JP2000112237A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a developing device itself or the inside of an equipment such as a copying machine or a printer using this developing device from being soiled by developer splashed at the outside of a developer recovery port and to enable an excellent-quality recorded image to be formed as the developing device constituted so that the developer is prevented from being leaked at both ends of a developing roll by using a pair of magnetic seal plates and the recovery port for recovering the developer to the inside of a housing by using the seal plates and the like is formed. SOLUTION: The under seal member 6 recovering toner dropping down from a developing area to the inside of the housing 3 and hermetically sealing a gap between the housing 3 and a latent image carrier 1 is arranged at the lower part of the developing roll 4 and between the developer recovery port and the carrier 1. Besides the auxiliary seal member hermetically sealing a space surrounded by the roll 4, the carrier 1 and the seal member 6 is projectingly arranged at both end parts of the roll 4 along the axial direction in the space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for visualizing an electrostatic latent image formed on a latent image carrier such as a photosensitive drum using a toner in an electrophotographic copying machine or a laser beam printer. More particularly, the present invention relates to an improvement for preventing a developer from leaking out of the developing device and contaminating the inside of a copying machine or the like.

[0002]

2. Description of the Related Art Conventionally, as a developing device for visualizing an electrostatic latent image formed on a latent image carrier such as a photosensitive drum, a two-component developer comprising a toner and a magnetic carrier has been used. Developing devices are known. The developing device includes a housing that accommodates a developer and has an opening facing the photosensitive drum, and a magnet roll that is disposed so as to close the opening of the housing and is magnetized with a plurality of magnetic poles. A magnetic roller in the housing is attracted to the surface of the developing roll by the magnetic force of the magnet roll to form a magnetic brush of developer, and the photosensitive drum is The toner adhered to the magnetic carrier is electrically adhered to the electrostatic latent image on the photoconductor drum by rubbing the surface of the photosensitive drum, thereby visualizing the electrostatic latent image with the toner. ing. The magnet roll is magnetized with an attracting pole, a transport pole, a main developing pole, and a peeling pole. The developer in the housing is driven by a magnetic field formed by the attracting pole and the transport pole having opposite polarities. While being attracted to the surface, it is peeled off from the developing roll by a repelling magnetic field formed by a peeling pole and a attracting pole having the same polarity.

The developer is constrained by the magnetic force of the magnet roll in the circumferential direction of the developing roll, and the developer does not leak out of the housing from the gap between the opening of the housing and the developing roll. In the axial direction of the developing roll, the developer easily leaks out of the housing from both ends of the developing roll, and it is necessary to seal between the opening of the housing and both ends of the developing roll by some means.

Conventionally, as a method of sealing between the both ends of the developing roll and the opening of the housing, a pair of magnetic sealing plates are attached to the inner surface of the housing through a slight gap with the outer peripheral surface of the developing roll. At the same time, the position of the magnetic seal plate is substantially aligned with both ends of the magnet roll included in the developing roll, and the leakage of the developer is prevented by a magnetic field formed between the magnetic seal plate and the magnet roll. (Hereinafter referred to as “magnetic sealing method”) is known. In this method, a magnetic field is formed between the magnetic seal plate and the magnet roll, so that the carrier is aggregated in a gap formed between the magnetic seal plate and the outer peripheral surface of the developing roll, whereby the developer is magnetically sealed. Leakage to both ends in the axial direction of the developing roll beyond the plate is prevented.

In order to enhance the sealing property of the developer by the seal plate, both ends of the side of the seal plate along the outer peripheral surface of the developing roll face the peeling pole and the transport pole magnetized on the magnet roll. Thus, a stronger magnetic field is formed at both ends to prevent the developer from leaking from both ends of the seal plate.

On the other hand, the developer adsorbed on the developing roll is separated from the developing roll by the repulsive magnetic field as described above when passing through the peeling pole. Therefore, in order to prevent the developer from leaking out of the housing, It is necessary to separate the inside and outside of the housing of the developing device at the magnetized position of the peeling pole. For this reason, in the conventional developing device using the magnetic sealing method, a plate-like member that maintains a predetermined gap from the outer peripheral surface of the developing roll is provided so as to face the peeling pole of the magnet roll, and this plate-like member and a pair of A slit-shaped developer recovery port is formed with the seal plate, and the developer magnetic brush rubbed against the photoreceptor drum is continuously recovered from the recovery port into the housing. The developer peeled from the roll is prevented from leaking out of the housing.

[0007]

However, in the conventional developing device configured as described above, the developer is separated from the developing roll in the housing immediately inside the developer collecting port, and the developer is located at such a position. When the rotation speed of the developing roll is high, the developer hardly enters the housing through the collecting port, and the density of the developer becomes extremely high outside the collecting port. For this reason,
There is a problem that the toner that seeks an escape place is scattered around the developer from the developer where the pressure is increased, and the toner contaminates the developing device itself and the inside of a device such as a copying machine or a printer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to prevent leakage of developer at both ends of a developing roll by using a pair of magnetic seal plates and to provide such a seal. In a developing device of a type in which a recovery port for recovering a developer is formed in a housing using a plate or the like, the developer itself or a copying machine using the developer scattered by the developer scattered outside the developer recovery port. To prevent the inside of devices such as printers and printers from being contaminated,
Accordingly, it is an object of the present invention to provide a developing device capable of forming a recorded image of good quality.

[0009]

In order to achieve the above object, a developing device of the present invention comprises a housing containing a two-component developer composed of a toner and a carrier and having an opening facing a latent image carrier. A developing roll that is disposed so as to close the opening of the housing, rotates while adsorbing the developer in the housing by magnetic force, and conveys the developer to a developing area facing the latent image carrier. The developer is fixed to the inner surface of the housing and opposed to the outer peripheral surface of the developing roll via a small gap, and a magnetic field is formed between the developing roller and the developing roller. A pair of side seal members that prevent leakage in the axial direction, and a housing that opposes the developing roll with a predetermined gap therebetween and that adsorbs the developer adsorbed on the developing roll to the housing. Assuming a developing device having a recovery port forming plate that forms a developer recovery port for recovery in combination with the side seal member, the developer recovery port is located below the developing roll and between the developer recovery port and the latent image carrier. Between the developing roll, the latent image carrier and the under seal, an under seal member for collecting the toner dropped from the developing area into the housing and sealing the space between the housing and the latent image carrier is provided. At both ends of the space surrounded by the members along the developing roll axial direction, auxiliary sealing members for sealing the space are protruded.

According to such technical means, an under seal member for sealing between the housing and the latent image carrier is provided below the developing roll and between the developer collecting port and the latent image carrier. The developer collecting port is open to a space surrounded by the developing roll, the latent image carrier, and the under seal member. Auxiliary seal members are provided at both ends of the space surrounded by these three members in the axial direction of the developing roll, so that the space where the developer collecting port is opened is the developing roll and the latent image carrier. , Surrounded by an under seal member and an auxiliary seal member,
It is substantially sealed from the space outside the developing device. For this reason, the pressure of the developer increases in front of the developer collection port with respect to the rotation direction of the developing roll, and even if toner is blown out of the developer, the toner is confined in the space where the developer collection port is open. And does not fly outside the developing device.

Here, the under seal member is provided between the housing and the latent image carrier so as to receive a toner lump or the like falling from the magnetic brush on the developing roll and not leak it out of the developing device. Any material may be used as long as it can be sealed, but in consideration of collecting the received toner in the housing and agitating it again with the carrier, a roll-shaped member that rotates in the opposite direction to the developing roll is preferable.

In addition, the recovery port forming plate may be one which forms a developer recovery port which communicates with the inside of the housing in combination with the side seal member to partition the inside and outside of the housing. It may be used as a collection port forming plate facing the roll, or another plate-shaped member may be provided upright on the housing. However, when the under seal member is formed in a roll shape as described above, it is preferable that the recovery port forming member also functions as a scraper for scraping the collected toner from the roll under seal member.

Further, the auxiliary seal member is provided at both longitudinal ends of a space surrounded by the developing roll, the latent image carrier and the under seal member, that is, at both ends along the axial direction of the developing roll. The auxiliary seal member may be provided in the housing or the like independently of the under seal member or the like as long as the space is sealed from the outside. However, from the viewpoint of simplification of the configuration of the developing device, the under seal member is formed in a roll shape as described above, and the shape of a pair of bearing members for supporting the rotation of the under seal member is improved to assist Preferably, the seal member is formed integrally with the bearing member.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show one embodiment of a developing device to which the present invention is applied. This developing device develops an electrostatic latent image written on the surface of a photosensitive drum (electrostatic latent image carrier) 1 using a two-component developer including a toner and a magnetic carrier.
A housing 3 having a developer stirring chamber 30 for accommodating and stirring the developer 2 and having an opening 31 opening toward the photoreceptor drum 1 is arranged so as to close the opening 31 of the housing 3. The developer 2 is rotated while adsorbing the developer 2 in the developer stirring chamber 30 by a magnetic force, and is moved to a development area A facing the photosensitive drum 1.
Is fixed to the housing 3 and opposed to the developing roll 4 with a predetermined gap therebetween, and regulates the amount of developer transported from the inside of the housing 3 to the developing area A. And a plate 5.

First, the developing roller 4 is provided with a rotatable cylindrical sleeve 41 disposed on the outer periphery of a substantially cylindrical magnet member 40 fixed and supported. The sleeve is formed by the magnetic force of the magnet member 40. The magnetic carrier is adsorbed on the surface 41 to form a magnetic brush of the developer 2 forming ears along the lines of magnetic force. The magnet member 40 is provided with a plurality of magnetic poles such as a peeling pole N1, an attracting pole N2, a transport pole S2, N3, and a developing main pole S1 in a clockwise order. Have been. Then, in the developing roll 4 of this embodiment having such a magnetic pole arrangement, the magnetic poles having different polarities alternately and successively adhere to the attracting pole N2 → the transport pole S2.
The developer is held on the surface of the sleeve 41 between the transport pole N3, the main development pole S1, and the separation pole N1, while the developer is separated between the separation pole N1, in which magnetic poles of the same polarity are arranged adjacently, and the adsorption pole N2. Peel off from the sleeve 41.

On the other hand, a partition plate 32 extending along the axial direction of the developing roll 4 is provided upright from the bottom plate of the housing 3 in the developer stirring chamber 30, and two stirring plates for stirring the developer 2 are provided. Channels 33 and 34 are formed on both sides of the partition plate 32. A front auger 35 for transporting the developer 2 toward the near side of FIG. 1 is provided in a front stirring path 33 located close to the developing roll 4, while being separated from the developing roll 4 by a partition plate 32. Rear stirrer 3
4 is provided with a rear auger 36 for transporting the developer 2 toward the back side of the paper of FIG. As shown in the plan view of FIG. 2, the upstream end of the front stirring path 33 and the downstream end of the rear stirring path 34 are provided such that one end thereof protrudes from one side of the housing 3. In addition, a supply port 38 for dropping the supply toner into the rear stirring path 34 is provided in the protrusion 37. The partition plate 32 is cut off at both ends of the front stirring path 33 and the rear stirring path 34 so that the front stirring path 33 and the rear stirring path 34 are connected to each other at such positions.

Therefore, when the front auger 35 and the rear auger 36 are driven to rotate, as shown by arrows in FIG. 2, the developer is supplied from the front stirring path 33 to the rear stirring path 34.
Circulating around the partition plate 32 in the form of a front stirring path 33, the developer 2 is stirred during such circulation,
Electric charge due to triboelectric charging is applied to the toner.
Further, a toner replenishing port 3
The replenishment toner dropped to the upstream side of the rear stirring path 34 through the rear stirring path 3 along with the developer flowing from the downstream side of the front stirring path 33 to the upstream side of the rear stirring path 34.
4 and is uniformly mixed with the developer before it is circulated through the first stirring path 33.

In order to positively supply the developer 2 to which the replenishment toner has been added and the toner density has been restored to a predetermined toner density, the developing roll 4 and the front auger 35 are arranged in the axial direction. A paddle wheel 39 having a plurality of parallel blades is provided, and the developer 2 overflowing from the front stirring path 33 due to the rotation of the front auger 35 is supplied to the developing roll 4 as the paddle wheel 39 rotates. Is configured. In addition, the paddle wheel 39 also plays a role of returning the developer 2 separated from the developing roll 4 to the front stirring path 33, whereby the developer 2 once separated from the developing roll 4 is stirred with the replenishment toner. This prevents the developer from being attracted to the developing roll 4 again.

The developer 2 thus supplied to the developing roll 4 forms a magnetic brush on the surface of the sleeve 41 by the magnetic force of the magnet roll 40. The magnetic brush forms a trimming plate with the rotation of the developing roll 4. When the position reaches 5, the spikes are trimmed to a predetermined length by the trimming plate 5 and fed to the developing area A facing the photosensitive drum 1 by further rotation of the developing roll 4. On the other hand, the tip of the magnetic brush cut by the trimming plate 5 is the paddle wheel 3
9 and is attracted to the developing roll 4 again with the rotation of the developing roll 4 and the paddle wheel 39 to form a magnetic brush.

In FIGS. 1 to 3, reference numeral 51 denotes a screw for fixing the trimming plate 5 to the housing 3, and reference numeral 52 denotes a motor (not shown) of the copying machine main body.
A gear for transmitting the rotation of the drive gear 52 to the paddle wheel 39, the front auger 35, and the rear auger 36. Reference numeral 57 denotes a gear for transmitting the rotation of the drive gear 52 to the sleeve 41. An upper cover 58 for covering the developer stirring chamber 30 of the housing 3 from above, and reference numeral 58 denotes a polyurethane sealing film for sealing a gap between the upper cover 57 and the photosensitive drum 1.

Next, FIG. 4 shows the structure of the developing roll 4 and a pair of magnetic seal plates (side seal members) 7 and 7 arranged near both ends in the axial direction. The developing roll 4 is a magnet roll 40 fixedly arranged as described above.
And a sleeve 41 rotating therearound. A pair of flange members 42f, 42r are fitted into the openings at both ends of the sleeve 41, and the rotation members projecting from the flange members 42f, 42r. Shafts 43f, 43
r is supported by the housing 3 via a bearing (not shown). Also, one rotation shaft 43r
Is formed in a hollow shape, and a keyway 44 for transmitting the rotational power of the drive gear 52 is cut out at an end thereof. Fixed shaft 4 protruding from magnet roll 40
5f, 45r are supported by the flange members 42f, 42r via bearings 46, and one of the fixed shafts 4f, 45r.
5r penetrates through the hollow rotating shaft 43r and protrudes to the outside, and is fixed to the housing 3. Therefore, when rotational power is transmitted from the drive gear 52 to the rotation shaft 43r, only the sleeve 41 rotates around the magnet roll 40 with the magnet roll 40 fixed.

On the other hand, the magnetic seal plate 7 has its surface direction orthogonal to the axial direction of the
Each is fixed to the inner surface of the as shown in FIG.
The end is opposed to the outer peripheral surface of the developing roll 4 between the scraper 60 and the trimming plate 5. The gap formed between the end of the seal plate 7 and the outer peripheral surface of the developing roll 4 is about 0.5 mm. The seal plate 7 is formed of a magnetic plate such as SUS, and forms a magnetic field between the seal roll 7 and the magnet roll 40 in the developing roll 4. To prevent leakage.

As described above, the developing roll 4 is composed of the magnet roll 40 and the sleeve 41 rotating around the magnet roll 40. The magnet roll 40 is shorter than the entire length of the sleeve 41 in the axial direction. The seal plate 7 is formed at a length corresponding to the distance between the inner surfaces, that is, the length corresponding to the development width of the electrostatic latent image, and the seal plate 7 is fixed at a position substantially matching the end face of the magnet roll 40.
For this reason, the magnetic field formed between the seal plate 7 and the magnet roll 40 does not spread in the axial end direction of the developing roll 4 from the position where the seal plate 7 is provided, and the developer 2 is sealed by the magnetic field. Aggregate in the gap with the developing roll 4 inside the plate 7. Therefore, basically, the developer does not leak beyond the seal plate 7 toward the axial end of the developing roll 4.
Further, a polyethylene cap member 8 is covered on the outer peripheral surface of the sleeve 41 located outside the development width, and the cap member 8 is easily charged to the same negative polarity as the toner because of its material. Even when the developer 2 leaks in the axial direction of the developing roll 4 beyond the seal plate 7, the toner in the developer does not adhere to and accumulate on both ends of the developing roll 4.

As shown in FIG. 1, both ends of the magnetic seal plate 7 along the circumferential direction of the developing roll 4 are opposed to the separation pole N1 and the transport pole S2 magnetized on the magnet roll 40, respectively. . This is because when the magnetic field between the seal plate 7 and the developing roll 4 overlaps with these magnetic poles, it becomes strongest, and the developer 2 leaks from both ends of the seal plate 7 along the circumferential direction of the developing roll 4. This is because it can be effectively prevented from being issued. Therefore, the trimming plate 5 for regulating the length of the spike of the magnetic brush attracted to the developing roll 2
Is provided at a position coinciding with one end of the magnetic seal plate 7, that is, at a position facing the transport pole S <b> 2 of the developing roll 4 to partition the inside and outside of the housing 3. Only the developer 2 attracted to the developing roll 4 is carried out.

On the other hand, a recovery port forming plate 60 for partitioning the inside and outside of the housing 3 is provided upright from the housing 3 below the developing roll 4.
The leading end of 0 faces the position matching the other end of the magnetic seal plate 7, that is, the peeling pole N1 of the developing roll 4. The collecting port forming plate 60 is disposed so that the leading end thereof keeps a gap of 2 to 3 mm from the outer peripheral surface of the developing roll 4, and as shown in FIG. Together with the magnetic seal plates 7, a recovery port 61 for the developer 2 is formed. Therefore, after the magnetic brush of the developer 2 rubs the photosensitive drum 1 in the developing area A, the magnetic brush from the developer collecting port 6 formed between the outer peripheral surface of the developing roll 4 and the tip of the collecting port forming plate 60. Collected in the housing 3. When the developer passes through the developer collecting port 61, the developer is immediately separated from the developing roll 4 by the repulsive magnetic field formed between the separating pole N1 and the attracting pole N2, and is conveyed to the developer stirring chamber 30 by the paddle wheel 39 as described above. Is done.

However, when the developer collecting port 61 is formed in conformity with the peeling pole N1 of the developing roll 4,
The developer 2 that has passed through the peeling pole N1 is immediately peeled off from the developing roll 4, and the developer easily stays in the housing immediately inside the developer recovery port 61. Therefore, the magnetic brush moves from the developer recovery port into the housing. When the rotation speed of the developing roll is high, the density of the magnetic brush tends to increase outside the developer collecting port 61. Therefore, immediately outside the developer recovery port 61, the toner is easily released from the magnetic carrier forming the magnetic brush, and the released toner contaminates the developing device itself and peripheral devices in the copying machine,
There is a disadvantage that the copy image quality is affected.

Therefore, in this developing device, first, as shown in FIG. 1, a seal roll (under seal member) 6 is provided below the developing roll 4 along the peripheral surface of the photosensitive drum 1, and the seal roll is provided. 6 is brought into contact with the above-described collection port forming plate 60 to seal the space between the housing 3 and the photosensitive drum 1. The seal roll 6 is provided very close to the photosensitive drum 1 (with a gap of about 1 mm), and is applied with the same bias voltage as that of the developing roll so as not to generate a potential difference with the developing roll. Further, since the seal roll 6 is located immediately below the development area A, the lump toner or the like generated in the development area A falls on the surface of the seal roll 6 and adheres thereto. The recovery port forming plate 60 in contact with the surface of the seal roll 6 functions as a scraper. By rotating the seal roll 6 in a direction opposite to that of the developing roll 4, the toner adhered to the surface of the seal roll 6 is removed. The developer collecting port 61 is scraped off by the collecting port forming plate 60 and the developer collecting port 61.
From the housing 3 together with the magnetic brush. The seal roll 6 is provided with a gap of 2 to 3 mm from the development roll 4 so as not to contact the magnetic brush of the developer 2 formed on the development roll 4.

Also, by disposing the seal roll 6 in this manner, the developer collecting port 61 has a space 9 (see FIG. 1) having a substantially triangular cross section surrounded by the development roll 4, the photosensitive drum 1, and the seal roll 6. (See).
A pair of auxiliary seal members 10 and 10 are provided at both ends of this space 9 so that floating toner does not blow out of the developing device from both ends of the space 9 along the axial direction of the developing roll 4.
Is provided. The auxiliary seal member 10 is shown in FIG.
As shown in FIG. 7, the bearing member 62 is formed integrally with the bearing member 62 that supports the rotation of the seal roll 6, and projects from the outer peripheral surface of the bearing member 62 in a shape substantially matching the cross-sectional shape of the space 9. In FIG. 5, reference numeral 63 denotes a bearing hole through which the rotating shaft of the seal roll 6 passes, and reference numeral 64 denotes an engagement projection for positioning the bearing member 62 with respect to the housing 3 in a non-rotating manner.

As a result, the space 9 in which the developer collecting port 61 is opened is also closed at both ends along the axial direction of the developing roll 4 by the auxiliary seal member 10. Even if a large amount of floating toner is generated on the outside, the toner does not blow out from the space 9 to the outside of the developing device, but is collected in the housing 3 by being dropped or deposited on the seal roll 6 or the like. Will be.
Therefore, it is possible to effectively prevent the developing device itself and the inside of a copying machine or the like using the developing device from being contaminated by the toner, and to prevent deterioration of the image quality of a copy image or the like. .

[0030]

As described above, according to the developing device of the present invention, the space in which the developer collecting port communicating with the inside of the housing is open is the developing roll, the latent image carrier, the under seal member, and the auxiliary seal. Since it is surrounded by members and is substantially sealed from the space outside the developing device, even if a large amount of floating toner blows out of the developer under increased pressure in front of the developer collecting port, the floating toner Can be confined in the space where the developer collection opening is open to prevent it from scattering outside the developing device, and the developing device itself and the inside of equipment such as copying machines and printers that use this Thus, it is possible to form a recorded image of good image quality.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of a developing device of the present invention.

FIG. 2 is a plan view showing a developing device according to the embodiment.

FIG. 3 is a side view illustrating the developing device according to the embodiment.

FIG. 4 is a cross-sectional view illustrating a configuration of a developing roll and an arrangement of a seal plate according to the embodiment.

FIG. 5 is a perspective view showing a bearing member of the seal roll according to the embodiment.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photoreceptor drum (latent image carrier), 2 developer, 3 housing, 4 developing roll, 6 seal roll (under seal member), 7 seal plate (side seal member),
10: auxiliary seal member, 60: recovery port forming plate, 61: developer recovery port,

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor, Kenno 2274 Hongo, Ebina-shi, Kanagawa Prefecture, F-term in Fuji Xerox Co., Ltd. (reference) 2H077 AB03 AD06 BA08 CA12 EA03 FA19

Claims (2)

[Claims] 1. A housing for accommodating a two-component developer composed of a toner and a carrier and having an opening toward a latent image carrier, and disposed so as to close the opening of the housing, and is provided with a magnetic force. A developing roll that rotates while adsorbing the developer in the housing and conveys the developer to a developing area facing the latent image carrier; and a developing roll fixed to the inner surface of the housing and slightly outside the outer peripheral surface of the developing roll. A pair of side seal members that prevent the developer from leaking from the housing in the axial direction of the developing roll by forming a magnetic field between the housing and the developing roll. The developer recovery port for recovering the developer adsorbed on the development roll into the housing while facing the development roll with the side seal member. A developing port provided with a recovery port forming plate for forming, between the developer recovery port and the latent image carrier, between the developer roll and the latent image carrier, recovering the toner dropped from the developing area into the housing; While providing an under seal member for sealing between the housing and the latent image carrier, both ends along a developing roll axial direction of a space surrounded by the developing roll, the latent image carrier and the under seal member are provided. ,
A developing device, wherein an auxiliary seal member for sealing the space is protruded. 2. The developing device according to claim 1, wherein the under seal member is formed in a roll shape that rotates in a direction opposite to a developing roll, and the auxiliary seal member is a bearing that supports rotation of the under seal member. A developing device, which is formed integrally with a member.