JPH0432878A - Developing device and process unit with the same - Google Patents

Abstract

PURPOSE:To prevent the leakage of a developer from the end of an elastic regulating member for regulating the thickness of a developer layer even if its dimension precision is not enhanced by providing a projecting part on a sealing member and holding a regulating plate end part there between the projecting part and a developer carrier. CONSTITUTION:The sealing member 9 abutting on the end part of a developer carrying member 8, and preventing the leakage of the developer from the end part of the developer carrying member 8 has the projecting part 9a projecting toward the central side of the developer carrying member 8 on a part corresponding to a position where the developer layer thickness regulating plate 11 abuts on the developer carrying member 8. The projecting part 9a is superimposed on the end part of the regulating plate 11, and holds the end part of the regulating plate 11 between the projecting part 11 and the developer carrier 8, and the leakage of the developer from the end of the regulating plate 11 is prevented. Thus, even if the dimension precision of a part such as the developer quantity regulating member 11 abutting on the developer carrying member 8 is not enhanced, the leakage of the developer on the end part of the regulating member 11 can be prevented by the leakage preventing sealing member 9, and excellent mass-productivity and manufacturability, and low cost can be attained.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to an electrophotographic copying machine, an electrophotographic laser beam printer, an electrostatic latent image developing device used in an electrostatic recording device, and an image carrier and a The present invention relates to a process unit having a device.

[Conventional technology and problems]

In a developing device, a generally roller-shaped developer carrying member rotates to convey developer to a developing area through which an image carrier passes. In the development area, developer is supplied from the developer carrying member to the image carrier, and the electrostatic latent image is developed.

A part of the circumferential surface of the developer carrying member faces into the developer applying chamber, and the developer is applied onto the circumferential surface of the developer carrying member within this applying chamber. The layer thickness of the developer applied to the developer carrying member is regulated by the regulating member, and then conveyed to the development area.

An elastic plate that is in contact with the developer carrying member is known as the above-mentioned regulating member. This method of regulating the layer thickness of the developer by bringing the elastic plate into contact with the developer carrying member and allowing the developer to pass through the nip between the two can form a thin and uniform layer of the developer. This is useful in that the developer can have sufficient triboelectric charge.

On the other hand, in order to prevent the developer from leaking from the end of the developer carrying member, a sealing member is provided on the side wall of the developer application chamber. Techniques for bringing them into contact are known.

By the way, if the regulating member is opposed to the developer carrying member with a gap therebetween, and therefore the regulating member may be a rigid body,
The sealing member can be attached by abutting against both end faces of the regulating member with strong pressure, and a gap between the regulating member and the leak-preventing sealing member can be eliminated.

However, if the regulating member is an elastic body in order to come into contact with the developer carrying member, if the sealing member is pressed against the end face of the regulating member with strong pressure, the regulating member will be elastically deformed, resulting in the formation of a toner layer. The thickness tends to become uneven. In order to prevent this, even if the leak-prevention sealing member is attached by applying weak pressure to both ends of the regulating member, the abutting pressure is not constant, and as a result, it is not reliable in preventing developer leakage at both ends of the regulating member. There was a problem of lack of sexuality. In addition, the dimensional accuracy of the parts of the developing device such as the regulating member must be made higher than necessary, resulting in poor mass production and manufacturability of the developing device, and a high price.

On the other hand, an image forming apparatus is known in which a process unit in which an image carrier, a developing device, or a charging device and a cleaning device are integrally supported by a support means is detachably attached to the main body of the image forming apparatus. This has the advantage of reducing the need for maintenance by specialists and providing high-quality images over a long period of time by replacing the process unit. However, since the process unit is attached to and detached from the image forming apparatus by manual operation by an operator, it is desired that the process unit be small. Therefore, it becomes necessary to downsize the developing device incorporated therein, and in such a small developing device, the developer carrying member must also have a small diameter. In order to control the thickness of the developer layer on such a small-diameter developer carrying member and to make the developer have sufficient triboelectric charge,
It is effective to use an elastic plate in contact with the developer carrying member as the layer thickness regulating member. However, when the developer leaks one after another from the end of the developer carrying member as described above, the leaked developer contaminates not only the inside of the process unit but also the inside of the main body of the image forming apparatus. It will be damaged.

[Purpose and outline of the invention]

Therefore, it is an object of the present invention to provide a solution that can be used without increasing the dimensional accuracy of parts such as a developer amount regulating member that comes into contact with a developer carrying member.
It is an object of the present invention to provide a developing device which can prevent developer leakage at the end of a regulating member by a leak-preventing seal member, has good mass productivity and manufacturability, and can be made inexpensive.

Another object of the present invention is to provide a process unit that integrally includes a developing device and an image carrier, using a developer amount regulating member that comes into contact with a developer carrying member, in which leakage of developer from an end of the developer carrying member is prevented. It is an object of the present invention to provide a process unit that can suppress staining of the inside of the process unit and the inside of an image forming apparatus to which the process unit is installed.

Therefore, the present invention provides a sealing member that is in contact with the end of the developer carrying member and prevents the developer from leaking from the end of the developer carrying member, and the sealing member that is in contact with the end of the developer carrying member and prevents the developer from leaking from the end of the developer carrying member. The part corresponding to the abutting position has a protruding part that protrudes toward the center of the developer carrying member, and this protruding part is overlapped with the end of the regulating plate, so that the regulating plate and the developer carrying member are overlapped with each other. The ends are sandwiched, and in this way, leakage of developer from the ends of the regulating plate is prevented.

〔Example〕

FIG. 4 is an explanatory diagram of an example of a laser beam printer to which the present invention can be used. 20 is a process unit which will be described later. The process unit 20 can be attached to and removed from the printer body by an operator's manual operation along a guide rail 22 disposed inside the printer body. The operator can take out the unit 20 that has reached its usable limit from the printer body and load a new unit 20 into the printer body.

The drum-shaped electrophotographic photoreceptor 1 in the unit 20 is scanned by the laser beam L, thereby forming an electrostatic latent image on the photoreceptor 1. The semiconductor laser 22 emits a laser beam L modulated by a recorded image signal from a document reading device, a computer, or the like. The laser beam L is scanned by a scanning means such as a rotating polygon mirror, and is scanned by a lens 2.
The light enters the photoreceptor 1 via the photoreceptor 4.

The electrostatic latent image formed on the photoreceptor 1 is developed by a developing device, which will be described later. A visible image obtained by development is transferred from the photoreceptor 1 to a transfer material 26 such as paper by a transfer roller 25.

The transfer material 26 is conveyed from the cassette 27 by a conveyance roller 28 toward the transfer roller 25 through a guide 29 . After the transfer, the transfer material 26 passes through the guide 30 to the fixing device 3.
1. The transfer material on which the image has been fixed by the fixing device 31 is discharged to the outside of the main body.

Note that 32 is a power source that is connected to the developing sleeve of the developing device when the unit 20 is loaded into the main body of the printer 21, and applies an oscillating bias voltage to the developing sleeve during the developing operation.

FIG. 5 shows a sectional view of the process unit 20. The various members within the unit are integrally supported by a frame 10.

A laser beam L enters the unit 10 almost horizontally from a slit-shaped exposure window 6 provided at the rear of the unit 20, passes through an optical path 17, and passes onto the photoreceptor 1 as an image carrier charged by a charger 22. An electrostatic latent image is formed by exposure at an exposure position 19. The photoreceptor 1 is rotationally driven in the direction of the arrow. A blade 4 is provided for cleaning developer remaining on the photoreceptor 1 after transfer. Further, a charger 2 consisting of a contact charging roller, a friction charging roller, or the like is provided between the blade 4 and the exposure position 19.

The charger 2 can also be a corona charger.

Further, a storage section 3 for a one-component developer T is provided below the optical path 17 for guiding the image information light, and a developer application chamber 7 is provided adjacent to the storage section 3 .

A cylindrical developing sleeve 8 is disposed in the cylindrical developing sleeve 20 such that a portion of its circumferential surface faces into the developer application chamber 7 and a portion of its circumferential surface faces the photoreceptor 1 . Developer is supplied to the developer application chamber 7 through an opening 3b formed in the partition wall 3a of the storage section 3 by a conveying member 3c rotating in the direction of the arrow. The developing sleeve 8 rotates in the direction of the arrow. Further, in the developer applying chamber 7, a developer amount regulating member (regulating blade) 11 and a developer leakage prevention member 9 are provided.

Note that when a magnetic developer is used as the one-component developer T, or when a two-component developer containing a magnetic carrier and toner is used as the developer, a non-magnetic sleeve is used as the sleeve 8, A magnet is arranged within this sleeve 8. Furthermore, if a non-magnetic developer is used after development by ], d, the above-mentioned magnet is not necessary, and the developer carrying member 8 may be a solid wax.

Now, the developer T that has entered between the developer application chambers 7 adheres to the sleeve 8 by electrostatic attraction and/or magnetic attraction. The layer thickness of the developer applied to the sleeve 8 in this way is such that at the position N, the side surface of the sleeve 8 is
The thickness is regulated to be thinner than the minimum gap between the drum 1 and the sleeve 8 in the developing area by a regulating sleeve 11 made of an elastic material that is in elastic pressure contact with the drum 1 . That is, in this embodiment, so-called non-contact development is performed.

In order to increase development efficiency in non-contact development, an oscillating bias voltage (
For example, a voltage obtained by superimposing an alternating current voltage and a direct current voltage is applied, and an oscillating electric field whose direction changes periodically is formed around the developing area. Of course, a DC bias voltage may be applied to the sleeve 8.

The minimum gap between the drum 1 and sleeve 8 in the developing area is 0.
．． 05 to 0.7 mm is appropriate.

Now, as the blade 11 for forming a thin layer of developer on the sleeve, a rubber plate with a thickness of 0.5 to 1.5 mm (
(urethane rubber, silicone rubber, etc.), and the thickness is 0.02
~0.2 mm metal plate spring (phosphor bronze, stainless steel, etc.) A flexible plate with sufficient bending elasticity such as a synthetic resin plate (polyethylene terephthalate etc.) with a thickness of 0.05 to 0.5 mm is used. . Among these, a rubber plate is preferable because it can be more uniformly pressed against the sleeve surface.

The blade 11 is fixed to a support plate 11a by adhesive or the like, and the support plate 11a is provided between the semicircular arc-shaped inner wall portions 10a at both ends of the developer application chamber 7, as shown in FIG. 6.9. The blade 11 is attached to both ends of the portion 10b with screws 12, and the blade 11 is curved in the developing chamber 7 and elastically abuts against the sleeve 8, as shown in FIG. When the developer passes through the contact area between the blade 11 and the sleeve 8, that is, the nip area, the layer thickness is regulated, and at this time, due to friction with the sleeve or plate, it has sufficient charge to develop the latent image. In the illustrated example, the plate 11 abuts the sleeve 11 in a direction counter to the direction of rotation of the sleeve 11. That is, with respect to the direction of rotation of the sleeve 11, the self [JE end 11b of the plate 11 is the support plate 11 a i:
It is also located upstream of the fixed fixed 'sV I +, c.

In such cases, thinner layer thicknesses of developer can be formed.

However, the blade 11 may be brought into contact with the sleeve 11 in a direction opposite to that illustrated, that is, in a forward direction with respect to the direction of rotation of the sleeve 11. In this case, the free end 1 of the blade 11
．． 1b is located downstream of the fixed end 11c with respect to the rotational direction of the sleeve 11.

In the case of the illustrated example, the blade 1 is placed at a position slightly offset toward the downstream side in the rotational direction of the sleeve than the free end 11b of the blade 11.
1 is in contact with the sleeve 8. Therefore, a slight gap, ie, a slit, is formed between the free end 11b of the blade 11 and the surface of the sleeve 8. The developer passes through the second slit and enters the abutment area between the plate 1-'11 and the sleeve 8, that is, the nip area, so when the blade J1 is installed in the counter direction with respect to the rotational direction of the sleeve, the above slit exists. It is important to do so.

On the other hand, when the blade 11 is provided in the forward direction of the sleeve rotation direction, as long as the side surface of the blade L-1''11 is in contact with the sleeve 8, the free end 11b may be in contact with the sleeve 8 or not. good.

Now, in order to prevent leakage of developer from both ends of the sleeve 8 in the axial direction, developer leakage prevention seal members 9 are slid on both ends of the sleeve 8 on the outside of both ends of the blade 11 in the longitudinal direction. being brought into contact with As shown in FIG. 5, the sealing member 9 is connected to an inlet where the developer on the sleeve that has passed through the developer area as the sleeve 8 rotates returns to the application chamber 7. It is in pressure contact with the outer circumferential surface of the sleeve 8 so as to be wrapped around it in the range reaching the outlet that exits toward the developing area.

On the other hand, as shown in FIG.
0a, and the upper end of the developer applying chamber 7 is pressed by the support plates 11a of the regulation blades 11 fixed to both ends of the part 10b, thereby forming a semi-circular inner wall part 10a.
is fixed. That is, the sealing member 9 is sandwiched between the side wall of the developer application chamber and the sleeve, and is held in a somewhat elastically compressed and deformed state.

The sealing member 9 may be made of felt such as wool or tetrafluoroethylene resin fiber, or a porous member (foam or open-pore material) such as urethane foam rubber Voatex (trade name, porous tetrafluoroethylene resin). It is made of and has flexibility.

In the present invention, in order to ensure that the leakage prevention seal member 9 prevents the developer from leaking from both ends of the regulation blade 11 at the opening facing the photoreceptor 1 of the developing device,
As shown in FIG. 7, the leak prevention seal member 9 is provided with a protrusion 9a that protrudes toward the regulating blade 11 side. Projection 9a
is provided on the leak-preventing seal member 9 so as to protrude toward the regulating blade 11 at a location on the circumferential surface of the developing sleeve 8 where it comes into contact with the regulating blade 11, that is, to protrude toward the axial center of the sleeve 8.

Therefore, as shown in FIG. 5.8.9, the protruding portion 9a of the leak-preventing seal member 9 attached to the semicircular arc-shaped inner wall portion 10a of the developer applying chamber 7 is such that the circumferential surface of the developing sleeve 8 is connected to the regulating plate 11. At the location where it comes into contact with the regulating blade 11, it is pressed against the regulating blade 11 by the inner wall portion following the semi-circular inner wall portion 10a of the developer application chamber 7, and is compressed and deformed elastically. As a result, both longitudinal ends of the regulating blade 11 are sandwiched between the protrusion 9a of the leak-preventing seal member 9 and the circumferential surface of the developing sleeve 8, and overlap the protrusion 9a. That is,
As shown in FIG. 1, the gap S between the leak prevention seal member 9 and the regulating blade 11 is
a closes the contact portion between both ends of the regulating blade 11 and the circumferential surface of the developing sleeve 8. Therefore, it is possible to reliably prevent the developer from leaking to the outside through the gap S.

Incidentally, as shown in FIG. 2, a cut, that is, a slit 13 can be provided along the longitudinal direction of the leak-preventing sealing member 9 at the proximal end of the protrusion 9a on the free end side of the blade 11. According to this, the pressure contact force at both ends of the regulating blade 11 due to the provision of the protrusion 9a can be reduced, unevenness in developer layer thickness can be further prevented, and the driving force of the developing sleeve 8 can be reduced. can do.

Further, as shown in FIG. 3, a tapered surface 9b may be provided at the tip of the protrusion 9a of the developer leak prevention member 9 so that the downstream portion is closer to the center of the sleeve in the axial direction than the upstream portion with respect to the sleeve rotation direction. . According to this, the flow of developer can be guided toward the center in the axial direction of the sleeve along the tapered surface 9b at the tip of the protrusion 9a, and the leakage prevention seal member 9 can prevent developer leakage at both ends of the developing sleeve 8. This can be made even more reliable. (In FIG. 1.2.3, arrow A indicates the moving direction of the developer, in this example, the rotating direction of the sleeve.) Note that the protrusion 9a of the sealing member is in contact with the free end 1.1a of the blade 11. It is preferable that the two ends of the plate 11 are brought into contact with both ends of the plate 11 at a position slightly offset toward the fixed end rather than the free end 11a. This is because when the free end 11a of the blade 11 is pressed against the sleeve 8 using the seat member, the amount of developer that passes through the free end 11a differs in the longitudinal direction of the blade, resulting in uneven developer layer thickness. Because it becomes easy.

Note that while the layer thickness of the developer is being regulated, a thin layer of developer exists at the nip between the blade 11 and the sleeve 8, so the blade 11 is not in contact with the sleeve 8 in a strict sense.

However, when there is no developer between the blade 11 and the sleeve 8, the blade 11 is in elastic contact with the sleeve 8, and the blade 11 is elastically biased in the direction of contact with the sleeve 8. Therefore, in this specification, it is said that the blade 11 contacts the sleeve and the developer passes through this contact portion.

In the above embodiments, the developing device was incorporated into a process unit having a photoreceptor, but the present invention provides a developing device that is fixed to the main body of an image forming apparatus, or a developing device that is attached to and detached from the main body of the image forming apparatus separately from the photoreceptor. It can also be applied to developing devices that can.

Further, the photoreceptor may be exposed to image information light using a light emitting diode array instead of a laser beam, or the photoreceptor may be exposed to reflected or transmitted light from the original to be transferred.

Furthermore, a member having an insulating surface may be used as the image carrier, and a latent image may be formed by applying an ion flow modulated by a recorded signal to this surface.

〔effect〕

Even without increasing the dimensional accuracy of the elastic regulating member for regulating the thickness of the developer layer, leakage of developer from the edge can be prevented with a simple configuration, and staining and deterioration of images can be prevented.

[Brief explanation of drawings]

Figures 1, 2, and 3 show embodiments of the present invention, and are views of the elastic regulating plate and sealing member unfolded on a plane, viewed from the sleeve surface side, and Figure 4 is an image to which the present invention can be applied. An explanatory diagram of an example of a forming device, FIG. 5 is an explanatory diagram of an embodiment of the present invention,
FIG. 6 is an exploded view of the developing device, FIG. 7 is a perspective view of the seal member, and FIGS. 8 and 9 are explanatory views of the attachment of the seal member and the elastic regulating plate. 8 is a sleeve, 9 is a sealing member, 9a is a protrusion, and 11 is an elastic regulating plate.

Claims (7)

[Claims] (1) The layer thickness of the developer carrying member that carries the developer applied in the developer applying chamber and conveys it to the developing area, and the developer that is in contact with the developer carrying member and is conveyed to the developing area. an elastic regulating plate for regulating the developer; and a sealing member that is in contact with the end of the developer carrying member to prevent the developer from leaking from the end of the developer carrying member; A protrusion that protrudes toward the center of the developer carrying member is provided at a portion corresponding to the position where the developer carrying member and the developer carrying member come into contact with each other. A developing device characterized in that an end portion of a regulating plate is sandwiched between a carrier member. (2) The developing device according to claim 1, wherein the protrusion of the seal member overlaps the regulation plate at a position away from the free end of the regulation plate. (3) The developing device according to claim 1 or 2, wherein the regulating plate is in contact with the developer carrying member in a counter direction with respect to the moving direction of the developer carrying member. (4) An image carrier on which an electrostatic latent image is formed, a developer for developing the electrostatic latent image formed on the image carrier, and a support means for integrally supporting the image carrier and the developer. The developing device is a process unit that is removably attached to the main body of the image forming apparatus, and the developing device includes a developer carrying member that carries the developer applied in the developer application chamber and conveys it to the development area, and a developer an elastic regulating plate that is in contact with the supporting member and regulates the layer thickness of the developer conveyed to the developing area; and an elastic regulating plate that is in contact with the end of the developer carrying member and that controls the development from the end of the developer carrying member. a sealing member for preventing leakage of the developer, and the sealing member has a protrusion protruding toward the center of the developer carrying member at a portion corresponding to the position where the regulating plate and the developer carrying member come into contact. 1. A process unit comprising: a protruding portion overlapping an end of the regulating plate, and sandwiching the end of the regulating plate with a developer carrier. (5) The charging member supported by the support means and the image information light to be exposed to the image carrier to form an electrostatic latent image at a position on the downstream side of the charging member with respect to the moving direction of the image carrier. The process according to claim (4), further comprising an opening through which the image carrier passes, and a cleaning means supported by the support means and for removing developer remaining on the image carrier before being charged by the charging member. unit. (6) The process unit according to claim 4 or 5, wherein the protrusion of the seal member overlaps the regulation plate at a position away from the free end of the regulation plate. (7) The process unit according to (4), (5), or (6), wherein the regulating plate is in contact with the developer carrying member in a counter direction with respect to the moving direction of the developer carrying member.