JP3101401B2 - Image forming apparatus and process cartridge detachable from image forming apparatus main body - Google Patents

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
The present invention relates to a process cartridge that can be attached to and detached from an image forming apparatus main body.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic apparatus, a developing device is provided in a developing device in order to keep a constant gap between an image carrier and a developer carrying member for applying a developer to the image carrier. The spacer is in contact with the image carrier.

[0003]

[0004]

In recent years, an image forming apparatus in which a process cartridge having an electrophotographic photosensitive member and a developing device supported by a common supporting means is attached to and detached from an image forming apparatus main body has been frequently used.

[0006]

[0007]

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and a process cartridge capable of stably bringing a spacer into contact with an image carrier.

[0009]

[0010]

[0011]

An image forming apparatus or a process cartridge according to the present invention comprises an image carrier for carrying a latent image, a developer carrier for carrying a developer, and both ends of the developer carrier. An interval determining member that contacts the image carrier to determine an interval between the image carrier and the developer carrying member; and a driving force to which a driving force for driving the developer carrying member is transmitted. An image forming apparatus comprising: a developing device having a transmitted member; wherein a moment acts so that the gap determining member is pressed against the image carrier when the driving force is transmitted to the driving force transmitted member. In the developing device, the elastic force of the elastic member acts only on the side of the developing device on which the driving force transmission member is provided, and when the driving force is transmitted to the driving force transmission member by the elastic force, the distance determination is performed. The member is Wherein the reducing moment acting to be pressed against the body.

[0012]

FIG. 5 is an explanatory view of an image forming apparatus according to an embodiment of the present invention. FIGS. 1, 2 and 3 are explanatory views of a main part of a process cartridge of the present invention, and FIG. FIG. 2 is a view as viewed in the direction BB of FIG. 3, and FIG. 3 is a view as viewed in the direction AA in FIGS.

In FIG. 5, the image forming apparatus main body 12 includes an optical device, a transfer material transporting device, a transfer device, a fixing device, a guide member 15 for guiding the process cartridge 11 to be attached to and detached from the main body 12, and a process cartridge 5. Photoconductor 1
And a motor 16 and a gear 17 for driving the developing roller 6.

The process cartridge 11 includes a drum-shaped electrophotographic photosensitive member 1 rotating in the direction of an arrow, an electro-optical device 2 for uniformly charging the photosensitive member 1, and a developing device for developing an electrostatic latent image formed on the photosensitive member 1. Device 3 and cleaning blade 5 for removing toner remaining on the surface of photoconductor 1 after transfer of the developed image
And these means are supported in a molded synthetic resin frame 18. Then, the process cartridge 11 slides along the guide member 15 and is taken in and out of the main body 12. As a result, when the toner in the developing device 3 is completely consumed, the process cartridge 11 is taken out of the main body 12 by an operator, and is replaced with a process cartridge in which the developing device is previously filled with the toner. 11 can be loaded into the body 12 by the operator. Further, by loading the process cartridge 11 containing a toner of a desired color into the main body 12, an image of a desired color can be output.

The developing device 3 has a toner container 8 containing a toner 9 as a developer, and a developing roller 6 rotatably provided in the container 8.

The developing roller 6 carries the toner supplied in the container 8, conveys the toner while rotating in the direction of the arrow, applies the toner to the electrostatic latent image formed on the photoreceptor 1, and develops the electrostatic latent image.

The minimum gap between the developing roller 6 and the photoreceptor 1 in the developing area is 50 μm to 400 μm, and the roller 6 is provided with a developer so as to be thinner than the minimum gap in the developing area. Is formed. That is, non-contact development is performed. The layer thickness of the developer (toner) is regulated by the doctor blade 10. At both ends in the longitudinal direction of the developing roller 6, thin annular spacers 7, 7 'made of synthetic resin are fitted concentrically with the roller 6, as shown in FIG. , 7 '
Are pressed against both ends in the longitudinal direction of the photoreceptor 1,
The gap is formed between the roller 6 and the photoconductor 1. A spacer roller may be fitted to the shafts 30 and 30 'of the roller 6 concentrically.

Next, the image forming operation will be described. First, the photosensitive member 1 is charged by the charger 2 and then scanned and exposed by the laser beam L modulated in accordance with the recorded image information signal to form an electrostatic latent image. It is formed. Laser beam L
Is formed by a known optical device 13 including a semiconductor laser, a rotating polygon mirror, an f-θ lens, and the like, and is reflected by the mirror 14 in the direction of the photoconductor 1.

The electrostatic latent image is developed by the developing device 3 as described above. The toner image thus obtained is transferred to a transfer material such as paper by the action of a transfer charger 18, and then the transfer material is separated from the photoreceptor 1 by the action of a separation charge eliminator 19.

The apparatus for transferring the transfer material includes a cassette 20 containing the transfer material, a pickup roller 21 for sending the transfer material from the cassette 20, and a transfer material to the transfer area in synchronization with the movement of the toner image. It has a registration roller 22 and transport guides 23, 24, 25.

The transfer material separated from the photosensitive member 1 is a guide 2
The toner image is sent to the fixing device 26 through the fixing device 5 and is fixed on the transfer material. The transfer material after fixing is discharged onto a tray 277.

In the illustrated example, the photosensitive member 1 is exposed to a laser beam. However, the photosensitive member may be exposed by light emitted from a light emitting diode array driven by an image signal.
The image of the document may be directly exposed to the photoconductor via a lens.

In FIG. 3, reference numeral 29 denotes a second gear coaxially fixed to the drum 1 at one end of the drum-shaped photosensitive member 1, and 28 denotes a roller 6 at one end of the roller 6 in the developing device longitudinal direction. And a first gear coaxially fixed. The second gear 29 is outside the developing device. The first and second gears 28 and 29 are in mesh with each other, and the drum 1 and the roller 6 rotate in conjunction with each other. When the cartridge 11 is loaded at a predetermined position in the apparatus main body 12 by the guide 15, the second gear 29 meshes with the gear 17 that is driven to rotate by the motor 16. As a result, the drum 1 is driven to rotate. On the other hand, the developing roller 6 rotates in the direction opposite to the rotation direction of the drum 1 by the first gear 28 receiving the transmission of the rotational driving force from the second gear 29.

The cartridge having the cleaning device 4 and the charging device 2 in addition to the drum-shaped electrophotographic photoreceptor 1 and the developing device 3 has been described. The present invention has the photoreceptor and the developing device. Also, a process cartridge having no charger can be applied.

In FIGS. 1, 2 and 3, the drum-shaped photosensitive member 1
The shafts 31, 31 'are rotatably supported by a synthetic resin support frame 32 molded integrally with the mold. In this embodiment, the cleaning device 4 is also fixed to the support frame 32. The frame 32 is fixed to the frame 18 in FIG.

The shafts 30 and 30 'of the developing roller 6 are rotatably supported by a synthetic resin developer container 8 integrally molded.

On one side of the longitudinal direction of the developing device 3, that is, on the side where the gear 28 is provided, the container 8 is rotatably supported by a shaft 33 fixed to a frame 32. ing. On the other side in the longitudinal direction of the developing device 3, the container 8 is rotatably supported by a shaft 34 fixed to a frame 32. Therefore, the developing device 3 can swing relative to the photosensitive member 1 with the shafts 33 and 34 as fulcrums.
The shafts 33 and 34 are preferably provided on the same straight line parallel to the axes of the photoconductor 1 and the developing roller 6.

Here, due to the gravity W applied to the developing device 3, the moment generated with respect to the fulcrum, that is, the shafts 33 and 34 urges the developing roller 6 toward the photosensitive member 29, whereby the spacers 7 and 7 ′ can be pressed against the photoconductor 29. The shafts 33 and 34 are provided at positions where a moment can be formed.

Further, the second gear 29 rotates to rotate the first gear 2.
When the driving force is transmitted to the first gear 2 as shown in FIG.
8 receives a force F directed by the second gear 29 in the direction of the pressure angle of the gear meshing portion. The moment generated with respect to the fulcrum, that is, the shafts 33 and 34 due to the force F is
In this embodiment, the developing roller 6 is urged in the direction toward the photosensitive member 1 so that the spacers 7 and 7 ′ are pressed against the photosensitive member 1. In other words, the shafts 33 and 34 are provided at positions where a higher moment can be generated by the force F.

The hole 35 provided in the container 8 to be fitted to the shaft 33 has a diameter substantially equal to the diameter of the shaft 33. Therefore, on the side where the first gear 28 exists, that is, on the side where the developing roller 6 receives the rotational driving force, the developing device 3 is displaced relative to the shaft 33 in a direction perpendicular to the longitudinal direction. do not do.

On the other hand, the hole 36 provided in the container 8 that engages with the shaft 34 is a long hole whose minor dimension is substantially equal to the diameter of the shaft 34. The long diameter direction of the long hole 36 is
This is a direction that intersects with the direction of gravity, and is a direction in which a portion of the developing roller 6 on which the gear 28 is not provided can be displaced in a direction to approach and separate from the photoconductor 1. In any case, since the hole 36 is a long hole, the side of the developing device 3 where the gear 28 is not provided is slightly displaced relative to the photoconductor 1 in a direction orthogonal to the longitudinal direction of the developing device 3. It is possible.

With the above arrangement, the pitch circle interval between the first gear 28 and the second gear 29 is accurately maintained at a required value, and the spacer 7 'as well as the spacer 7 is securely attached to the photosensitive member 1. Is guaranteed to abut. That is,
The positioning of the developing device 3 with respect to the photoconductor 1 is performed by using the shaft 33 and the hole 3.
5 and two spacers 7, 7 '.

Next, the change in the pressure (hereinafter referred to as SD pressure) between the spacers 7, 7 'and the drum-shaped photoreceptor 1 when the amount of toner in the container 8 is changed is examined. The results are shown in FIG. 6, the vertical axis represents the SD pressure, and the horizontal axis represents the container 8.
Is the ratio (%) of the amount of the developing toner in the container 8 to the upper limit amount of the toner that can be stored in the container 8. Line (7) indicates the SD pressure between the spacer 7 and the photoconductor 1, and line (7 ') indicates the SD pressure between the spacer 7' and the photoconductor 1.

As can be seen from FIG. 6, the SD pressure (7) for the spacer 7 on the side where the drive input gear 28 is provided.
Is larger than the SD pressure (7 ') for the spacer 7' on the opposite side. This means that the moment due to the force F in the pressure angular direction at the meshing portion of the gear shown in FIG. 4 acts more strongly on the spacer 7 than on the spacer 7 '.

The SD pressure (7) decreases with a decrease in the amount of toner in the container 8, while the SD pressure (7 ') changes little. The reason is that the supporting hole 36 on the side where the spacer 7 'is provided is a long hole, so that the contact portion between the photosensitive member 1 and the spacer 7' is changed according to the change in the amount of toner in the developing device. It is considered that the reason for this is that the shaft 34 is displaced in the long hole 36 in the direction of the major axis thereof to suppress the fluctuation of the SD pressure (7 ').

Therefore, in order to suppress the fluctuation of the SD pressure (7), only in the longitudinal direction of the developing unit, that is, in the longitudinal direction of the developing roller, the developing unit is provided only on the side where the drive input gear 28 is provided. 3, an elastic force for reducing the moment C about the shaft 33 due to the gravity W is applied.

That is, one end of the tension spring 37 is engaged with the pin 38 implanted in the container 8, and the other end is engaged with the pin 39 implanted in the frame 32. , About the axis 33, the clockwise moment C due to the gravity W
A moment D in the opposite direction is formed. However, at the position where the spacer 7 is pressed against the photoconductor 1, the magnitude of the moment D is smaller than the magnitude of the moment C, so that the spacer 7 is reliably pressed against the photoconductor 1 by the gravitational moment C. . Further, the above-mentioned moment by the spring 37 is in the opposite direction to the above-mentioned moment by the force F in FIG. 4, and the moment by the force F also reduces the force for pressing the spacer 7 against the photosensitive member.

In any case, as described above, SD
The pressures (7) and (7 ') are reduced and made equal, and the SD pressures (7) and (7) associated with a decrease in the amount of toner in the container 8 are reduced.
The reduction rates of (7 ') are made equal to each other.

By appropriately selecting the elastic tension of the spring 7, for example, both the SD pressure (7) and the SD pressure (7 ') are about 1.5 kg when the toner is filled in the container 8. When the toner in the container 8 is emptied, it can be about 0.5 kg.

In the above embodiment, the shaft 33 is set in the frame 32,
Although the hole 35 is provided in the container 8, the shaft 33 is
May be provided in the frame 32. Similarly, the shaft 34 may be provided in the container 8 and the long hole 36 may be provided in the frame 32.

In the above embodiment, the fulcrum means 33, 3
The position 4 is set such that the force F in the pressure angular direction at the meshing portion of the first and second gears 28 and 29 forms a moment for urging the developing roller 6 in the direction toward the photoconductor 1. Although set, the moment may be set at a position where a moment in the opposite direction is formed. In this case, the shaft 33 is located on the opposite side of the extension line (broken line) of the force F from the position shown in FIG.
In the same rotational direction as the moment D, which contributes to the reduction of the SD pressures (7) and (7 ').

Further, in the above example, the minute gap is formed between the developing roller and the photosensitive member by the spacers 7 and 7 '.
Using an elastic, for example, a conductive rubber developing roller,
The present invention can also be applied to a developing device of a type in which the latent image is developed by pressing this against a photosensitive member. In this case, the spacer may not be provided.

The present invention is particularly useful for a process cartridge having a developing device having a large toner storage amount.
The present invention is also applicable to an image forming apparatus in which a photoconductor and a developing device can be individually attached to and detached from an image forming apparatus main body.

[0044]

As described above, according to the present invention,
The elastic force of the elastic member acts only on the side of the developing device on which the driving force transmission member is provided, and when the driving force is transmitted to the driving force transmission member by this elastic force, the interval determining member carries the image. Since the moment acting so as to be pressed against the body is reduced, the contact pressure of the gap determining member on the side where the driving force transmitting member is provided with the image carrier and the contact pressure of the gap determining member on the opposite side with respect to the image carrier are reduced. Variations from the contact pressure can be suppressed, and the spacing member can be stably brought into contact with the image carrier.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of a process cartridge to which the present invention is applied.

FIG. 2 is a view of the process cartridge as viewed in a direction BB of FIG. 3;

FIG. 3 is a perspective view of the process cartridge shown in FIG.
The figure seen in the direction.

FIG. 4 is an explanatory diagram of a force in a pressure angle direction of a gear meshing portion and a position of a fulcrum means.

FIG. 5 is an explanatory diagram of one embodiment of the present invention.

FIG. 6 is an explanatory diagram of an SD pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 3 Developing device 6 Developing roller 7, 7 'Spacer 8 Developer container 11 Process cartridge 12 Electrophotographic apparatus main body 15 Guide 28 First gear 29 Second gear 33 Shaft 34 Shaft 35 Shaft hole 36 Slot 37 Spring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-21049 (JP, A) JP-A-3-84849 (JP, U) JP-A-62-25955 (JP, U) JP-A-2- 47653 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08 G03G 15/20 G03G 15/00 550

Claims (4)

(57) [Claims] An image carrier that carries a latent image; a developer carrier that carries a developer; and an image carrier that is provided at both ends of the developer carrier and abuts on the image carrier to contact the image carrier with the developing device. A developing device having an interval determining member for determining an interval between the developer carrying member and a driving force transmitting member to which a driving force for driving the developer carrying member is transmitted; In the image forming apparatus, when a driving force is transmitted to a member, a moment acts so that the gap determining member is pressed against the image carrier. The side on which the driving force transmitting member of the developing device is provided Only when the driving force is transmitted to the driving force transmission member by this elastic force, the moment acting to press the distance determining member against the image carrier is reduced. Image characterized by Forming apparatus. 2. A side of the developing device on which the driving force transmission member is provided, the developing device is supported such that the developing device is not substantially displaced in a direction perpendicular to a longitudinal direction of the developing device. 2. The image forming apparatus according to claim 1, wherein the side on which the driving force transmission member is not provided supports the developing device so as to be displaceable in a direction perpendicular to a longitudinal direction thereof. 3. 3. An image forming apparatus, comprising:
An image carrier for carrying a latent image, a developer carrier for carrying a developer, and a contact between the image carrier and the developer carrier provided at both ends of the developer carrier and in contact with the image carrier; A developing device having a driving force transmitting member to which a driving force for driving the developer carrying member is transmitted, the driving force being transmitted to the driving force transmitting member; In a process cartridge in which a moment acts so that the gap determining member is pressed against the image carrier when the force is transmitted, the elasticity of the elastic member is provided only on the side of the developing device on which the driving force transmitting member is provided. When a force is applied and the driving force is transmitted to the driving force transmission member by the elastic force, a moment acting to press the space determination member against the image carrier is reduced. Process mosquito Cartridge. 4. The side of the developing device on which the driving force transmission member is provided is supported so that the developing device is not substantially displaced in a direction perpendicular to a longitudinal direction of the developing device. 4. The process cartridge according to claim 3, wherein the developing device is supported on a side where the driving force transmission member is not provided so as to be displaceable in a direction perpendicular to a longitudinal direction of the developing device.