JPH03287186A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the increase of the driving torque of a developing roll and to prevent a white stripe by forming a developer puddle part near a pole on the upstream side of a same pole magnetization part so that it may not come in contact with a photosentive body. CONSTITUTION:By utilizing attraction force by the non magnetic pole area of the same pole magnetization part M1 and a different pole S2 on the upper- stream side than the part M1, the developer puddle part 38 is formed near the pole N3 on the upstream side of the part M1 and between the poles S2 and N3. Namely, since the poles N3 and N4 have the same polarity, the developer is temporarily restrained by the pole N3 and the restrained developer tries to return to the pole S2 along a magnetic flux, so that the developer puddle part 38 is formed. Since the puddle part 38 does not come in contact with the photosensitive body, stress between the photosensitive body and the developing roll is avoided. Even when the white stripe is caused in a bristle height regulating member 36, it is prevented by the puddle part 38.

Description

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

(Prior Art) Conventionally, as the above-mentioned developing device, one provided with a height regulating plate for regulating a developer conveyance path that is sent to a photoreceptor in a developing section is known. However, this regulating plate is easily clogged with foreign matter, and when this clog occurs, white spots appear on the image corresponding to this area. Therefore, as a measure to prevent white streaks, a magnetic material or a magnetic field generating means is disposed along the developing roll between the regulating plate and the developing section to make the developer stand up in the developing area. A developing device has been proposed that attempts to form a developer layer with a completely uniform thickness before reaching the developer (Japanese Unexamined Patent Publication No. 1983-1992).
], Publication No. 54472).

(Problems to be Solved by the Invention) In the above-mentioned conventional apparatus, a magnet in which N and S poles are arranged alternately is used as the magnet of the developing roll, and there is a gap between the developing roll and the magnet. As the amount of developer that accumulates decreases, the ability to transport the developer to the white smear area is low, making it impossible to completely prevent white smear, and it is necessary to place magnetic materials, etc., quite close to the developing sleeve, and both The inventor has confirmed that due to the narrow spacing, a problem arises in that the driving torque of the developing roll becomes large.

The present invention has been made to address these conventional problems, and an object thereof is to provide a developing device that can prevent white streaks without increasing the driving torque of the developing roll.

(Means for Solving the Problems) In order to solve the above problems, a first invention uses a developing roll having at least one homopolar magnetized part between the brush height regulating part and the developing area. The developer is supplied to the developer leg, the white scum disappears, and the developer that can no longer be held in the developer accumulation section sequentially jumps to the downstream side frame and is uniformly supplied, thereby allowing development to be performed. At the same time, a developer flow in the opposite direction from the upstream pole to a different pole on the upstream side occurs on the developing roll, causing disturbance of the developer, and the amount of charge also becomes 2 parts.

(Example) Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a developing device according to the invention (2), which is roughly composed of a supply section 10, a density detection section 20, a developing section 30° collection section 40, and a toner replenishment section 50.

Supply Section 10 The main stirring chamber 11 of the supply section 10 is provided with a bucket roll 12 . This bucket roll 12 has side plates 14 provided at both ends of a shaft 13. ．． A plurality of packets 15 are horizontally hung on the outer periphery of the packet 14 and can be rotated in the direction of arrow a.

Concentration Detection Unit 20 In the device, a developer accumulation portion is formed near the second side frame of the homopolar magnetized portion so as not to contact the photoconductor, and in the second aspect of the invention, the developer accumulation portion is The upstream pole and the different pole upstream thereof form an angle with respect to the center of the developing roll, and the upstream pole and the downstream frame of the same pole magnetized portion make an angle with the center. When the angle is φ, θ<
It was made to be formed as φ.

Further, in the third invention, the developer accumulation portion has a different polarity strength of A Gauss on the upstream side of the upstream pole, a strength of B Gauss of the upstream pole, and a strength of C of the downstream frame. When it is Gaussian, it is formed as A+B>C,
In the fourth invention, the developer reservoir is formed by a magnetic material or magnetic field generating means provided near the second side frame.

(Operation) By configuring as in the first to fourth inventions,
The developer supply part concentration detection part 20 is provided at the rear of the supply part 10, is continuous with the main stirring chamber 11, and is connected to the main stirring chamber 11. A spiral roll 22 is placed on a conveying path 21 formed in parallel.
is the provision. This spiral roll 22 is shown in FIG.
As shown in Fig. 13, a feeding member 24 is provided at the center of a shaft 23, and spiral blades 2 with opposite spiral directions are provided on both sides of the feeding member 24.
5, and the direction in which the developer is conveyed by the rotation of the spiral roll 22 is different on the left and right sides of the feeding member 24. That is, in FIGS. 2 and 3, the spiral blade 25 on the left side has the ability to convey to the right, and the spiral blade 25 on the right has the ability to convey to the left. Furthermore, an opening 27 is provided in the wall 26 between the supply chamber 11 and the conveyance path 21 at a portion facing the feeding member 24 .

Furthermore, a toner concentration detection sensor 28 is provided at the center bottom of the conveyance path 21 to measure changes in magnetic permeability of the developer.
The sensor surface is approximately aligned with the bottom surface of the conveyance path 21.

111, 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 100 with a predetermined cap, and is configured to rotate in the direction of arrow C about a shaft 34. Further, the cylindrical body 31 is connected to an electric voltage 32, and a predetermined bias voltage VB is applied thereto.

A magnet body 33 that forms a developing roll together with the cylindrical body 31 is fixed inside the cylindrical body 31 in a non-rotating state. Moreover, this magnet body 33 has a plurality of magnetic poles (N, SN2.S2.N3.N, . . .
S3. N5) on the outer periphery in this order, and the magnetic poles N3 and N
4. Make the magnetic poles N5 and N1 adjacent to each other, and place the middle between them with the same-pole magnetized portion M(.

N2, and the same-polarity magnetized portion M is located between the brush height regulating member 36 and the developing area X, and is slightly larger than the developing area The same-polarity magnetized portion M2 is located at a portion facing the bucket roll 12.

Then, the non-magnetized region of the same-pole magnetized portion M1 and the same-pole magnetized portion M,
Using the attraction force due to the different poles S, which are more upstream, S,',
Between the N3 poles, the upstream side iv in the same polar magnetized part M, the collection part 4
0 The collection part 40 is located above the supply part 10 and is partitioned from the supply part 10 by a partition wall 41, and the front wall 42 of the partition wall 41 is formed with a predetermined distance from the cylindrical body 31, and the upper end thereof and the height regulating member A passage 43 is provided between the partition wall 41 and
A conveyance path 45 communicating with the main stirring chamber 11 is provided between the rear wall 44 and the upper cover 29 of the concentration detection section 20 . In addition, two feeding blades 474 are provided in the auxiliary stirring chamber 46 of the recovery section 40.
8 are provided at the front and rear, and are designed to rotate in the directions of arrows d and e, respectively.

■ Toner replenishment section 50 The toner replenishment section 50 is formed with a storage chamber 51 and a replenishment chamber 54, and the storage chamber 51 has stirring blades 52 and 53 indicated by arrows f,
A brush roll 55 is provided in the supply chamber 54 so as to be rotated in the direction of the arrow. Further, the supply chamber 54 communicates with the auxiliary stirring chamber 46 via a mesonue 56 provided at the bottom thereof.

B: A developer pool 38 is formed near the developing operation pole N3. That is, the developer is N3. Since the N4 pole is the same pole, it is temporarily restrained by the N3 pole, and this restrained developer moves along the magnetic field lines to S2.
A developer pool 38 is formed as the developer tries to return to the pole.

In addition, since the developer pool does not come into contact with the photoreceptor, stress between the photoreceptor and the developing roll can be avoided.
This leads to longer life of the developer.

The height regulating member 36 is attached to the upper part of the developer tank, and its tip is opposed to the outer peripheral surface of the cylindrical body 31 with a predetermined gap Dn+.

The leveling member 37 is attached to the developing tank via the height regulating member 36, and the cylindrical body 3 near the same polar magnetized portion M is located at the tip thereof.
1 with a predetermined cap DB2 facing each other. Note that the tip of the leveling member 37 is connected to the cylindrical body 31.
It is oriented diagonally along the direction of arrow C with respect to the wide line on the outer circumferential surface of , so that the developer conveyed from the direction of arrow C does not stay in front of the leveling member 37 .

The developing operation will be explained.

A two-component developer consisting of toner and magnetic carrier is used, and is housed in the main stirring chamber 11.

The developer in the main stirring chamber 11 is mixed in the surrounding bucket 15 based on the rotation of the bucket roll 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 detection section 20 by the conveying action of the bucket 15, and the developer scooped into the bucket I5 is supplied to the outer circumference of the cylindrical body 31 in the supply area P.

Note that the conveyance amount of the developer scooped into the bucket 15 is regulated by a Mylar plate 49 provided under the partition wall 41, and the supply amount is adjusted to be constant.

The developer sent to the concentration detection section 20 is conveyed toward the center by the spiral blades 25 by the rotation of the spiral roll 22, then merges and mixes at the center, and is scooped up by the feeding member 24 and sent to the main stirring chamber 11. sent back to. The developer sent back to the main stirring chamber 11 is dispersed left and right by the mixing and stirring action of the bucket roll 12. In addition, the second
As shown in FIG. 3, if the blades 16 and 16 are provided at the center of the brush trolley 12 and their angles with respect to the shaft 13 are reversed, the developer sent back from the conveyance path 21 will be actively While being distributed to the left and right, the conveyance path 21
A part of the developer sent back from the left side of the transport path 21 is transported to the right side of the main stirring chamber 11, and a part of the developer sent back from the right side of the transport path 21 is transported to the left side of the main stirring chamber 11. There is no inconvenience that the left and right developers are mixed and the toner concentration (mixing ratio by weight of 1 hener to carrier) of the left or right developer is reduced.

Further, the toner concentration of the developer is detected by a toner concentration detection sensor 28 located at the center. The toner concentration detected here is
Since the detection value is related to a mixture of the developer sent by the left and right blades, the detected value is an average value, and the detected value does not vary greatly due to a local decrease in toner concentration. Therefore, stable toner concentration management is possible.

On the other hand, the supply area P comes into contact with the electrostatic latent image formed on the holding surface on the outer circumference of the cylindrical body 31, and as a result, based on the potential difference between the surface potential of this electrostatic latent image and the developing bias voltage (8), , toner is electrostatically deposited on the electrostatic latent image.

Here, as mentioned above, the developer restrained by the N3 pole is 83
Either a developer pool 38 is formed as the developer tries to return to the pole, or the developer that can no longer be held in the developer pool 38 jumps to the N4 pole one by one and is uniformly supplied, thereby causing development. Even if a white stain forms on the height regulating member 36, this developer accumulation portion 38 prevents the white stain from forming. In particular, regarding the formation of this accumulation part 38, it is necessary to
If there is a difference of 200 Gauss or more between the magnetic force at the point where the magnetic force falls between the 3-pole and the N4-pole, a better accumulation will occur.

Further, since a developer flow occurs in the opposite direction from the N3 pole to the 32 pole on the developing roll, the developer is disturbed, and the amount of charge is increased to perform good development.

The developer that has passed through the development area 36 regulates the conveyance amount.

The developer that has come off the discharge path due to the height regulating member 36 is transferred to the path 4.
3 and is collected into the auxiliary stirring chamber 46 of the collection section 40.

Therefore, the developer remains in front of the height regulating member 36 indefinitely and is not subjected to stress, thereby reducing deterioration of the developer.

As shown in FIG. 3, the developer that has passed through the tip of the height regulating member 36 passes through the magnetic pole N7. S7. It is conveyed in the state of a magnetic brush on the opposing part of N3. Further, when the developer passes through the opposing portion of the magnetic pole N3, it is released from the restraining force of the magnetic pole at the opposing portion of the homopolar magnetized portion M, and flies in the form of a lump in the transport direction. This flying developer collides with the leveling member 37 and is leveled to a certain layer thickness (corresponding to the gap I) na, and the cylindrical body 3
1 in the direction of arrow C, the cylindrical body 31 and the photoreceptor 10
0 to the development area X.

In the development area
It is transported in the direction of arrow C. Then, the same-polar magnetized portion M between the magnetic poles N5 and N is released from the restraining force of the magnetic poles, and falls into the supply chamber 11 and is collected.

The developer regulated by the height regulating member 36 and collected in the collection section 40 is transported rearward within the auxiliary stirring chamber 46 by the rotation of the transport blades 47 and 48, and is supplied to the supply chamber 11 through the transport 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 stirring blades 5253 of the toner replenishing section 50 rotate,
The toner in the storage section 51 is sent to the supply chamber 54. Supply room 5
The toner supplied to the toner 4 is conveyed in the direction indicated by the arrow as the brush roll 55 rotates, passes through the mesh 56 , and falls and is supplied to the auxiliary stirring chamber 46 . Here, the lumped toner is not supplied as is to the auxiliary stirring chamber 46, and the toner passing through the mesh 56 falls in a dispersed state, so that it is quickly thrown into the developer in the auxiliary stirring chamber 46. When mixed with these developers, it is immediately charged. Therefore, uncharged toner is not subjected to development, and the generation of toner powder smoke and blurring on images are reduced.

Next, the second to fourth inventions are substantially the same except for the specific configuration of the developing section 30 that forms the developer reservoir 38, and corresponding parts are designated by the same numbers. We will mainly explain the different parts.

FIG. 5 shows the developing section 30 of the developing device according to the second invention, in which the upstream pole N3 and the front pole S upstream thereof form an angle O1 with respect to the center of the developing roll. The developer pool 38 is formed such that θ<φ, where φ is the angle φ formed with respect to the center of the downstream frame N4 in the same-polarity magnetized portion M.

FIG. 6 shows the developing section 30 of the developing device according to the third invention, in which the strength of the upstream pole N3 - the different pole S on the stream side is A Gauss, and the strength of the upstream pole N3 is B Gauss, and when the strength of the downstream frame N4 is C Gauss, A -1-B
> As C, the developer reservoir 38 is placed on the back side with a magnetic material, etc. 39
is installed. With such a configuration, the magnetic material etc. 3
9. This is to create a sealing effect between the tip and the cylindrical body 31.

FIG. 9 shows a developing section 30 that is either a homopolar magnetized section or does not participate in development, and has a plurality of magnetic poles (N, , S, , N, S).

S3. N3. S4. N4) are arranged in this order, with the magnetic pole N3 facing the development area The magnetized portion M1 is positioned between the brush height regulating member 36 and the tip portion. Then, a magnetic material 39 is attached to the upper inner surface of the leveling member 37 near the upstream pole S2, and the developer reservoir member 38 is
It is formed.

FIGS. 10 and 11 show an example in which two developing rolls are used, with the two sides consisting of a cylindrical body 31a and a magnet body 33a, and the lower side consisting of a cylindrical body 31b and a magnet body 33b.

In the case of FIG. 10, the magnet body 33a has a plurality of magnetic poles (S2.N3.S3.N3.N4.S4), and the magnet body 33b has a plurality of magnetic poles (S, N, N5, S5 type). This is because S acts to store developer.
3. This is because the N4 pole attempts to transport the developer from the pool to the downstream side, whereas the N3 pole does.

FIG. 7 and subsequent figures show the developing section 30 in several embodiments of the developing device according to the fourth invention, all of which include a magnetic material or magnetic field generating means (hereinafter referred to as magnetic material) in the vicinity of the upstream pole N3 or S2. etc.) 39 is provided to form the developer reservoir portion 3.
8.

Of these, the magnetic pole arrangement in the developing section 30 shown in FIG. 7 is basically the same as that shown in FIGS. 4 to 6, and is attached to the inner surface of the second part of the leveling member 37.

The arrangement order of the magnetic poles in the developing section 30 shown in FIG.
Although it is the same as that shown in FIGS. to 6, the upstream pole N3 is placed close to the tip of the leveling member 37,
Along with this, the different pole S2 on the upstream side is also arranged at a position closer to the tip than in the case of FIGS. 4 to 6, and
N6 of the tip. S6) are arranged in this order.

Also, magnetic pole N3. The same-polarity magnetized part M1 between N4 is placed in the second development area Xa, the same-polarity magnetized part M between magnetic poles S, and S6 is placed opposite to the supply area P, and the magnetic pole S5 is placed in the lower development area xb. Opposingly, the leveling member 37 near the two-part side frame N3
A magnetic material 39 is attached to the inner surface of the upper part. Then, as shown by the arrows, the developer is moved from the magnetic poles S to N.
, S, N2. S, N3N,, S4. N5. S, No, S
It is intended to be moved to o.

In the case of FIG. 11, the magnet body 33a has a plurality of magnetic poles (N2.
S3. N1. S4. N4. S, , ) are attached to the magnet body 33b with a plurality of magnetic poles (S+, N+, S2+ N5+ so.

S7. N, , S8) are arranged in this order. In addition, magnetic pole S6. The same-polar magnetized portion M between S7 faces the lower development area Xl, the same-pole magnetized portion M between S8 faces the supply area P, and the magnetic pole N4 faces the upper development area Xa
The upstream pole S is opposed to the upstream pole S.

This is done by attaching a magnetic material 39 between both developing rolls near the developing rolls.

Then, as indicated by the arrows, the developer is transferred from the magnetic pole SI to the magnetic pole N, . . . S7. N2. S3. N3. S4. , N4S5.
N1. S6. S,,N6. It is intended to be moved to S8.

In particular, when forming the homopolar magnetized portion M1 on the lower developing roll in this way, if the developer accumulation in the second side frame S6 is not properly disposed of, the photoconductor 100 and the cylindrical body 31b will be damaged. The developer may become clogged between the upper and lower cylindrical bodies 31a, 31.
The developer may get into the space between the two and cause a blockage. On the other hand, if a magnetic material 39 is arranged as shown in FIG.
The direction of the magnetic lines of force generated by the magnetic pole S6 can be adjusted as appropriate, and the clogging of the developer as described above can be avoided.

Note that the three shapes of the magnetic bodies extend in the axial direction of the developing roll and can take various shapes. For example, FIG. 12 shows a rectangular shape, FIG. 13 shows a wavy shape, and FIG.
The diagram has a checkered pattern.

(Effects of the Invention) As is clear from the above description, according to the first to fourth inventions, even if only white soot is generated due to clogging with foreign matter in the brush height regulating portion, the white soot is removed by the developer accumulation portion. It is possible to eliminate this.

In addition, in the developing roll 2, the developer is disturbed by the developer flow in the opposite direction from the 2 part side frame to the different poles on the upstream side, and the amount of charge is reduced to 2 parts, resulting in good development. This has the effect of making it possible.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a developing device according to the first to fourth inventions, FIG. 2 is a perspective view showing the supply section of the device shown in FIG. 1 and the flow of developer before and after it, and FIG. A sectional view taken along the line ■-■ in Fig. 2, Figs. 4 to 11 are partially enlarged sectional views of the developing section of the apparatus shown in Fig. 1, and Figs. 12 to 14 show various magnetic materials, etc. FIG. 30...Developing section, 3L 31a, 31b...Cylindrical body, 32...Magnet body, 36...Bear height regulating member, 38
・Developer accumulation part, 39...magnetic material, etc., X, X,,X
,,...Development area, Ml homopolar magnetized part. Figure 10 Figure 11

Claims (4)

[Claims] (1) In a developing device using a developing roll having at least one homopolar magnetized portion between the height regulating portion and the development area, the developing device is placed near the upstream pole of the homopolar magnetized portion. A developing device characterized in that a developer reservoir is formed so as not to come into contact with a photoreceptor. (2) The developer accumulating portion is arranged such that the angle between the upstream pole and the different pole on the upstream side is θ, and the angle between the upstream pole and the same pole magnetized portion on the downstream side is θ. 2. The developing device according to claim 1, wherein the developing device is formed such that θ<φ, where φ is an angle formed by the side poles with respect to the center. (3) The developer accumulation portion has a different pole strength upstream of the upstream pole of A Gauss, a strength of the upstream pole of B Gauss,
When the strength of the downstream pole is C Gauss, A+B>
A claim characterized in that it is formed as C.
1) The developing device according to item 1). (4) The developing device according to claim 1, wherein the developer pool is formed by a magnetic material or a magnetic field generating means provided near the upstream pole.