JP3243707B2 - One-component developing device and image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile, a printer, and the like. More specifically, the present invention relates to a developer which is frictionally charged at a contact portion with a developer carrier. The present invention relates to a one-component developing device including a developer supply member for supplying a developer.

[0002]

2. Description of the Related Art Conventionally, as a one-component developing apparatus of this type, for example, as shown in FIG. 3, a toner 7 contained as a non-magnetic one-component developer in a developer container is used.
Drum 1 as an image bearing member while carrying on the surface
A developing roller 2 serving as a developer carrier to be transported upward; and a toner supply roller 3 serving as a developer supply member that is disposed in contact with the development roller 2 and supplies toner 7 to the development roller 2. It is known that a roller 3 supplies a toner 7 frictionally charged at a contact portion with the developing roller 2 to the surface of the developing roller 2.

In this type of one-component developing system using a one-component developer, the developer-carrying member is compared with a two-component developing system using a two-component developer including a toner and a carrier. Poor ability to carry developer.

As shown in FIG. 3, in a one-component developing apparatus adopting a system for supplying toner to the surface of the developing roller 2 by frictional charging between the toner supplying roller 3 and the developing roller 2, In order to supply the toner to the portion of the surface where no toner is attached by frictional charging with the toner supply roller 3 until the toner saturation carrying amount is reached, the surface portion of the toner supply roller 3 It is necessary to rotate the developing roller 2 while passing through the contact portion several times.

For these reasons, when an image requiring a large amount of toner 7 such as a solid image is formed, the toner supply to the photosensitive member 1 by the developing roller 2 cannot keep up, and the trailing edge of the formed image May decrease. Therefore, there is a problem that it is difficult to increase the image forming speed.

Here, the present applicant has previously used a developer carrying member as a developer carrying member from a dielectric portion having a surface regularly or irregularly distributed over a small area and a grounded conductive portion. At a contact portion between the developer carrier and the developer supply member rotating at a position where the developer carrier is in contact with the surface thereof, the one-component developer is frictionally charged, and the dielectric portion is charged with the developer supply member and the one-component developer. The developer is charged by friction to form a large number of minute electric fields near the surface of the developer carrier, and the minute electric field transfers the one-component developer from the developer supply member to the developer carrier to form a developer carrier. A multi-layer developing device has been proposed above (JP-A-4-127177). According to this developing device, the developer can be supported in multiple layers by using a large number of minute electric fields, so that the above problem may be solved.

However, in this developing device, the developer carrying capacity of the developer carrying member is increased so that the dielectric portion of the developer carrying member is frictionally charged to form the above-mentioned minute electric field, and the developer can be carried in multiple layers on the surface. Even if the height is increased,
When the ability of the developer supply member to supply the developer onto the developer carrier due to triboelectric charging is low, the developer is developed on the developer carrier until the developer carrying amount corresponding to the developer carrying capacity reaches a saturated amount. The agent cannot be carried. Therefore, when an image requiring a large amount of developer, such as a solid image, is developed, there is a risk that the density at the rear end of the image is reduced.

As described above, means for improving the ability of the developer supply member to supply the developer to the developer carrying member by frictional charging to such an extent that the shortage of the amount of the developer adhered on the developer carrying member can be covered. There is no current situation. Thus, by providing a plurality of developer supply members and supplying the developer onto the developer carrier by frictional charging in a plurality of times, the shortage of the amount of the developer adhered on the developer carrier is covered. It is possible to do. For example, in the example of FIG. 4, a first toner supply roller 3 and a second toner supply roller 31 are provided, and the supply of the toner 7 onto the developing roller 2 by friction charging is performed in two times.

[0009]

However, when the toner 7 is supplied to the developing roller 2 in two separate times as in the example of FIG. 4, the toner 7 is supplied by the first toner supply roller 3. As shown in FIG. 5, on the surface of the developing roller 2 after the toner layer 5a is formed, the toner layer 5a made of a toner that is frictionally charged is frictionally charged less than the toner forming the toner layer 5a. In some cases, a toner layer 5b made of an unfilled toner is formed. Then, the toner layer 5
b is transported to the contact portion with the second toner supply roller 31 with the movement of the development roller 2, so that the second toner supply roller 31 has a capability of supplying the toner onto the development roller 2 by frictional charging. However, there is a problem that it may not be able to fully exert the effect.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a one-component developing apparatus having a plurality of developer supply members, wherein the developer of the developer supply member by friction charging is used. By improving the developer supply capacity on the carrier compared to the conventional technology, it is possible to stabilize the image density by adhering a desired amount of the developer on the developer carrier and improve the image forming speed. is there.

[0011]

To achieve the above Symbol purpose Means for Solving the Problems] The invention of claim 1 includes a developer carrier for conveying on an image bearing member while bearing the developer on the friction chargeable surface A developer supply member that is arranged in contact with the developer carrying member and supplies the developer to the developer carrying member; and a contact portion between the developer carrying member and the developer supplying member, In a one-component developing apparatus that frictionally charges the surface of the developer and the developer carrier, and that the developer supply member supplies the frictionally charged developer to the frictionally charged surface of the developer carrier. providing a plurality of developer supplying member, between said developer supply member, a developer removing member for removing a portion of the developer adhering to the developer carrying member surface provided, and the above-described developer removing member, Above
Downstream from the developer removing member in the moving direction of the image material carrier
From the developer supply member located on the side
For preventing the above-mentioned developer from entering the developer carrier
It is characterized in that an agent intrusion prevention member is provided .

According to a second aspect of the present invention, there is provided a photoconductor, and
Image forming apparatus having a developing device for supplying a developer and performing development
2. The one-component developing device according to claim 1, wherein said developing device is used as said developing device.
It is characterized by using an apparatus .

[0013]

According to the first and second aspects of the present invention, the developer carrying member is located above the developer layer carried on the surface by frictional charging at a contact portion with the developer supply member and has insufficient charging. Is removed by a developer removal member provided between the developer supply members, and then comes into contact with the next developer supply member. Then, the next developer supply member further supplies the frictionally charged developer onto the developer carrier at a contact portion with the developer supply member.

Further, the developer intrusion preventing member is provided for developing the developer from a space between the developer removing member and the developer supply member located downstream of the developer removing member in the moving direction of the developer carrying member. It prevents entry into the surface of the agent carrier.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a developing device of an electrophotographic copying machine will be described below. FIG. 1A is a front view illustrating a schematic configuration of a developing device according to the present embodiment.
FIG. 2B is an enlarged view showing the vicinity of a contact portion between a developing roller and a toner supply roller in the developing device. In FIG. 1A, a developing device 20 is disposed on the right side of a photosensitive drum 1 as an image carrier that is driven to rotate clockwise with an arrow. Around the photosensitive drum 1, a well-known charging device, an exposure optical system, a transfer separation device, a cleaning device, and a static eliminator (all not shown) are provided for performing an electrophotographic process. Developing device 20 of the present embodiment
Is a casing provided with an opening facing the surface of the photosensitive drum 1, a developing roller 2 as a developer carrying member, a part of which is exposed from the opening and is driven to rotate in a counterclockwise direction by an arrow at a predetermined peripheral speed. A first toner supply roller 3 and a second toner supply roller 31 as developer supply members which are driven to rotate in the counterclockwise direction by an arrow while being pressed against the right side of the development roller 2; A hopper section as a developer storage means, which is formed on the right side of the casing and accommodates a component-based developer (hereinafter, referred to as toner) 7, faces the photosensitive drum 1 by rotation of the developing roller 2. And a layer thickness equalizing plate 8 as a developer regulating member for equalizing the thickness of the toner layer on the developing roller 2 conveyed to the developing area A which is a portion.

The developing roller 2 is arranged such that the toner layer on the developing roller 2 is in contact with the surface of the photosensitive drum 1 in the developing area A as shown in FIG. Alternatively, non-contact development may be performed by opposing the photosensitive drum 1 surface with a predetermined gap.
The developing roller 2 and the layer thickness equalizing plate 4 are supplied with an appropriate developing bias voltage by a bias power supply (not shown).
For example, DC, AC, DC superimposed AC, pulse voltage, or the like is applied. In particular, in the case of non-contact development, it is desirable to apply a voltage (alternating current, alternating current superimposed on direct current, pulse voltage, or the like) having an alternating component with good flight conditions.

The developing roller 2 of the present embodiment is designed so that a dielectric portion capable of holding electric charges and a grounded conductor portion are exposed in a small area in a small area for the purpose of increasing the amount of adhered toner. Is used. The size of the dielectric portion is, for example, 50 to 200 in diameter.
It should be about μm. Such dielectric portions are dispersed randomly or according to a certain rule. It is preferable that the area ratio between the two parts is, for example, such that the area of the dielectric part is in the range of 40 to 70% of the whole. As the material of the dielectric portion, a material having such a resistance that electric charges are not accumulated by frictional charging by the first and second toner supply rollers 3 and 31 is used.
In order to form a desired surface layer, for example, after knurling the surface of the cored bar roller to form a predetermined groove, the cored bar is coated with an insulating resin, for example, and then the surface is cut to form the cored bar. As a conductor part, the resin in the groove serves as a dielectric part,
Each of them can be formed by being exposed on the surface.

The first toner supply roller 3 is disposed so as to be buried in the stored toner 7 in the hopper at a position upstream of the second toner supply roller 31 in the surface movement direction of the developing roller 2. . Further, the second toner supply roller 31 is arranged so that a part thereof is exposed from the inside of the stored toner 7. Further, the first toner supply roller 3 and the second toner supply roller 31 are configured by, for example, including an elastic foam layer on a cored bar, and the toner is contained in at least the vicinity of the surface of the elastic foam layer. There are a number of holes in the surface for holding. The material of the elastic foam layers of the first and second toner supply rollers 3 and 31 is such that a desired frictional charge can be applied to the toner and the dielectric portion of the development roller 2 by contact with the development roller 2. In the triboelectric series, it is desirable to employ, for example, an intermediate material between the material of the toner 7 and the material of the surface portion of the developing roller 2. The first and second toner supply rollers 3 and 31
Is driven by a driving unit such as a motor (not shown) so that the surface moves in a direction opposite to the surface of the developing roller 2 at a contact portion with the developing roller 2.

The cores of the first and second toner supply rollers 3 and 31 are also supplied with a bias voltage (not shown) to the same voltage as that applied to the developing roller 2 or to a predetermined polarity. When the charged toner is supplied to the supply roller 3,
A voltage may be applied such that an electric field that receives an electrostatic force from the side 31 toward the developing roller 2 is formed between the developing roller 2 and the electric field.

The layer thickness equalizing plate 4 is made of a material
As with the surface materials of the first and second toner supply rollers 3 and 31, it is desirable to employ a material located between the toner material and the dielectric material in the charging sequence.

In the developing device 20 shown in FIG. 1A, the toner 7 stored in the hopper is supplied to the surface of the toner supply roller by its own weight due to the shape of the hopper and the fluidity of the toner. Toner 7 in hopper
May be provided on the surface of the toner supply roller, and an agitation supply member such as an agitator for agitating the stored toner 7 may be provided.

In the above construction, the first toner supply roller 3 buried in the toner 7 contained in the hopper is held on the surface of the conductive elastic foam layer or in a hole opened on the surface. the toner 7 is conveyed toward the contact portion B ₁ of the developing roller 2 by a counterclockwise rotation.

Then, due to the friction between the developing roller 2, the toner 7, and the first toner supply roller 3, the dielectric portion of the developing roller 2 is charged with a polarity opposite to the desired toner charging polarity (in normal development (P / P)). Is a charge of the same polarity as the charge of the photoconductor, and is a charge of the opposite polarity to the charge of the photoconductor in reversal development (N / P), and a microfield (a minute electric field) is formed on the developing roller 2. On the other hand, the toner 7 carried on the first toner supply roller 3 is rubbed between the developing roller 2 and the supply roller 3 and has a desired polarity (in normal development, the polarity is opposite to the photoconductor charge, and the reverse development is performed). Has the same polarity as the photoconductor charge).

The charged toner 7 on the toner supply roller 3 is electrostatically attracted by the microfield on the developing roller 2 and adheres to the surface of the developing roller 2. Thus, the developing roller 2 exits the contact portion B ₁ in a state carrying the toner 7 with a sufficient amount of charge.

The toner 7 adhering at the contact portion B ₁ becomes a toner layer on the developing roller 2, and the toner layer is rotated by the developing roller 2 in the direction of the arrow, and the developing roller 2 and the second toner supply roller 31 are rotated. Doo is transported toward the contact portion B ₂ in contact. In the contact portion B _2, toner 7 held in the second toner supplying roller 31 is frictionally charged by the same way as the contact portion B _1, the developing roller 2 surface on which the toner layer by the supplying roller 31 is formed Supplied to
Attaches to the surface. Thus, the developing roller 2 exits the contact portion B ₂ in a state carrying the toner 7 charged in the multilayer. Then, the toner layer on the developing roller 2 that has passed through the contact portion B ₂ is rubbed uniformly by the thickness equalizing plate 4 in contact with the developing roller 2 to be a uniform thin layer.
The developer is conveyed to the developing area A by the rotation of the developing roller 2. In the developing area A, the developing is performed while the surface of the developing roller 2 and the surface of the photosensitive drum 1 to which the optimum developing bias is applied by the contact or non-contact developing method are moved at substantially constant speed.

The residual toner in the non-image area remaining on the surface of the developing roller 2 without adhering to the surface of the photosensitive drum 1 when passing through the developing area A is mechanically and electrically supplied by the first toner supply roller 3, for example. The electric charge on the developing roller 2 is also fixed by the frictional charging of the first toner supply roller 3, whereby the surface of the developing roller 2 is initialized. (Hereinafter, margin)

[0027] In the structure described above, the toner layer of the developing roller 2 surface having passed through the contact portion B ₁ of the first toner supplying roller 3, as shown in FIG. 5 described above, good friction In some cases, a toner layer 5b made of a toner that is less frictionally charged than the toner that forms the toner layer 5a is formed on the toner layer 5a made of the charged toner. Then, the toner layer 5b is rotated by the rotation of the developing roller 2 and the second toner supply roller 31 is rotated.
The second toner supply roller 31 can satisfactorily charge the uncharged toner in the hopper portion carried on the surface at the contact portion B ₂ with the developing roller 2 by being transported to the contact portion B ₂ with the developing roller 2. Therefore, there is a possibility that the ability to supply the toner onto the developing roller 2 due to frictional charging may be lower than that of the first toner supply roller 3.

Therefore, in this embodiment, as shown in FIGS. 1A and 1B, the developing roller 2 is provided between the first toner supply roller 3 and the second toner supply roller 31.
A toner removing blade 41 is provided as a developer removing member for scraping off the toner layer 5b of the upper toner layer from above the developing roller 2.

In the example shown in FIGS. 1A and 1B, the toner removing blade 41 has one end portion bent, for example, to have a substantially L-shaped cross section, and has a counter direction with respect to the direction in which the developing roller 2 moves. The other end is fixed to a support holder 8 fixed to, for example, the side wall of the developing device so that the bent portion comes into contact with the surface of the roller 2. In this embodiment, the toner removing blade 41 is made of the same material as the layer thickness equalizing plate 4 and has the same function as that of the layer thickness equalizing plate 4, namely, the thickness of the toner layer on the developing roller 2 is reduced. It also has the function of equalizing.

Here, the non-charged toner in the hopper is
The toner removing blade 41 and penetrates from between the second toner supplying roller 31 may be deposited on the developing roller 2 surface having passed through the contact portion B _1. Also in this case, the toner supply capability of the second toner supply roller 31 may be reduced.

Therefore, in this embodiment, a hopper is disposed between the toner removing blade 41 and the toner supply roller adjacent to the removal blade 41 on the downstream side in the rotation direction of the developing roller 2, that is, the second toner supply roller 31. A seal member 9 is provided as a developer intrusion preventing member for preventing uncharged toner in the section from intruding.

As shown in FIGS. 1A and 1B, the sealing material 9 has, for example, one end attached to the support holder 8 and the other end in the trailing direction with respect to the second toner supply roller 31. That is, they are arranged so as to come into contact with the supply roller 31 in the direction in which they are pulled. For this reason, the non-charged toner in the hopper is removed by the toner removal blade 41.
In addition, the seal member 9 disposed so as to straddle the second toner supply roller 31 prevents the removal from entering between the removal blade 41 and the supply roller 31.

According to the present embodiment, the toner layer on the surface of the developing roller 2 that has passed through the contact portion B ₁ with the first toner supply roller 3 becomes the second toner layer with the rotation of the developing roller 2. when it is conveyed to the contact portion B ₂ of the supply roller 31, the toner layer 5b consisting of toner poorly triboelectric charging, as shown in FIG. 2, the developing roller 2 and the toner removing blade 41 It is scraped off from the roller 2 at the contact portion and the thickness is made uniform,
The toner layer 5 is made of a well-charged toner and has a uniform thickness. In addition, since the uncharged toner is prevented from entering between the toner removing blade 41 and the second toner supply roller 31 by the sealing material 9, the toner layer 5 has a uniform thickness of the well-charged toner. while the layer is transported toward the contact portion B _2.

At the contact portion B ₂ , the second toner supply roller 31 moves onto the developing roller 2 by frictional charging as compared with the case where a toner layer made of a toner that is not so charged is conveyed. The toner supply capacity is improved, and the non-charged toner in the hopper portion held in the surface of the conductive elastic foam layer or in the hole opened in the surface is favorably charged by friction with the surface of the developing roller 2 so that the developing roller Supply to 2 surfaces. As a result, a desired amount of toner is supplied and adhered to the surface of the developing roller 2, so that the image density is reduced when a solid portion of an image is developed or an image is continuously formed as in the related art. Therefore, the image density is stable, and the image forming speed can be improved.

Further, in the present embodiment, the sealing material 9 prevents the uncharged toner from entering the hopper from between the toner removing blade 41 and the second toner supply roller 31, so that the second toner supply roller 31 can be satisfactorily frictionally charge the toner 7 in the contact portion B _2.

In this embodiment, the toner removing blade 41 is disposed so as to contact the developing roller 2 in the counter direction with respect to the surface moving direction.
1 can also be arranged to contact the roller surface in the trailing direction. Further, a magnetic toner can be used in place of the non-magnetic toner as a one-component developer.

It should be noted that the present invention is not limited to the above embodiment, but can be modified. For example, the above embodiment is an example in which two developer supply members are provided, but the number of developer supply members is not particularly limited. In the above embodiment, the developer removal blade is provided between the two developer supply members. However, when three or more developer supply members are provided, the developer removal blade is provided between each developer supply member. It is preferable to provide a member, but it is sufficient that the member is provided at least upstream of a contact portion of the developer supply member, which is disposed at the most downstream in the direction of movement of the surface of the developer carrier, with the developer carrier.

[0038]

According to the first and second aspects of the present invention, a plurality of developer supply members are used to supply the developer to the developer carrier, and the developer carrier is provided between the developer supply members. In order to remove the insufficiently charged developer located on the upper portion of the developer layer and to allow the developer supply member located at the subsequent stage to sufficiently exhibit the developer supply ability on the developer carrier due to triboelectric charging. Accordingly, the image forming speed can be improved while stabilizing the image density by adhering a desired amount of the developer on the developer carrier.

Further, the developer intrusion prevention member, a developer removing member, from between the developer supplying member in proximity to the developer removing member moving direction downstream side of the developer carrying member, the developer is the developer carrying As it prevents invasion toward the body surface,
In comparison with the case where the less-charged developer adheres due to such intrusion and comes into contact with the later-stage developer supply member, the supply of the developer by frictional charging at the later-stage developer supply member is better. Can be performed.

[Brief description of the drawings]

FIG. 1A is a front view illustrating a schematic configuration of a developing device according to an embodiment. FIG. 3B is an enlarged view showing the vicinity of a contact portion between a developing roller and a toner supply roller in the developing device.

FIG. 2 is an enlarged view showing a toner layer after passing through a first toner supply roller in the developing device.

FIG. 3 is a front view showing a conventional developing device.

FIG. 4 is a front view showing another conventional developing device.

FIG. 5 is an enlarged view showing the vicinity of a contact portion between a developing roller and a toner supply roller in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Developing roller 3 First toner supply roller 31 Second toner supply roller 4 Layer thickness equalizer 41 Toner removal blade 5 Toner layer 7 Toner 8 Holder 9 Sealing material

Continuation of the front page (56) References JP-A-5-53428 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08

Claims (2)

(57) [Claims] A developer carrying member which carries the developer on the surface capable of being triboelectrically charged and conveys the developer onto the image carrier; and a developer carrier disposed in contact with the developer carrier, and A developer supply member for supplying the developer, wherein at a contact portion between the developer carrier and the developer supply member, the developer and the surface of the developer carrier are frictionally charged, and the developer carrier is friction charged surface of the body, in one-component developing device that supplies developer to the developer supply member is charged by friction, a plurality of said developer supplying member, between the developer supplying member, developer carrying A developer removing member for removing a part of the developer attached to the body surface is provided , and the developer removing member and the developer carrying member are moved in the moving direction.
The developer located downstream of the developer removing member
Between the supply member and the developer carrier on the developer carrier
A one-component developing device provided with a developer intrusion prevention member for preventing intrusion of a developer . 2. A photoreceptor and a toner supplied to the photoreceptor.
An image forming apparatus comprising: a developing device for forming an image; wherein the one-component developing device according to claim 1 is used as the developing device .