JPH0359581A - Developing device - Google Patents

Abstract

PURPOSE:To secure the contact width of a developer with an electrostatic latent image and the contact time by providing a magnet of polarity identical to the developer inside a cylinder that faces a photosensitive body and rotates and drives and in the vicinity of a part where the photosensitive body faces the cylinder. CONSTITUTION:The developer is maintained on the outer periphery of a thin film member 34 by the magnetic force of the magnet, and the thin film member 34 closely adheres to the outer periphery of the cylinder 31 by the magnetic attraction of the developer. The developer is not affected by magnetic force in an area facing the identical polarity part, and the thin layer member 34 does not closely adheres to the outer periphery of the cylinder 31 but forms a bulge, whose outside surface comes into contact with the outer periphery of the photosensitive body 100. Consequently, when the cylinder 31 rotates, the developer moves together with the thin layer member 34, discontinuously jumps in the identical polarity part, and is maintained at a constant layer thickness by regulating members 36 and 37. Thus, the developer is stably supplied to the part where the thin layer member 34 faces the photosensitive body 100.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a developing device such as a copying machine.

[Conventional technology and its problems]

In a developing device that visualizes an electrostatic latent image by bringing developer into contact with a photoreceptor, the contact width between the photoreceptor and the developer.

It is important to increase the contact time in order to increase development efficiency. In particular, its importance increases in high-speed, durable copying machines and the like.

For this reason, conventionally, a so-called magnetic brush type developing device is used, in which a magnetic developer is held on the outer circumference of a cylindrical body with a magnet arranged inside, and this developer is brought into contact with a photoreceptor to develop an electrostatic latent image. A device has been proposed that includes a plurality of the cylindrical bodies and develops an electrostatic latent image multiple times. However, this developing device has a problem in that it becomes larger as the number of cylindrical bodies increases. In order to solve this problem, if the diameter of the cylindrical body is made smaller, the rotational speed must be increased accordingly, and at the same time, the internal magnet becomes smaller and the magnetic force becomes weaker, resulting in the inconvenience that the developer loses its magnetic binding force and scatters. occurs.

In addition, an electrode member is provided near the opposing portion of the cylindrical body and the photoconductor, and cascade development is performed by using this electrode member to cause the developer to fall along the outer peripheral surface of the photoconductor, and the fallen developer is then returned to the cylindrical body. The items to be collected are Special Publication No. 53-26496.
It is proposed in the publication.

However, this developing device has the problem that the charged developer electrically adheres to the electrode member, making it impossible to maintain an effective bias between the electrode member and the photoreceptor, resulting in a state where development is impossible. Ta.

[Means to solve the problem]

The present invention has been made to solve the above-mentioned problems, and includes a developing device including: 1, a cylindrical body facing the photoreceptor and driven to rotate; 111. A thin film member having a circumferential length slightly longer than the circumferential length of the cylindrical body and sheathed on the cylindrical body; , iv. A magnetic developer held on the outer periphery of the thin film member by the magnetic force of the magnet body; and V. A regulating member that faces the outer periphery of the thin film member covering the same polar portion and comes into contact with the magnetic developer. .

[Effect]

According to the above configuration, the developer is held on the outer periphery of the thin film member by the magnetic force of the magnet, and the thin film member is brought into close contact with the outer periphery of the cylindrical body based on the magnetic attraction force of the developer. In addition, in the area facing the same pole part, the developer is not subjected to magnetic binding force, or even if it is subjected to magnetic binding force, it is weak, so the thin film member in the area facing the same pole part is attached to the outer periphery of the cylindrical body. The extra length, that is, the portion longer than the circumference of the cylindrical body gathers there to form a slack (bulge), and the outer surface of this bulge comes into contact with the outer circumferential surface of the photoreceptor.

When the cylindrical body rotates, the thin film member rotates accordingly,
The developer held on the outer periphery also moves.

The developer moves together with the thin film member, is released from the magnetic binding force at the same polar portion, and flies discontinuously. This flying developer is leveled to a constant layer thickness by a regulating member, and is stably supplied to the opposing portion of the thin film member and the photoreceptor.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 A. Configuration of Developing Device The developing device 1 shown in FIG.
It consists of

Supply section 10 A supply chamber 11 of the supply section 10 is provided with a supply blade 12 . This supply vane 12 has a plurality of scooping plates 15 horizontally mounted on the outer periphery of side plates 14 and 14 provided at both ends of a shaft 13, and is rotatable in the direction of arrow a.

ii. Concentration Detection Section 20 The concentration detection section 20 is provided at the rear of the supply section 10, and a conveyance blade 22 is provided on a conveyance path 21 that is continuous with and parallel to the supply chamber 11. As shown in FIG. 2, the conveying blade 22 has a scooping plate 24 at the center of a shaft 23, and a plurality of blades 25 are arranged on both sides of the scooping plate 24 at predetermined intervals. These blades 25 are attached at different angles on the left and right sides of the scooping plate 24, so that the general feeding direction due to the rotation of the conveying blades is different on the left and right sides. That is, in FIG. 2, the left wing 25 has the ability to convey to the right, and the right wing M425 has the ability to convey to the left. In addition, the supply chamber 11 and the conveyance path 2
An opening 27 is provided in the wall 26 between the scooping plate 24 and the scooping plate 24. Furthermore, a toner concentration detection sensor 28 for measuring changes in magnetic permeability of the developer is provided at the center bottom of the conveyance path 21, and its sensor surface is substantially aligned with the bottom surface of the conveyance path 21.

Mountain, developing section 30 In the developing section 30, the cylindrical body 31 is made of a non-magnetic material,
It is arranged to face the photoreceptor lOO with a predetermined gap therebetween, and is configured to rotate in the direction of arrow C about an axis (not shown). Further, the cylindrical body 31 is connected to a power source 32, and a predetermined bias voltage 8 is applied thereto.

Does the magnet body 33 extend in the axial direction of the cylindrical body 31? a number of magnetic poles (N,,N,,S,,N3.N4.S,.

N, , S3) are provided on the outer periphery in this order, and the magnetic poles N1 and N
2. The magnetic poles N3 and N4 are adjacent to each other, and the intermediate areas thereof are designated as non-magnetic pole regions M, , M, which are fixed in a non-rotating state inside the cylindrical body 31. The non-magnetic pole region M is located slightly above the portion facing the photoreceptor 100, and the non-magnetic pole region M is located at the portion facing the supply blade 12.

The thin film member 34 is a thin-walled (0.2 mm thick) cylindrical body having a circumference slightly longer than the circumference of the cylindrical body 31.
The exterior is covered in 1. This thin film member 34 is made of nylon, polyimide, or polycarbonate, and is made of carbonate to give it electrical conductivity.

The regulating member 36 is attached to the upper part of the developer 1177,
Its tip is opposed to the upper outer peripheral surface of the thin film member 34 with a predetermined gap I)a+.

The leveling member 37 is attached to the developing tank via the regulating member 36, and its tip is opposed to the area facing the non-magnetic pole area M1 of the thin film member 34 with a predetermined gear DB2. Further, the tip portion of the leveling member 37 is inclined toward the moving direction of the thin film member 34, and is 17 to prevent the developer from accumulating on the upstream side of the leveling member 37.

The iv8 recovery part 0 part 40 is located above the supply part 10 and is partitioned from the supply part 10 by a partition wall 41. The front wall 42 of the partition wall 41 is formed with a predetermined spacing from the cylindrical body 31, and its upper end A passage 43 is provided between the rear wall 44 of the partition wall 41 and the upper cover 29 of the concentration measuring section 20, and a drop path 45 leading to the supply chamber II is provided between the rear wall 44 of the partition wall 41 and the upper cover 29 of the concentration measurement section 20. In addition, the collection section 4
0 is provided with two feeding blades 47 and 48 at the front and rear, and are designed to rotate in the directions of arrows d and e, respectively.

v. Toner Replenishment Unit 50 The toner replenishment unit 50 is formed with a storage chamber 51 and a replenishment chamber 54, and the storage chamber 51 is provided with a stirring blade 52. 53 is arrow f,
The brush roll 55 is provided in the replenishment chamber 54 so as to be rotated in the direction g. Further, the supply chamber 54 communicates with the empty chamber 46 via a mesh L56 provided at the bottom thereof.

B Developing operation The developing operation will be explained.

A two-component developer consisting of toner and magnetic carrier is used, and is stored in the supply chamber 11. Further, the developer is also magnetically attracted to the outer circumference of the thin film member 34.
Due to the magnetic adsorption force of the developer, the excess portion of the thin film member 34 is concentrated on the portion facing the non-magnetic pole area M, forming a bulge 35, and the outer circumference of this bulge 35 is brought into contact with the outer circumference of the photoreceptor 100. be. Note that the contact width α of the bulge 35 is set to be wider than the width at which the developer contacts the photoreceptor in a magnetic brush type developing device, for example, about 6 to 12 mm.

The developer in the supply chamber 11 is mixed by the surrounding scooping plate I5 based on the rotation of the supply blade 12, and the toner and carrier come into frictional contact and are charged to opposite polarities. Further, the developer is sent over the wall 26 to the concentration measuring section 20 by the conveying action of the scooping plate 15, and the developer scooped by the scoop vi15 is supplied to the outer peripheral portion of the thin film member 34 in the supply area P.

Note that the developer scooped by the scoop 1f15 is regulated by a regulating member 49 formed of a brush provided under the partition wall 41, and the supply amount is adjusted to be constant.

The developer sent to the d8 measurement 20 is conveyed toward the center by the blades 25 by the rotation of the conveying blades 22,
Then, they merge at the center, are scooped up by the scooping plate 24, and sent back to the supply chamber 11.

The developer sent back to the supply chamber 11 is dispersed left and right by the mixing and stirring action of the supply blades 12. Note that, as shown in FIG. 2, if two elliptical blades 16 and 16 are provided at the center of the supply blade 12 and their angles with respect to the shaft 13 are set oppositely, the developer sent back from the conveyance path 21 The developer is actively distributed to the left and right, and a portion of the developer sent back from the left side of the conveyance path 21 is distributed to the right side of the supply chamber 11.
Also, a part of the developer sent back from the right side of the conveyance path 21 is conveyed to the left side of the supply chamber 11, so that the left and right developers are mixed, and the toner and layer side (carrier side) of the developer on the left or right side are mixed. There is no inconvenience that the toner weight a (total ratio) decreases.

Further, the toner concentration of the developer is measured by a toner 13 degree detection sensor 28 located at the center. The toner concentration measured here is related to the mixture of the developer sent by the left and right blades, so the detected value is an average value, and the detected value varies greatly due to a local decrease in toner concentration. There's nothing to do. Therefore, stable toner concentration management is possible.

On the other hand, the developer held on the outer periphery of the thin film member 34 in the supply area P is held based on the magnetic attraction force of the magnet 33, is conveyed in the direction of arrow C by the rotation of the cylindrical body 31, and is transferred to the regulating member 36. Regulated.

The developer regulated by the regulating member 36 passes through the passage 43 and is collected by the collecting section 40 . Therefore, the developer does not remain indefinitely in front of the regulating member 36 and is not subjected to stress, and deterioration of the developer is reduced.

As shown in FIG. 3, the developer that has passed through the tip of the regulating member 36 is directed to the magnetic poles N, S3, . It is conveyed in the state of a magnetic brush by the opposing part of N. Further, when the developer passes through the opposing portion of the magnetic pole N, it is released from the restraining force of the magnetic pole at the opposing portion of the non-magnetic pole region M, and flies discontinuously in the transport direction in the form of a lump. This flying developer collides with the leveling member 37 and is leveled to a certain layer thickness (corresponding to the gap I), held by the thin film member 34 and conveyed in the direction of arrow C, and is exposed to the thin film member 34. It is fed into the contact area X with the body 100.

The developer conveyed through the contact area X moves from the direction of arrow i due to the contact pressure of the thin film member
, and an electrostatic latent image is formed on the surface of the photoreceptor 100, based on the potential difference between the surface potential of the electrostatic latent image and the developing bias voltage VB transmitted from the cylindrical body 31 to the thin film member 34. , toner electrostatically adheres to the electrostatic latent image area.

When there is a relative speed difference between the thin film member 34 and the photoreceptor 100, the developer conveyed through the contact area X is subjected to a burr effect. Therefore, the carrier that has lost toner due to development is mixed with the carrier that still retains toner, and the carrier that has lost toner does not come into continuous contact with the photoreceptor. Therefore, the toner attached to the electrostatic latent image on the photoconductor 100 is not taken away by the carrier that has lost the toner, and the toner is attached to the electrostatic latent image at a nearly -like density, resulting in a flat image (edge). (only the non-enhanced image) is obtained.

The developer that has passed through the contact area X is subjected to the magnetic binding force of the magnetic pole N, is held by the thin film member 34 again in a magnetic brush state, and is conveyed in the direction of arrow C. Then, it is released from the restraining force of the magnetic poles in the non-magnetic pole area M between the magnetic poles N3 and N4, and falls into the supply chamber II.

The developer regulated by the regulating member 36 and collected in the collecting section 40 is conveyed backward through the empty chamber 46 based on the rotation of the feeding blades 47 and 48, and is supplied to the supply chamber 11 through the falling path 45.

When it is determined that the toner concentration of the developer is lower than a predetermined reference value based on the output of the toner concentration detection sensor 28, the blades 52 and 53 of the toner replenishment section 50 rotate, and the toner in the storage section 51 is transferred to the replenishment chamber 54. send to. Supply room 54
The toner fed by J% is conveyed in the direction of the arrow as the plan roll 55 rotates, passes through the mesh 56, and is dropped into the empty chamber 46. Here, the toner that has become a lump is directly transferred to the empty chamber. Since the toner that passes through the mesh 56 without being supplied to the mesh 56 falls in a dispersed state, it is quickly mixed with the developer in the empty space 46, and is instantly charged by being mixed with the developer. , uncharged toner is not subjected to development, and the generation of toner powder smoke and fogging on images are reduced.

Embodiment 2 In the developing device shown in FIG. 4, the tip of the regulating member 37 is brought into contact with the thin film member 34. In the developing device shown in FIG. Even in this case, as shown in the figure, the developer is leveled at the tip of the regulating member 37 and enters the contact area X with a uniform thickness. Note that the regulating member 37 does not need to be fixed, and may be biased against the thin film member 34 with a constant pressure so as to follow the vibrations caused by the rotation of the thin film member 34.

Embodiment 3 FIG. 5 is a partially enlarged view of the thin film member 34, in which V-shaped grooves 348 extending in the axial direction are provided at predetermined intervals on the outer periphery of the thin film member 34. This V-shaped groove 34a has, for example, an opening angle θ of 90°, a depth I of 0.12 mm, and a pitch δ of 2 mm.

According to this thin film member 34, as shown in FIG. 6, the thin film member 34 that enters the contact area
The width of the contact area X becomes wider.

Therefore, the contact efficiency between the developer and the electrostatic latent image is increased, and a high-quality image can be obtained even when the photoreceptor 100 and the thin film member 34 are moved at high speed.

Further, the frictional force between the V-shaped groove 343 and the developer is improved, and the developer transporting ability of the thin film member 34 and its stability are increased. This conveying ability and stability can be further increased by providing minute irregularities 34b on the outer periphery of the thin film member 34 by blasting or the like, as shown in FIG.

Note that the V-shaped grooves 3 and 1a may be provided on the inner circumferential surface of the thin film member 34, or may be provided on both the inner circumferential surface and the outer circumferential surface.

The V-shaped groove 34a is formed by the method shown in FIG. 6 or 7.

In the method shown in FIG. 7, the thin film member 34 is closely covered with a core material 60, and the thin film member 34 is attached to a cylindrical cutter 61 having V-shaped teeth 62 on the inner surface.
, and the teeth 62 scrape the outer circumference of the thin film member in the axial direction to form a V-shaped groove 34a.

In the method shown in FIG. 8, the thin film member 34 is closely covered with the core material 63, has V-shaped teeth 65 in the axial direction on the outer peripheral surface, and
The heating roller 64 connected to the above is pressed against the outer peripheral surface of the thin film member 34, the core material 63 and the heating roller 64 are rotated, and the thin film member 34 is heated and melted by the teeth 65 to form M34a.
form.

Embodiment 4 Figures 9 and 10 show d thickness at both ends of the thin film member 34)-)7
Q is pasted and reinforced, and a perforaire-J shift 1 is provided continuously in the circumferential direction on the reinforced portion, while a sprocket 72 is provided at a corresponding position on the cylindrical body 31.

According to this developing device, there is no relative slippage between the thin film member 34 and the cylindrical body 31, and the developer can be stably supplied to the contact area X.

In this embodiment, in order to prevent the iI\ membrane member 34 from tearing from the perforation/yon 71 part, the door Q is reinforced, but the sheet 70 is not provided with the perforation 71 and is used only for reinforcement. It may also be pasted blue.

In this case, the strength at both end portions of the thin film member 34 is increased, and the developer in these portions can be pressed against the photoreceptor 100 with the same force as that in the central region.

By the way, when forming the groove 34a of the third embodiment in the thin film member 34 shown in FIG. 9.10, as shown in FIG.
A perforation/yon 71 is provided in the region between the grooves 34a.

〔Effect of the invention〕

As is clear from the following explanation, in the developing device according to the present invention, since a sufficient contact width and contact distance between the developer and the electrostatic latent image can be ensured, the development efficiency of the electrostatic latent image is good.

In addition, in the area facing the same polarity, the developer either does not fly discontinuously and passes through, or it is leveled to a constant thickness by a leveling member, so the contact area with the photoreceptor is The movement of the developer through the area is continuous and even.

Therefore, even in the case of high-speed development, the electrostatic latent image can be developed uniformly and in a high density state.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the developing device, Figure 2 is the supply section and density 4]
FIG. 3 is a partially enlarged cross-sectional view of the developing device; FIG. 4 is a partial cross-sectional view of the developing device;
FIG. 5 is a partially enlarged cross-sectional view of the thin film member, FIG. 6 is a partial cross-sectional view showing the developer in the thin film key (in a pushing state, and FIGS. 7 and 8 are perspective views showing the method of forming the oil film member. Fig. 9 is a partial front view of the thin film member, Fig. 10 is a partially enlarged sectional view of the a-film member, and Fig. 11 is a side view of a cylindrical body equipped with a sprocket 6111. ■...Developing device, 10. - Supply section, 11... Supply chamber, 12... Supply blade, 20... Concentration measurement unit, 21. Conveyance path, 22... Conveyance blade, 30... Developing unit, 31.
... Cylindrical body, 34 ... aV membrane member, 35 ... bulge, 36 - regulation member, 37 ... leveling member, 40 ... recovery section, 41 ... partition wall, 46 empty room, 50 ...・Toner lin supply section.

Claims (1)

[Claims] (1) A cylindrical body facing a photoconductor and driven to rotate, and a magnet body located inside the cylindrical body and having a same-pole portion adjacent to the same pole near a portion where the photoconductor and the cylindrical body face each other. , a thin film member having a circumference slightly longer than the circumference of the cylindrical body and enclosed in the cylindrical body; and a magnetic developer held on the outer periphery of the thin film member by the magnetic force of the magnet body. A developing device comprising: a regulating member that faces the outer peripheral portion of the thin film member that covers the same polar portion and contacts the magnetic developer.