facing the image carrier by the developer,
The developer carrying member is formed of a conductive member, and the restricting member is formed of a restricting member main body layer made of a conductive layer, and a high resistance layer provided on the side of the main body layer facing the developer carrying member. The developing device further comprises a power supply for applying a voltage to the main body layer. 2. The volume average particle diameter of the developer is 4 to 9 μm.
2. The developing device according to claim 1, wherein 3. A one-component developer carried on a developer carrier is regulated by a developer regulating member abutting on the developer carrier to form a thin layer of the developer, A developing device that conveys the latent image formed on the image carrier by the developer to the developing unit that is conveyed to the developing unit facing the image carrier by the developer,
The developer carrying member is formed of a conductive member, and the regulating member includes a regulating member body, a high resistance layer on a side facing the developer carrying body, and an electrode layer provided between the regulating member body and the body. And a power source for applying a voltage to the electrode layer. 4. The developing device according to claim 3, wherein the application of the voltage by the power source is performed while constant current control is performed so that the flowing current is constant. 5. The developing device according to claim 3, wherein the voltage is applied by the power source while performing constant voltage control so that the applied voltage is constant.