JP3090041B2 - 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 an electrostatic latent image formed on the surface of a photoreceptor drum and a method for developing the electrostatic latent image with toner. The present invention relates to a developing device used in an image forming apparatus such as a laser printer that transfers an image formed on a sheet to form an image, and particularly, applies toner discharged from a toner supply port formed in the developing device to a supply roller. In this process, it is possible to apply fresh toner uniformly over the entire supply roller while effectively preventing low-quality toner that is difficult to use for development from accumulating in the developing chamber. Therefore, the present invention relates to a developing device in an image forming apparatus capable of forming an image having excellent image quality with excellent durability and stability over a long period of time.

[0002]

2. Description of the Related Art Hitherto, various types of developing devices used in image forming apparatuses such as laser printers have been proposed. Such developing devices are unitized and configured to be detachable from a laser printer. And a replaceable toner cartridge for storing toner, and a toner supply hole formed substantially at the center in the width direction of the toner cartridge and a toner supply hole formed on the frame side. Is generally configured to supply toner from a toner supply port composed of FIG. 6 shows an example of such a developing device.
It will be described based on. FIG. 6 is an explanatory view schematically showing a main part of a conventional developing device.

In FIG. 6, a developing device has a toner cartridge 100 in which toner is stored and a toner supply hole is formed at a substantially central position in the width direction, and the toner is stirred in the toner cartridge 100. An agitator 103 that supplies toner from the toner supply port 101 to the developing chamber 102 is provided. In frame F,
Toner supply holes are formed corresponding to the toner supply holes formed in the toner cartridge 100.
The toner supply port 101 is constituted by the two toner supply holes. The toner supply roller 1 is located at a lower position in the developing chamber 102 closed by the upper frame F1 and the lower frame F2.
The toner supply roller 104 supplies the toner supplied from the toner supply port 101 to the developing roller 105. Further, the developing roller 105
A blade 107 is fixed to the inner wall of the upper frame F1 above the fixing member 106 via a fixing member 106. The blade 107 acts to regulate the thickness of the toner layer supplied to the surface of the developing roller 105. . Further, the developing roller 1
Numeral 05 is arranged so as to be in contact with the photosensitive drum 108, and an electrostatic latent image is formed on the surface of the photosensitive drum by an exposure device (not shown) that scans a laser beam based on image data. The developing roller 105 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 108 to perform toner development of the image.
The image developed on the surface of toner image 8 is transferred onto a sheet fed from a sheet feeding unit (not shown) to form an image.

[0004]

In the toner cartridge 100 of the conventional developing device, if the toner spills outside and scatters when the toner cartridge 100 is replaced, the toner adheres to other portions of the laser printer. The toner supply port 101 needs to be prevented from being stained.
Usually, only one portion is formed substantially at the center in the width direction of the toner cartridge 100 (the direction perpendicular to the paper surface in FIG. 5 and coincides with the width direction of the laser printer).

Therefore, when the toner is supplied from the toner cartridge 100 to the developing chamber via the toner supply port 101, the toner tends to stay in the central portion of the toner supply roller 104.
4, the supply of toner to both ends is insufficient. In such a case, it is not possible to uniformly supply the toner over the entirety of the toner supply roller 104 and apply the toner.
The toner cannot be uniformly supplied to the electrostatic latent images on the developing roller 105 and the photosensitive drum.
As a result, in the image formed on the paper, there is a problem that density unevenness occurs at the center and both ends, and it is not possible to form an image having good image quality.

To solve the above problem, the toner supply port 10
1 may be formed over the entire width of the toner cartridge 100 so that the toner is supplied over the entire toner supply roller 104.
The toner supplied to both sides of the toner image 04 tends to stay in that portion. At this time, since the toner is used from fresh toner which is easy to use for image development, only poor quality toner which is hard to use for image development remains at both ends of the toner supply roller 104. .
Therefore, even in such a case, there remains a problem that an image having good image quality cannot be formed.

[0007] The present invention has been made to solve the conventional problems, which is formed in the developing device, toner
When the toner discharged from the toner supply port for supplying the toner from the cartridge to the developing chamber is applied to the supply roller, poor quality toner that is difficult to use for development stays in the developing chamber. It is possible to constantly apply fresh toner uniformly over the entire supply roller while effectively preventing the accumulation, and thus, it is possible to obtain an image having excellent image quality with excellent durability and stability for a long time. It is an object of the present invention to provide a developing device in an image forming apparatus that can be formed over a range of time.

[0008]

According to a first aspect of the present invention, there is provided a developing device for an image forming apparatus for forming an image by an electrophotographic process, wherein the developing device is arranged to face a photosensitive drum. A developing roller for developing the electrostatic latent image formed on the photosensitive drum with toner,
In a developing device having a supply roller disposed to face a developing roller and supplying toner to the developing roller, toner is supplied to the developing chamber from a toner cartridge formed on both sides of the developing chamber provided with the developing roller and the supply roller. You
Toner supply port of the order, and toner cart Li from the developing chamber
A toner suction port for returning toner into the toner cartridge, and a supply roller disposed near the toner supply port and the toner suction port for conveying and circulating toner from the toner supply port toward the toner suction port. And an auger member to be adhered to the auger.

In the developing device according to the first aspect, when an image is formed in the image forming apparatus, the toner cartridge is removed from the toner cartridge.
The toner is discharged from a toner supply port for supplying the toner to the image chamber, and is attached to a supply roller. At this time, an auger member is disposed near the toner supply port, and toner is transferred from the developing chamber to the toner via the auger member.
-The toner is transported and circulated toward the toner inlet for returning the toner into the cartridge,
While being circulated between the cartridge and the developing chamber, the toner is uniformly applied over the entire supply roller. As described above, the toner applied to the supply roller is supplied to the developing roller, and the developing roller supplies the toner to the electrostatic latent image formed on the surface of the photosensitive drum, thereby forming the electrostatic latent image. Perform toner development. Thereafter, the image developed with the toner on the surface of the photosensitive drum is transferred to a sheet, and an image is formed on the sheet.

According to the first aspect of the present invention, the auger member is disposed near the toner supply port, and toner flows from the toner supply port toward the toner suction port via the auger member .
The toner is conveyed and circulated between the toner cartridge and the developing chamber. This makes it possible to constantly apply fresh toner evenly over the entire surface, thereby making it possible to uniformly supply toner even to the electrostatic latent image on the developing roller and the surface of the photosensitive drum. This makes it possible to form an image having excellent image quality with excellent stability over a long period of time.

According to a second aspect of the present invention, in the developing device of the first aspect, the auger member is formed with spiral teeth extending from one end to the other end. In the developing device according to the third aspect, in the developing device according to the second aspect, the auger member causes the toner from the toner supply port to adhere to the supply roller while being transported by the helical teeth and to transfer the toner to the toner suction port. It is characterized by the following. In the developing device according to the second or third aspect, the auger member conveys the toner from the toner supply port to the toner suction port through the spiral teeth extending from one end to the other end, and supplies the toner to the supply roller. The toner is applied and transferred to the toner suction port, so that the toner is transferred to the toner cartridge while being transported through the auger member.
Since the toner is circulated between the supply roller and the supply roller, fresh toner can be constantly applied over the entire supply roller.

Further, a developing device according to a fourth aspect of the present invention is a developing device in an image forming apparatus for forming an image by an electrophotographic process, wherein the developing device is disposed opposite to the photosensitive drum and formed on the photosensitive drum. In a developing device having a developing roller that develops an image with toner and a supply roller disposed to face the developing roller and supplying toner to the developing roller, the developing device is formed at a central position of a developing chamber provided with the developing roller and the supply roller. From the toner cartridge
A toner supply opening for supplying toner to the developing chamber, formed in the developing chamber on both sides of the toner supply opening, a developing chamber
A pair of toner suction ports for returning toner into the toner cartridge, and a toner supply port and a toner supply port are disposed in the vicinity of each toner suction port, and the toner from the toner supply port is conveyed and circulated toward each toner suction port. An auger member to be attached to the supply roller.

According to the fourth aspect of the present invention, when an image is formed by the image forming apparatus , toner is supplied to the developing chamber from a toner cartridge formed at a central position of the developing chamber.
Is discharged from the toner supply port and attached to the supply roller. At this time, an auger member is disposed at a position near the toner supply port, and toner is formed on both sides of the toner supply port via the auger member .
The toner is conveyed and circulated toward each toner suction port for returning the toner from the developing chamber into the toner cartridge, so that the toner is supplied to the supply roller while being circulated between the toner cartridge and the developing chamber . It will be uniformly applied over the whole. As described above, the toner applied to the supply roller is supplied to the developing roller, and the developing roller supplies the toner to the electrostatic latent image formed on the surface of the photosensitive drum, thereby forming the electrostatic latent image. Perform toner development. Thereafter, the image developed with the toner on the surface of the photosensitive drum is transferred to a sheet, and an image is formed on the sheet.

According to a fourth aspect of the present invention, an auger member is disposed in the vicinity of the toner supply port, and toner is transferred from the toner supply port to the toner cartridge through the auger member toward the respective toner suction ports on both sides thereof. Since the toner is conveyed and circulated between the developing roller and the developing roller, it is possible to effectively prevent poor-quality toner, which is hardly used for development, from staying and accumulating in the developing chamber, and to constantly refresh the entire supply roller. Toner can be uniformly applied to the developing roller and the electrostatic latent image on the surface of the photoreceptor drum.
This makes it possible to form an image having excellent image quality with excellent stability over a long period of time.

According to a fifth aspect of the present invention, in the developing device of the fourth aspect, the auger member conveys the toner from a position corresponding to the toner supply port toward both ends. According to a sixth aspect of the present invention, in the developing device of the fifth aspect, the auger member is formed with spiral teeth extending from a center position to both ends. In the developing device according to the fifth and sixth aspects, the auger member conveys the toner from the toner supply port to each of the toner suction ports on both sides of the auger member through the spiral teeth extending from the center position to the other end. The toner is circulated between the toner cartridge and the developing chamber while being conveyed through the auger member, while being adhered to the supply roller and transferred to each toner suction port. It is possible to always apply fresh toner over the entire area.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device in an image forming apparatus according to the present invention will be described in detail with reference to the drawings based on an embodiment in which the present invention is embodied as a developing device of a laser printer. First, a schematic configuration of the laser printer according to the first embodiment will be described with reference to FIGS. FIG. 1 is an exploded perspective view of main components of the laser printer, and FIG. 2 is a side sectional view of the laser printer.

In FIG. 1, the main body case 1 of the laser printer P is formed by integrally molding a main frame 1a and a main cover 1b by injection molding or the like. The main frame 1a includes a scanner unit 2, a process unit 3,
The fixing unit 4 and the paper feeding unit 5 are mounted from above. Further, the main cover 1b covers the outer surfaces of the main frame 1a on four sides (front and rear and both right and left sides). Further, a drive system unit 6 including a drive motor and a gear train is housed in a storage recess 33 formed by an outer surface of the main frame 1a and an inner surface of the main cover 1b.
And inserted and fixed from below.

The top surfaces of the main frame 1a and the main cover 1b are covered with a top cover 7, and the top cover 7 is used to penetrate an operation panel 1c that is formed to project upward from the main frame 1a. Hole 7
a and an opening 7b for penetrating the base of the sheet feeding unit 5. Further, a pair of brackets 9 having support shafts 9a protruding inward on both sides thereof are provided on the front side (right side in FIG. 1) of the top cover 7 (in FIG. 1, Only one of them is shown), and the support shaft 9a of each bracket 9 supports a support hole 8b of each support portion 8a formed on both sides of the paper discharge tray 8. As a result, the paper discharge tray 8 is attached to the top cover 7.
Is rotatably supported with respect to. Also, the top cover 7
A step 7e is formed between the upper surface of the side portions 7c and the upper surface of the central portion 7d on the upper surface of the paper discharge tray 8 when the paper discharge tray 8 is not used.
Is formed on the central portion 7d of the top cover 7 to form a storage recess 7f (see FIG. 2). Thereby, the paper discharge tray 8 is stored in the storage recess 7f by rotating to the storage position on the top cover 7 side when not in use, and is rotated from the storage position in the direction opposite to the storage direction during use. Accordingly, the sheet discharged from the fixing unit 4 is set at a stack position (see FIG. 2) where the sheets are sequentially stacked.

Next, a schematic configuration inside the laser printer P will be described with reference to FIG. In FIG. 2, sheets 50 are stored in a stacked state in a feeder case 5a of the sheet feeding unit 5, and a leading end of each sheet 50 is provided with a biasing spring 10a provided in the feeder case 5a. The paper feed roller 11 and the paper separating member 62 that are pressed toward the paper feed roller 11 via the plate 10 and are rotated by being transmitted with power from the drive system unit 6.
And are separated one by one. Paper 50 separated
Is supplied to the process unit 3 by a pair of upper and lower registration rollers 13 and 14.

The process unit 3 supplies toner to an electrostatic latent image formed on the surface of the photosensitive drum 12 in accordance with image data via a laser optical system provided in the scanner unit 2 and described later. This is a unit for performing latent image toner development. More specifically, the process unit 3 includes a photosensitive drum 12 and a transfer roller 17 in contact with an upper surface thereof, a scorotron-type charger 18 disposed below the photosensitive drum 12, and a photosensitive drum in the sheet feeding direction. A developing device having a developing roller 19 and a toner supply roller 20 disposed upstream of the photosensitive drum 12; a detachable toner cartridge 21 serving as a toner storage unit disposed upstream of the developing device 19; Cleaning roller 22 disposed at
And so on.

An auger roller 34 is rotatably disposed above the toner supply roller 20 in the developing chamber of the developing device. The auger roller 34 develops from the toner cartridge 21 through the toner supply port 21A (formed of a hole formed on one side (left side in FIG. 4) of the toner cartridge 21 and a hole formed on the unit frame 25). The toner supplied to the chamber is
Above the toner cartridge 21 toward the toner inlet 21B (formed of a hole formed in the other side of the toner cartridge 21 (the right side in FIG. 4) and a hole formed in the unit frame 25). I do. Thus, auger roller 3
4, the toner supplied from the toner supply port 21A to the developing chamber side is conveyed and circulated above the toner supply roller 20 in the direction of the toner suction port 21B. The toner is supplied while being adhered to the toner supply roller 20. The detailed configuration of the auger roller 34 will be described later.

The blade 24 is fixed to the lower surface of the unit frame 25 above the developing roller 19 by an L-shaped blade fixing member 36. Such a blade 24
Is for regulating the thickness of the toner layer supplied from the toner supply roller 20 onto the developing roller 19 to a predetermined thickness.

Further, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 12 by scanning (scanning) a laser beam from the scanner unit 2 on the charged layer formed by the charger 18. The toner in the toner cartridge 21 is agitated by the agitator 23 and is supplied to the toner supply port 21.
After being released from A, the toner is carried on the outer peripheral surface of the developing roller 19 via the toner supply roller 20, and the thickness of the toner layer is regulated by the blade 24. The electrostatic latent image formed on the photosensitive drum 12 is visualized by toner adhered from the developing roller 19, and is transferred to a sheet 50 passing between the transfer roller 17 and the photosensitive drum 12. And
The toner remaining on the photosensitive drum 12 is temporarily held by the cleaning roller 22, returned to the photosensitive drum 12 at a predetermined timing, and collected by the developing roller 19 into the developing chamber.

The process unit 3 configured as described above is made into a cartridge by being incorporated in a unit frame 25 made of synthetic resin, and this process unit 3 made into a cartridge is detachably attached to the main frame 1a. Be attached.

The scanner unit 2 includes a known laser optical system, and scans the laser optical system based on predetermined image data to form an electrostatic latent image on the surface of the photosensitive drum 12. . More specifically, the scanner unit 2 is disposed below the process unit 3, and a scanner cover 26 is attached to the upper surface of the scanner unit 2. The scanner cover 26 is fixed to the main frame 1a on the upstream side of the bottom plate 27 so as to cover most of the opening. The scanner unit 2 as an exposure unit includes a laser light emitting unit (not shown), a scanner motor 28, a polygon mirror 29, a lens 30, a reflecting mirror 31, and the like arranged on a lower surface side of a scanner cover 26. ,
The light passes through a glass plate 33 inserted into a horizontally long scanner hole 32 formed so as to extend along the axis of the photosensitive drum 12 at the scanner cover 26 and irradiates the outer peripheral surface of the photosensitive drum 12 in the process unit 3. Is done. Thus, an electrostatic latent image is formed on the outer peripheral surface of the photosensitive drum 12 by exposure in accordance with the image data. As described above, the toner is supplied to the electrostatic latent image formed on the photosensitive drum 12 by the laser optical system of the scanner unit 2 through the process unit 3, and the toner development of the electrostatic latent image is performed. Will be

As described above, the toner image based on the electrostatic latent image formed on the photosensitive drum 12 in the process unit 3 is transferred onto the sheet 50 fed to the process unit 3, and thereafter, the fixing unit 4 In the fixing unit 4, the toner image transferred onto the sheet 50 via the pair of heating rollers 15 and the pressing roller 16 is thermally fixed. Thereafter, the paper 50 on which the image is formed is discharged while being sequentially stacked on the discharge tray 8 at the stack position by the rollers 15 and 16. Here, in FIG. 2, the trajectory R of the sheet 50 fed from the sheet supply unit 5 to the sheet discharge tray 8 is indicated by a two-dot chain line.

Next, a detailed configuration of the developing chamber in the process unit 3 will be described with reference to FIGS.
FIG. 3 is a side sectional view of the process unit 3, and FIG. 4 is a front sectional view showing the inside of the developing chamber. The developing chamber D includes an upper seal member 37 disposed on the lower surface of the upper frame 25A of the unit frame 25, a lower frame 25B of the unit frame 25, and a pair of side walls formed on both sides of the developing chamber D and formed of a sponge material. Seal member 38 (see FIG. 4)
It consists of a space surrounded by. Further, the toner supply roller 20 is configured by coating a roller member 20C made of a sponge material around a roller shaft body 20B having a roller shaft 20A formed at both ends thereof, and each roller shaft 20A is provided with a side seal member. 38, and is supported by a pair of support plates 39 rotatably attached to the lower frame 25B on the outside thereof (see FIG. 4).

The center of rotation of each support plate 39 is indicated by C in FIG. Further, each support plate 39 is provided with the developing roller 19.
Are rotatably supported, and each support plate 3 is urged clockwise in FIG. 3 via an urging spring (not shown).
The developing roller 19 is rotated clockwise around the rotation center C, and the developing roller 19 is brought into contact with the photosensitive drum 12. As described above, since the toner supply roller 20, the auger roller 34, and the developing roller 19 are integrally supported on each support plate 39, the positional relationship between the toner supply roller 20, the auger roller 34, and the developing roller 19 is determined. Adjustment can be easily performed as a unit, and maintenance and the like can be easily performed.

Further, as shown in FIG.
4 has a spiral tooth 34A spirally formed from one end (the left end in FIG. 4) to the other end (the right end in FIG. 4), and has a roller shaft 34B similar to that of the toner supply roller 20. , Each supporting plate 39. When the auger roller 34 is rotated clockwise in FIG. 3, the toner supplied from the toner supply port 21 </ b> A sequentially flows to the left of the developing chamber D above the toner supply roller 20 according to the spiral direction of the spiral teeth 34 </ b> A. To the right (arrow A direction)
And a part of the toner is returned into the toner cartridge 21 from the toner inlet 21B. As described above, based on the toner conveying action of the auger roller 34, the toner in the toner cartridge 21 is circulated along the path from the toner supply port 21A to the toner cartridge 21 via the toner suction port 21B, and therefore, is used for image development. Unused toner is conveyed and circulated as described above and returned to the toner suction port 21B, so that the toner does not stay in the developing chamber D for a long time. Thus, fresh toner can always be supplied from the toner cartridge 21. Also,
Since the toner is agitated and circulated by the auger roller 34 as described above, the fluidity of the toner can be favorably maintained without the toner being hardened in the developing chamber D.

As described above, the auger roller 34 functions to convey and circulate the toner supplied from the toner supply port 21A into the developing chamber D in the direction of the toner suction port 21B above the toner supply roller 20. Thus, the toner supply roller 2 does not locally stay
0, the toner can be uniformly supplied over the entire surface and the toner can be deposited. Further, based on the fact that the toner is conveyed and circulated from one end to the other end thereof above the toner supply roller 20 via the auger roller 34, the toner supply roller 2
0, it is possible to constantly apply fresh toner uniformly over the entire surface of the developing roller 19, thereby making it possible to uniformly supply the toner to the developing roller 19 and the electrostatic latent image on the surface of the photosensitive drum 12. Thus, an image having good image quality can be formed over a long period of time.

[0031] In the developing apparatus according to as described in detail first implementation embodiment above, the toner in the vicinity of the toner supply port 21A, Ogarora 34 is disposed, from the toner supply opening 21A through the helical teeth 34A of Ogarora 34 Inlet 2
1B, the toner is conveyed and circulated along the path leading to the toner cartridge 21, so that the toner is conveyed and circulated from one end to the other end above the toner supply roller 20. During this process, fresh toner is constantly circulated, and such toner can be uniformly applied over the entire toner supply roller 20. As a result, the toner can be uniformly supplied to the developing roller 19 and the electrostatic latent image on the surface of the photosensitive drum 12 via the toner supply roller 20, so that an image having good image quality can be formed on the sheet 50. It can be formed over a long period of time.

Next, a developing device according to a second embodiment will be described with reference to FIG. FIG. 5 is a front sectional view showing the inside of the developing chamber in the developing device according to the second embodiment.
The developing device according to the second embodiment has basically the same configuration as the developing device according to the first embodiment, and the toner supply port 21A is formed substantially at the center of the toner cartridge. A pair of toner inlets 21B are formed on both sides of the toner supply port 21A, and an auger roller is disposed on both sides of the toner inlet 21A from the toner supply port 21A based on the arrangement of the toner supply ports 21A and the toner inlets 21B. The only difference from the first embodiment is that the toner is transported and circulated toward 21B. Therefore, in the following description, the description will focus on only the points different from the first embodiment.

In FIG. 5, the developing device includes a toner supply port 21A formed of a hole formed substantially at the center of the toner cartridge 21 and a hole formed on the unit case 25 side corresponding to the hole. And a pair of toner suction ports 21 provided on both sides of the toner supply port 21A.
B (similar to the toner supply port 21A)
1 and each hole formed in the unit case 25 corresponding to each hole). Further, in the vicinity of the toner supply port 21A and each toner suction port 21B, an auger roller 3 that conveys and circulates the toner discharged from the toner supply port 21A toward each toner suction port 21B above the toner supply roller 20.
5 is rotatably arranged. Auger roller 3
5 has a central position 35C (almost the toner supply port 21A).
(Which coincides with the central position of the toner supply roller 20), spiral teeth 35A are formed spirally from both ends toward the opposite ends.
It is supported by. As a result, the auger roller 35 is moved to the position shown in FIG.
When rotated in the clockwise direction, the toner supplied from the toner supply port 21 </ b> A sequentially flows in both directions (in the direction of arrow A) of the developing chamber D in accordance with the spiral direction of the spiral teeth 35 </ b> A above the toner supply roller 20. Conveyed.

As described above, based on the toner conveying action of the auger roller 35, the toner in the toner cartridge 21 is circulated along the path from the toner supply port 21A to the toner cartridge 21 through each toner suction port 21B.
Therefore, the toner not used for developing the image is transported and circulated as described above and returned to each toner inlet 21B, so that the toner does not stay in the developing chamber D for a long time. Thus, fresh toner can always be supplied from the toner cartridge 21. Further, since the toner is stirred and circulated by the auger roller 35 as described above, the fluidity of the toner can be favorably maintained without the toner being hardened in the developing chamber D.

As described above, the auger roller 35 functions to convey and circulate the toner supplied from the toner supply port 21A into the developing chamber D in the direction of each toner suction port 21B above the toner supply roller 20. Accordingly, the toner can be uniformly supplied over the entirety of the toner supply roller 20 and deposited on the toner supply roller 20 without locally retaining the toner. In addition, since toner is conveyed and circulated from the center to both ends of the toner supply roller 20 above the toner supply roller 20 via the auger roller 35, fresh toner is uniformly applied to the entire toner supply roller 20 at all times. As a result, it is possible to uniformly supply toner even to the electrostatic latent image on the surface of the developing roller 19 and the photosensitive drum 12, and to form an image having good image quality for a long period of time. Is what you can do.

As described in detail above, in the developing device according to the second embodiment, the auger roller 35 is disposed near the toner supply port 21A and each toner suction port 21B.
The toner is conveyed and circulated along the path from the toner supply port 21A to the toner cartridge 21 through the respective toner suction ports 21B via the spiral teeth 35A of the auger roller 35, so that the toner is located above the toner supply roller 20 at the center thereof. Is configured to be conveyed and circulated in the direction from both ends to both ends, so that fresh toner is constantly circulated during the conveyance and circulation, and such toner is uniformly distributed over the entire toner supply roller 20. Can be deposited. As a result, the toner can be uniformly supplied to the developing roller 19 and the electrostatic latent image on the surface of the photosensitive drum 12 via the toner supply roller 20, and an image having good image quality can be formed on the sheet 50. It can be formed over a long period of time. It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications can be made without departing from the spirit of the present invention.

[0037]

As described above, in the developing device according to the first aspect , toner is supplied from the toner cartridge to the developing chamber.
Auger member is disposed at a position near the toner supply port for toner, and toner is developed from the toner supply port through the auger member.
Between the toner cartridge and the developing chamber toward the toner inlet for returning the toner from the chamber to the toner cartridge.
Based on the fact that forced conveyed circulated, poor toners hardly used in the developing quality uniform always fresh toner over the entire effectively preventing while supplying roller to be accumulated staying in the developing chamber Can be adhered to. This makes it possible to uniformly supply toner even to the electrostatic latent image on the developing roller and the surface of the photosensitive drum, and to form an image having excellent image quality with excellent durability and stability over a long period of time. can do.

Further, in the developing device according to the second and third aspects, the auger member conveys the toner from the toner supply port to the toner suction port via the spiral teeth extending from one end to the other end. was transferred to the toner suction port with depositing to the supply roller while, therefore, the toner, and the toner cartridge while being conveyed through the auger member
Since the toner is circulated between the developing roller and the developing chamber, fresh toner can always be applied to the entire supply roller.

Further, in the developing device according to the fourth aspect, the toner
In the vicinity of the preparative <br/> toner supply opening for supplying toner to the developing chamber from over the cartridge, the auger member is disposed, the current toner on both sides from the toner supply port via the auger member
The toner cartridge and the developing chamber are moved toward each toner inlet for returning the toner from the image chamber into the toner cartridge.
Based between that are allowed to transport circulation, always fresh toner over the entire effectively preventing while supplying roller that bad toners hardly used in the developing quality is accumulated staying in the developing chamber Can be uniformly applied.
This makes it possible to uniformly supply toner even to the electrostatic latent image on the developing roller and the surface of the photosensitive drum, and to form an image having excellent image quality with excellent durability and stability over a long period of time. Is what you can do.

Further, in the developing device according to the fifth and sixth aspects, the auger member is directed from the toner supply port to each of the toner suction ports on both sides of the auger member via the spiral teeth extending from the center position to the other end. was transferred to the toner inlet with depositing to the supply roller while conveying the toner Te, therefore, the toner between the toner, which is transported via the auger member
It will be circulated between the cartridge and the developing chamber ,
Fresh toner can always be applied over the entire supply roller.

As described above, the present invention supplies toner from the toner cartridge formed in the developing device to the developing chamber.
When applying toner discharged from the toner supply port for supply to the supply roller, the toner of the supply roller is effectively prevented while poor-quality toner, which is hardly used for development, stays and accumulates in the developing chamber. A developing device in an image forming apparatus capable of forming an image having good image quality with excellent durability and stability over a long period of time because fresh toner can be uniformly applied at all times over the entirety. Can be provided.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of main components of a laser printer.

FIG. 2 is a side sectional view of the laser printer.

FIG. 3 is a side sectional view of a process unit.

FIG. 4 is a front sectional view showing the inside of a developing chamber in the developing device according to the first embodiment.

FIG. 5 is a front sectional view showing the inside of a developing chamber in a developing device according to a second embodiment.

FIG. 6 is an explanatory view schematically showing a main part of a conventional developing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body case 3 Process unit 12 Photoreceptor drum 20 Toner supply roller 21 Toner cartridge 21A Toner supply port 21B Toner suction port 25 Unit frame 34, 35 Auger roller 34A, 35A Helical tooth 39 Support plate D Developing room P Laser printer

Continuation of the front page (56) References JP-A-5-107908 (JP, A) JP-A-1-134479 (JP, A) JP-A-3-260678 (JP, A) JP-A-5-72891 (JP) JP-A-9-222796 (JP, A) JP-A-5-46024 (JP, A) JP-A-4-53986 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB (Name) G03G 15/08

Claims (6)

(57) [Claims] 1. A developing device in an image forming apparatus for forming an image by an electrophotographic process, comprising: a developing roller disposed to face a photosensitive drum and developing an electrostatic latent image formed on the photosensitive drum with toner. A developing roller having a supply roller disposed opposite to the developing roller and supplying toner to the developing roller, wherein a toner cartridge is formed on both sides of the developing chamber provided with the developing roller and the supply roller.
Toner supply opening for supplying the over, and toner from the developing chamber
A toner suction port for returning toner into the cartridge, and a supply roller disposed near the toner supply port and the toner suction port while conveying and circulating toner from the toner supply port toward the toner suction port. And an auger member to be attached to the image forming apparatus. 2. The developing device according to claim 1, wherein the auger member has spiral teeth extending from one end to the other end. 3. The image according to claim 2, wherein the auger member attaches the toner from the toner supply port to the supply roller while transporting the toner by the spiral teeth, and transfers the toner to the toner suction port. A developing device in the forming device. 4. A developing device in an image forming apparatus for forming an image by an electrophotographic process, wherein the developing roller is disposed to face the photosensitive drum and develops an electrostatic latent image formed on the photosensitive drum with toner. A supply roller that is disposed opposite to the development roller and supplies toner to the development roller, wherein the development roller and the supply roller are provided at a central position of the development chamber, and the toner cartridge is moved from the toner cartridge to the development chamber.
A toner supply opening for supplying the toner, formed on the developing chamber on both sides of the toner supply opening, a developing chamber
And a pair of toner suction ports for returning toner into the toner cartridge from the toner supply port, and a toner supply port is disposed at a position near each toner suction port, and conveys and circulates toner from the toner supply port toward each toner suction port. An auger member to be attached to the supply roller. 5. The developing device according to claim 4, wherein the auger member transports the toner from a position corresponding to the toner supply port toward both ends. 6. The developing device according to claim 5, wherein the auger member has helical teeth extending from a center position toward both ends.