JPH10307474A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the function of preventing the scattering of toner by eliminating gaps in the inner corner parts of a sheet member with which the developing region between a photoreceptor drum and a developing roller is blocked so as to prevent the scattering of the toner. SOLUTION: The sheet member 24 stuck/fixed to a fixed member 50 in the vicinity of a developing sleeve is constituted of a contact main body part 241 and an extension part 242 extended in the rotational direction of the photoreceptor drum not shown by the figure, from both end parts of the contact main body part 241. The inner corner parts 243 between the contact main body part 241 and the extension part 242 are formed into radiused shapes and at the time of attaining sticking to the fixed member 50, sticking is attained in a state where the extension part 242 approaches inward. Thus, the inner corner parts 243 bulge toward a drum side and follow the surface of the drum, to be deformed and closely stuck. Further, sticking ranges are made small in the vicinities of the inner corner parts 243, so as to obtain sufficient bulges.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an image forming apparatus such as a copying machine, a printer and a facsimile, and more particularly, to a sealing technique for preventing toner scattering in a developing area between a latent image carrier and a developing sleeve. About.

[0002]

2. Description of the Related Art In a developing device using a two-component developer composed of a toner and a carrier, a toner is supplied from a magnetic brush of a developing sleeve disposed in parallel and close to a photosensitive drum as a latent image carrier. Visualization of the electrostatic latent image on the drum has been performed, but a part of the toner supplied from the magnetic brush scatters and stains the inside of the machine and each component,
As a result, there is a problem that image quality is reduced. For this reason, the vicinity of the developing area between the photosensitive drum and the developing sleeve is closed with a flexible sheet member commonly called an entrance seal. FIG. 13 is a sectional view showing an example of the configuration. In FIG.
01 is a photosensitive drum, 102 is a developing sleeve, A is a developing area, 103 is an entrance seal, 104 is a developing sleeve 10
A fixed member 106 positioned above the developing member 2 to supply the developer to the developing sleeve 102 by stirring and conveying;
Denotes a developing case. The entrance seal 103 has an upper end side adhered and fixed to the fixing member 104 with a double-sided tape 105, and is arranged in an inclined state so as to close the development area A. The lower end of the entrance seal 103 as a free end is in contact with the surface of the photoconductor drum 101, so that the gap is eliminated by always rubbing even when the photoconductor drum 101 rotates so that the toner does not scatter upward. ing.

The area B between the photosensitive drum 101 and the developing sleeve 102 located below the developing area A is not closed, but this is because the surface of the photosensitive drum 101 on which the toner image This is because it cannot be rubbed with a member or the like. However, since the area B is also a target area for preventing toner scattering, the gap s is made as small as possible to suppress toner scattering as much as possible.

On the other hand, at the end of the developing sleeve 102, that is, at the end of the magnetic brush, there is a problem that not only the toner is scattered but also the carrier is easily detached from the ears of the magnetic brush. When the carrier comes off, it falls and contaminates the inside of the machine and other components, and a good image cannot be obtained, or when the carrier comes off, the amount of developer to be stored in the developing hopper decreases, resulting in a good image. May not be obtained.
Therefore, it is necessary to close the end of the developing sleeve 102 as well. In order to close the end of the developing sleeve 102, a dedicated sheet member for closing the end is not separately provided, but is integrally formed with the entrance seal 103. This is because it is more advantageous from the viewpoint of cost and assembly. Specifically, the shape is as shown in FIG. In FIG. 14, the inlet seal 103 and the developing sleeve 102 are shown in plan and separated from each other in order to clarify the corresponding relationship in the longitudinal direction.

[0005] As shown in FIG.
A contact body 201 extending parallel to the axial direction of the photosensitive drum 101 and contacting the surface thereof;
1 are extended from both ends of the photosensitive drum 101 in the rotation direction. The lower edge 201a of the contact body 201 contacts the surface of the photosensitive drum 101. The width e of the contact body 201 is the photosensitive drum 1
01 and the developing sleeve 10
The area is set to be smaller than the area c of the ears of the second magnetic brush. The width d of the extension 202 is set to be larger than the area c of the ear of the magnetic brush 205 of the developing sleeve 102. By covering the end of the magnetic brush 205 with the extension portion 202, carrier scattering due to toner scattering and carrier detachment is prevented.

Here, the length of the entrance seal 103 with respect to the photosensitive drum 101, that is, the state of contact with the photosensitive drum 101 when h in FIG. 14 is changed will be considered with reference to FIG. In FIG. 15, components other than the photosensitive drum 101 and the entrance seal 103 are omitted. As shown in FIG. 15 (a), inlet seal 103 are installed on the fixed member 104 at an angle theta ₁ from its upper end P, the lower end is assumed to contact the surface and to Q ₁ photosensitive drum 101 . Contact body 2 without changing the position of P and the angle θ ₁
01, and only the length h ₁ is sequentially determined as h ₂ , h ₃ , h ₄ (h ₁ <
h ₂ <h ₃ <h ₄ ), the photosensitive drum 10
FIG. 1 shows a contact state of the contact body 201 with respect to the surface of FIG.
5 (b), (c), and (d).
In other words, the flexible inlet seal 103 gradually moves from an abutting state at the front end to a so-called abdomen state in an arc. (D) shows complete per belly state, i.e., inlet seal 103 indicates a substantially overlapping state and the tangent of the surface of the photosensitive drum 101 at Q _4. Further, the position of Q _{4 in} this state is substantially on a line connecting the center of the photosensitive drum 101 and the center of the developing sleeve 102. When the length is h ₄ or more, the belly hits at the same position as Q ₄ .

When the entrance seal 103 has a U-shape as shown in FIG. 14, the length in the direction toward the photosensitive drum 101 is considered to be a combination of two types of h and b. In FIG. 15A, h ₁ and b are h ₄ or more in FIG. 15D because they cover the entire developing sleeve 102.
Therefore, the way of contact is naturally the contact body 201 and the extension 2
02 differs from FIG.
(A) In the extension 202, the contact body 201 and the extension 20
The vicinity of the inner corner portion 203 which is the joint of No. 2 is continuously shown in FIG.
The photosensitive drum 101 is hit so that the state shown in FIG. 15A changes to the state shown in FIG. Therefore, if the inner corner 203 is a right angle as shown in FIG.
The vicinity of 03 does not fit the curved surface of the photosensitive drum 101, and as shown in FIG. 16, a gap g is formed to cause toner scattering.

In order to cope with this, conventionally, as shown in FIG. 17, a method of gradually changing the shape of the inner corner portion 203 has been devised so that no gap is formed at the inner corner portion 203.

[0009]

However, the technique of improving the fitting accuracy to the photosensitive drum by devising the shape of the inner corner portion as described above is actually a work of making the photosensitive drum. It is extremely difficult to find an optimum shape that can abut the curved surface of the first member neatly and can cope with various situations such as a dimensional error of the peripheral parts related to the installation of the inlet seal and a displacement of the assembly. In other words, the dimensional accuracy is required for the entrance seal itself and peripheral parts, and the margin for installation deviation of the entrance seal and peripheral parts is reduced, resulting in an increase in cost.

Therefore, according to the present invention, the entire entrance seal always comes into contact with the surface of the photosensitive drum neatly under various circumstances without requiring the dimensional accuracy and the installation accuracy as described above, and as a result, contamination inside the apparatus due to toner scattering. It is an object of the present invention to provide a developing device capable of preventing a decrease in image quality based on the image quality.

[0011]

When the inner corner is inflated by using the flexibility which is a material characteristic of the entrance seal and is brought into contact with the surface of the photosensitive drum, the inner corner is curved on the photosensitive drum. In this way, errors due to the difference in the contact state between the contact body and the extension and the installation errors of peripheral parts can be absorbed by the follow-up contact of the inner corners, so that strict dimensional accuracy is not required. . As long as the size of the bulge of the inner corner portion is kept at a certain value or more, the advantage of the above-described copying characteristics can be obtained. This is the purpose of the present invention. Specifically, according to the first aspect of the present invention, the vicinity of a developing area for visualizing an electrostatic latent image formed on a latent image carrier with a developing sleeve is used to prevent toner scattering or the like. Closed by a flexible sheet member, the sheet member is affixed to a fixing member located in the vicinity of the developing area, and extends in the axial direction of the latent image carrier, and contacts the latent image carrier. In a developing device formed in a U-shape comprising a contact body portion that contacts and extension portions extending in the rotation direction of the latent image carrier at both end portions of the contact body portion, the contact body portion and the extension portion Are formed in an R-shape, and the leading ends of the two extended portions are mutually axially inside the latent image carrier so that the inner corner swells toward the latent image carrier. Approached and attached to the fixing member, and
In order to increase the degree of freedom of the inner corner portion with respect to the fixing member, the area to be pasted is set small near the inner corner portion.

According to the second aspect of the present invention, the vicinity of the developing area for visualizing the electrostatic latent image formed on the latent image carrier with the developing sleeve is flexible to prevent toner scattering and the like. Is closed by a sheet member having a property, and the sheet member is attached to a fixing member located in the vicinity of the developing area, and extends in the axial direction of the latent image carrier and comes into contact with the latent image carrier. In a developing device formed in a U-shape comprising a contact body portion and extension portions extending at both ends of the contact body portion in the rotation direction of the latent image carrier, the developing device is provided between the contact body portion and the extension portion. Are formed in an R-shape, and the distal ends of the extended portions are mutually inwardly axially of the latent image carrier so that the inner corners swell toward the latent image carrier. Approached and affixed to the fixing member, and the inner corner portion Inner corner portion near such freedom is increased with respect to the fixed member is not made paste for fixing members, adopts a configuration that.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. First, an image forming system of an image forming apparatus (here, a copying machine) in which the developing device of the present invention is used will be described with reference to FIGS. 8 to 10, the photosensitive drum 1 as a latent image carrier is neutralized by the neutralizing light 7 while rotating and moving in the direction of the arrow, and the surface potential is averaged to a reference potential of 0 to -150V. Next, the photosensitive drum 1 is charged by the charging device 2, and the surface potential becomes around -900V. Charged photosensitive drum 1
The image light 3 is irradiated at the exposure unit, and a portion (image portion) where the image light 3 is not irradiated is formed into a toner image (visible image) by the toner on the developing roller 4 in the developing unit.
At this time, a bias of about −200 V is applied to the developing sleeve 4, but the surface potential of the portion (image portion) of the photosensitive drum 1 where the image light 3 is not irradiated is −500 to −−.
Since the voltage is maintained at 850 V, the toner on the developing sleeve 4 adheres to this image portion.

While the photosensitive drum 1 further rotates,
Transfer paper is supplied from a paper supply unit (not shown). The transfer paper is fed at a timing such that the leading end of the transfer paper coincides with the leading end of the toner image formed on the photosensitive drum 1, and the transfer device 5 transfers the transfer paper onto the photosensitive drum 1 at the transfer unit. Is transferred. The transfer paper on which the toner image has been transferred is sent to a fixing unit (not shown), where the toner image is fused by heat and pressure of a fixing device (not shown), and then discharged outside the machine as a copy. On the other hand, the toner remaining on the photosensitive drum 1 without being transferred to the transfer paper is scraped off by the cleaning blade 6 of the cleaning unit. This allows
The photoreceptor drum 1 is in an initial state where no toner is attached, and moves to the next image forming step again.

In the present embodiment, the photosensitive member and an image forming apparatus such as a charging device, a developing device, and a cleaning device disposed around the photosensitive member are usually provided with a case around an integral photosensitive drum called a process cartridge. 40, it is stored as a unit. This process cartridge has an external appearance as shown in FIG. 8, and removes residual toner scraped off from the photosensitive drum 1 by the cleaning blade 6 as shown in FIG.
To the recycled toner transport section on the front side of the case 40, and is sent to the developer agitating section of the developing device by the toner recycling belt 9 provided in the recycled toner transport section, so as to be reused as recycled toner. Has become. Next, the developing device in the process cartridge will be described. The developing sleeve 4 has a fixed shaft in which a five-pole magnet is arranged, and is configured to cover the outer peripheral surface with a magnetic pipe material such as aluminum.
The rotation of the pipe material causes the developing container 41 (case 40) to rotate.
(A two-component developer composed of a carrier formed of a small iron ball and a toner) is pumped onto the developing sleeve 4 by the magnetic force of a magnet, and is developed by the developing unit of the photosensitive drum 1. Moved to This developing sleeve 4
The amount of the developer supplied to the photosensitive drum 1 by the doctor blade 10 is controlled by the doctor blade 10 to prevent the occurrence of image density defects and uneven density due to excess or deficiency. Is regulated to be a certain amount.

The developing container 41 (developing cover) formed integrally with the case 40 is provided with a pair of stirring screws 11 for stirring and circulating the developer.
The rotation of the stirring screw 11 causes the developing container 4
While the developer in 1 is being stirred, the developer is circulated and conveyed in a loop along the axial direction of the developing sleeve 4. here,
Of the developer moved to the developing section of the photosensitive drum 1 by this circulation, the carrier is taken into the developing container 41 by the rotation of the developing sleeve 4 and circulated again, but is charged by stirring and adheres to the carrier. The toner carried to the developing section of the photosensitive drum 1 adheres to an image portion formed on the photosensitive drum 1 by electrostatic force and is consumed. Therefore, as is well known, it is necessary to replenish the toner in this type of image forming apparatus in a timely manner in accordance with its consumption. A toner supply port 12 for taking in the toner is provided. This toner supply port 1
2 is supplied by a toner supply unit 15 including a bottle-shaped toner cartridge. The toner supply unit 15 is detachably provided on a side surface of the developing container 41. Further, as shown in FIGS. 8 and 9, the developer case 16 is provided on the upper part of the developing container 41.

As shown in FIGS. 9 and 10, a seal unit 17 for closing the developing area between the photosensitive drum 1 and the developing sleeve 4 so that the toner is not scattered is provided at the portion of the doctor blade 10. I have. Next, the toner scattering prevention structure in the developing area will be described in detail. FIG.
As shown in FIG. 7 and FIG.
1 support hole 18 of support member 18 positioned on both side plates
The shafts 4a and 4b at both ends thereof are inserted through a and are rotatably supported. Each support member 18 is integrally formed with a bracket 19 extending in the axial direction of the developing sleeve 4.
The doctor blade 10 is fixed to the support member 18 via the bracket 19. The bracket 19 and the doctor blade 10 are formed with fixing holes 19a and 10a, respectively, so that the fixing screw 20 and the nut 21 integrally connect the two members. Seal unit 1
7 is a support member 18 so as to cover the doctor blade 10.
A holding member 23 made of plastic and having a substantially U-shaped cross section, and an inlet seal 24 as a flexible sheet member mainly attached to the front surface (the photosensitive drum 1 side) of the holding member 23. It is composed of

As shown in FIG. 1, the inner width of the holding member 23 is set slightly smaller than the width of the supporting member 18 so that the holding member 23 is elastically fitted to the supporting member 18 by a pushing operation from above. I have. A long hole 26 is formed on the back surface of the holding member 23 at a position corresponding to the fixing screw 20.

As shown in FIG. 2, the entrance seal 24 extends in the axial direction of the photosensitive drum 1 and abuts the main body 241 in contact with the drum surface. And an extension 242 extending in one rotation direction. Contact body 241 and extension 242
Are formed in a rounded R shape. The size of R varies depending on the size of the photosensitive drum 1 and the installation position of the entrance seal 24. For example, for a drum diameter of 30 mm, the entrance seal 24 is installed in a positional relationship as shown in FIG. In case, 5-10mm
The position is appropriate and may be roughly determined within this range.

FIG. 2 shows a developed state of the entrance seal 24 before being installed in the developing device.
When a straight line J parallel to a straight line I drawn perpendicular to the first contact ridge line 244 is imagined on the extension 242, in a state where the entrance seal 24 is actually installed in the developing device, as shown in FIG.
The virtual straight line J is fixed with a double-sided tape or the like so that both the virtual straight lines J are inclined inward in the axial direction of the photoconductor 1. In other words, the distance e5 between the distal ends of the extension portions 242 in FIG. 2 is set to be shorter like e6 after installation. This is the basis of the present invention.

FIG. 4 shows a state in which the inlet seal 24 is actually attached to the fixing member 50 by the above method. The area indicated by hatching is the range of adhesion with the double-sided tape. In this embodiment, the fixing member 50 is constituted by the holding member 23 and the supporting member 18 shown in FIGS. When the extension portion 242 is inclined and attached as described above, as shown in FIG. 5, the inner corner portion 243 is attached to the photosensitive drum 1 in order to absorb dimensional wrinkles (distortion) due to the inclination.
Bulges to the side (front side of the drawing). Since the inner corner portion 243 is formed in an R shape, the bulge is formed with a gentle roundness without locally protruding. Therefore, the inner corner portion 243 follows the surface of the photosensitive drum 1 which is a curved surface, that is, the inner corner portion 243 follows and deforms and adheres. Inner corner 243
As described above, the swelling deformation is not local but swelling with a certain range, so that even if there is a shape error of the inlet seal 24 or an installation error of the fixing member 50, these dimensional errors are sufficiently absorbed. And a uniform contact state can be obtained. Therefore, high precision in production and assembly is not required.

The degree to which the extension 242 is inclined is shown in FIG.
The dimension f in FIG. 3 is suitably about 1 to 3 mm if b = about 40 mm.
Depending on the conditions, the dimensions may be other than the above, but since only the inclination is changed, the optimum degree can be easily found. As a method of inclining the extension 242,
For example, as shown in FIG. 4, an inclined reference line N or a step is formed on the fixing member 50 in advance, and the
The outer edges 242a of the two may be matched. The bulging deformation of the inner corner portion 243 can also be obtained by forming the extension portion 242 into a shape that is originally divergent and vertical at the time of installation.

By the way, as shown in FIG.
If the second width e11 cannot be sufficiently secured, the degree of the bulging deformation of the inner corner portion 243 decreases. In other words, the degree of freedom of the inner corner 243 with respect to the fixing member 50 is reduced. In this case, the following deformation function of the inner corner portion 243 with respect to the surface of the photosensitive drum 1 is small, and there is a possibility that the adhesion may be incomplete. The present invention seeks to overcome this.

In order to solve the above-mentioned concern, as shown in FIG. 1, the area (adhesion area) to be attached to the fixing member 50 near the inner corner 243 is reduced. That is, an L-shaped region 52 that is not bonded as compared with FIG. 4 is provided (claim 1). As a result, the restraint of the fixing member 50 on the inner corner 243 is reduced, so that the extension 242 is formed.
Even if the width e11 of the inner corner portion 2 cannot be sufficiently secured.
Reference numeral 43 indicates that sufficient swelling deformation capable of obtaining good adhesion can be obtained. The specific dimensions and range shape for reducing the bonding range in the vicinity of the inner corner 243 are appropriately set to be optimal based on conditions such as the width e11 of the extension 242.

Next, another embodiment will be described with reference to FIGS. The present embodiment is an example corresponding to a case in which sufficient swelling deformation of the inner corner 243 cannot be obtained even by reducing the bonding range near the inner corner 243 according to the above embodiment. In the present embodiment, as shown in FIG. 11, the bonding in the vicinity of the inner corner 243 is prevented (claim 2). Specifically, the vertically-long rectangular bonding region 54 shown in FIG. 1 is eliminated. As a result, the inner corner portion 243 can be sufficiently swelled and deformed to obtain good adhesion. In the case of the present embodiment, a gap portion communicating between the entrance seal 24 and the fixing member 50 to the outside is provided. Is present, and there is a possibility that the toner leaks in the arrow Y direction and scatters. In order to deal with this, FIG.
As shown in FIG. 2, a sponge member such as urethane foam is provided by bonding to the 55 fixing member 50 to seal between the inlet seal 24 and the fixing member, specifically, for example, in a gap region having a horizontal width w and a vertical width t. ing. By doing so, toner leakage in the arrow Y direction can be prevented, and the elasticity of the sponge member 55 causes the extension 242 to be forcibly brought into close contact with the surface of the photosensitive drum 1, so that the sealing performance is further improved.

[0026]

As described above, according to the first aspect of the present invention, the inside corner of the U-shaped sheet member is formed into an R shape, and the inside corner is formed on the side of the latent image carrier. Since it is configured to be attached to the fixing member so as to swell, and the attachment range in the vicinity of the inner corner is reduced, a good function of adhering to the surface of the latent image carrier due to gentle swelling of the inner corner is obtained. In addition, toner scattering can be prevented without requiring dimensional accuracy and assembly accuracy of the sheet member and its peripheral parts. Therefore, it is possible to prevent the inside of the apparatus and each device from being stained and the image quality from being reduced due to the contamination. Also,
By reducing the attachment range near the inner corner, a sufficient bulging deformation of the inner corner can be obtained even if the area of the deformable portion of the sheet member with respect to the latent image carrier is small.

According to the second aspect of the present invention, since the configuration is such that the vicinity of the inner corner is not adhered, the lower limit position is provided, so that the bulging deformation function of the inner corner can be further improved. it can.

[Brief description of the drawings]

FIG. 1 is a plan view of a developing device according to the present invention in a developed state in which a sheet member is installed.

FIG. 2 is a plan view of a deployed state before the installation of the sheet member.

FIG. 3 is a plan view showing displacement of an extension when the sheet member is installed.

FIG. 4 is a plan view showing the basic shape of the sheet member according to the present invention in an unfolded state.

FIG. 5 is an essential part perspective view showing a bulge of an inner corner portion.

FIG. 6 is an exploded perspective view around a sheet member in the developing device of the present invention.

FIG. 7 is a cross-sectional view around a sheet member of the image forming apparatus including the developing device of the present invention.

FIG. 8 is a perspective view of a process cartridge.

FIG. 9 is a sectional view of a main part of an image forming apparatus including a developing device of the present invention.

FIG. 10 is a partially omitted perspective view of a process cartridge.

FIG. 11 is a plan view of a deployed state of a seat member according to another embodiment.

FIG. 12 is a sectional view around a sheet member of an image forming apparatus according to another embodiment.

FIG. 13 is a cross-sectional view around a sheet member of a conventional image forming apparatus.

FIG. 14 is a plan view showing a relationship between a conventional sheet member and a developing sleeve.

FIG. 15 is a side view illustrating a change in the contact state of the sheet member with the photosensitive drum.

FIG. 16 is a perspective view illustrating a contact state of a conventional sheet member with a photosensitive drum.

FIG. 17 is a plan view showing a modification of the conventional sheet member.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum as latent image carrier 4 developing sleeve 24 sheet member 241 contact body 242 extension 243 inner corner

Claims (2)

[Claims] 1. A developing member for visualizing an electrostatic latent image formed on a latent image carrier with a developing sleeve is provided by a flexible sheet member for preventing toner scattering and the like. A closed main body that is closed, the sheet member is attached to a fixing member located in the vicinity of the development area, extends in the axial direction of the latent image carrier, and contacts the latent image carrier; In a developing device having a U-shape formed by extending both ends of a contact main body portion in a rotation direction of the latent image carrier, an inner corner between the contact main body portion and the extension portion has an R shape. The fixing member is formed in a shape, and the distal ends of the two extended portions are brought closer to each other inward in the axial direction of the latent image carrier so that the inner corners protrude toward the latent image carrier. And the degree of freedom of the inner corner portion with respect to the fixing member Wherein the area to be pasted is set small in the vicinity of the inner corner portion so as to increase the size. 2. A developing member for visualizing an electrostatic latent image formed on a latent image carrier with a developing sleeve is provided by a flexible sheet member for preventing toner scattering and the like. A closed main body that is closed, the sheet member is attached to a fixing member located in the vicinity of the development area, extends in the axial direction of the latent image carrier, and contacts the latent image carrier; In a developing device having a U-shape formed by extending both ends of a contact main body portion in a rotation direction of the latent image carrier, an inner corner between the contact main body portion and the extension portion has an R shape. The fixing member is formed in a shape, and the distal ends of the two extended portions are brought closer to each other inward in the axial direction of the latent image carrier so that the inner corners protrude toward the latent image carrier. And the degree of freedom of the inner corner portion with respect to the fixing member Wherein the vicinity of the inner corner portion is not attached to a fixing member so that the size of the developing device becomes larger.