JP3350200B2 - Developing device in image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a developing device in an image forming apparatus such as a laser beam printer, a copying machine, a facsimile machine and the like.

[0002]

2. Description of the Related Art Conventionally, as an apparatus of a dry developing system for supplying a developing agent to a developing area on the surface of a photosensitive drum and performing development, there is a developing apparatus as disclosed in Japanese Patent Publication No. 4-48232. is there. In this developing device, a developing unit case adjacent to a photosensitive drum is previously provided with an empty chamber for storing a developer (a mixture of a magnetic carrier and a magnetic toner), and a magnetic roller is provided on an inner peripheral portion of the outer peripheral surface. And a developing sleeve for carrying a mixture of the toner and the magnetic carrier. Further, a partition for partitioning the developing unit case and the toner supply chamber provided with the toner stirring member is provided with a toner supply slit extending in the axial direction of the development sleeve and communicating with the empty chamber. The toner supply chamber is provided with a stirring member for supplying the toner to the slit and the empty space.

[0003] As shown in FIG. 12 in the prior art, a blade 37 for adjusting the height of the magnetic brush on the developing sleeve 32 is provided on the developing unit case 30.
Thereby, a magnetic brush having a predetermined height is formed on the outer peripheral surface of the developing sleeve 32, and toner is supplied from the developing sleeve 32 side toward the peripheral surface of the photosensitive drum 7 during an image forming operation. It is known to be configured as such.

Incidentally, the leakage of the developer such as the toner and the magnetic carrier in the developing unit case 30 from the portion other than the peripheral surface of the developing sleeve 32 is caused by the photosensitive drum 7 and the paper to be fed. Since the surface and the like are inadvertently stained and the toner is wasted, as shown in FIGS. 12 and 13, both left and right side plate portions 30 a ( (Only one of them is shown in the figure), a semicircular notch 33 is formed so that a semicircular portion of the developing sleeve 32 is fitted, and a band-shaped sealing material 34 made of a felt material or the like is formed along the notch 33. While
The front plate 30b of the developing unit case 30 along the axial direction of the developing sleeve 32 is provided with the blade so that an appropriate gap is formed between the front plate 30b and the outer peripheral surface of the developing sleeve 32 to form a magnetic brush having a predetermined height. 37 is attached.

[0005]

In this case, the semicircular notch 33 and the side plate 30 in the developing unit case 30 are used.
At the connecting portion 30c with the a, the sealing material 34 is bent in a direction opposite to the bending direction of the semicircular notch 33. At this time, although the bending radius of the connecting portion 30c is small, the small bending portion 34b of the sealing material 34 bent along the small bending connecting portion 30c is located between the peripheral surface end of the developing sleeve 32 and the side surface. A substantially triangular gap S is generated when viewed, and the gap S cannot be closed by the blade 37.
There is a disadvantage that the toner inside leaks out.

The present invention has been made to solve this technical problem. Leakage of toner can be easily prevented by devising a shape of a connecting portion between a notch and a side plate in a developing unit case. An object is to provide a developing device.

[0007]

In order to achieve the above object, a developing device in an image forming apparatus according to the present invention comprises a cylindrical developing sleeve rotatably mounted in an opening of a developing unit case in the developing device. In the image forming apparatus, a semicircular notch is formed on both left and right plates of the opening in the developing unit case, and a projection is formed at a corner between the both notches and the end faces of the left and right plates. A seal material disposed to abut substantially half-circumferential portions of both left and right circumferential ends of the developing sleeve, and a semi-circular end face of the notch portion via projections from end faces of left and right side plates of the opening; And the blades are disposed on the end faces of the left and right side plates.
It is arranged so as to come into contact with the sealing material .

[0008]

Next, an embodiment of the present invention will be described. FIG. 1 is a schematic side sectional view of a printer 1 as an image forming apparatus, and FIG. 2 is a partially cutaway perspective view of a developing unit case in the developing device. In the printer 1 according to the present embodiment, a paper feed cassette 3 is detachably mounted on one upper side of a 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. Are separated one by one and conveyed to a photoreceptor unit 9 including a photoreceptor drum 7 and a transfer roller 8 via a pair of convey rollers 6. A developing device 10 to be described later is arranged on the side close to the paper feed cassette 3 adjacent to the photoreceptor unit 9, and a fixing unit 13 including a heating roller 11 and a pressing roller 12 is arranged on the opposite side.

Below the photoreceptor unit 9, a scanner unit 17, which includes a laser emitting unit 14, a lens 15, a reflecting mirror 16, etc., control boards 18, 19, and a power supply unit 20
The cover body 21 is provided with a plurality of operation buttons 22. The surface of the photosensitive drum 7 charged in advance by the charger 23 is irradiated with light emitted from the scanner unit 17 in accordance with image data transmitted from an external device such as a computer (not shown). 7, an electrostatic latent image is formed on the surface of developing device 1
0, the developing sleeve 32 is rotated in the direction of arrow A to supply the toner in the form of powder and the latent image is visualized by supplying the toner. Then, the toner image is transferred to the sheet (recording medium) supplied during the period, and then the toner image is fixed on the sheet by applying heat and pressure to the transferred image by the fixing unit 13 and discharged. The paper is discharged from the paper roller pair 24 to the paper discharge tray 25 of the printer 1.

Since the internal structure of the developing device 10 is substantially the same as the conventional structure as shown in FIG. 12, the same members are designated by the same reference numerals, and detailed description thereof will be omitted. The main part of the embodiment will be described below with reference to FIGS. Developing unit case 3 in developing device 10
The opening 31 of “0” is opened so as to face the peripheral surface of the photosensitive drum 7. A developing sleeve 32 having a built-in magnet roller (not shown) is rotatably disposed in the opening 31, and one outer peripheral surface of the developing sleeve 32 is disposed so as to face the outer peripheral surface of the photosensitive drum 7. ing.

The left and right side plates 30a, 30a of the opening 31 in the developing unit case 30 are formed with cutouts 33 each having a substantially semicircular arc having a radius substantially equal to the radius of the developing sleeve 32 in a side view. And, in each of the notches 33,
As shown in FIG. 5 and FIG.
Notch step 35 having a substantially semicircular arc shape in side view for attaching 4
To form Each notch 35 and the left and right side plates 3
0a and 30a are connected to the stepped portion 35a on the end face side,
As shown in FIGS. 2 and 3, a belt-like sealing material 34 formed integrally with a projection 36 projecting inward in the radial direction such as the axial center direction of the developing sleeve 32 and having a substantially rectangular cross section is formed. To the left and right side plates 30a, 30 of the opening.
The notch 35 is disposed along the semicircular end face of the cutout step 35 from the step 35a on the end face side of FIG.

With such a configuration, the semi-circular inner diameter side of the sealing material 34 attached to each of the notch steps 35 is in contact with the substantially half-circumferential portions at the left and right circumferential ends of the developing sleeve 32. (See the dashed line in FIG. 4). After the sealing member 34 is thus provided, a blade 37 for adjusting the height of the magnetic brush is attached to the front plate 30b of the developing unit case 30 along the axis of the developing sleeve 32 with a set screw 38 or the like. . In this case, as shown in FIG. 3 and FIG.
The end 34a of the sealing member 34 is restrained by sandwiching the end 34a of the fourth member 4 between the step 35a and the blade 37. It is more preferable that an adhesive is applied to the surface of the step 35a, the projection 36, and the notch step 35, and the sealing material 34 is adhered and fixed along the surface, so that the sealing material 34 cannot be separated.

Thus, the longitudinal edge 37a of the blade 37
As shown in FIG. 3, a gap 39 having a dimension H1 for regulating the height of the magnetic brush is formed between the protrusion 36 and the peripheral surface of the developing sleeve 32. As shown in the drawing, when the seal member 34 is bent radially outward of the developing sleeve 32, the seal member 34 is pressed radially inward of the developing sleeve 32, and the seal member 34 And the developing sleeve 3
2 can be in close contact with both left and right ends of the peripheral surface of the developing sleeve 32.
There is no gap that communicates with the outside of the left and right side plates 30a, 30a.

Therefore, the magnetic carrier and toner (developer) in the developing unit case 30 do not leak to the outside of the side of the developing unit case 30, so that it is possible to prevent the inconvenience of contamination of the paper by the developer and to prevent the developer from being inconvenient. This has the effect that unnecessary consumption can be prevented. In the second embodiment shown in FIGS. 9 to 11, a substantially semicircular notch step 35 is formed inside the left and right side plates 30a, 30a of the developing unit case 30, and the notch step is formed. A projection 36 is integrally formed at a connecting portion between the step 35 and the step 35a along the inner end face of the side plate 30a. The semicircular end face of the notch step 35 is formed from the step 35a via the projection 36. A band-shaped sealing material 34 may be provided along the direction.

In both of the above embodiments, a semi-arc notch step 35 is formed along the semi-arc notch 33,
The seal material 34 is attached to the notch step 35, but the notch step 35 is not formed.
It goes without saying that a band-shaped sealing material 34 may be provided along the projection 36 at the connection portion between the third and right and left side plates, and fixed with an adhesive.

[0016]

As described above, the developing device in the image forming apparatus of the present invention has a cylindrical developing sleeve rotatably mounted on the opening of the developing unit case of the developing device. In the device, a semicircular notch is formed on both left and right side plates of the opening in the developing unit case,
A projection is formed at the corner between both the cutouts and the end surfaces of the left and right plates, and seal materials arranged so as to abut substantially half of the left and right circumferential ends of the developing sleeve are provided on the left and right sides of the opening. Arranged along the semicircular end face of the notch through the projection from the end face of the plate , the blade is attached to the end face of the left and right side plates
The sealing member is disposed so as to come into contact with the sealing member .

[0017] Thus, at the location of the projection, the sealing member is bent in a radially outward direction of the developing sleeve, closer to the projection
Sandwich the end of the sealing material between the protrusion and the blade.
As a result, the sealing material is pressed inward in the radial direction of the developing sleeve, and the sealing material is sharpened on the inner diameter side near the protrusion, so that the sealing material comes into close contact with both left and right ends of the peripheral surface of the developing sleeve. As a result, there is no gap between the left and right ends of the peripheral surface of the developing sleeve and the outsides of the left and right side plates of the developing unit case.

As a result, the developer such as toner in the developing unit case does not leak out unnecessarily, thereby preventing waste of the developer and developing the image on paper (recording medium) for image formation. This has the effect of preventing the generation of stains due to the agent. In addition, since the projection is formed at the connecting portion between the cutout portion and the end surfaces of the left and right side plates, the production cost is not increased.

[Brief description of the drawings]

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

FIG. 2 is a partially cutaway perspective view of a main part of a developing unit case.

FIG. 3 is a front view of a developing unit case.

FIG. 4 is a side view showing a mounting direction of a developing sleeve and the like.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a view taken along line VI-VI of FIG. 4;

FIG. 7 is an enlarged sectional view taken along line VII-VII of FIG. 3;

8 is an enlarged sectional view taken along line VIII-VIII in FIG. 7;

FIG. 9 is a partially cutaway front view of another embodiment.

FIG. 10 is a sectional view taken along line XX of FIG. 9;

11 is a sectional view taken along line XI-XI in FIG.

FIG. 12 is a side sectional view of a developing unit case of a conventional example.

FIG. 13 is a perspective view of a developing unit case and a sealing material in a conventional example.

[Explanation of symbols]

 Reference Signs List 1 printer 7 photoreceptor drum 10 developing device 30 developing unit case 30a, 30a left and right side plates 31 opening 32 developing sleeve 33 notch 34 sealing material 35 notch step 36 protrusion 37 blade

Claims (1)

(57) [Claims] 1. An image forming apparatus comprising: a developing unit case in which a cylindrical developing sleeve is rotatably mounted in an opening of the developing unit case; A notch is formed, a projection is formed at a corner between the both notches and the end surfaces of the left and right side plates, and the developing sleeve is disposed so as to abut substantially half-circumferential portions at both left and right circumferential ends of the developing sleeve. A sealing material is provided along the semicircular end surface of the notch through a projection from the end surfaces of the left and right side plates of the opening, and a blade is provided on the end surface of the left and right side plates. Shi
A developing device in the image forming apparatus, wherein the developing device is disposed so as to be in contact with the sealing material .