JPH05224517A - Developing device - Google Patents

Abstract

PURPOSE:To suppress the occurrence of the scattering of toner, the surface staining on an image, etc., and to stably execute a toner thin layer forming function over a long period by preventing the passage of electrostatically uncharged toner on a toner regulating part, even if the press-contacting force of the toner regulating member, with a toner carrying/transporting member is set small. CONSTITUTION:An insulating sheet 8 is stuck to the toner regulating member 6 for making toner T supplied onto a roller-like toner carrying/transporting member 5, into a thin layer, and brought into press-contact with the toner carrying/transporting member 5. An alternating electric field is formed between a metallic elastic plate 7 constituting the main body of the toner regulating member 6, and the toner carrying/transporting member 5, and the toner going to a part for making the toner into the thin layer is made to reciprocate between the plate 7 and the member 5 and made into a powder-mist state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device equipped with a toner carrying and conveying member and a toner regulating member.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a facsimile or a printer, which forms a predetermined electrostatic latent image on a latent image carrier, the electrostatic latent image is visualized as a toner image. In addition, dry type developing devices are widely adopted.

In such a developing device, one-component toner is used, and this toner is supplied onto, for example, a roller-shaped toner carrying / conveying member, and a toner layer having a predetermined layer thickness is formed on the toner carrying / conveying member. It is known to form. The one-component toner is a developer that contains only toner particles or an auxiliary agent externally added thereto and does not contain carrier particles.

FIG. 6 shows an example of a conventional developing device of such a type.

The developing device 100 is opposed to a drum-shaped photosensitive member 101, which is an example of the structure of a latent image carrier, and a toner T of one component is stored inside the developing container 102. The toner is supplied to the toner supply member 104 while being stirred by the agitator 103. The toner supply member 104 is made of, for example, a sponge roller or a brush roller that has been subjected to a conductive treatment, and is pressed against the outer peripheral surface of the roller-shaped toner carrying and conveying member 105 so as to bite into it.

The toner carrying and conveying member 105 is shown in FIG.
In the case of the roller body as shown in FIG. 3, it is also called a "developing roller", and it is arranged to face the photoconductor 101 and is rotationally driven in the direction of the arrow in the figure. Toner supply member 10 that bites into the toner carrying and conveying member 105
Reference numeral 4 denotes the toner carrying / conveying member 1 in the forward direction (indicated by the arrow in the figure) with respect to the toner carrying / conveying member 105 or in the opposite direction.
It is designed to be rotationally driven at a linear velocity ratio of, for example, about 0.5 to 2.5 times that of No. 05. Generally, a developing bias voltage having a predetermined polarity is applied to the photoconductor 101.

The toner supply member 104 collects the toner T in the developing container 102 in the vicinity of the toner carrying / conveying member 105 by the above-described rotation and frictionally charges the toner T to a predetermined polarity. The charged toner is attached and carried on the toner carrying and carrying member 105, and carried by the rotation of the member 105. The toner regulating member 106 regulates the layer thickness of the toner carried and conveyed on the toner carrying and conveying member 105 while leveling the toner as a toner layer. As described above, the toner regulating member 106 serves to regulate the layer thickness of the toner supplied to the toner carrying / conveying member 105 to form a toner layer.

The toner having a desired uniform layer thickness is
The toner is conveyed to the developing area 109 between the photosensitive member 101 and the toner carrying and conveying member 105 which are rotationally driven in the direction of the arrow, and here,
The latent image is electrostatically transferred to the electrostatic latent image formed on the photoconductor 101, and the latent image is visualized as a toner image. A technique for reducing the thickness of a single-component toner is disclosed in, for example, Japanese Patent Publication Nos. 63-16736 and 63-15580.

In order to reduce the cost of the developing device and further downsize it, it is advantageous to employ the developing device using the one-component toner as described above. In this case, in order to carry a fixed amount of charged toner in a thin layer on the toner carrying / transporting member 105 and to electrostatically transfer the carried toner to an electrostatic latent image, the toner regulation is performed. The mass per unit area (M / A) of the toner layer on the toner carrying and conveying member that passes through the member 106 and is conveyed to the developing area 109, and the charge amount per unit mass (Q / M) are Regardless, or
It is desirable that they remain constant regardless of changes in the environment.

Further, the mass M / A per unit area of the toner layer on the toner carrying / conveying member means that the electrostatic latent image on the photoconductor and the surface of the toner carrying / conveying member move at a constant speed. However, it is desirable that a sufficient image density be obtained. As a specific example, the value is in the range of 0.5 to 2.0 mg / cm ² . Further, as the charge amount Q / M per unit mass, the absolute value is 5 to 20.
It is better to set in the range of μc / g.

By the way, in this type of developing device,
Normally, the toner regulating member 106 is composed of a blade-shaped elastic body, but such a member is used as the toner carrying and conveying member 10.
When the pressure contact force is set to a low value, for example, 40 g / cm or less, when the toner is pressed against 5 through the toner, the toner flow member F follows the force of the toner flow F and the toner regulating member 1
The uncharged toner in the developing container 102, which flows into the toner regulating section between the toner carrying member 105 and the toner carrying member 105, also passes through the toner regulating section without being regulated.

The toner that has passed through the toner regulating member 106 in this manner adheres to the background portion of the photosensitive member 101 to cause background stains due to the insufficient charge amount, or the photosensitive member 101 or The toner is easily scattered around the toner carrying member 105, and the inside of the image forming apparatus becomes soiled with the toner.

On the other hand, the pressure contact force of the toner regulating member 106 with respect to the toner carrying and conveying member 105 is, for example, 40 g / cm.
If it is set higher than the above, the rotational load of the toner carrying and conveying member 105 increases, and the mass M per unit area of the toner layer is increased.
/ A becomes small.

When M / A is reduced, the image density is lowered when the moving speeds of the electrostatic latent image on the photosensitive member and the surface of the toner carrying and conveying member 105 are the same. If the toner carrying / conveying member 105 is rotated at a high speed in order to prevent this decrease, the driving torque increases and a larger capacity motor is required, which is also disadvantageous in terms of cost. Further, when the pressure contact force is increased, when the toner passes through the toner regulation portion, the load applied to the toner is further increased, and as a result, the toner regulation member is
The toner adheres to the toner, which interferes with the toner regulating action, and lowers the durability of the device.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent uncharged toner from passing through a toner regulating portion even if the pressure contact force of the toner regulating member with respect to the toner carrying and conveying member is set small. Another object of the present invention is to provide a developing device capable of suppressing the occurrence of toner scattering and background stains on an image and stably performing a thin layer forming function of toner for a long period of time.

[0016]

In order to achieve the above object, the present invention regulates the toner carrying and carrying member carrying and carrying toner and the layer thickness of the toner supplied to the toner carrying and carrying member. A developing device that has a toner regulating member that forms a toner layer, and that visualizes an electrostatic latent image formed on a latent image carrier as a toner image by toner whose layer thickness is regulated by the toner regulating member. In the above, between the toner regulating member portion on the upstream side with respect to the moving direction of the toner and the toner bearing conveying member portion facing the toner regulating member portion which is in pressure contact with the toner carrying member via the toner. In addition, the present invention proposes a developing device provided with means for forming a periodically changing electric field.

In the toner carrying and conveying member, the surface portion is a surface portion in which a conductive portion and a dielectric portion are dispersed and mixed, and by applying an electric charge to the dielectric portion, the dielectric portion and the conductive portion are electrically conductive. It is effective to form a minute closed electric field between the parts to hold the toner.

Further, the pressure contact portion of the toner regulating member, which comes into pressure contact with the toner carrying / transporting member via the toner, is an insulating portion. The insulating portion is located upstream of the insulating portion in the toner moving direction, and the toner carrying member is carried. It is effective that the toner regulating member portion facing the conveying member is a conductive portion.

Further, it is effective that the toner regulating member is composed of a metal elastic plate having an insulating sheet fixed to a portion including the pressure contact portion.

Further, it is effective that the toner regulating member is composed of an elastic rubber blade having a conductive portion serving as an electrode sheet surface.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a developing device according to an embodiment of the present invention. The developing device 10 is opposed to a drum-shaped photoconductor 1 which is an example of the configuration of a latent image carrier, and a developing container 2 of the developing device 10 contains a toner T of one component. Reference numerals 3, 4 and 5 respectively denote an agitator, a toner supply member, and a toner carrying and conveying member,
Since these correspond to the agitator 103, the toner supply member 104, and the toner carrying / conveying member 105 in the conventional developing device shown in FIG. 6, the description of the material type and the function thereof is omitted here for convenience. To do.

Reference numeral 6 denotes a toner regulating member, and the regulating member 6 has the same basic function as the conventional toner regulating member, and the toner supplied onto the toner carrying and conveying member 5 is leveled. To form a toner layer having a constant layer thickness. The toner of which the layer thickness is regulated in this manner is carried to the developing area 9 while being carried by the toner carrying and carrying member 5 which rotates counterclockwise, where the toner is transferred to the photoconductor 1 which rotates in the arrow direction. The formed electrostatic latent image is visualized as a toner image, which is no different from the conventional developing device.

Generally, this type of toner regulating member 6 is
As shown in FIG. 4, the free end of the toner contacting member P, which is composed of a blade-shaped elastic plate and is in contact with the toner carrying member 5 via the toner, has a free end. Is arranged on the downstream side in the moving direction, or, as shown in FIG. 5, the free end of the toner regulating member 6 is arranged on the upstream side with respect to the pressure contact portion P. Although FIG. 1 belongs to the former method shown in FIG. 4, the present invention can be applied to a developing device of any method.

In any case, the toner supply member 4 is provided in the minute wedge-shaped gap 11 between the toner carrying / conveying member 5 and the toner regulating member 6 regardless of the arrangement method of the toner regulating member 6. Not only the toner that is frictionally charged by the mutual sliding action between the toner carrying member 5 and the toner carrying member 5 and adheres on the toner carrying member 5, but also the uncharged toner in the developing container 2 is mixed therein. To do.

By removing excess toner unsuitable for development from the wedge-shaped gap 11 slightly upstream of the pressure contact portion P between the toner carrying / conveying member 5 and the toner regulating member 6, the photosensitive member 1 is removed. The toner layer can be stably formed with a low pressure contact force (blade pressure) of the toner regulating member 6 with respect to. If an elastic blade is used for such a toner regulating member, such pressure is in the range of, for example, about 0.5 to 5.0 g / cm in linear pressure. The smaller this pressure is, the more the toner carrying and conveying member 5 is driven. Is not a heavy burden.

As a means for removing the toner clogging in the wedge-shaped gap 11 as described above, the toner carrying member 5 and
By forming an alternating electric field that periodically changes with the toner regulating member 6, the toner existing in the gap 11 can be reciprocated at high speed between them, and this movement causes the toner to be in a mist state. Can be In this way, the insufficiently charged toner is scattered and the developer container 2
Of the toner, and only a sufficiently charged toner adheres to the toner carrying and conveying member 5 by a certain amount, and the toner is sent to the developing area 9. With such a function, the toner regulating member 6
The pressure contact force with respect to the toner carrying / conveying member may be such that the toner remaining on the toner carrying / conveying member is leveled.

The above-mentioned alternating electric field may be formed over the entire surface between the toner regulating member 6 and the toner carrying and conveying member 5, but the toner present in the wedge-shaped gap 11 is atomized. It is sufficient to form an alternating electric field in at least this gap 11 since it is sufficient to delimit it. From this point of view, the present invention is directed to the toner moving direction (rotational direction of the toner carrying / conveying member 5) with respect to the pressure contact portion P of the toner regulating member 6 which comes into pressure contact with the toner carrying / conveying member 5 via the toner. A periodically changing electric field is formed in a region between the toner regulation member portion 6a on the upstream side and the portion of the toner carrying and conveying member 6 facing the toner regulation member portion 6a.
At least in this region, a periodically changing electric field is formed. As a means for forming such an electric field, in the embodiment shown in FIG. 1, a bias applying power source 12 for applying an AC bias voltage to the toner regulating member 6 is used.
The toner regulating member 6 forms at least the alternating electric field, and for example, a portion indicated by reference numeral 6a is a conductive portion made of a conductive material.

When the surface of the toner carrying / conveying member 5 is insulative, there is no problem even if the pressure contact portion P is electrically conductive. On the other hand, the toner carrying and conveying member 5
Is entirely conductive, or the surface thereof is partially conductive, when the above bias voltage is applied to the toner regulating member 6, the toner regulating member 6 and the toner carrying and conveying member 5 are separated from each other. Current leakage occurs.

In order to prevent the occurrence of this problem, the pressure contact portion P of the toner regulating member 6 which is pressure-contacted to the toner carrying and conveying member 5 via the toner is made an insulating portion so that the above-mentioned current leakage can be prevented. It is desirable to do. In this case as well, the toner regulating member portion 6a, which is on the upstream side of the toner moving direction (rotational direction of the toner carrying and conveying member) and faces the toner carrying and conveying member, is a conductive portion also in this case. So that the alternating electric field can be formed without any trouble.

In the embodiment shown in FIG. 1, the main body of the toner regulating member 6 is composed of the metal elastic plate 7 to obtain the above-mentioned conductive portion (portion 6a), and the insulating sheet is provided in the portion including the pressure contact portion P. The (dielectric sheet) 8 is fixed to obtain the above-mentioned insulating portion.

By the way, the surface portion of the toner carrying / conveying member 5 is a surface portion in which the conductive portion and the dielectric portion are minutely dispersed and mixed, and the conductive portion serves as the conductive base of the toner carrying / conveying member. When it is in an electrically connected state,
For example, by applying electric charge to the dielectric portion by friction between the surface portion and the toner supply member 4, a large number of minute closed electric fields are formed between the conductive portion and the dielectric portion. Can be favorably held on the toner carrying and conveying member 5. In such a good holding state, the toner atomized before forming the thin layer can be uniformly sucked onto the toner carrying and conveying member, and a good and uniform toner layer can be formed. .. As a technique relating to a toner carrying and conveying member having a conductive portion and a dielectric portion on the surface, Japanese Patent Application No. 2-275061 of the present applicant has already been proposed.

The surface of the toner carrying / conveying member 5 as described above is such that the conductive portion and the dielectric portion are mixed with each other in, for example, a lattice pattern, an iris pattern, a stripe pattern, or another regular pattern. Or, the surface is such that the dielectric particles are irregularly dispersed and exposed on the surface of the conductive resin. A minute closed electric field is formed between the conductive portion and the dielectric portion, and the toner is favorably held on the toner carrying and conveying member by the action of this electric field.

The toner carrying and conveying member as described above is an example of the toner carrying and carrying member whose surface is partially conductive, and an example of the toner carrying and carrying member wholly conductive is the surface of aluminum. There is one in which toner is mechanically conveyed by a sandblasted roller, and when any of the toner carrying and conveying members 5 is used, the toner carrying and conveying member 5 of the toner regulating member 6 is used. By forming the pressure contact portion P with respect to the insulating portion as an insulating portion, even if an alternating electric field that allows the toner to reciprocate is formed between the toner carrying and conveying member 5 and the toner regulating member 6, the toner regulating member 6 and the toner regulating member 6 It is possible to prevent mutual current leakage with the conductive portion of the carrying / conveying member 5.

As a result, a bias voltage having sufficient strength to remove unnecessary toner from the toner retention portion 11 can be applied to the toner regulating member. In this way, it is possible to form a toner layer suitable for development with a toner that is favorably charged. Further, when the surface of the toner carrying / transporting member is composed of a conductive portion and a dielectric portion, and a minute electric field is formed between the both by the electric charge accumulated in the dielectric portion, the above-mentioned atomized state As a result, the toner can be sucked onto the toner carrying and conveying member with fine regularity, and a good toner layer having a thickness suitable for development can be formed.

Now, a more specific embodiment of the configuration shown in FIG. 1 will be described. Toner regulating member 6 shown in FIG.
Is a blade type toner regulating member, the main body of which is composed of the metal elastic plate 7 having a spring property as described above, and the facing surface including the pressure contact portion P of the toner regulating member 6 to the toner carrying and conveying member 5. Is the surface of the insulating sheet 8. That is, as shown in FIG. 2, the toner regulating member 6 is
Dielectric sheet 8 having a thickness t in the range of 0.05 to 2.00 mm
However, the metal elastic plate 7 is integrally attached to the abdomen on the free end side.

Here, the amount of protrusion of the dielectric sheet 8 from the pressure contact portion P is L _1, and the length of the metal elastic plate 7 that can be effectively used as an electrode is L _2. The protrusion amount L ₁ of the former is 0.5
A range of up to 5.0 mm is suitable.

Now, in FIG. 2, with respect to the pressure contact portion P,
Assuming that there is an L ₂ portion serving as an effective electrode on the upstream side in the moving direction of the surface of the toner carrying / conveying member 5 (moving direction of the carried toner), the thickness t of the dielectric sheet 8 described above is assumed.
Or the distance H ₁ between the L ₂ portion and the surface portion of the toner carrying member 5 due to the difference in the protrusion amount L _1, etc.
H ₂ changes.

Now, assuming that the roller-shaped toner carrying and conveying member 5 having a diameter D is used, the shortest gap H ₁ and the longest gap H ₂ between the conveying member 5 and the metal elastic plate 7 are as follows. Become. ^{_{H 1 = t + L 1 2}} / D H 2 = t + (L 1 + L 2) 2 / D

Further, assuming that the potential difference V between the metal elastic plate (hereinafter referred to as a blade electrode) 7 and the toner carrying / conveying member 5, the electric field E between them is in the following range. 1000 ≦ V / H ₂ <E <V / H ₁ ≦ 8000

The electric field is strong enough to cause the toner in the toner reservoir 11 (FIG. 1) to reciprocate between the toner carrying member 5 and the L ₂ portion of the blade electrode 7. It is necessary to have
00 V / mm or more is required, and it is necessary to set it to 8000 V / mm or less to prevent leakage.

Now, the thickness t of the dielectric sheet 8 is, for example, 0.
2 mm, the protrusion amount L ₁ is 1 mm, and the diameter D of the toner carrying member 5 is 20 mm, the effective electrode width L ₂ is
For example, when it is set to 1 mm, the shortest gap H ₁ is 0.
25 mm and the longest gap H ₂ is 0.4 mm. At this time, the bias voltage applied to the blade electrode 7 is required to be 400 V or more for the toner to move to one side, and therefore Vp-p (peak to peak) is required to be 800 V or more.

At this time, assuming that the linear velocity of the toner carrying and conveying member 5 is Vs with respect to the length L _{2 of} the effective electrode portion (the portion to which an electric field above the minimum electric field is applied), Vs adheres to the toner carrying and conveying member 5. In order to reciprocate the above-mentioned toner at least once to make it into a powder mist state, the cycle of the applied bias must be shorter than the time for which it passes through the portion corresponding to the electrode of the toner carrying and conveying member 5. Therefore, as shown below, the frequency f of the applied bias needs to be higher than Vs / L ₂ . f> (Vs / L ₂ )

Now, assuming that the linear velocity Vs of the toner carrying / conveying member 5 at the time of rotation is 150 mm / sec, the frequency f may be 150 Hz or more. The material of the dielectric sheet 8 located at the pressure contact portion P is polyurethane,
Use a material such as polycarbonate with a linear pressure of 0.5
It is good to set it to about 30 g / cm. By doing so, the amount of toner passing through the toner regulation member 6 is regulated stably.

In any case, in this example, the toner regulating member 6 carries the toner carrying and conveying member on the upstream side in the moving direction of the toner on the toner carrying and conveying member 5 with respect to the insulating portion such as the dielectric sheet 8. The conductive part L is provided on the surface facing the member.
_It has _two . In FIG.
The bias applying power source 12 includes an AC power source 12A and a DC power source 1
2B, which causes the toner to reciprocate between the toner carrying / conveying member 5 and the conductive portion L ₂ of the toner regulating member 7, together with the metal elastic plate 7 serving as an electrode. A means for forming an electric field to be obtained is configured.

With the above-described structure, the toner scattering and the background stain on the image can be suppressed, and the pressure contact force of the toner regulating member can be reduced, so that the toner thin layer function can be stably performed for a long period of time. You will be able to carry out.

In the embodiment shown in FIG. 3, the toner regulating member is
The elastic rubber blade 17 has a conductive portion serving as an electrode sheet surface.

The main body of the toner regulating member 16 is composed of an elastic rubber blade 17. Toner regulating member 1 of this example
In the case of 6, there is an advantage in that the pressure in the press contact portion P is made uniform by the rubber elasticity. A sheet-shaped electrode 18 is fixedly attached to the elastic rubber blade 17 forming the main body so as to be located on the upstream side of the pressure contact portion P.

Here, when the distance from the pressure contact portion (pressure contact) P to the electrode 18 is L ₁ and the thickness of the sheet electrode 18 is t, the shortest gap H ₁ between the toner carrying member 5 and the electrode 18 is obtained. The longest gap H ₂ is as follows. ^{_{H 1 = L 1 2 / (}} D-t) H 2 = (L 1 + L 2) 2 / (D-t)

Also in this example, the bias conditions applied to the electrode 18 are the same as those in the above-mentioned embodiment. In this example, under the action of rubber elasticity,
Since the toner is regulated, the pressure is made uniform and a smooth and stable toner layer can be obtained. Therefore, since such a toner layer is used in the developing step, the electrostatic latent image formed on the photoconductor and the toner layer are brought into non-contact with each other to cause the toner to fly to the latent image. This system can also be effectively applied to the system, so that an image with good uniform density can be obtained. Of course, these points also apply to the contact type.

The inventors of the present invention conducted the following two experiments.
Image quality was evaluated.

Example 1: A drum-shaped organic photoconductor is used as an electrostatic latent image carrier, and negative-positive development is carried out with a toner having a negative charge. In this case, the photoconductor charging potential is-.
850V, and the exposed portion potential was -100V. The toner carrying / conveying member (developing roller) and the toner supplying member (conductive sponge) were connected so as to have the same potential, and DC of -700 V was applied as a developing bias to the substrate of the toner carrying / conveying member. The developing roller used is one in which square groove knurling is performed on an aluminum pipe base, silicone resin is applied, and then surface cutting is performed to expose the conductive surface. A stainless steel blade having a thickness of 0.1 mm was used as the toner regulating member. A polycarbonate sheet having a thickness of 0.1 mm was attached to the portion of the toner regulating member facing the toner carrying and conveying member. Then, Vp-p of 12 is applied to the toner regulating member as a toner layer forming bias.
A superposed AC bias of DC-800V was applied at 00V and a frequency of 1 kHz. The linear pressure at the pressure contact portion of the toner regulating member was set to 10 g / cm. The toner layer thus formed has a mass per unit area (M / A) of 1.2.
mg / cm ² , charge amount per unit mass (Q / M) is -10 μc /
g, and the toner is well regulated. The linear velocity of the photoconductor was 150 mm / sec, and the developing roller was rotated at substantially the same velocity. A high-quality image with good uniformity was stably obtained by flying-developing the toner layer with a gap of 0.12 mm between the developing roller and the photoconductor.

Example 2 Under the same developing conditions as above, a toner carrying / conveying member (developing roller) used was an aluminum pipe which had been sandblasted. Then, a urethane rubber having a thickness of 2.0 mm is used as the toner regulating member. An electrode sheet having a thickness of 0.2 mm was attached to the surface of the toner regulating member 1.2 mm upstream from the pressure contact portion between the toner regulating member and the toner carrying and conveying member. Then, Vp- is applied to the toner regulating member as a toner layer forming bias
A p-1200V, a frequency of 1 KHz, and a DC-800V superimposed AC bias were applied. Further, the linear pressure at the pressure contact portion of the toner regulating member was set to 5 g / cm. The toner layer thus formed has a mass per unit area (M / A) of 1.3 mg / cm ² , and a charge amount per unit mass (Q / M) is -8.
It was μc / g, the toner was well regulated, and it was suitable for image formation.

In each of the embodiments described above, a non-magnetic toner or a magnetic toner can be used as the toner. The present invention can also be applied to a developing device that uses magnetic toner, for example, a magnet is provided inside the toner carrying and conveying member, the toner carrying and conveying member is stopped, and the magnet inside is rotatably driven to carry the toner. is there. The present invention is also applicable when the toner regulating member is formed in a shape other than the blade, for example, a roller shape, and the toner carrying and conveying member is formed in a belt shape.

[0055]

According to the developing device of the first aspect, in forming the toner layer on the toner carrying and conveying member,
For uncharged toner, before going to the toner control section,
Since the toner is returned to the side of the developing container, it is possible to suppress toner scattering due to the uncharged toner and background stain on the image. Further, since the pressure contact force of the toner regulating member with respect to the toner carrying / conveying member can be reduced, it is possible to reduce the rotational load of the toner carrying / conveying member, and further to perform a stable toner thinning function for a long period of time. You can

According to the developing device of the second aspect, the toner can be satisfactorily held on the toner carrying / conveying member, so that the toner thin layer having a good uniform thickness is formed on the toner carrying / conveying member. Can be formed.

According to the developing device of the third aspect, it is possible to prevent a leak between the toner carrying and conveying member and the toner regulating member.

According to the developing device of the fourth aspect, since the main body of the toner regulating member is the metal elastic plate having the spring property, the spring pressure does not fluctuate with time, and the toner is stabilized. The effective thinning function can be performed for a long period of time.

According to the developing device of the fifth aspect, since the pressing force of the toner regulating member to the toner carrying and conveying member is made uniform by the elastic action peculiar to rubber, a toner layer having a uniform and constant thickness is formed. Obtainable.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a developing device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a main part of a developing device according to an embodiment of the present invention.

FIG. 3 is a configuration diagram showing a main part of another embodiment of the present invention.

FIG. 4 is an explanatory diagram related to an example of a method of deploying a toner regulation member.

FIG. 5 is an explanatory diagram according to another example of a method of deploying a toner regulation member.

FIG. 6 is a schematic configuration diagram of a conventional developing device.

[Explanation of symbols]

 5 Toner-carrying / conveying member 6 Toner regulating member 7 Metal elastic plate 8 Dielectric sheet 10 Developing device 16 Toner regulating member 17 Elastic rubber blade 18 Sheet electrode

(72) Inventor Yuichi Ueno 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Akira Sawada 1-3-3 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd.

Claims (5)

[Claims] 1. A toner carrying member for carrying and carrying toner, and a toner regulating member for regulating the layer thickness of the toner supplied to the toner carrying member to form a toner layer. In a developing device that visualizes an electrostatic latent image formed on a latent image carrier as a toner image with toner whose layer thickness is regulated by a regulation member, toner regulation that presses the toner carrying and conveying member via toner A means for forming a periodically changing electric field is provided between the toner regulation member portion on the upstream side in the toner movement direction with respect to the pressure contact portion of the member and the toner carrying and conveying member portion opposed thereto. A developing device. 2. The surface portion of the toner carrying and conveying member is
The conductive portion and the dielectric portion are the surface portion in which they are dispersed and mixed, and by applying an electric charge to the dielectric portion, a minute closed electric field is formed between the dielectric portion and the conductive portion to hold the toner. The developing device according to claim 1, configured as described above. 3. A toner-contacting portion of the toner-regulating member, which comes into pressure contact with the toner-carrying / conveying member via the toner, serves as an insulating portion, which is located upstream of the insulating portion in the toner movement direction. 3. The developing device according to claim 1, wherein the toner regulating member portion facing the conveying member is a conductive portion. 4. The developing device according to claim 1, wherein the toner regulating member is composed of a metal elastic plate having an insulating sheet fixed to a portion including a pressure contact portion thereof. 5. The developing device according to claim 3, wherein the toner regulating member is composed of an elastic rubber blade having a conductive portion serving as an electrode sheet surface.