JP3283701B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly, to a structure for moving a developer on a surface of a developing roller having a magnetic pole for forming a magnetic brush.

[0002]

2. Description of the Related Art Conventionally, in a developing device used in an image forming apparatus such as an electrophotographic copying machine or a printer, a two-component developer obtained by mixing a magnetic carrier and a magnetic or non-magnetic toner is used. When this developer is used, developers that are agitated and mixed and subjected to triboelectric charging of opposite polarities are supplied to the developing roller. Such a developer is carried in a state in which a magnetic brush is formed on the surface of a developing roller provided with a developing main pole and a magnet for transporting the developer, and an electrostatic latent image carried on a photoreceptor. By electrostatic attraction,
It is used for visible image processing of a latent image.

In such a magnetic brush developing device, there is a case where only one developing roller is provided. In this case, a sufficient supply of developer is caused due to a relatively narrow developing area for the photosensitive member. May not be possible. Therefore, in this case, it is necessary to set the linear velocity of the developing roller to, for example, three times or more the linear velocity of the photosensitive member to compensate for the shortage of the supply amount of the developer. However, when such a linear velocity ratio is set, there is a possibility that a defective portion called a solid cross white spot may occur at the rear end or the front end of the visible image on the photoconductor.

In order to solve such a problem, there has been proposed a configuration in which a plurality of the above-described developing rollers are arranged in parallel along the moving direction of the photoconductor to lengthen the developing area. However, when a plurality of developing rollers are provided, when a part of the developer carried on the sleeve surface moves in conjunction with the rotation of the sleeve, the gap at the position where the developing rollers are closest to each other is removed. In some cases, the vehicle may pass through a predetermined transport path. This is referred to as entrainment, and means that the proper delivery of the developer is not performed between the adjacent developing rollers. More specifically, the developing roller is arranged in a vertical relationship along the moving direction of the photoconductor, and, for example, the developer mixed and supplied to the lower developing roller is supplied to the developing roller. A configuration is used in which the developer is transported from the roller to the upper developing roller, and the developer is transferred from the upper developing roller to the lower developing roller along a developing region which is a portion facing the photoconductor. In this case, as shown by reference numeral C1 in FIG.
A part of the developer supplied to the upper developing roller A passes through the gap at the closest position between the developing rollers without being transferred to the lower developing roller B, and sandwiches the developing roller. It is brought to the opposite side of the development area. Further, for example, when a part of the developer released from the paddle wheel or the like reaches the lower developing roller B, as shown by a reference numeral C2, the developer remains attracted by the magnetic force of the lower developing roller, and In some cases, the toner may be directly conveyed to the portion of the lower developing roller B facing the photoconductor through the gap between the closest rollers. In this case, the rotation of the developer carried on the upper developing roller A is referred to as upper rotation, as indicated by reference numeral C2. Such rotation of a part of the developer carried on the lower developing roller B is called lower rotation. When such a rotation occurs, for example, in the case of the upper rotation, the amount of the developer carried on the lower developing roller is reduced due to an insufficient amount of the developer delivered to the lower developing roller. May be reduced to cause a reduction in image density or scattering of toner may occur.

[0005] In the case of the downward rotation, the amount of the developer carried on the developing roller becomes excessive, and when the developer is brought into contact with the photosensitive member, the rotational load on the photosensitive member is varied to reduce the speed unevenness. May cause. For this reason, there is a risk that the image may have stripe-shaped density unevenness, or that an excess amount of the carried toner may collide with a part of the housing of the developing device, be crushed and fall, and contaminate the periphery.

Conventionally, as a configuration for preventing the toner in the developer from scattering, a sheet-like member made of a single elastic body is provided in a cantilever shape at a position passing through the doctor blade in the rotation direction of the developing sleeve. And a top end thereof is brought into contact with the surface of the photosensitive drum to shield the upper part of the developing sleeve that has passed through the doctor blade to prevent the developer from being scattered (for example, the prior application of the present applicant). Japanese Patent Application No. 54-155401.

FIG. 11 is a diagram showing the above proposed configuration.
In the developing unit, a sheet-like member 52 is provided above a developing nip A corresponding to a position where a magnetic brush carried on a developing roller 51 disposed opposite to the photosensitive drum 50 is in contact. I have. This sheet-shaped member 52 is the same as that shown in FIG.
As shown in FIGS. 1 and 12, the support member 54 supported by the doctor blade 53 has a cantilever shape with the base end fixed, and the free end comes into contact with the surface of the photosensitive drum 50. I have.

[0008]

However, in such a proposed configuration, the developer is not
The photosensitive drum 50 and the developing sleeve 51 are opposed to each other, and reach the developing area (developing nip portion) where the magnetic brush contacts, after passing through the doctor blade 53. The photosensitive drum 50 from the time
The toner and the carrier are liable to be scattered due to the centrifugal force of the ears formed by the rotation and the magnetic force of the developing roller 51 and the air flow due to the rotation of the photoconductor drum 50 in the section until the surface of the photoconductor drum 50 is opposed. The scattered toner may cause background contamination of the photosensitive drum 50. For this reason, in the above-described proposed configuration, the adhesion that is influenced by the amount of bite of the sheet-shaped member 52 to the surface of the photoconductor drum 50 becomes important.

If the amount of bite of the sheet-like member 52 is small, the contact property with respect to the surface of the photosensitive drum 50 is deteriorated as shown in FIG. 13, and as shown by the symbol a in FIG.
Sheet-like member 52 in the rotation direction of photoconductor drum 50
Toner tends to leak toward the upstream side of the position.
Also, as shown in FIG. 12, if the corrugated portion 52A is partially formed along the longitudinal direction of the sheet-shaped member 52 and the linearity on the ridge line is poor, the adhesion of the photosensitive drum 2 in the axial direction is deteriorated. As a result, the toner scatters from the waving portion 52A.

On the other hand, if the amount of bite of the sheet-shaped member 52 is large, the free end of the sheet-shaped member 52 and the surface of the photosensitive drum 50 can sufficiently contact each other, so that the above-mentioned poor adhesion is deteriorated. However, the sheet-like member 52 that has entered the development area (development nip portion) is
As indicated by the symbol F in FIG.
Will be pressed strongly against the surface of the For this reason, the photosensitive drum 50 carrying the latent image is
2 causes frictional electrification, and the latent image being carried is easily broken. Such destruction of the latent image causes a defective image including white stripes and black stripes to be formed. Moreover, due to the high agent pressure, the gap between the leading end of the sheet-like member 52 and the surface of the photosensitive drum 50 (the position indicated by the symbol b in FIG. 14)
When a foreign substance such as a carrier in the developer is caught in the toner, the foreign substance is pressed against the surface of the photoconductor drum 50, thereby scratching the surface of the photoconductor drum 50 or causing the streak-like image Is obtained. As described above, when the sheet-shaped member 52 is used, it is necessary to manage dimensional accuracy that affects the adhesion between the sheet-shaped member 52 and the photosensitive drum 50.
This causes an increase in the cost of the mechanism.

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing apparatus which can prevent a developer from being scattered outside a developing area and prevent a defective image from being formed by a simple structure.

[0012]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a developing roller for forming a magnetic brush, which is disposed in the vicinity of the surface of a latent image carrier and is opposed to the developing roller. In a developing device provided with a doctor blade for defining the layer thickness of the developer carried on the roller, an elastically deformable sheet material is used, a part of which is folded and both ends are fixed to form a fixed portion. A developer scattering prevention member comprising a low friction member whose folded surface contacts only the surface of the latent image carrier; and a support member to which a fixing portion of the developer scattering prevention member is attached. The agent scattering prevention member is in contact with the latent image carrier at an upstream side of a region where the developer contacts the latent image carrier in the traveling direction of the latent image carrier.

According to a second aspect of the present invention, in the developing device according to the first aspect, the developer scattering prevention device is characterized in that a folded portion is filled with an elastic body.

According to a third aspect of the present invention, in the developing device according to the first aspect, the developer scattering prevention member is filled with a fluid in a folded portion.

According to a fourth aspect of the present invention, in the developing device according to the first aspect, the developer scattering prevention member makes contact between the developer and the latent image carrier in the traveling direction of the latent image carrier. It has a size that can cover the entire area of the developing unit opening surface located on the upstream side of the region, one end of which is always fixed to the developing unit side, and the other end covers the developing unit opening surface and the developing unit opening surface. It is characterized by being selectively fixed to a position where it can be opened.

According to a fifth aspect of the present invention, in the developing device of the first aspect, the developer scattering prevention member is connected to a blowing means for constantly flowing fresh air in the folded portion. And

[0017]

According to the first aspect of the present invention, the folded portion of the developer scattering preventing member can contact the surface of the photoreceptor drum with a low contact resistance with a contact width. Further, since the developer scattering prevention member is located above the developing nip, it is possible to make it hard to receive the pressure of the developer carried on the surface of the developing roller.

According to the second aspect of the present invention, the folded back portion of the developer scattering prevention member is applied to the surface of the photosensitive drum by the elastic force of the elastic body acting in addition to the stiffness of the folded back portion itself. Contact width can be secured.

According to the third and fifth aspects of the present invention, it is possible to obtain a state in which the folded portion of the developer scattering prevention member is in soft contact with the surface of the photosensitive drum by the fluid, and at the developing nip portion by the fluid. Temperature rise can be suppressed.

According to the fourth aspect of the present invention, a state in which the entire area of the developing unit opening surface is covered by the developer scattering prevention member and a state in which the entire area of the developing unit opening surface is opened can be set.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a sectional view showing the overall configuration of a developing device according to the present invention.
The following describes the configuration together with the function. The developing device 1 includes a developing container 1A and a toner replenishing section 1B. The developing container 1A is a drum-shaped photosensitive member that is a latent image carrier that can move in a direction indicated by an arrow AO in FIG.
(Hereinafter, referred to as a photosensitive drum) 2, and a toner supply unit 1B is mounted on the developing container 1A.

A stirring roller 3 and a paddle wheel 4 are provided inside the developing container 1A.
The paddle wheel 4 pumps up a two-component developer composed of a magnetic or non-magnetic toner and a magnetic carrier which are agitated and mixed and frictionally charged to opposite polarities. Further, the toner replenishing section 1B
When the density of the toner supplied to the photosensitive drum 2 decreases, the toner T is fed toward the stirring roller 3 by the rotation of the toner supply roller 1B1.

At a position where the developer is pumped up by the paddle wheel 4, a plurality of developing rollers 5, 6 are provided in proximity to the photosensitive drum 2.

The developing rollers 5 and 6 are disposed upstream and downstream along the moving direction of the photosensitive drum 2, respectively.
The one located upstream is the first developing roller 5, and the one located downstream is the second developing roller 6.

These first and second developing rollers 5 and 6 are
A main part includes a sleeve rotatable in a counterclockwise direction in the figure by a drive unit (not shown) and a mag roller fixed inside the sleeve. The sleeve is made of a non-magnetic material such as aluminum or stainless steel, and the mag roller is a magnetic pole formed by kneading a ferrite magnet or a rubber magnet, or a mixture of nylon powder and ferrite powder, along the circumferential direction. It has a plurality of arrangements. The magnetic pole will be described later.

In the developing container 1A, at a position where an arbitrary point on the peripheral surface of the first developing roller 5 reaches before facing the photosensitive drum 2, the layer thickness of the magnetic brush carried by the developing roller 5 is set. Doctor blade 7 for regulating
Is provided. In the vicinity of the doctor blade 7, a separator 8 having one end in the extension direction positioned near the doctor blade 7 and the other end in the extension direction positioned above the stirring roller 3 is disposed. At the other end of the separator 8 in the extending direction, a rotatable transport screw 9 is provided.
Is arranged. Reference numeral 10 denotes a rectifying member for rectifying the developer in a direction indicated by a broken line.

In the developing container 1 A having such a configuration, the developer is pumped up by centrifugal force generated when the paddle wheel 4 rotates, and is discharged toward the first developing roller 5.

Part of the released developer is indicated by an arrow A in the figure.
As shown by reference numeral 1, the toner is directly supplied to the first developing roller 5 and is carried on the surface of the first developing roller 5. Another part of the discharged developer is repelled by hitting the second developing roller 6 and is carried on the surface of the first developing roller 5 by the magnetic force of the first developing roller 5 side.

In order to supply the developer to the first developing roller 5 also from the second developing roller 6, the amount of rebound from the second developing roller 6 is increased. For this purpose, it is necessary to relatively increase the rotation speed of the paddle wheel 4 and increase the centrifugal force.

The developer carried on the first developing roller 5 moves on the roller surface with the rotation of the developing sleeve.
After the layer thickness is regulated by the doctor blade 7, the developing roller 5 reaches the first developing region D1 where the photosensitive drum 2 is opposed. When the developer that has reached the developing area D1 moves to a position where the action of the magnetic force on the first developing roller 5 side is weakened, the rotation of the developing sleeve on the second developing roller 6 side and the magnetic force from the mag roller , The second developing roller 6 and the photosensitive drum 2
Are transported toward the second developing area D2 facing thereto. At the position where the magnetic force of the second developing roller 6 stops acting, it falls to the bottom of the developing container 1A and is again stirred by the paddle wheel 4.

The developer scraped off by the doctor blade 7 is guided by the separator 8 toward the transport screw 9 located at the other end in the extension direction, and is dropped on the stirring roller 6 by the transport screw 9. ing. For this reason, a slit for dropping the developer is provided at the other end of the separator 8 in the extension direction.
Is formed at a position opposed to.

On the other hand, in the mag rollers provided on the first and second developing rollers 5 and 6, the arrangement of the magnetic poles is set as follows. In FIG. 1, a chain line shown in the developing roller indicates the position of the magnetic pole, and the number of magnetic poles on the first developing roller 5 side is an odd number along the circumferential direction (in the figure,
Symbols P _{11 to} P ₁₅ ) and an odd number of magnetic poles along the circumferential direction on the second developing roller 6 side (the symbol P _{21 in the} figure).
To P ₂₃₎ are arranged.

The order of transporting the developer by each of these magnetic poles is as follows.
_{P 13 → P 14 → P 15} → P 11 → P 12 → P 23 → P
₂₁ → P ₂₂ are set in this order, and the polarity of each magnetic pole is set in order of P ₁₃ (S pole) → P ₁₄ (N very)
→ P ₁₅ (S pole) → P ₁₁ (N pole) → P ₁₂ (S pole) → P ₂₃
Different poles are alternately arranged in the order of (N pole) → P ₂₁ (S pole) → P ₂₂ (N pole).

With such a magnetic pole setting, the first developing roller 5 side has an odd number of poles, so that there is always a place where the same poles are lined up. the pole _{P 12} and _{P 13} will be aligned with S poles both of. The position where the same poles are arranged is the position where the first and second developing rollers 5 and 6 are closest to each other. In FIG. 1, the magnetic pole P ₁₂ is the rotation of the first developing roller 5. In the direction (clockwise) upstream, the magnetic pole P
₁₃ are arranged on the downstream side in the rotation direction (clockwise) of the first developing roller 5.

With the above-described arrangement of the magnetic poles, a repulsive magnetic field is generated between the first and second developing rollers 5 and 6 between the closest positions between the developing rollers. .

In this embodiment, the paddle wheel 4 to the first
The developer supplied to the first developing roller is transported toward the first developing area D1 while being carried by the first developing roller 5. The developer that has passed through the first development area D1 is
Upon reaching the position of _12, by the repulsive magnetic field is generated between the pole P ₁₃ which is set to the magnetic poles and the poles, enters between the position between the developing roller 5 and 6 is closest Is prevented from doing so. As a result, the transfer direction is
Is forcibly set in the direction toward the developing roller 6 of the second
Made by the magnetic force of the developing roller 6 side of the pole P ₂₃ passed by it to the second developing roller 6.

On the other hand, at a position passing through the doctor blade 7 in the rotation direction of the first developing roller 5, a developer scattering preventing member 1C used in an embodiment of the developing device according to the present invention is provided. The developer scattering prevention member 1C includes:
FIG. 2 is a sheet-like member having a low coefficient of friction using an elastic material such as a polyester film and a polyurethane rubber.
As shown in FIG. 3, a part thereof is folded in a horizontal U-shape, and the folded part is formed in a bag portion 1 </ b> C <b> 1 that can be brought into contact with the surface of the photosensitive drum 2 (hereinafter, for convenience, The folded portion will be described as a substitute for the bag portion 1C1).

The support member 1D is used for attaching the developer scattering prevention member 1C, and has a concave portion 1D1 which can be fitted to a convex portion 7A formed on the doctor blade 7. The support member 1D is configured such that the upper and lower ends of the developer scattering prevention member 1C are fixed to the upper and lower surfaces, respectively, by bonding or the like.

The support member 1D can be fitted to the convex portion 7A of the doctor blade 7 and assembled, whereby the projecting position of the developer scattering preventing member 1C with respect to the surface of the photosensitive drum 2 can be defined. The arrangement of the fixed developer scattering prevention member 1C with respect to the photosensitive drum 2 is accurately set.

Since the present embodiment has the above configuration, the developer scattering prevention member 1C is obtained as a sub-assembly by being attached to the support member 1D. The developer scattering member 1C is provided with a concave portion 1D of the support member 1D.
By fitting 1 into the convex portion 7A of the doctor blade 7, positioning with respect to the photosensitive drum 2 is performed and the photosensitive drum 2 is incorporated into the developing unit.

The developer scattering prevention member 1C contacts the bag portion (the folded portion) 1C1 with a contact width (nip width) along the circumferential direction of the photosensitive drum 2. For this reason, it is possible to press and contact the surface of the photosensitive drum 2 in a state where the stiffness is doubled as compared with the case where a single-piece sheet member is used. Moreover, the developer scattering prevention member 1C can reduce the variation in the length of the photosensitive drum 2 in the axial direction due to the variation in the longitudinal direction to half. Accordingly, the developer scattering prevention member 1C can reduce the occurrence of wavy portions in the longitudinal direction and can make surface contact with the surface of the photosensitive drum 2, so that the photosensitive drum 2
Adhesion with the surface is secured.

Further, since the developer scattering prevention member 1C has a low friction coefficient, when the adhesion is ensured, dragging due to rotation of the photosensitive drum 2 is prevented. Peeling is prevented.

The developer scattering preventing member 1C is not limited to the above-mentioned materials, but may be, for example, a polyurethane rubber or a resin tape coated with a polymer.

According to the present embodiment, the developer scattering prevention member 1C, which has a low coefficient of friction and is made of a sheet-like member made of an elastic member, connects the bag portion 1C1 to the photosensitive drum 2.
The surface of the photosensitive drum 2 can be prevented from scattering toward the upstream side of the developing unit in the rotation direction of the photosensitive drum 2 while maintaining close contact with the surface. Further, the developer scattering prevention member 1 </ b> C is
Since the contact position between C1 and the surface of the photosensitive drum is located at a position above and away from the developing nip, it is difficult to receive the agent pressure of the magnetic brush. Thereby, the photosensitive drum 2
Abnormal pressing on the surface of the substrate is prevented, and the occurrence of scratches is prevented. Further, the developer is applied to the bag portion 1C of the developer scattering prevention member 1C.
Leakage between the upper surface of the photoconductor drum 2 and the surface of the photoconductor drum 2 is also prevented, so that damage to the surface of the photoconductor drum 2 can also be avoided.

Next, a second embodiment of the developing device according to the present invention will be described with reference to FIG.

This embodiment is characterized in that a structure for preventing toner from adhering to the lower surface of the developer scattering preventing member 1C is provided. As shown in FIG. 4, the developer scattering prevention member 1C is provided on the photosensitive drum 2 where the bag 1C1 is located.
And is extended to a position near the doctor blade 7 and attached to the lower surface of the support member 1D. The developer scattering prevention member 1C used in this embodiment is made of a polyester film that can be frictionally charged by a magnetic brush of the developer that has passed through the doctor blade 7. The developer scattering prevention member 1C made of such a frictionally chargeable material is frictionally charged to a polarity opposite to the polarity of the toner in the developer by being rubbed by the magnetic brush of the developer passing through the doctor blade 7. Then, a part of the toner in the developer passing through the doctor blade 7 is absorbed. As a result, as shown by the one-dot chain line in FIG. 4, the toner adhering to the lower surface near the bag portion 1C1 of the developer scattering prevention member 1C and trying to accumulate is electrostatically attracted to the bag portion 1C.
1 is removed from the lower surface. As described above, since the toner that tends to adhere to the lower surface near the bag portion 1C1 is eliminated, the toner does not drop to the developing nip.
It is possible to prevent the image from being stained.

When utilizing the charging characteristics of the developer scattering prevention member 1C as described above, the charging is not limited to simply performing frictional charging, but may be positively performed. For this purpose, the developer scattering prevention member 1C is formed of a conductive member, and a charge for injecting a charge having a polarity opposite to the charge characteristic of the toner is injected, or a potential difference at which the toner can be adsorbed is set. It is desirable to perform a bias for this purpose. As the developer scattering prevention member 1C used in this case, a polyester film or a polyurethane rubber coated with a conductive layer is selected.

According to such a configuration, by setting the potential difference, the movement of the toner to be attached to the lower surface of the leading end of the developer scattering prevention member 1C is prevented while the influence on the latent image potential is reduced, and the adhesion / propulsion is prevented. It is possible to prevent the accumulated toner from dropping into the developing nip. As a result, since the toner does not fall into the developing nip, it is possible to prevent image contamination.

Next, a third embodiment of the developing device according to the present invention will be described with reference to FIG. The present embodiment is characterized in that the contact width of the bag portion 1C1 of the developer scattering prevention member 1C can be ensured. The bag 1C1 of the developer scattering prevention member 1C is filled with an elastic body 10 made of urethane foam.

In this embodiment, since the elastic force from the elastic body acts in addition to the stiffness due to the shape of the bag portion 1C1 in the developer scattering prevention member 1C, the deformation of the bag portion 1C1 is suppressed, and the photosensitive member is exposed to light. The contact width with respect to the body drum 2 can be secured. Further, in the present embodiment, the bag portion 1C
Since the mass of the elastic body 10 can be increased by expanding the internal space of the photosensitive drum 1, the adjustment of the contact width with respect to the surface of the photosensitive drum 2 and the adjustment of the contact pressure can be respectively performed according to the increase of the mass. Become. This makes it possible to set the adhesion of the bag 1C1 under optimal conditions.

Next, a fourth embodiment of the developing device according to the present invention will be described with reference to FIG. The present embodiment is characterized in that the contact when securing the contact width of the bag portion 1C1 of the developer scattering prevention member 1C is made flexible, and the temperature rise in the developing nip can be suppressed by the cooling effect of the fluid. And The developer scattering prevention member 1C is partially folded back to form a bag portion 1C1, and the bag portion 1C is formed.
The ends of the sheet-like pieces forming the sheet 1 are joined to each other via the auxiliary member 11, and the longitudinal ends are closed as shown in FIG. And this bag part 1C1
Is filled with a fluid 12. As the fluid, a fluid having a large effect as a refrigerant, such as pure water, is selected. In this embodiment, the contact for securing the contact width of the bag portion 1C1 can be made flexible, and the air around the bag portion 1C1 is cooled by the fluid, so that the magnetic brush and the photosensitive drum are cooled. The cooling of the developing nip, which is increasing in temperature due to rubbing, can be performed. Further, it is also possible to suppress a rise in temperature in the bag portion 1C1 that comes into contact with the photoconductor drum 2, thereby improving the thermal durability of the bag portion 1C1.

Next, a fifth embodiment of the developing device according to the present invention will be described with reference to FIGS. The present embodiment is characterized in that the developer scattering preventing member 1C can be used as a cover of the developing unit. Developer scattering prevention member 1
C1 is formed of a sheet-like member having a size capable of covering the entire surface of the developing unit opening including the developing nip, and a lower surface corresponding to one end thereof is partially folded back to form a bag portion 1C1 and a supporting member. The upper surface, which is fixed to the lower surface of 1D and corresponds to the other end, is removably attached at a position where the entire developing unit opening including the developing nip can be opened as shown in FIG. In the developer scattering prevention member 1C, the lower surface of the bag portion 1C1 is fixed to the lower surface of the support member 1D by sticking or the like. It is detachably attached to the device by screwing or a magic tape (trade name). A part of the upper surface of the bag portion 1C1 is fixed to the upper surface of the support member 1D by sticking or the like, like the lower surface. A part of the upper surface constitutes a base when the end of the upper surface extension piece is turned back, as shown by a two-dot chain line in FIG. In the present embodiment, the developer scattering prevention member 1C is detachably supported at a position where the upper surface thereof can open the entire developing unit opening, and is detached from this position, as shown in FIG. The developing unit is detachably supported at a position capable of covering the entire opening of the developing unit. According to the present embodiment, by selecting the support position of the upper surface of the developer scattering prevention member 1C, the entire developing unit opening can be opened during the developing process, and the entire developing unit opening can be covered during the non-developing process. To form a cover for the opening of the developing section. Accordingly, when the entire surface of the developing unit opening is covered, the outflow of the developer from the developing unit opening can be prevented, so that the operator's hands are not stained during maintenance or transportation.

Next, a sixth embodiment of the developing device according to the present invention will be described with reference to FIG. The present embodiment is characterized in that the bag portion of the developer scattering prevention member is used as an air passage, and the developing nip can be cooled while ensuring the contact width of the bag portion with air passing through the air passage. .

The developer scattering prevention member 1C is connected at one end in the longitudinal direction to an air passage 1E communicating with the bag portion 1C1, and has the other end in the longitudinal direction communicating the bag portion 1C1 with the outside air. .

In this embodiment, the space inside the bag 1C1 is increased by flowing new air in the direction indicated by the arrow to secure the contact width with the photosensitive drum 2, and the air around the bag 1C1 is released. By being cooled,
It is possible to cool the developing nip whose temperature is rising due to rubbing between the magnetic brush and the photosensitive drum. Further, it is also possible to suppress a rise in temperature in the bag portion 1C1 that comes into contact with the photoconductor drum 2, thereby improving the thermal durability of the bag portion 1C1.

[0056]

According to the first aspect of the present invention, the folded portion of the developer scattering preventing member can contact the surface of the photosensitive drum with a low contact resistance with a contact width. Further, since the developer scattering prevention member is located above the developing nip, it is possible to make it hard to receive the pressure of the developer carried on the surface of the developing roller. This allows
It is possible to improve the adhesion of the developer scattering prevention member to the surface of the photoconductor drum and to reliably prevent the developer from scattering. Further, since the pressure of the developer is hardly received, it is possible to reduce the damage to the surface of the photosensitive drum.

According to the second aspect, in addition to the stiffness of the folded back portion of the developer scattering prevention member, the elastic force of the elastic body acts, whereby the folded back portion with respect to the surface of the photosensitive drum. Therefore, it is possible to secure the adhesion between the photoconductive drum and the folded portion, and to surely prevent the developer from scattering.

According to the third and fifth aspects of the present invention, it is possible to obtain a state in which the bag of the developer scattering prevention member is in soft contact with the surface of the photosensitive drum by the fluid.
Since the temperature rise in the developing nip due to the fluid can be suppressed, the contact width of the bag portion with the photosensitive drum is secured to prevent the developer from being scattered, and the thermal contact of the contact portion with the photosensitive drum is prevented. Durability can be improved.

According to the fourth aspect of the present invention, a state in which the entire area of the opening of the developing section is covered by the developer scattering prevention member and a state in which the entire area of the opening of the developing section is opened can be set. It is possible to prevent contamination around the developing unit and the operator.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall configuration of a developing device of the present invention.

FIG. 2 is a schematic diagram for explaining an embodiment of the developing device according to the present invention.

FIG. 3 is an external view of a developer scattering prevention member shown in FIG. 2;

FIG. 4 is a schematic diagram for explaining a second embodiment of the developing device according to the present invention.

FIG. 5 is a schematic diagram for explaining a third embodiment of the developing device according to the present invention.

FIG. 6 is a schematic diagram for explaining a fourth embodiment of the developing device according to the present invention.

7 is an external view of a developer scattering prevention member used in the embodiment shown in FIG.

FIG. 8 is a schematic diagram for explaining a fifth embodiment of the developing device according to the present invention.

9 is an external view of a developer scattering prevention member used in the embodiment shown in FIG.

FIG. 10 is a perspective view illustrating a developing device according to a sixth embodiment of the present invention.

FIG. 11 is a schematic diagram for explaining a conventional configuration of a developing device.

12 is an external view of a developer scattering prevention member used in the conventional configuration shown in FIG.

13 is a schematic diagram for explaining a problem in the developing device shown in FIG.

FIG. 14 is a schematic view for explaining another problem in the developing device shown in FIG. 11;

FIG. 15 is a schematic diagram for explaining a state of transporting a developer in an example of a developing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developing device 1C developer scattering prevention member 1C1 bag portion located at folded portion 1D support member 2 photoreceptor drum 5 first developing roller 6 second developing roller 7 doctor blade

Continuation of the front page (56) References JP-A-63-108369 (JP, A) JP-A-63-155065 (JP, A) JP-A-1-94362 (JP, A) JP-A-2-50180 (JP, A) , A) JP-A-3-145667 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/08-13/095 G03G 15/08-15/095

Claims (5)

(57) [Claims] A developing roller for forming a magnetic brush, which is disposed in opposition to the vicinity of the surface of the latent image carrier, and a doctor blade for defining a layer thickness of the developer carried on the developing roller. In the developing device, an elastically deformable sheet material is used, a part of which is folded and both ends are fixed to form a fixed portion, and the folded portion is folded.
Surface is provided with a support member and a developer scatter preventing member made of a low friction member in contact only the surface of the latent image bearing member, the fixing portion of the developer scatter preventing member is attached, the upper Symbol developer scatters The prevention member is provided in the traveling direction of the latent image carrier.
Above the area where the developer contacts the latent image carrier
A developing device, wherein the developing device is in contact with the latent image carrier on the upstream side . 2. The developing device according to claim 1, wherein said developer scattering preventing device has an elasticity inside the folded portion.
A developing device characterized by being filled with a body . 3. The developing device according to claim 1, wherein the developer scattering preventing member has a fluid inside the folded portion.
Wherein the developer is filled . 4. A developing device according to claim 1 , wherein said developer scattering preventing member is provided in a direction in which said latent image carrier travels.
Above the area where the developer contacts the latent image carrier
A size that can cover the entire area of the developing unit opening surface located on the flow side
One end of which is always fixed to the developing unit side, and the other end is
Opening the developing unit opening surface and opening the developing unit opening surface
Wherein the developing device is selectively fixed to a position where the developing device can perform the developing. 5. The developing device according to claim 1, wherein the developer scattering preventing member is always provided in the folded portion.
A developing device, wherein a blowing means for flowing new air is connected .