JP2000075649A - Developing cartridge and image forming apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent dust and fluff from adhering to a shutter covering a developing roller, to perform well without interrupting image exposure of an exposure unit, and to output a clear image. It is another object of the present invention to provide a developing cartridge. SOLUTION: A shutter 21BO of a black developing cartridge 21B is located close to an axis of an optical path 8 of a laser beam for performing image exposure at a distance of about 15 mm or less.
The shutter 21BO is made of a hydrophilic polymer and has a permanent resistance of 10 ⁵ to 10 ¹³ Ω / □, which contains a hydrophilic polymer, in order to prevent adhesion of dust, fluff and the like to the shutter 21BO that may cause interruption of the laser beam. It was formed of a prevention resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and a developing cartridge.

[0002] In the present invention, an image forming apparatus refers to an apparatus which forms an image on a recording medium by using an electrophotographic image forming process, such as an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc. ), A facsimile machine and a word processor. The developing cartridge is a device in which the developing means is integrally formed as a cartridge, and this cartridge is detachable from the main body of the image forming apparatus.

[0003]

2. Description of the Related Art In recent years, there has been an increasing demand for an electrophotographic color image forming apparatus capable of forming a color image. A configuration in which, for example, a four-color developing device is installed in a color image forming apparatus by arranging it in a rotary is known (for example, US Pat. No. 4,707,1).
08, USP. No. 5,040,031).

[0004] The installation configuration of such a four-color developing device is as follows.
It is very effective in forming a color image.

[0005]

On the other hand, a future network-compatible color image forming apparatus needs to support a large amount and high-speed output regardless of whether a color document can be output. It is also desirable to reduce the cost per copy page to the same level as a monochrome image forming apparatus.

In order to meet such a demand, consumable parts used in the image forming apparatus, for example, a developing device and an image carrier (electrophotographic photosensitive member), or these developing devices and the image carrier are integrally formed. It is necessary to extend the life of the developing cartridge, process cartridge, and the like configured as described above.

On the other hand, in order to reduce the size of the image forming apparatus,
The process kit, which is a consumable part, is disposed close to the inside of the apparatus main body. For this reason, for example, a shutter (protective member) covering the developing roller of the developing cartridge is moved with respect to the optical path of the laser beam from the exposure unit. It has been evacuated to a nearby location.

Therefore, if dust or fluff adheres to the shutter, a part of the optical path of the laser beam for performing image exposure is blocked by the adhered matter, resulting in poor image exposure. Image omission sometimes occurred.

An object of the present invention is to prevent dust and fluff from adhering to a shutter covering a developing roller, to perform a satisfactory operation without hindering image exposure of an exposure unit, and to output a clear image. To provide a developing cartridge and an image forming apparatus.

[0010]

The above object is achieved by a developing cartridge and an image forming apparatus according to the present invention.
In summary, the present invention is a developing cartridge for developing an electrostatic latent image formed on an electrophotographic photoreceptor, which is detachable from an image forming apparatus main body, wherein the openable and closable shutter for covering the developing roller has the above-mentioned configuration. In the developing cartridge, the shutter is formed of a material having a surface resistance of 10 ¹³ Ω / □ or less, the developing cartridge being located close to an optical path for image exposure to the photoreceptor. According to the present invention, the material of the shutter is a permanent antistatic resin containing a hydrophilic polymer. The gap between the shutter and the optical path for image exposure is within 15 mm.

According to the present invention, there is provided an image forming apparatus provided with an electrophotographic photosensitive member on which an electrostatic latent image is formed, and a developing unit for developing the electrostatic latent image, wherein the developing unit is any one of the above-mentioned units. An image forming apparatus is formed on the developing cartridge.

[0012]

Embodiments of the present invention will be described below in more detail with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of the image forming apparatus of the present invention. This image forming apparatus is configured as a color laser printer.

First, the overall configuration of the image forming apparatus according to the present embodiment will be described.

[Overall Description of Image Forming Apparatus] As shown in FIG. 1, a color laser printer includes an electrophotographic photosensitive member (photosensitive drum) 15 rotating at a constant speed, a fixed black developing cartridge 21B, and a rotating type. Three-color developing cartridge, ie, yellow developing cartridge 20
The image forming unit includes a Y, magenta developing cartridge 20M, and a cyan developing cartridge 20C.

Below the image forming section, an intermediate transfer drum (hereinafter referred to as an intermediate transfer drum) which holds the color toner image formed and transferred by the image forming section and further transferred to the recording medium 2 fed from the sheet feeding cassette 1. (Intermediate transfer member) 9.

The recording medium 2 on which the toner image has been transferred from the intermediate transfer drum 9 is conveyed to a fixing unit 25 to fix the toner image on the recording medium 2, and then discharged rollers 34, 35, 36
To the discharge section 37 on the upper surface of the apparatus. Recording medium 2
For example, paper, an OHP sheet, or the like is used.

Rotary color developing cartridges 20Y-20
The C and fixed black developing cartridges 21B are configured to be individually detachable from the printer main body 100.

Next, the configuration of each part of the image forming apparatus will be described in detail.

[Drum Unit] The photosensitive drum 15 and the container 14 of the cleaning device also serving as a holder for the photosensitive drum 15 are integrally formed in a drum unit 13. This drum unit 13 is detachably supported by the printer main body 100 so that the user can easily remove it, and is replaced when the photosensitive drum 15 reaches the end of its life.

In this embodiment, the photosensitive drum 15 has an organic photoconductor layer applied to the outside of an aluminum cylinder having a diameter of 62 mm, and is rotatably supported by the container 14 of the cleaning device as described above. ing. A drive motor (not shown) is disposed at one end of the photosensitive drum 15, and by transmitting this driving force, the photosensitive drum 15
Is rotated counterclockwise in the figure according to the image forming operation.

The photosensitive drum 15 is provided with a cleaner blade 16 and a primary charging means 17 along the peripheral surface.
The cleaner blade 16 is in contact with the photosensitive drum 15, and after transferring the toner image, removes the transfer residual toner remaining on the surface of the photosensitive drum 15.

[Primary Charging Means] The primary charging means 17 is a conductive roller using a contact charging method. The conductive roller 17 is brought into contact with the photosensitive drum 15 and a voltage is applied to the conductive roller 17. , Photosensitive drum 1
5 is uniformly charged.

[Exposure Means] Exposure to the photosensitive drum 15 is performed from the scanner unit 30. That is, when an image signal is given to the laser diode, the laser diode irradiates an image corresponding to the image signal to the polygon mirror 31.

The polygon mirror 31 is a scanner motor 3
1a, the image light which is rotated at high speed and reflected by the polygon mirror 31 selectively exposes the surface of the photosensitive drum 15 rotating at a constant speed via the imaging lens 32 and the reflection mirror 33, and is exposed to the surface of the photosensitive drum 15 An electrostatic latent image is formed.

[Developing Unit] In this embodiment, the photosensitive drum 1
In order to develop the electrostatic latent image on the developing device 5, as described above, three rotary developing cartridges 20Y, 20M, 2M and 2M for developing the yellow, magenta, and cyan colors are used.
0C and one fixed black developing cartridge 21B.

When forming a color image, one of the intermediate transfer drums 9
The developing rotary 23 rotates with each rotation, and the yellow developing cartridge 20Y and the magenta developing cartridge 20 are rotated.
The development is performed in the order of M, cyan developing cartridge 20C, and finally, developing is performed with black developing cartridge 2B1.

[Color Developing Cartridges] Each of the three color developing cartridges 20Y, 20M, and 20C contains toner equivalent to 7000 pages of image formed sheets (A4, 4% printing). These developing cartridges 20 </ b> Y to 20 </ b> C are detachably held by a developing rotary 23 that rotates about a shaft 22.

At the time of image formation, the developing cartridges 20Y to 20C rotate around the shaft 22 while being held by the developing rotary 23, and stop at a position where a predetermined developing cartridge faces the photosensitive drum 15, and It is positioned with respect to the photosensitive drum 15. FIG. 1 shows a state in which the yellow developing cartridge 20 </ b> Y stops at a position facing the photosensitive drum 15 and is positioned.

As shown in FIG. 2, the developing cartridge 20Y sends the yellow toner in the toner container 20YV to the supply roller 20YR by the feed mechanism 20YT.
The blade 20Y pressed against the outer peripheral surfaces of the supply roller 20YR and the developing roller 20YS rotating clockwise in the drawing.
B applies a thin layer of toner to the surface of the developing roller 20YS that rotates clockwise in the figure, and applies a triboelectric charge to the toner. The developing roller 21YS has a minute interval (about 300 μm) with respect to the photosensitive drum 15 by a spacer mechanism.

Then, by applying a developing bias to the developing roller 20YS facing the photosensitive drum 15, the latent image on the photosensitive drum 15 is developed, and a yellow toner image corresponding to the latent image is formed.

The magenta developing cartridge 20M and the cyan developing cartridge 20C have the same device configuration as described above, and perform development by the same mechanism.

Each of the developing rollers of the color developing cartridges 20Y to 20C is connected to a high-voltage power supply and a driving source for each color developing provided in the printer main body when each developing cartridge is rotated to the developing position. Are sequentially and selectively applied with a developing voltage, and driving is transmitted.

[Intermediate Transfer Body] The intermediate transfer drum 9 applies the toner image on the photosensitive drum 15 visualized by each developing cartridge four times (Y, M,
In order to receive multiple transfer over the four colors C and B), the photosensitive drum 15 rotates clockwise in synchronization with the outer peripheral speed of the photosensitive drum 15. Further, the intermediate transfer drum 9 that has received the multiple transfer transfers the toner images of the respective colors on the intermediate transfer drum 9 to the recording medium 2 at the same time, by nipping and transporting the recording medium 2 by a transfer belt 10 to which a voltage is applied. .

The intermediate transfer drum 9 according to the present embodiment has a configuration in which the outer circumference of an aluminum cylinder 12 having a diameter of 186 mm is covered with an elastic layer 11 such as a medium resistance sponge or medium resistance rubber. The intermediate transfer drum 9 is rotatably supported, and rotates by being driven by a gear (not shown) fixed integrally.

[Cleaning Unit] The cleaning unit cleans the transfer residual toner remaining on the photosensitive drum 15 after the toner image developed on the photosensitive drum 15 by the developing unit is transferred to the intermediate transfer drum 9. is there. The removed toner that has been cleaned is stored in the cleaner container 14.

This container 14 can store the removed toner for the life of the photosensitive drum 15 (image formation for about 5,000 pages) or more. Therefore, the cleaner container 14 includes the photosensitive drum 15
Is replaced as soon as it reaches the end of its service life.

In this embodiment, a cleaning blade 16 is used as a cleaning member. The cleaning blade 16 is used in contact with the surface of the photosensitive drum 15.

[Sheet Feeding Unit] The sheet feeding unit feeds the recording medium 2 to the image forming unit, and includes a sheet cassette 1 containing a plurality of recording media 2, sheet feeding rollers 3, 4, It mainly comprises a retard roller 5, a paper feed guide 6, a transport roller 7, and a registration roller 8 for preventing feeding.

At the time of image formation, the paper feed roller 3 is driven and rotated in accordance with the image forming operation, separates and feeds the recording medium 2 in the cassette 1 one by one, is guided by the paper feed guide 6, and To the registration roller 8 via

During the image forming operation, the registration roller 8 controls the non-rotational operation of keeping the recording medium
Is carried out in a predetermined sequence, and the toner image is aligned with the recording medium 2 in the next transfer step, that is, the transfer step.

[Transfer Section] The transfer section includes a swingable transfer belt 10 as a transfer member. Transfer belt 10
Is a belt whose surface layer is formed of rubber having a high resistance (surface resistance of 10 ⁹ to 10 ¹³ Ω) and a base material of medium resistance (surface resistance of 10 ⁴ to 10 ⁶ Ω). Possible and rotate.

While the four-color toner image is being formed on the intermediate transfer drum 9, that is, while the intermediate transfer drum 9 is being rotated a plurality of times, the transfer belt 10 is maintained so as not to disturb the image.
Is located below the solid line in the figure and is separated from the intermediate transfer drum 9.

After the formation of the four color toner images on the intermediate transfer drum 9, the transfer belt 10 is indicated by a dotted line in the figure by a cam member (not shown) in accordance with the timing of transferring the toner images to the recording medium 2. At the upper position, it is pressed against the intermediate transfer drum 9 via the recording medium 2 with a predetermined pressure. At this time, a bias is applied to the transfer belt 10 at the same time, and the toner image on the intermediate transfer drum 9 is transferred to the recording medium 2.

Here, the intermediate transfer drum 9 and the transfer belt 1
0 means that the recording medium 2 sandwiched between them is conveyed at a predetermined speed to the left in the figure at the same time as the transfer process is performed, and is transferred to the fixing device 25 which performs the next process. Sent to.

[Fixing Section] The fixing device 25 fixes the toner image transferred onto the recording medium 2 and, as shown in FIG. 1, includes a fixing roller 26 and a pressure roller 27 pressed against the fixing roller 26. Become. The fixing roller 26 and the pressure roller 27 are formed as hollow rollers, and the heater 2
8, 29 are provided.

The fixing roller 26 and the pressure roller 27 are rotated to heat and press the recording medium 2 sandwiched therebetween to fix the toner image and to convey the recording medium 2.

[Black Developing Cartridge] Overall Structure The black developing cartridge 21B is attached to and detached from the apparatus main body at a fixed position between the rotary type color developing cartridges 20M to 20C and the laser scanner unit 30, as shown in FIG. It is freely attached.

As shown in FIG. 2, the black developing cartridge 21B feeds the black toner in the toner container 21BG toward the developing roller 21BS facing the photosensitive drum 15 by the feeding mechanism 21BT.
A blade 21BB pressed against the outer peripheral surface of the developing roller 21BB applies a thin layer of toner to the surface of the developing roller 21BS and imparts a triboelectric charge to the toner. Then, by applying a developing bias to the developing roller 21BS, the latent image on the photosensitive drum 15 is reversely developed by a jumping developing method to form a toner image corresponding to the latent image.

At both ends of the developing roller 21BS, FIG.
As shown in the figure, the spacer roller 21BK is arranged coaxially, and the outer diameter of this spacer roller is the developing roller 21BS.
Is slightly larger than the outside diameter. When the spacer rollers come into contact with the outer peripheral surface of the photosensitive drum 15,
A minute interval (about 300 μm) between the developing roller 21BS and the photosensitive drum 15 is secured.

In consideration of the toner consumption, the toner capacity of the black developing cartridge 21B is about twice as large as the toner capacity of other color developing cartridges and is equal to or more than 17000.
The toner is equivalent to a page (A4, 4% printing).

As described above, the black developing cartridge 21
The installation position of B is between the color developing cartridges 20Y to 20C and the laser scanner unit 30. By arranging in this way, even if toner leaks when the color developing cartridge rotates, the toner can be prevented from being scattered to the optical components such as the laser scanner unit 30 by the developing cartridge 21B. This prevents the toner from adhering to the polygon mirror 31, the imaging lens 32, the reflection mirror 33, and the like, thereby preventing the latent image from being formed.
Useful for obtaining clear output images.

As shown in FIG. 2, on the bottom of the toner containing portion 21BG,
As shown in FIG. 4, a low-resistance cover sheet 21BR is adhered. In this embodiment, the cover sheet 21BR
Is made of an ultrahigh molecular weight polyethylene sheet material having a surface resistance of 10 ⁶ Ω or less. Since the cover sheet 21BR has low resistance, its surface is not significantly charged,
Also, it has excellent surface slipperiness. With these two characteristics, adhesion of toner floating in the image forming apparatus main body is prevented.

Cartridge Configuration In the black developing cartridge 21B, the developing section frame 21BL and the toner storage section 21BG shown in FIG. 1 are integrally connected by ultrasonic bonding. Black magnetic toner is stored in the toner storage unit 21BG.

As shown in FIG.
As shown in FIG. 2, a projection 62 is formed, and the projection 62 is in contact with a part of the housing of the toner storage unit 21BG. In this state, when a part of the housing of the toner storage unit 21BG is held by the receiving table 61 and a part of the developing unit frame 21BL is pressurized and vibrated by the horn 60, the protrusion 62 is melted, and the developing unit 21BG and the toner storage unit 21BG are developed. The unit frame 21BL is joined.

As shown in FIG. 22, the distance between the inner end where the horn 60 is in close contact with the developing unit frame 21BL and the projection 62 is B, and the outer end where the horn 60 is in close contact with the developing unit frame 21BL and the projection 62 are In the related art, when A is the distance, A ≦ B, so that the developing frame 21BL may be warped.

In this embodiment, as shown in FIG. 23, A and B are adjusted so that B <A. By adjusting such bonding conditions, the warpage of the developing unit frame 21BL can be reduced. For this reason, for example, the blowing prevention sheet 21 adhered to the developing section frame 21BL
The warpage of the BF is reduced, and the blowout prevention sheet 21BF
Can stably contact the developing roller 21BS.

Developing Portion The developing portion 21BV of the black developing cartridge 21B has a stirring member 2 as shown in FIGS. 3, 16, 17, and 18.
1BH and the rotating member 21BI are arranged. In this embodiment, the stirring member 21BH has one end supported by the hole 21BC of the developing unit frame 21BL, the other end supported by the hole of the rotating member 21BI, and the other end supported by:
The stirring member 21BH is fixed to the rotating member 21BI in the axial direction immovably.

More specifically, a part of the other end of the stirring member 21BH is made thicker by pressing, and this thick part is realized by press-fitting the hole into the hole of the rotating member 21BI. On the other hand, the hole 21BC of the developing unit frame 21BL has a tapered shape so that the end of the stirring member 21BH does not slide on the surface. Specifically, the taper angle is 2 ° or more.

In the present embodiment, the dimension of the thick portion at the end of the stirring member 21BH is D, and the diameter of the hole of the rotating member 21BI is H.
Then, the difference DH ≦ 0.1 mm. Thereby, the rotating member 21BI of the stirring member 21BH
Of 500 g or more can be secured.

As shown in FIG. 17, the depth of the hole 21BC of the developing frame 21BL is L1, and the stirring member 21
When the length of the straight portion at the end of BH is L2, L
2> L1. With such a dimensional relationship, the bending root of the shaft of the stirring member 21BH is prevented from axially interfering with the hole entrance of the developing unit frame 21BL. Further, a hole 21B of the developing unit frame 21BL is formed.
By chamfering the entrance of C, the entrance of the hole 21BC is more positively released from the bending root of the stirring member 21BH so that the above-mentioned interference does not occur.

The agitating member 21BH of the present embodiment should not fall off the developing unit frame 21BL after assembly.
As shown in FIG. 3 and FIG. 18, a stopper 21BJ is stopped inside the rotating member 21BI as a retaining member.

As shown in FIG. 3, a developing roller 21BS, a coating blade 21BB, a shutter 21BO which is a protection member for the developing roller 21BS, and the like are arranged in the developing section 21BV in addition to the stirring member 21BH.

In this embodiment, the magnet sheet 42 is arranged within 15 mm from the surface of the developing roller 21BS. The magnet sheet 42 can be bonded to, for example, a part of the developing unit frame 21BL, a part of the shutter 21BO, and a part of the coating blade 21BB.

The total length of the magnet sheet 42 is longer than the area where the toner applied on the developing roller 21BS is applied. The magnet sheet 42 is arranged in parallel with the axis of the developing roller 21BS. By arranging the magnet sheet 42 in this manner, the magnetic toner floating from the developing roller 21BS can be positively collected, and the toner can be prevented from adhering to other areas.

[0066] The toner container configuration toner containing portion 21BG, FIG 5 (B arrow view of FIG. 4),
As shown in FIG. 7, upper and lower openings are formed, a lid 21BD is joined to the upper opening, and the lower opening 2 is formed.
An opening seal member 43 is adhered to 1BA.

A partition member 44 having a plurality of partition walls is provided directly above the lower opening 21BA. The wall surface of the first partition 44A of the partition member 44 is
It is formed larger than the area of the lower opening 21BA. The wall surface of the partition wall 44A is formed so as to have an inclination angle of about 15 ° with respect to the adhesive surface of the opening seal member 43 and to have an inclination angle of about 5 ° with respect to the horizontal plane of the apparatus main body.

The direction in which the black developing cartridge 21B is removed from the apparatus main body is the same as the longitudinal direction of the developing cartridge 21B. The partition member 44 has a second
Of the developing cartridge 21B in a direction perpendicular to the direction in which the developing cartridge 21B is removed from the apparatus main body.

As shown in FIG. 5, a first stirring section 21BM and a second stirring section 21BN are provided inside the toner storage section 21BG.
The first feed member 21BT and the second feed member 21BU are rotatably supported by the respective stirring units.

In this embodiment, the end of the second feed member 21BU in the rotational radius direction is stopped so as to face the tip of the first partition 44A of the partition member 44. Further, the first feed member 21BT and the second feed member 21BU
Have a phase difference of about 90 ° from each other.
Specifically, the first feed member 21BT is stopped at a position rotated by about 90 ° upstream with respect to the second feed member 21BU.

At the factory, the first feed member 21BT
And the second feed member 21BU is adjusted to the stop position described above before shipment.

As shown in FIG. 7, two drive shafts 21BW are provided in the holes on the side surfaces of the toner containing portion 21B.
Inserted with BE. Feeding members 21BT, 21BU
Is driven and rotated by the drive shaft 21BW.

Opening Seal Member The opening sealing member 43 adhered to the lower opening 21BA of the toner container 21BG in FIG. 7 is shown in FIG. 8, FIG. 9, FIG.
As shown in FIG. 11, a film 43A covering the opening 21BA and a tape 43B, which is a flexible member, are integrated by heat welding to form a tear seal member. The film 43A uses a uniaxially stretched film material or sheet material having a tear property in one direction. For example, uniaxially stretched polyethylene, uniaxially stretched polypropylene, and uniaxially stretched expanded polypropylene are used.

The tape 43B must have sufficient strength to tear the film 43A, and preferably has a tensile strength that is about three times that of the film 43A. As the material, various films or sheet materials such as biaxially oriented polyester, biaxially oriented polypropylene, polystyrene, and biaxially oriented nylon are used.

The film 43A and the tape 43B are as shown in FIG.
As shown in FIG. 25, the four sides are continuously joined, and the free end side (right side in FIG. 10) of the tape 43B is folded back. As shown in FIG. 25, the free end side of the folded tape 43B is folded. When the film 43A is pulled, the tape 43B
Is torn in a certain direction while maintaining the width.

In this embodiment, as shown in FIGS. 10 and 11, in addition to the above-described four-sided joint (first joint) 45,
A spot-like joint (second joint) 46 is provided discontinuously near the turning point. Conventionally, tape 43B
24, the unfolded margins overlap as shown in FIG. 24 at the turning point of the film 43A. However, in the present embodiment, since the second joint 46 is provided, Overlap of the margins of the joint is prevented.

By the way, the film 43A and the tape 43B
Comparing the tensile elongation of the film 43A, the film 43A has greater elasticity than the tape 43B. For example, when the black developing cartridge 212B is dropped, the toner is biased in the container, and the pressure of the biased toner layer causes the opening seal member 43 to open.
Swells. The larger the bulging amount, the more the film 43A
Can be suppressed.

In another example of this embodiment, as shown in FIGS. 12 and 13, the corners where the first joints (joints on four sides) 45 intersect are formed in an arc shape. Thereby, the above swelling amount can be increased. In still another example shown in FIGS. 14 and 15, the joints at both ends of the joints 45 on the four sides are bent, so that the amount of swelling can be further increased.

[0079] As shown in the toner seal member diagram 19, the toner seal member 40 is divided into a first layer 40A and the second layer 40C. First layer 40
A is made of a fiber having a low coefficient of friction and abrasion resistance. As the fiber, a synthetic fiber such as a fluororesin fiber, polyester, acrylic, or nylon, a semi-synthetic fiber such as rayon, or a mixture of these is desirable.

In general, it is preferable to use fluororesin fibers, for example, polytetrafluoroethylene (P
TFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PE
A), an ethylene-tetrafluoroethylene copolymer (E
TFE) can be used.

In this embodiment, the first layer 40A is made by mixing PTFE and felting. As shown in FIG. 20, the above-mentioned felt uses a fork needle 41 to protrude the fiber from felt cotton to a height of 0.5 to 5 mm to form a loop-like raised brush 40AC. Then, a polyurethane foam (for example, Polon manufactured by Inoac) having a first layer 40A and a second layer 40C as a cushioning material is applied to a double-sided tape 40B having no base material (for example, No.5619 manufactured by Nitto Denko Corporation, Sumitomo 3M Company). (F-9469PC, etc.). Furthermore, the second layer 40
A double-sided tape 40D (also having no base material) is adhered to the outside of C.

As shown in FIGS. 5 and 21, the toner seal member 40 is provided in the opening 2 of the black developing cartridge 21B.
It is fixed outside 1BA. Toner container 21BG
The toner inside the developing roller 21BS from the opening 21BA
The toner seal member 40 is in close contact with a part of the outer peripheral surface of the developing roller 21BS. The napping direction (falling direction) of the raised brush 40AC of the toner seal member 40 faces the inside of the developing roller 21BS.

Although the toner seal members 40 of this embodiment are disposed at both ends of the developing roller 21BS of the black developing cartridge 21B, both ends of the developing rollers of the color developing cartridges 20Y to 20C or the photosensitive drum of the drum unit 13 are used. Needless to say, they may be arranged at both ends of the first.

The shutter configuration black developing cartridge 21BS includes a developing roller 21BS.
As shown in FIGS. 4, 5, 6 (viewed from the arrow A in FIG. 4), and FIG. 26, the shutter 21BO is held so as to be rotatable. As shown in FIGS. 4 and 6, a shutter opening / closing member 21BP is provided on a holder 21BY disposed on the rear side of the developing cartridge 21BS.
Are rotatably mounted and are pushed in one direction by a spring (not shown).

Further, a shutter shaft 21BQ is disposed across the holder 21BX disposed on the front side, and is provided coaxially with the axis of the developing roller 21BS.
It is rotatably supported by a mounting member. In this state, the other end 21BP1 of the shutter opening / closing member 21BP
When a rotational moment is applied to the photosensitive drum 15 in a direction perpendicular to the generatrix, the shutter opening / closing member 21BP
The shutter 21BO rotates around Pa and the shutter 21BO smoothly rotates.

In order to realize the rotation of the shutter opening / closing member 21BP, in the present embodiment, the opening / closing guide member 51 is arranged on the swing guide 50 shown in FIG. The member 51 is fixed to the swing guide section 50. The opening / closing guide member 51 has a slope 51a that is gentle to the vertical direction of the paper surface of FIG. 2, and when the user inserts the black developing cartridge 21B into the swing guide portion 50 to some extent, the end of the arm of the shutter opening / closing member 21BP is moved. It contacts the slope 51 a of the opening / closing guide member 51. When the insertion of the cartridge 21B is further continued, the tip of the arm of the shutter opening / closing member 21BP moves along the inclined surface 51a of the opening / closing guide member 51, and a rotational moment in a direction perpendicular to the generatrix of the photosensitive drum 15 is applied. Can be

The shutter 21BO is located close to the axis of the optical path 18 of the laser beam for performing image exposure shown in FIG. 3 at a distance of about 15 mm or less. Therefore, if dust, fluff or the like adheres to the shutter 21BO, a part of the laser beam is blocked, which may cause a defect such as missing image.

The feature of the present invention is that the adhesion of dust, fluff, etc. to the shutter 21BO is materially prevented. That is, the shutter 21BO has a surface resistance of 10 ⁵ to 10
It is characterized by being formed of a ¹³ Ω / □ permanent antistatic material. In the present example, it was formed of a permanent antistatic resin containing a hydrophilic polymer and having a surface resistance of 10 ⁵ to 10 ¹³ Ω / □.

By forming the shutter 21BO with such a material, dust, fluff and the like can be removed from the shutter 21BO.
O can be prevented from being electrostatically attached to O, and stable image exposure can be performed without a part of the laser beam being blocked.

Examples of the hydrophilic polymer to be contained in the permanent antistatic resin include polyethylene glycol-methacrylate copolymer, poly (ethylene oxide / propylene oxide) copolymer, polyethylene glycol-based polyamide, polyethylene glycol-based polyesteramide, and poly (epichlorohydrin). / (Ethylene oxide) copolymer and the like.

As described above, the present invention has been described by taking a color image forming apparatus as an example. However, the present invention is not limited to this, and can be applied to a monochrome image forming apparatus, and similar effects can be obtained.

[0092]

As described above, according to the present invention,
The shutter that protects the developing section of the developing cartridge is made of a permanent antistatic material, so that dust, fluff, etc. does not adhere electrostatically to the shutter, which can block a part of the optical path of image exposure. In addition, an image can be formed by performing stable image exposure. Also, when a resin containing a hydrophilic polymer is used as a permanent antistatic material, the surface of the shutter can be cleaned on an assembly line, stored for a long time after assembly, and even when used in a low humidity environment. Performance can be stably maintained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a cross-sectional view illustrating a part of a black and yellow developing cartridge among the developing cartridges installed in the image forming apparatus of FIG. 1;

FIG. 3 is an enlarged sectional view showing the black developing cartridge of FIG. 2;

FIG. 4 is a front view of the black developing cartridge.

FIG. 5 is a view taken in the direction of arrow B in FIG. 4;

FIG. 6 is a view taken in the direction of arrow A in FIG. 4;

FIG. 7 is an exploded perspective view showing a toner container of the black developing cartridge.

8 is a perspective view showing the toner container of FIG. 7 upside down.

FIG. 9 is a perspective view illustrating a state where a developing unit frame is installed on the toner storage unit of FIG. 8;

FIG. 10 is a plan view showing an unsealing seal member of the black developing cartridge.

11 is a front view showing the toner container in which the lower opening is closed by the unsealing seal member of FIG. 10;

FIG. 12 is a plan view showing another example of the opening seal member.

FIG. 13 is a front view showing the toner container in which the lower opening is closed by the unsealing seal member of FIG. 12;

FIG. 14 is a plan view showing still another example of the opening seal member.

FIG. 15 is a front view showing the toner container in which the lower opening is closed by the unsealing seal member of FIG. 14;

FIG. 16 is a sectional view showing a developing unit frame.

17 is an enlarged cross-sectional view illustrating the vicinity of one end of a stirring member of the developing unit frame of FIG. 16;

18 is an enlarged cross-sectional view showing the vicinity of the other end of the stirring member of the developing unit frame of FIG.

FIG. 19 is an explanatory diagram illustrating a toner seal member of the black developing cartridge.

FIG. 20 is an explanatory view showing a method for processing the toner seal member of FIG. 19;

FIG. 21 is a perspective view illustrating an end of the black developing cartridge with some components omitted.

FIG. 22 is a cross-sectional view showing a conventional joint between a toner storage unit and a developing unit frame.

FIG. 23 is a cross-sectional view illustrating a joint portion between the toner containing unit and the developing unit frame in the present embodiment.

FIG. 24 is an explanatory view showing opening of a conventional opening seal member.

FIG. 25 is an explanatory diagram showing opening of the opening seal member in the present embodiment.

FIG. 26 is a perspective view illustrating an appearance of a black developing cartridge.

[Explanation of symbols]

 Reference Signs List 15 photosensitive drum 18 optical path 21B black developing cartridge 21BO shutter 21BP shutter opening / closing member 21BQ shutter shaft 21BS developing roller 21BV developing unit 50 swing guide 51 opening / closing guide member

Claims (4)

[Claims] 1. A developing cartridge for developing an electrostatic latent image formed on an electrophotographic photosensitive member, the developing cartridge being detachable from an image forming apparatus main body, wherein an openable and closable shutter covering a developing roller is provided to the photosensitive member. In a developing cartridge positioned close to an optical path of image exposure, the shutter is formed of a material having a surface resistance of 10 ¹³ Ω / □ or less. 2. The developing cartridge according to claim 1, wherein the material of the shutter is a permanent antistatic resin containing a hydrophilic polymer. 3. The developing cartridge according to claim 1, wherein a gap between the shutter and an optical path for image exposure is within 15 mm. 4. An image forming apparatus comprising: an electrophotographic photosensitive member on which an electrostatic latent image is formed; and a developing unit for developing the electrostatic latent image, wherein the developing unit is any one of claims 1 to 3. An image forming apparatus formed on the developing cartridge according to the above item.