JP3094255B2 - Developing unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for preventing a developer from leaking from a developing device installed in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art Generally, an electrophotographic image forming apparatus such as a copying machine or a printer includes a platen on which a document is placed, a document irradiation lamp reciprocating below the platen, a reflection mirror, a fixed projection lens and a reflection mirror. A scanning optical system configured;
A photoconductor drum that is rotated by being charged with a predetermined potential by a band electrode; a developing device that applies toner to an electrostatic latent image formed on the photoconductor drum surface by the scanning optical system to develop the electrostatic latent image; A transfer pole for transferring a toner image onto a recording paper surface, which is a transfer material conveyed below the body drum surface; a separation electrode and a removal electrode; and fixing the toner image transferred onto the recording paper surface. The fixing device includes a fixing device and a cleaning device that removes toner, paper dust, and the like remaining on the photoconductor surface after the transfer.

[0003] A desired toner image is successively recorded on the surface of a recording sheet conveyed intermittently according to a predetermined conveying path.

FIG. 4 is a cross-sectional view of a main part of the developing device 6, and FIG.
Is a developing device main body that forms the housing of the developing device 6, 22 is a first stirring member, 23 is a second stirring member, 24 is a supply roller, 26 is a developing sleeve, and 28 is a developing member provided on the peripheral surface of the developing sleeve 26. A cylindrical bar 28 a is a developer thin film forming means having rigidity for regulating the amount of developer, 28 a is a spring plate for regulating the amount of developer transported, and the cylindrical bar 28 has no developer in the developing sleeve 26. It is pressed with a constant load in this state. 27 is a scraper that cuts off the ears of developer, 25 is a stirring partition,
Reference numeral 21 denotes an upper lid integrally attached to the upper surface of the developing device main body.

The toner supplied into the developing unit 6 is sufficiently stirred and mixed with the carrier by the second stirring member 23 rotating in the direction of the arrow and the first stirring member 22 rotating so as to overlap each other in the opposite direction. The supplied upper developer D is sent to the developing sleeve 26 via the supply roller 24.

The first agitating member 22 and the second agitating member 23 are screw-shaped members having a left-handed helical angle rotating in opposite directions of arrows, and are conveyed to the back side by the thrust of the first agitating member 22. The toner and the carrier sequentially pass over the agitation partition plate 25 whose upper edge is inclined low in the depth direction of the drawing, and the second
A supply roller that moves to the stirring member 23 side, is conveyed to the near side of the drawing by the thrust, and is a uniform developer D that is frictionally charged by the mixing action of the toner and the carrier therebetween, and is sponge-shaped and rotates in the direction of the arrow. 24 adheres in a layer on the peripheral surface of the developing sleeve 26 which rotates clockwise as shown by the arrow.

The toner conveyed by the developing sleeve 26 is applied to the electrostatic latent image formed on the peripheral surface of the photosensitive drum 3 adjacent to the developing sleeve 26 at a predetermined gap with a predetermined gap. Is developed. The rotation of each of the first and second stirring members 22 and 23, the supply roller 24 and the developing sleeve 26 is transmitted to each other by a drive transmission mechanism mounted on a side surface of the developing device main body 20.

The toner scattered in the image forming apparatus is sucked by suction provided at an appropriate position.

[0009]

However, as shown in FIG. 4, when the spikes of the developer are cut by a scraper 27 located diagonally above and to the right of the developing sleeve 26, the cut developer gradually accumulates and develops. 26 and the scraper 27 and the developer reservoir D ₁ as shown in FIG between a relatively narrow space between the lower surface of the upper lid 21 are formed. The air flow caused the air flow coming is the developer D and subsequently napping cuts are accumulated occur convection in the opposite direction strikes the developer pool D ₁ in the direction of the arrow by a developing sleeve 26 rotating at high speed The toner separated from the developer D is
Opening 20 formed by the lower surface of the developing sleeve 26 and the peripheral surface of the developing sleeve 26
a to leak and scatter into the image forming apparatus. Then, the scanning optical system is contaminated, and the toner image to be developed and the gears of the main body are adversely affected. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a developing device in which a developer does not leak into an image forming apparatus.

[0010]

The above object is achieved by the following a,
b.

(A) The electrostatic latent image formed on the image carrier is
In the developing device of the image forming apparatus that applies and develops the toner conveyed by the developing sleeve in the developing area, a scraper that cuts off the ears of the developer, on the downstream side in the developing sleeve rotation direction from the developing area. In the developing device main body forming the housing of the developing device, on the downstream side of the developing region with respect to the developing sleeve rotation direction, and on the upstream side of the scraper, and on the peripheral surface of the developing sleeve. A developing device comprising: an air discharge hole provided at a position facing the upper side; and a filter for preventing developer leakage provided at the air discharge hole.

(B) In section a, the upper end surface of the developing device body facing the peripheral surface of the image carrier is extended in the circumferential direction of the image carrier, and the peripheral surface of the image carrier and the developing device body are extended. A predetermined gap between the developing device and the upper end surface of the developing device.

[0013]

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is a side sectional view showing the arrangement and configuration of an air discharge hole and a filter provided in the developing device of FIG. 1, the top view of FIG. 2, and the image forming apparatus of FIG. This will be described with reference to a side sectional view showing the structure and a side sectional view showing the structure of the conventional developing device in FIG. However, the present invention is not limited to this embodiment. Each member of the developing device having the same function as the conventional one is denoted by the same symbol.

The function and operation of the developing device 6 are exactly the same as those of the conventional developing device, so that the description thereof will be omitted, and the present invention and the related differences will be described.

As shown in FIG. 3, the electrophotographic image forming apparatus 18
A platen glass P on which an original M is placed is provided on the upper surface of the main body 1, and a scanning optical device 2 is provided below the platen glass P in the main body 1. The scanning optical device 2 includes a reciprocating original irradiation lamp 2a, a first mirror 2b, second and third mirrors 2c forming a V-shape, a fixed lens 2d, and a fourth mirror 2e. A photoconductor drum 3 is provided in the center of the main body 1 so as to be rotatable in the direction of the arrow, and a band electrode 4 for uniformly charging the photoconductor 3a along the rotation direction and a toner replenishing device around the photoconductor drum 3. A developing device 6 in which toner is supplied by the developing device 5 and a developing sleeve 6a is built in;
A transfer electrode 7, a separation electrode 8, a neutralizing electrode 9, and a cleaning device 10 are sequentially arranged. Paper cassette 11,
In 11 ', two types of recording paper of different sizes are stored and set in the main body 1. 12 is the paper cassette 11
Is a first paper feed roller for feeding the recording paper stored in the printer to a standby position before the second supply roller 13, and is a roller 12a, which is rotated via a belt to prevent double feeding of the recording paper.
12a and a stop roller (also called a separation roller) 12b. Reference numeral 13 denotes an appropriate timing for temporarily stopping the recording paper fed by the first paper feed roller 12 at the standby position, and thereafter, matching the leading end of the visible image on the photoconductor 3a with the leading end of the recording paper at the transfer position. A second paper feed roller for feeding paper again toward the transfer position, and a guide plate 14 for guiding the recording paper fed by the first paper feed roller 12 to the position of the second paper feed roller 13, It is opened and closed by operating a lever (not shown) so that the jam paper can be taken out by putting a hand. Reference numeral 15 denotes a conveying device that conveys the transferred recording paper to a fixing position, and a fixing device 16 includes a heating roller.
16a and a pressure roller 16b. Reference numeral 17 denotes a paper discharge roller for discharging the fixed recording paper to the outside of the main body.

In the above-described apparatus, when the copy button is operated, the original M on the platen glass P is exposed and scanned by the scanning optical device 2, and an electrostatic latent image of the original M is formed on the photosensitive member 3a of the photosensitive drum 3. You. This electrostatic latent image is developed
The visible image is transferred by the transfer electrode 7 to the recording paper fed from one of the paper feed cassettes 11 and 11 'of the main body 1. After the transfer, the recording paper is separated from the photoreceptor 3 a by the separation electrode 8, and the conveyance device 15 fixes the recording paper.
The sheet is conveyed to the fixing roller 16, where it is fixed and discharged by a discharge roller 17. In this way, the required toner images are successively recorded on the recording paper.

An air discharge hole and a filter, which are means for preventing leakage of the developer provided in the developing device of the present invention, are arranged as follows.

As shown in FIGS. 1 and 2, at the position of the upper cover 21 facing the peripheral surface of the developing sleeve 26, a number of air discharge holes 30 formed in a rectangular shape having a predetermined size as shown in the figure. twenty one
Are arranged at regular intervals in the longitudinal direction (the direction perpendicular to the paper surface of FIG. 1).

The filter member 31 is an elongated sheet-like member made of, for example, polyester fiber, and covers the upper surface of the air discharge hole 30 formed in the upper lid 21 with, for example, a double-sided tape, without any gap. Is pasted on.

As shown in FIG. 1, the front end of the upper cover 21 facing the peripheral surface of the photosensitive drum 3 extends in the peripheral direction of the photosensitive drum 3 from the conventional position, and the inner side is in contact with the peripheral surface of the developing sleeve 26. A developer leakage preventing wall 21a is formed concentrically with a predetermined gap, and the outside thereof is formed by an arc substantially concentric with the peripheral surface of the photosensitive drum 3, as shown in FIG. It is provided facing the peripheral surface of the body drum 3. A bottleneck 32 formed between the outer surface of the leakage prevention wall 21a and the peripheral surface of the photosensitive drum 3 makes it difficult for the developer D and toner in the developing device 6 to leak into the image forming apparatus 18. The distance between the bottlenecks 32 is set to 3 mm or less, preferably
It is set to around 1.3mm. With the air discharge hole 30, the filter member 31, and the developer leakage preventing wall 21a configured as described above, the above-described flow of air and the developer D scattered at the time of cutting by the scraper 27 are completely collected by the filter member 31. Only the clean air is discharged out of the developing device 6 in the direction of the arrow.

Accordingly, leakage of the developer D and toner from the developing device 6 is prevented, and the inside of the image forming apparatus 18 is always kept clean. Also highly effective in the developer D and toner leak preventing the air discharge holes 30 and the filter member 31 to the toner scattering during napping cut by even example scraper 27 in the absence of the developer pool D ₁ described above above It is arranged at an appropriate position corresponding to the characteristics of the developing device 6 irrespective of the position. Further, the filter member 31 can be replaced at any time during predetermined maintenance or at an appropriate time.

In this manner, a good toner image is always developed on the peripheral surface of the photosensitive drum 3.

[0024]

According to the present invention, the developer reservoir formed in the developing device by the air discharge hole and the filter member provided in the developing device of the present invention,
The developer scattered at the time of cutting the ears was collected by the filter member and prevented from leaking into the image forming apparatus. Further, since a developer leakage preventing wall provided at the front end of the upper lid forms a bottleneck having an appropriate width between the photosensitive drum and the peripheral surface thereof, leakage of the developer is further prevented.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing the arrangement and configuration of an air discharge hole and a filter provided in a developing device according to an embodiment of the present invention.

FIG. 2 is a top view of the above.

FIG. 3 is a side sectional view showing a configuration of the image forming apparatus.

FIG. 4 is a side sectional view showing a main configuration of a conventional developing device.

[Explanation of symbols]

3 Photoreceptor drum 6 Developing device 18 Image forming device 20 Developing device main body 21 Upper cover 21a Developer leakage preventing wall 26 Developing sleeve 27 Scraper 30 Air exhaust hole 31 Filter member 32 Bottleneck D Developer D ₁ Developer reservoir

Claims (2)

(57) [Claims] 1. A developing device of an image forming apparatus for applying a toner conveyed by a developing sleeve in a developing area to an electrostatic latent image formed on an image carrier and developing the electrostatic latent image, wherein the developing sleeve is larger than the developing area. On the downstream side in the rotation direction, a scraper that cuts the ears of the developer, and on the developing device main body that forms the housing of the developing device, on the downstream side of the developing region with respect to the developing sleeve rotation direction, And an air discharge hole provided at a position upstream of the scraper and opposed to above the peripheral surface of the developing sleeve, and a filter for preventing developer leakage provided at the air discharge hole. A developing device comprising: 2. The image forming apparatus according to claim 1, wherein an upper end surface of the developing device body facing the peripheral surface of the image carrier is extended in a circumferential direction of the image carrier, and a peripheral surface of the image carrier and an upper distal surface of the developing device body are formed. 2. The developing device according to claim 1, wherein a predetermined gap is provided between the developing devices.