JP3248765B2 - 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 for visualizing an electrostatic latent image in an electrophotographic device or an electrostatic recording device, and more particularly to a developing device for preventing a developer from leaking.

[0002]

2. Description of the Related Art A developing device is provided with a developing roller (developer supplying means), and supplies a developer to an electrostatic latent image formed on a photosensitive drum (image carrier) by rotation of the developing roller. And develop, and after the development, a part thereof is collected.

In addition, seals are provided at both ends of the developing roller.
A sealing member (a regulating member) is provided, and the leakage of the developer from both ends of the developing roller is prevented by these sealing members.

The layer thickness of the developer on the developing roller is regulated by a doctor blade, but the regulation is not always constant.
(Toner replenishment, etc.).

The change in the developer layer is small around the central portion of the developing roller, which is an image forming area. Conversely, a portion where the magnetic force of the magnet roller in the developing roller is weak, or the developer is This is remarkable at both ends of the developing roller where the developing roller easily accumulates.

[0006]

In the prior art, however, the thickness of the seal member has conventionally been such that the developer supply side is the upstream side in the rotation direction of the developing roller and the developer collection side is the downstream side in the rotation direction. Therefore, the amount of developer supplied at the upstream end of the developing roller is equal to the amount of developer drawn in at the downstream end of the developing roller. For this reason,
When the amount of the developer increases at the upstream side in the rotation direction of the developing roller, especially at the end thereof, the toner conveyed to the downstream side in the rotation direction of the developing roller is kicked by the seal member and is directed to the outside. There is a problem that the airplane scatters and contaminates the inside of the machine, and furthermore, an image cannot be output.

Accordingly, the present invention provides a developing device capable of preventing the leakage of the developer by increasing the drawable amount of the developer at the both ends of the developer supply means on the downstream side in the rotation direction. Aim.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is provided along a predetermined direction facing an image carrier on which an electrostatic latent image is formed, and has a magnet inside the surface. A developer supply unit for supplying and developing the developer to the electrostatic latent image by developing and supplying the developer to the electrostatic latent image by rotating the developer supply unit; A magnetic portion provided at both ends in the predetermined direction along the rotation direction and located on the developer supply side and a magnetic portion having a smaller magnetic force than the magnetic portion and located on the developer recovery side. And a regulating member for regulating leakage of the developer.

[0009]

By making the magnetic force of the magnetic part located on the developer collection side of the magnetic member smaller than the magnetic force of the magnetic part located on the developer supply side, the amount of developer drawable on the developer collection side is increased. To ensure that the developer can be recovered.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIGS.

FIG. 2 shows the structure of an image forming apparatus 1 employing the developing device of the present invention.

In FIG. 2, a photosensitive drum 3 as an image carrier is provided at a substantially central portion of the image forming apparatus main body 2 so as to be rotatable in the direction of an arrow. This photosensitive drum 3
It is formed of an organic photoconductor (OPC) -based photoconductive material.

Around the photoreceptor drum 3, a static eliminator 4, a scorotron charger 6 as a charging unit, a laser device 7 as an electrostatic latent image forming unit, are sequentially arranged along the rotation direction.
Developing device 8, transfer device 9, and cleaning device 5
Are arranged. The image forming unit 10 forms a toner image on the peripheral surface of the photosensitive drum 3 as a developer image.

In the apparatus main body 2, a sheet P as a material to be transferred taken out from the paper feed cassettes 11 a and 11 b mounted inside the apparatus main body 2 is transferred to the photosensitive drum 3 of the image forming unit 10. The paper discharge tray 1 disposed on the other side of the apparatus main body 2 via the image transfer section 12 between the transfer roller 9 and the transfer roller 9
A paper transport path 14 is formed as a transfer medium transport path leading to 3.

The image transfer section 12 of the paper transport path 14
After aligning the leading edge of the paper P taken out of the paper feed cassettes 11a and 11b via the paper feed rollers 15a and 15b, the aligning roller which feeds the paper P to the image transfer unit 12 at a time is provided. A pair of rollers 16 are arranged.

The sheets P taken out of the sheet cassettes 11a, 11b are guided by guides 23, 23 and transport rollers 24, 2.
The fixing device 17 for fixing the toner image transferred to the sheet P and the fixed sheet P are discharged to the discharge tray 13 downstream of the image transfer section 12. A discharge roller pair 18 is provided.

Further, on the discharge side of the discharge roller pair 18, a gate 20 for switching the discharge direction of the paper P is provided. When the gate 20 is switched in the direction of the solid line, the sheet is discharged to the sheet discharge section 22 formed of a recess formed on the upper surface side of the apparatus main body 2 with the image forming surface down. I have.

Next, an image forming operation of the image forming apparatus 1 configured as described above will be described.

As the photosensitive drum 3 is rotated, the peripheral surface of the photosensitive drum 3 is substantially uniformly negatively charged by the scorotron charger 6. Subsequently, the charged area is irradiated with a laser beam 7 </ b> A according to image information to be recorded from the laser device 7, and is exposed to form an electrostatic latent image on the surface of the photosensitive drum 3. Next, the electrostatic latent image faces the developing device 8 as the photosensitive drum 3 rotates.

Here, toner is attached to the electrostatic latent image on the photosensitive drum 3 to form a toner image. In this case, the toner adheres to the light irradiation area and is subjected to so-called reversal development. The developed toner image is then transported to a transfer area facing the transfer unit 9.

On the other hand, a paper feed roller 15a
The paper feed cassette 11a (11b) is rotated by the rotation of (15b).
The sheet is taken out from the printer and is sent through the aligning roller pair 16 in synchronization with the rotation of the photosensitive drum 3.

The back side of the paper P conveyed here is charged by the transfer roller 9 to a positive polarity. Therefore, the toner image on the surface of the photosensitive drum 3 is electrostatically attracted to the paper and transferred.

The sheet after the transfer is sent to a fixing device 17, where the toner is melted and fixed on the sheet by heat and pressure, and then discharged.

By the way, on the surface of the photosensitive drum 3 after the transfer, there is a small amount of toner that has not been completely transferred and remains. This toner is cleaned by the cleaning device 5. After being cleaned in this way, the photosensitive drum 3 is neutralized by the static eliminator 4 and then charged by the charger 6 and then exposed by the laser device 7 to form an electrostatic latent image, again (second time). The developer reaches the developing cleaning position facing the developing device 8.

As shown in FIGS. 1 and 3, the developing device 8 is provided with a developing roller 31 as developer supply means in the developing container 30 so as to be rotatable in the direction of the arrow. The developing roller 31 has a magnet roller 3 inside.
1a, and is opposed to the photosensitive drum 3.

The developing roller 31 is configured to rotate in the same direction as the rotating direction of the photosensitive drum 3 at the contact portion, that is, in the width direction.

In the developing container 30, the toner conveying amount by the developing roller 31 is regulated above the developing roller 31, and a thin layer of the toner is formed on the surface of the developing roller 31. Is provided.

At both ends of the developing roller 31, seal members (regulating members) 34, 34 for preventing leakage of the developer to the outside are provided. As shown in FIG. 3, these seal members 34, 34 are notched at the lower half inner surface side, that is, a portion of the developing roller 31 which is located on the upstream side in the rotation direction on the developer supply side. than the thickness t _1, the thickness t ₂ of the portion located downstream in the rotational direction as a developer recovery side is formed thinner is small.

During development, the developing roller 31 is rotated, and the developer is conveyed in the direction of arrow B in the figure and supplied to the photosensitive drum 3, whereby the electrostatic latent image on the photosensitive drum 3 is developed.

After the development, the developer remaining on the developing roller 31 is drawn into the lower side of the developing container 30 and collected as shown by an arrow C.

At the time of this development, the layer formation of the developer on the development roller 31 is as shown in FIG.
When the developer is tilted or the bulk of the developer is increased due to toner replenishment, as shown by a broken line in FIG.
Swells.

In this case, the amount of developer drawn in at the lower side of the developing roller 31 increases. However, as described above, the thickness of the seal member 34 at the downstream side in the rotation direction of the developing roller 31 is increased. Since it is formed to be thin, the resistance at the time of pulling in the developer is small and it can be collected well.

The relationship between the thickness of the seal member 34 and the amount of developer falling is as shown in FIG. That is, - increased drop amount of the developer according to the lower side of the thickness t ₂ dimensions of seal member 34 is increased, the dimensions of the thickness t ₂ is fallen amount of the developer decreases with decreasing .

It should be noted that the present invention is not limited to the above embodiment, but may be as shown in FIG.

That is, when the thickness of the seal member 34 is t
_The case where only the thickness t ₁ on the upper side of the seal member 34 is increased from the state of ₁ = t ₂ .

The embodiment according to FIG. 6 differs from the embodiment according to FIG. The one shown in FIG. 3 increases the amount of developer that can be drawn in on the developer recovery side after development without changing the developer amount on the developer supply side. On the other hand, the one shown in FIG. 6 reduces the amount of developer on the developer supply side by cutting as shown in FIG. 7, and increases the amount of developer that can be drawn in on the developer recovery side after development. It is the same as before without any change. That is,
In the present invention, the relationship between the amount of developer on the developer supply side and the amount of developer withdrawable on the developer recovery side is relatively the amount of developer on the supply side <the amount of developer withdrawable on the recovery side. I just want to be in a relationship. Therefore, as a method for this, either the amount of the developer on the supply side is positively reduced or the amount of developer that can be drawn in on the collection side is positively increased. The embodiment illustrated in FIG. 6 is the former embodiment, and the embodiment illustrated in FIG. 3 is the latter embodiment.
Further, t ₁ = t ₂ means that the amount of the developer on the developer supply side is equal to the amount of the developer that can be drawn in on the developer recovery side, and the size of the seal member is different from that of the embodiment of the present invention. This corresponds to a case where the length is kept constant without changing between the agent supply side and the recovery side.

However, the cut of the developer at this time is performed on the transported developer other than the image area.

At this time, the amount of the developer falling due to the regulation of the end-portion developer is as shown in FIG.
As the thickness t ₁ is increased, it is reduced, and conversely, as the thickness t ₁ is reduced, the amount of developer falling increases and deteriorates.

As shown in FIG. 9, the present invention may be applied to an agent developing system.

Here, the thickness t ₁ and t ₂ of the seal member 41 are upside down, which is due to the fact that the developing roller 31 is rotated in the reverse direction. The function is exactly the same as that of the quiz method described above.

However, in the case of the agent system, the developer may not fall down, but in this case, the developer blows out from the upper portion of the developing container 30 or the developer is not supplied.
There is a problem that clogging occurs between the drum 31 and the photosensitive drum 3.

In the above embodiment, the case where a two-component developer is used is shown, but the present invention can also be applied to a developing device using a magnetic one-component developer.

However, in the case of a one-component developing device, the developer inside the developing device does not rise due to toner replenishment, and the amount of toner (developer) originally contained is large, that is, when the bulk is high. And the developing roller 31
The swelling of the upper toner layer occurs, and toner (developer) drop occurs. On the other hand, the same effect as described above is obtained, and toner (developer) drop occurs. Can be reduced.

The present invention may be as shown in FIGS.

In this embodiment, a magnetic seal member 51 is used as a seal member, and as shown in FIG. 13, the magnetic seal member 51 is used so that an increased amount of developer can be drawn in. of lowering the magnetic force of the lower side C ₂ parts weaken the developer binding between N ₃ made to pull close proximity -S, it was easy pull a developer.

As shown in FIG. 14, when the magnetic force of the magnetic seal 51 was less than 300 gauss (G), the amount of the developer falling was reduced, and it was found that the magnetic seal 51 became a practical level.

[0047] The magnetic sheet - strongly upper side C ₁ force Le 51, for example 400 may be a Gaussian (G).

In this case, as described above, the limit amount of the drawn-in developer is not increased (the magnetic constraint of the developer that hinders the drawing-in is eliminated), and the transfer is performed without changing the drawn-in limit amount. The amount of the developer is cut as shown by a one-dot chain line in FIG. 13 to reduce the transport amount at the end.

However, the cutting at this time is performed on the transported developer in the image forming area.

At this time, the amount of developer drop due to the regulation of the edge transport developer is shown in FIG.
It was found that by increasing the magnetic force to 300 gauss (G) or more, the amount of the developer falling was reduced, and the developer level reached a practical level.

[0051]

As described above, according to the present invention,
The amount of developer that can be drawn in on the developer collection side at both ends of the developer supply unit can be increased, and even if the amount of developer on the supply side of the developer supply unit increases, the developer can be supplied from both ends of the developer supply unit. This has the effect of being able to collect well without leaking.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a developing device according to an embodiment of the present invention.

FIG. 2 is a front view schematically showing an internal configuration of an image forming apparatus employing the developing device of FIG.

FIG. 3 is a diagram showing a state in which the developing device of FIG. 1 is viewed from a direction of an arrow A.

FIG. 4 is a diagram showing a state in which a developer is biased on a developing roller of the developing device of FIG. 1;

FIG. 5 is a graph showing a relationship between a thickness dimension of a seal member of the developing device of FIG. 1 and a drop amount of a developer.

FIG. 6 is a cross-sectional view illustrating a developing device according to another first embodiment of the present invention.

FIG. 7 is a view showing a developer layer on a developing roller of the developing device of FIG. 6;

8 sheets of the developing device of FIG. 6 - a graph showing the relationship between the thickness dimension of t ₁ part of seal member and the developer drop amount.

FIG. 9 is a configuration diagram showing a developing device according to another second embodiment of the present invention.

FIG. 10 is a diagram showing a state viewed from the direction of arrow A in FIG. 9;

FIG. 11 is a configuration diagram illustrating a developing device according to a third other embodiment of the present invention.

FIG. 12 is a front view showing a state viewed from the direction of arrow A in FIG. 11;

FIG. 13 is a view showing a developer layer offset on the developing roller of FIG. 11;

[Figure 14] Shi of the developing device of FIG. 11 - graph showing the relationship between the magnetic force of the C ₂ parts of seal member and the developer drop amount.

[Figure 15] Shi of the developing device of FIG. 11 - graph showing the relationship between the force and the developer dropping amount of C ₁ part of seal member.

[Explanation of symbols]

3 photoreceptor drum (image carrier), 31 developing roller (developer supply means), 34, 34, 41, 51 ... seal member.

Claims (1)

(57) [Claims] An image bearing member on which an electrostatic latent image is to be formed is provided along a predetermined direction. A developer is supplied to the electro-latent image for development, and after the development,
A developer supply unit that collects the remaining developer; and a magnetic unit that is provided at both ends of the developer supply unit in the predetermined direction along the rotation direction and is located on the developer supply side. And a regulating member having a small magnetic force and located on the developer collection side, and regulating leakage of the developer.