JPH0836307A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] A side seal member 55, which is in sliding contact with the circumferential surface of a cylindrical developing sleeve 18 in which a magnet roller 17 is installed, is carried on the circumferential surface of the developing sleeve 18 and integrally rotates. It is prevented that the developer is rubbed by a magnetic carrier and a developer such as a magnetic toner. [Arrangement] The regions affected by magnetism at the left and right ends of the magnet roller 17 are set so as to be located inward from the left and right ends of the developing sleeve 18 by an appropriate dimension so that the one side of the circumference of the photoconductor drum is reached. Side-seal members 55 are formed on the left and right side plates of the opening of the developing unit case facing each other so as to form substantially semi-circular cutouts, and slide-contact with substantially half-circumferential portions of the left and right circumferential ends of the developing sleeve 18. The magnet roller 17 was arranged and fixed so as to be located outside the area on the left and right ends of the magnet roller 17 which is influenced by magnetism and along the semicircular surface of the notch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of image forming apparatuses such as laser printers, copiers and facsimile machines.

[0002]

2. Description of the Related Art Conventionally, as a dry developing type apparatus for supplying a developer to a developing area on the surface of a photosensitive drum to develop, it is disclosed in Japanese Patent Publication No. 4-73794 and Japanese Patent Publication No. 4-48232. And there is a developing device as shown in FIGS. This developing device includes a photosensitive drum 1.
00 inside the chamber 102 of the developing unit case 101,
A developing sleeve 104 and a toner agitating member 105 which store an initial developer (a mixture of a magnetic carrier and a magnetic toner) in advance and which is provided with a magnet roller 103 in an inner diameter portion to carry a mixture of a toner and a magnetic carrier on an outer peripheral surface.
Is provided.

Further, the chamber 102 and the toner supply chamber 10
The developing sleeve 10 is provided on the partition wall 106a for partitioning
4, a toner supply slit 107 that extends in the axial direction of 4 and is connected to the chamber 102 is opened, and the toner supply chamber 10 is opened.
A stirring member 108 for supplying toner from the slit 107 in the direction of the chamber 102 is provided inside the unit 6.

Then, as shown in FIG. 10 in the prior art, a trimmer blade 109 for appropriately adjusting the size of the gap S from the outer peripheral surface of the developing sleeve 104 is provided on the front plate 101b of the developing section case 101. A magnetic brush having a predetermined height is formed on the outer peripheral surface of the developing sleeve 104, and toner is supplied from the developing sleeve 104 side toward the peripheral surface of the photosensitive drum 100 during an image forming operation. Known to make up.

By the way, if the developer such as toner or magnetic carrier in the developing unit case 101 leaks out from a portion other than the circumferential surface portion of the developing sleeve 104, it is caused by the photosensitive drum 100 or the paper fed. The surface of the developing unit 101 is carelessly soiled and the toner is wasted. Therefore, in order to prevent the toner from leaking, as shown in FIGS. A notched portion 110 having a semi-circular arc shape is formed so that the semicircular portion of the developing sleeve 104 is fitted (only one side is shown in the drawing).
A belt-shaped side seal member 111 made of a felt material or the like is additionally provided along the line 10.

[0006]

However, as shown in FIG.
As shown in FIG. 5, the width dimension Ho of the side seal member 111 that is in sliding contact with both left and right end portions (only one is shown in the drawing) of the circumferential surface of the developing sleeve 104 is large, and one side edge of the band-shaped side seal member 111 is large. However, there is the following problem when the magnet roller 103 is arranged so as to overlap the left and right end edges of the magnet roller 103 in the developing sleeve 104 by the dimension of H1. That is, due to the magnetic force of the magnet roller 103,
The magnetic carrier and the magnetic toner are magnetically attracted to the outer peripheral surface of the developing sleeve 104 with a proper thickness.

Therefore, as described above, when the one side edge of the side seal member 111 is arranged so as to overlap the left and right end edges of the magnet roller 103 in the developing sleeve 104 by a dimension of H1, the developing sleeve 104 is arranged. As described above, the magnetic carrier and the magnetic toner, which are magnetically attracted and rotate integrally with the developing sleeve, rub against the side edges of the fixed side seal member 111 at the left and right ends of the circumferential surface. In particular, since the magnetic carrier and the magnetic toner are strongly magnetically attracted to the circumferential surface of the developing sleeve 104 by the magnetic force of the magnet roller 103, the felt material forming the side seal member 111 loses its hair and scatters to develop. If it adheres to the sleeve 104 or the like, it adversely affects the image formation. Furthermore, after a long period of use, the side edge of the side seal member 111 is scraped off by the magnetic carrier or the like and is consumed, so that the original sealing function cannot be exerted, and the circumferential surface of the chamber 102 becomes ineffective. There has been a problem that the gaps formed at the left and right end portions gradually increase during long-term use, and it becomes impossible to prevent the magnetic carrier and the magnetic toner in the developing unit case 101 from leaking out.

Further, the magnetic carrier and magnetic toner that have entered the sliding contact surface between the side seal member 111 and the developing sleeve 104 are strongly pressed against the surface of the developing sleeve 104 by the side seal member 111, and the toner is developed. There was also a problem of sticking to the surface. In this case, there is a problem that the toner is reflected on the photosensitive drum 103 due to the stuck toner, and a black streak is formed on the edge portion of the sheet (a portion corresponding to the outside of the image forming area).

Such a problem is caused as long as the side seal members are arranged within the range where the influence of the magnetic field at the left and right end portions of the magnet roller 103 extends to the left and right end portions of the circumferential surface of the developing sleeve 104. It happened. The present invention has been made to solve these conventional technical problems, and an object of the present invention is to provide an image forming apparatus capable of easily preventing toner leakage.

[0010]

In order to achieve the above-mentioned object, an image forming apparatus of the present invention is provided with an axis line of the photoconductor drum in an opening of a developing unit case facing one side of a circumference of the photoconductor drum. In an image forming apparatus in which a cylindrical developing sleeve containing a magnet roller having parallel axes is rotatably mounted, an area where magnetism influences at both left and right end portions of the magnet roller is located at both left and right end portions of the developing sleeve. Set so as to be located inwardly by an appropriate size from the above-mentioned portion, and substantially semi-circular arc-shaped notches are formed on the left and right side plates of the opening in the developing unit case. A side seal member disposed so as to be in sliding contact with a substantially half-circumferential portion of the portion, outside or in a region where a magnetic effect is exerted on both left and right end portions of the magnet roller. A position is and which is disposed along the semicircular surface of the notch.

[0011]

Next, an embodiment of the present invention will be described. 1 is a schematic side sectional view of a printer 1 as an image forming apparatus, and FIG. 2 is a side end view of an image forming unit.
FIG. 3 is a perspective view of each component of the image forming unit. In the printer 1 of this embodiment, a paper feed cassette 3 is detachably mounted on one side of the main body case 2, and a recording medium stacked in the paper feed cassette 3 by a paper feed roller 4 and a separation pad 5. The paper P is separated one by one and is conveyed to the image forming unit 8 via the conveying roller pairs 6 and 6.

Below the image forming unit 8 including the developing device 7, the photosensitive drum 13, the transfer roller 21 and the like, a scanner unit 14 including a laser emitting portion, a lens, a reflecting mirror and the like is disposed, and further, the scanner unit 14 is disposed. A control board, a power supply unit and the like are arranged below. The surface of the photoconductor drum 13 precharged by the charging device 22 in the image forming unit 8 is irradiated with laser light emitted from the scanner unit 14 according to image data transmitted from an external device such as a computer (not shown). Then, an electrostatic latent image is formed on the surface of the photoconductor drum 13, and then a metal developing sleeve 18 made of aluminum or the like having a magnet roller 17 in the developing device 7 rotates in the direction of arrow A to perform triboelectric charging. After developing the latent image into a visible image by supplying the powdery toner thus produced, the photosensitive drum 13
The toner image is transferred onto the sheet P supplied between the transfer roller 21 and the transfer roller 21, and then transferred by the fixing unit including the heating roller 9 and the pressing roller 10 adjacent to the image forming unit 8. The toner image is fixed on the paper P by applying heat and pressure to the formed image, and the paper P is discharged from the paper discharge roller pair 11 to the paper discharge tray 12 of the printer 1.

A flip-up rotary type cover body 15 is rotatably attached to the upper portion of the image forming unit 8, and the cover body 1 is attached to the upper surface of the main body case 2.
Similarly, a flip-up rotatable lid 16 for covering the image forming unit 5 and the image forming unit 8 is pivotally attached. In addition,
In this embodiment, the developing method used is 9 for magnetic carrier.
Nonmagnetic toner is 2% to 5% at 5% to 98% (weight ratio)
Of a so-called two-component developing method of (weight ratio) or a so-called 1.5-component developing method of magnetic carrier of 30% to 80% (weight ratio) and magnetic toner of 20% to 70% (weight ratio). Either may be used.

Next, the structure of the image forming unit 8 will be described below with reference to FIGS. The image forming unit 8 includes the photosensitive drum 13, a transfer roller 21 in contact with the upper surface thereof, a charging device 22 arranged below the photosensitive drum 13, and a developing device arranged upstream of the photosensitive drum 13 in the sheet feeding direction. 7, a detachable toner cartridge 23 as a developer (toner) supply portion disposed further upstream thereof, a cleaning device 52 disposed downstream of the photosensitive drum 13, and the like.
An electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 13 by scanning the charged layer formed by the charging device 22 with a laser beam from the scanner unit 14. The developer (toner) in the toner cartridge 23 is carried on the outer peripheral surface of the developing sleeve 18 after being sequentially stirred by the first stirring means 24 and the second stirring means 25 of the developing device 7. The electrostatic latent image on the photosensitive drum 13 is visualized by the developer adhering from the developing sleeve 18, and is transferred onto the sheet P passing between the transfer roller 21 and the photosensitive drum 13. The developer remaining on the photosensitive drum 13 is collected by the cleaning device 52.

The image forming unit 8 includes an outer case 28, which will be described later, and a developing section case 2 fitted in the outer case 28.
The image forming unit 8 which is made into a cartridge by being assembled with the cartridge 9 is detachably mounted in the main body 2. As shown in FIG. 3, a pair of left and right pivots 30 horizontally projecting from the upper end of the developing unit case 29 near the developing sleeve 18 is attached to one side plate of the outer case 28 to which the photosensitive drum 13 is rotatably mounted. By pivotally attaching the circular hole 31 formed in 28a and the side case 32 attached to the other side plate 28b, the developing unit case 29 is centered on the pivot shaft 30 with respect to the outer case 28 as indicated by arrow B in FIG. It can pivot up and down as shown. The charging device 22 and the cleaning device 52 are mounted on the outer case 28.

The developing device 7 has a developing case 29 as an outer shell. That is, the first stirring means 2
The fourth stirring means 25 is attached to the developing unit case 29. A toner cartridge accommodating portion 34 is formed in a portion of the developing portion case 29 located on the opposite side of the trimmer blade 33, which will be described later, with the first stirring blade 24 interposed therebetween, and the toner cartridge accommodating portion 34 includes the toner cartridge accommodating portion 34. An elongated hole 35 for supplying the toner in 23 to the first stirring blade 24 is opened.

A protective member 36 is provided on the outer case 28 so as to extend between the left and right side plates 28a and 28b and cover the transfer roller 21. A sheet insertion port 37 is opened between one lower end of the protective member 36 and the upper wall 29a of the developing unit case 29, and a sheet ejection port 38 is provided between the other lower end and the upper wall of the cleaning device 52. It is open.
The sheet insertion port 37 and the sheet ejection port 38 are located opposite to the contact point between the photosensitive drum 13 and the transfer roller 21.

Further, at the upper portion of the upper wall 29a of the developing section case 29, the paper P separated by the paper feed roller 4 is guided through the paper insertion opening 37 between the photosensitive drum 13 and the transfer roller 21. A guide body 39 for doing this is provided. The lower feed roller 6 of the pair of upper and lower feed rollers 6, 6 is pivotally supported by the guide body 39, and the upper feed roller 6 is pivotally supported by the cover body 15.

The lower surface of the outer case 28 is shown in FIG.
An exposure hole 40 for irradiating the photosensitive drum 13 with laser light from the scanner unit 14 described in 1. is formed so as to extend along the axis of the photosensitive drum 13. The opening 53 of the developing unit case 29 in the developing device 7 is disposed so as to face the peripheral surface of the photosensitive drum 13.
It is opened long along the axis of 3. This opening 53
And a developing sleeve 18 having a magnet roller 17 inside is rotatably disposed in the inner side of the developing sleeve 18.
Is arranged so that one side of the outer peripheral surface thereof faces the outer peripheral surface of the photosensitive drum 13.

The left and right side plates 53a, 53a of the opening 53 in the developing unit case 29 are each provided with a substantially semi-circular cutout 54 having a radius slightly larger than the outer peripheral radius of the developing sleeve 18 in a side view. And each of these notches 5
As shown in FIGS. 5 and 6, a strip-shaped side seal member 55 having a width dimension H2 made of a felt material or the like is attached to 4 by adhesion or the like.

In this case, when the areas affected by magnetism at both the left and right ends of the magnet roller 17 are set to be inside the left and right ends of the developing sleeve 18 by an appropriate dimension H3, it is shown in FIG. As described above, the layer thickness t1 of the developer 56 of the magnetic carrier and the magnetic toner, which is magnetically attracted by the magnetic force of the magnet roller 17 and is formed on the outer circumferential surface of the developing sleeve 18, is substantially uniform over the length of the magnet roller 17. Then, for example, t1 = 5 mm
To a certain extent, the influence of the magnetic force becomes weaker at the portions extending toward the left and right end portions of the developing sleeve 18 than at the left and right end portions of the magnet roller 17, and the magnetic attraction causes the development on the circumferential surface of the developing sleeve 18. The layer of the agent 56 is, for example, t
It becomes about 2 = 1 mm.

Therefore, a side seal member is arranged along the semicircular surface of the cutout portion 54, and is arranged so as to be in sliding contact with the substantially semicircular portions of the left and right circumferential ends of the developing sleeve 18. It is preferable that 55 is provided outside the region affected by magnetism at the left and right ends of the magnet roller 17. Then, as shown in FIG.
A gap of dimension H4 is formed between the end portion of the layer 6 and the side end surface of the side seal member 55. This allows
The developer 56 (magnetic carrier and magnetic toner) that is magnetically attracted and rotates integrally with the developing sleeve 18 can be prevented from rubbing against the side edge of the fixed side seal member 55, and the magnetic force of the magnet roller 17 can be prevented. As in the conventional case where the side seal member is arranged within the range of influence, the developer 56 strongly magnetically attracted to the circumferential surface of the developing sleeve 18 causes the bristles of the felt material forming the side seal member 55 to be removed. The developing sleeve 18
Etc., and may adversely affect image formation,
Furthermore, the phenomenon that the side edge of the side seal member 55 is scraped off by the developer 56 and consumed due to long-term use and the original seal function cannot be exerted is eliminated.

The magnetic carrier and the magnetic toner do not enter the sliding contact surface between the side seal member 55 and the developing sleeve 18 and stick to the developing sleeve 18. There is no problem of entering. As a result, it is possible to form a good image without causing an image stain due to the hair loss of the felt material or a stain of the paper due to the sticking of the magnetic toner on the developing sleeve 18, and at the same time, it is possible to form a good image. The durability of the seal member 55 is improved, and a stable sealing effect can be exhibited for a long period of time.

In the above-mentioned embodiment, the side end of the side seal member 55 is arranged outside the region of the magnet roller 17 which is affected by the magnetism, but the side seal member 55 is located at a portion where the magnetism influence is small. You may set so that the side edge of may be located. In this case, the layer of the developer 56 is in sliding contact with the side end of the side seal member 55 to some extent, but the magnetic carrier and magnetic toner attracted to the surface of the developing sleeve 18 has a weak magnetic attraction force, so that the side seal member 55 is removed. No stress is generated in the felt material to the extent that hair loss occurs, and the developer enters the contact surface between the side seal member 55 and the developing sleeve 18, and the side seal member 55 causes the developer to contact the developing sleeve 18. The pressure is not so strong that it sticks, and the adverse effects such as abrasion of the side seal member 55 and sticking of the developer are sufficiently mitigated in practical use.

Further, a step 57 at the opening edge of the bottom plate 29b of the opening 53 in the developing section case 29 is formed along the axis of the support shaft 17a of the magnet roller 17 (see FIG. 5). The trimmer blade 33 is erected on 57 via a bottom seal band 58 such as a sponge. This allows
A gap S of about 300 μm (micron) is formed between the upper edge of the trimmer blade 33 and the lower circumferential surface of the developing sleeve 18 to control the thickness of the developer layer carried on the developing sleeve 18. Is.

In this case, the left side plate 53 of the developing unit case 29
After inserting the trimmer blade 33 into the rectangular hole 60a (see FIGS. 4 and 5) in the mounting plate portion 59a formed integrally with a, attach the left end portion of the trimmer blade 33 to the back surface of the mounting plate portion 59a. By fixing the position with the screw 61a and fixing the fixture 59b provided with the rectangular hole 60b (see FIG. 4) into which the right end portion of the trimmer blade 33 is inserted to the outside of the developing unit case 29 with the attachment screw 61b, The right end portion of the trimmer blade 33 is freely position-controlled in its longitudinal movement. At this time, the upper end surfaces near the left and right end portions of the trimmer blade 33 are abutted against a part of a pair of bearings on both sides for rotatably supporting the developing sleeve 18 to determine the relative positions of the both. As a result, the gap S can be accurately formed and assembled.

In the factory, the image forming unit 8 of this type has an initial toner (initial developer) of a magnetic carrier and a magnetic toner in a chamber in which the developing sleeve 18 is arranged for test printing such as print quality. ). However, the lower end of the semicircular portion of the cutout portion 54, the inner edge of the side seal member 55, and the trimmer blade 3
In the three-part gathering portion with the upper edge of 3, the initial toner (initial developer) leaks to the outside of the image forming unit 8 at the time of product shipment in the gap for forming the thickness of the developer layer. Easy to put out. That is, in the gap, the magnetic carrier and the magnetic toner are liable to leak out since the magnet roller 17 is located outside the magnetic influence area or the magnetic influence area is small.

In order to prevent this inconvenience, auxiliary seal members 62, 62 having a downward U-shaped cross section made of synthetic resin sponge are fitted to the left and right end portions of the upper edge of the trimmer blade 33 with an adhesive or the like. Fix it. in this case,
The auxiliary seal member 62 is installed at the opening 53
It is set so as to overlap with the inner edge of each of the side seal members 55 by a dimension H5 at the right and left cutout portions 54 in FIG. 6 (see FIG. 6). As a result, when the trimmer blade 33 is mounted, the auxiliary seal is provided between the lower end of the semicircular portion of the cutout portion 54, the inner edge of the side seal member 55, and the upper edge of the trimmer blade 33. The upper end of the member 62 can be closed, and the initial toner (initial developer) can be prevented from leaking out (see FIG. 7B).

Incidentally, the auxiliary seal members 62, 62 on both sides
Is located outside the image forming range in the axial direction of the photoconductor drum 13, so that normal image forming operation is not hindered. Further, when the auxiliary seal member 62 is adhesively fixed to the trimmer blade 33, the auxiliary seal member 62 is adhered except the upper end portion of the trimmer blade 33, that is, the portion forming the gap S for regulating the layer thickness and its vicinity. In this way, the adhesive that is interposed between the two is prevented from accidentally protruding above the gap S and damaging the surface of the developing sleeve 18.

[0030]

As described above, in the image forming apparatus of the present invention, the axis line parallel to the axis of the photoconductor drum is provided in the opening of the developing unit case facing one side of the circumference of the photoconductor drum. An image forming apparatus in which a cylindrical developing sleeve containing a magnet roller having a magnet is rotatably mounted, and a region of the developing roller having left and right ends is affected by magnetism. More appropriately set so as to be located inward, and substantially semi-circular cutouts are formed on the left and right side plates of the opening in the developing unit case, and the left and right circumferential ends of the developing sleeve are formed. A side seal member disposed so as to be in sliding contact with a substantially half-circumferential portion of the magnet roller outside the region where the magnetic influence is exerted on the left and right end portions of the magnet roller or a portion where the influence is small. And in which is disposed along the semicircular surface of the notch.

Therefore, it is possible to prevent the developer (magnetic carrier and magnetic toner) that is magnetically attracted by the magnetic force of the magnet roller in the inner diameter portion and rotates integrally with the developing sleeve from rubbing against the side edge of the fixed side seal member. It is possible to remove the side seal member by the developer strongly magnetically attracted to the circumferential surface of the developing sleeve as in the conventional case where the side seal member is arranged within the range where the magnetism of the magnet roller influences. The scraps scattered and adhere to the developing sleeve etc., which adversely affects the image formation,
Further, there is no phenomenon that the side edge of the side seal member is scraped off by the developer and consumed due to long-term use, and the original seal function cannot be exerted.

Further, the magnetic carrier and the magnetic toner do not enter the sliding contact surface between the side seal member and the developing sleeve and stick to the developing sleeve, which causes black streaks on the paper. No problem occurs. As a result, a good image can be formed, the durability of the side seal member is improved, a stable sealing effect can be exerted for a long period of time, and the image quality is not deteriorated.

Further, since the above-described structure is a very simple structure in which the positional relationship between the side seal member and the left and right ends of the magnet roller having the inner diameter of the developing sleeve is set, the manufacturing cost is not increased. Play.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a printer.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a perspective view of each component of the image forming unit.

FIG. 4 is a perspective view of each part of the developing unit case.

FIG. 5 is a perspective view of a main part of a cutout portion, a side seal member, and a trimmer blade.

FIG. 6 is a partially cutaway cross-sectional view showing an arrangement relationship of a side seal member and the like with respect to a developing sleeve.

7A is a sectional view taken along line aa of FIG. 6, FIG. 7B is a sectional view taken along line bb of FIG. 6, and FIG. 7C is a sectional view taken along line cc of FIG. It is a figure.

FIG. 8 is an operation explanatory view.

FIG. 9 is a side sectional view of a conventional developing unit case.

FIG. 10 is a perspective view of a developing unit case and a sealing material portion in a conventional example.

FIG. 11 is a cross-sectional view showing a positional relationship among a developing sleeve, a magnet roller, and a side seal member in a conventional example.

[Explanation of symbols]

 1 Printer as Image Forming Device 8 Image Forming Unit 13 Photosensitive Drum 17 Magnet Roller 18 Developing Sleeve 29 Developing Part Case 33 Trimmer Blade 54 Notch Part 55 Side Seal Member

Front page continuation (72) Inventor Fumio Morita 15-1 Naeshiro-cho, Mizuho-ku, Nagoya-shi Brother Industries, Ltd. (72) Inventor Hiroshi Igarashi 15-1 Naeshiro-cho, Mizuho-ku, Nagoya-shi Brother Industries, Ltd.

Claims (1)

[Claims] 1. A cylindrical developing sleeve in which a magnet roller having an axis parallel to the axis of the photosensitive drum is internally mounted rotatably in an opening of the developing unit case facing one side of the circumference of the photosensitive drum. In the image forming apparatus configured as described above, the regions affected by magnetism at the left and right end portions of the magnet roller are set so as to be appropriately inwardly located from the left and right end portions of the developing sleeve, and the developing portion case is provided. A substantially semi-circular cutout is formed on both left and right side plates of the opening, and a side seal member is disposed so as to be in sliding contact with substantially half circumferential portions of both left and right circumferential ends of the developing sleeve. The roller is arranged so that it is located outside the region where the influence of magnetism is exerted on the left and right ends of the roller, or is a portion where the influence is small, and along the semicircular surface of the cutout portion. A characteristic image forming apparatus.