JP2000089565A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device constituted so that the soil or the failure thereof caused by the splash of toner from occurring by preventing a flexible developer shielding member brought into contact with an image carrier from being turned up. SOLUTION: This image forming device is provided with the flexible developer shielding member 18 brought into contact with the outside circumferential surface 1a of the image carrier 1 in a trailing direction with respect to the rotating direction A of the carrier 1 obtained at an image forming time and set for separating the developer supply part of a developing device 10 from the outside and a cleaning blade brought into contact with the outside circumferential surface 1a so as to recover the toner left there. Besides it is constituted so that the carrier 1 is rotated in a rotating direction B being reverse to the rotating direction A obtained at the image forming time when an image forming action is finished. Then, the whole length L2 of the shielding member 18 in the longitudinal direction is set to be longer than the whole length L1 of the carrier 1 in the axial line 0 direction so that both end parts 18c and 18d of the shielding member 18 are not brought into contact with the outside circumferential surface 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus having a developer shielding member for shielding a developer supply section and a cleaning blade.

[0002]

2. Description of the Related Art An image forming apparatus includes a developing device for supplying a toner for developing an electrostatic latent image formed on an image carrier typified by a drum or a belt-shaped photoconductor to an outer peripheral surface of the image carrier. Equipped. For example, in the developing device described in JP-A-10-10864, a flexible developer shielding member is provided in contact with the outer peripheral surface of the image carrier in order to prevent toner from scattering from the developer supply unit. And shields the developer supply unit from the outside. Generally, the developer shielding member is provided so as to contact in the trailing direction with respect to rotation of the image carrier during image formation. A cleaning device provided with a cleaning blade for collecting the toner remaining on the image carrier is disposed near the periphery of the image carrier. The cleaning blade is provided on the outer peripheral surface of the image carrier in contact with the rotation of the image carrier during image formation in a counter direction. In such an image forming apparatus, the scraped toner is deposited on a wedge-shaped portion formed by the contact between the cleaning blade and the image carrier, so that the accumulated toner is promoted to flow out from the end of the cleaning blade. For this purpose, the image carrier is rotated in the direction opposite to the direction at the time of image formation every time the image formation is completed.

[0003]

However, if the image carrier is rotated in the direction opposite to the direction at the time of image formation every time the image formation is completed, the image carrier is rotated in the counter direction with respect to the developer shielding member, and the image carrier is rotated. The developer shielding member generates dust due to variations in the contact angle with the developer shielding member, variations in the friction coefficient of the outer peripheral surface of the image carrier, and environmental changes, or variations in the friction coefficient of the developer shielding member itself and environmental changes. May cause. If left in this state, the developer shielding member made of a flexible material undergoes plastic deformation, and the state of contact with the image carrier deteriorates, causing toner to scatter from the developer supply unit. Would. In particular, when the image carrier rotates during image formation with respect to the developer supply unit, the toner scattered on the upstream side may stain various parts around the image carrier and cause various problems. As for the spots where the developer shielding member has a mark, the front and rear ends of the member in the longitudinal direction are overwhelmingly large, and the ridgeline of the contact end between the developer shielding member and the image carrier rarely has an extreme undulation. Occasionally, it may occur at both ends. SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which prevents a flexible developer shielding member coming into contact with an image carrier from being lifted up, thereby preventing the device from being stained or deficient due to toner scattering.

[0004]

According to the first aspect of the present invention,
A flexible developer shielding member that contacts the outer peripheral surface of the image carrier in a trailing direction with respect to rotation during image formation of the image carrier with the developer supply unit of the developing device separated from the outside; A cleaning blade that is provided in contact with the outer peripheral surface of the body and that collects toner remaining on the outer peripheral surface, and that rotates the image carrier in a direction opposite to a rotation direction at the time of image formation at the end of image formation. The length of the developer shielding member in the longitudinal direction is set to be longer than the length of the image carrier in the axial direction. For this reason, both ends located in the longitudinal direction of the developer shielding member protrude outward from both ends of the image carrier,
Contact between the image carrier and both ends of the developer shielding member is eliminated, and the generation of sharp edges at both ends of the developer shielding member, which is overwhelmingly large, is prevented.

According to a second aspect of the present invention, the entire length of the cleaning blade in the longitudinal direction is set to be equal to or slightly shorter than the entire length of the developer shielding member, and both ends located in the longitudinal direction of the cleaning blade and the developer shielding member. The positional relationship of each member is set so that both ends are aligned, and furthermore, the toner is prevented from leaking to both ends of the cleaning blade and the downstream side in the rotation direction of the image carrier during image formation close to the both ends. A predetermined gap is provided between the barrier member. For this reason,
Part of the transfer residual toner that reaches the cleaning blade is not cleaned by the cleaning blade, but slips through the set gap to form a toner band at a position facing both ends of the developer shielding member. It is supplied to a contact portion with the image carrier. For this reason, the supplied transfer residual toner acts as a lubricant on the contact portion between the developer shielding member and the image carrier, and it is possible to prevent the both ends of the developer shielding member from being rounded.

According to a third aspect of the present invention, in the second aspect of the present invention, each of the gaps is provided between the downstream side of the cleaning blade in the rotation direction of the image carrier during image formation and the developer shielding member. An elastic member is provided at a portion facing in the circumferential direction so as to be able to contact the outer peripheral surface of the image carrier. For this reason, the layer thickness of the toner band formed by passing through the gap between both ends of the cleaning blade and the barrier member is regulated by the elastic member before the developer shielding member. The developer shielding member can be supplied to a wider area of the contact portion between the image bearing member and the developer shielding member. Extreme undulation of the ridgeline is also suppressed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. In each embodiment, components having the same functions are denoted by the same reference numerals as those used in the first embodiment. However, detailed description is omitted.

(First Embodiment) The image forming apparatus shown in FIG. 1 has a drum-shaped photosensitive member 1, which is an example of an image carrier, a first charging device 2, which performs preceding charging upstream, and a first exposure. Part 3,
A two-component first developing device 10 that performs development in advance, a second charging device 4 that performs charging downstream of the first developing device 10, a second exposure unit 5, and development that downstream of the second exposure unit 5 1 Second component
Developing device 20, transfer device 30, cleaning device 40,
The static eliminator 6 is disposed near the peripheral portion of the photoconductor 1. The image forming apparatus includes a photoelectric conversion element (CCD) that can read a document placed on a document placement unit (not shown) in two colors (black and red), and converts exposure light emitted from a light irradiation unit (not shown) into a polygon. By irradiating the outer peripheral surface 1a of the photoconductor 1 from the first exposure unit 3 and the second exposure unit 5 via the mirror 7, the plurality of reflection mirrors 8 and the lens 9, an electrostatic latent image corresponding to each color is formed. I have. The photosensitive member 1 is driven by a driving unit (not shown) in a direction indicated by an arrow A during image formation (hereinafter referred to as “rotation direction A”).
), And is rotated in the direction indicated by arrow B (hereinafter referred to as “rotation direction B”) each time the image formation is completed.

The first developing device 10 contains a two-component developer therein, and is provided with a toner replenishing device 50 as shown in FIG. The toner replenishing device 50 supplies replenished toner onto the replenishing roller 51 by an agitator 52 provided therein, and replenishes toner from the replenishing roller 51 into the developing device 10 while detecting toner concentration by toner concentration control means (not shown). ing. The replenished toner is mixed and stirred with the developer in the first developing device 10 by the agitator 15 of the first developing device 10 disposed below the replenishing roller 51, and is sent to the paddle wheel 14 side. The sent developer is conveyed to the developing roller 11 having a magnet disposed on the upstream side among the two developing rollers 11 and 12 provided side by side in the rotation direction A of the photoconductor 1, and The layer amount is regulated by the blade 13 and is used for developing an electrostatic latent image corresponding to black formed on the outer peripheral surface 1a in the first exposure unit 3 in advance. After that, the developer is transferred to the developing roller 12 on the downstream side, used for further development, and returned to the developing device 10 again. The developer that has not passed through the doctor blade 13 is laterally moved in the longitudinal direction of the apparatus by the separator 16 and the screw 17, and
And circulates inside the developing device 10. In the present embodiment, the developer supply unit 25 refers to a portion where the developing rollers 11 and 12 and the photoconductor 1 face each other.

A second developing device 20 shown in FIG. 1 develops an electrostatic latent image corresponding to red color formed on the outer peripheral surface 1a by the second exposure unit 5, and includes a one-component developer housed therein. Is transported to the outer peripheral surface 1a by the developing roller 21 and the supply roller 22.

As shown in FIG. 3, the cleaning device 40 is supported by a holder 42 and is
a cleaning blade 41 pressurized toward a;
The brush roller 43 scrapes off and removes the transfer residual toner on the outer peripheral surface 1a. The scraped toner is transported by the transport screw 44 to the front and rear of the apparatus (in the axial direction of the photoreceptor 1) and collected by a collecting unit (not shown). To be discharged.

The cleaning blade 41 is provided so as to come into contact with the photosensitive member 1 in the counter direction with respect to the rotation direction A of the photosensitive member 1. A cleaning seal member 45 for preventing toner from leaking further upstream is provided in contact with the outer peripheral surface 1a on the upstream side in the rotation direction A with respect to the brush roller 43, and further on the upstream side. Is provided with a separation claw 46.

As shown in FIG. 1, the transfer means 30 is disposed between the separation claw 46 and the second developing device 20. The transfer unit 30 includes a transfer belt 33 that is wound around a driving roller 31 and a driven roller 32 and rotates counterclockwise.
Are brought into contact with the outer peripheral surface 1a to form the transfer section 34. In the transfer section 34, a sheet 26, which is an example of a transfer material, is formed using a pair of paper feed rollers 23 and a pair of registration rollers 24.
The transfer section 34 conveys the electrostatic latent image at the same time as the front end of the sheet 26. The paper 26 is transferred to the transfer unit 34.
While the toner image is being transferred, the toner image is conveyed to a fixing unit (not shown) by the transfer belt 33. When the paper 26 is wound up in close contact with the photoconductor 1 by the transfer operation, the paper 26 is separated from the outer peripheral surface 1 a by the separation claw 46.

As shown in FIG. 2, a flexible developer shielding member 18 is provided upstream of the developing roller 11 in the rotation direction A.
Is arranged. The developer shielding member 18 has a tip 1
8a is in elastic contact with the outer peripheral surface 1a in the trailing direction with respect to the rotation direction A, and prevents scattering of toner from the developer supply unit 25. The developer shielding member 18 is arranged so as to be parallel to the axis O of the photosensitive member 1.
The base end 18b is attached to the casing 10a via a support member 19. The developer shielding member 18 is made of a polyurethane sheet which is a flexible member.

As shown in FIGS. 4 and 5, the developer shielding member 18 has an entire length L in the same longitudinal direction as the axial direction of the photosensitive member 1.
2 is L2 with respect to the total length L1 of the photosensitive member 1 in the axial direction.
> L1. Further, both end portions 18c, 18 located in the longitudinal direction of the developer shielding member 18 are provided.
d is arranged so as to protrude outward from both end surfaces 1b and 1c of the photoconductor 1, respectively.

According to the image forming apparatus in which the developer shielding member 18 is arranged and set as described above, both ends 18c and 18d of the developer shielding member 18 protrude outside the both ends 1b and 1c of the photosensitive member 1. Outer peripheral surface 1a and both ends 18c, 18
This eliminates the contact with the developer shield member d, and can prevent the occurrence of chipping at both end portions 18c and 18d of the developer shielding member 18, which has conventionally been overwhelmingly large, with a simple configuration. Therefore, it is possible to prevent the image forming apparatus from being stained or defective due to toner scattering from the vicinity of the developer supply unit 25.

(Second Embodiment) In this embodiment, the overall length L3 of the cleaning blade 41 in the longitudinal direction and the developer shielding member 1
8 with respect to the photosensitive member 1 with the total length L2, and the barrier member 4
7A and 47B are different from the first embodiment. Other configurations are the same as those of the first embodiment.

As shown in FIGS. 6 and 7, the total length L3 of the cleaning blade 41 in the longitudinal direction, that is, the axial direction of the photosensitive member 1 is set to L3 ≦ L2 with respect to the total length L2 of the developer shielding member 18. ing. Preferably L3 <
L2 is set to increase the total length L2 of the developer shielding member 18. It is preferable that the total lengths L2 and L3 are set to have a relationship of L4 ≦ L2 and L3 with respect to the total length L4 of the image forming area 1d of the photoconductor 1, respectively.

The barrier members 47A, 47B are provided at both ends 41a, 41 located in the longitudinal direction of the cleaning blade 41.
Outside of b, it is fixed to the holder 42. The barrier members 47A and 47B prevent the transfer residual toner from leaking downstream in the rotation direction A. Barrier members 47A, 4
7B is arranged with a predetermined gap S between the both ends 41a and 41b. Each of the gaps S is formed at a position facing the both ends 18 c and 18 d of the developer shielding member 18 in the circumferential direction. The predetermined gap S is a dimension that allows a necessary and sufficient amount of untransferred toner to pass through the developer shielding member 18 when the photoconductor 1 rotates in the rotation direction A, and has a gap of about 3 mm to 10 mm. Is appropriate.

According to the image forming apparatus having such a configuration,
When the photoreceptor 1 rotates in the rotation direction A and the transfer residual toner reaches the cleaning blade 41, a part of the toner passes through the set gaps S without being cleaned by the cleaning blade 41 as shown in FIG. As a result, the toner bands 49, 49 are formed on the outer peripheral surface 1a outside the image area 1d and facing the both ends 18c, 18d, respectively, due to the toner slipping along with the rotation of the photoconductor 1 in the rotation direction A. As shown in FIG.
Transfer residual toner is positively supplied from the toner bands 49, 49 to the contact portions 70, 70 between the photosensitive members 1 and c, 18d, respectively. Therefore, the supplied untransferred toner acts as a lubricant on the contact portions 70 and 70, respectively, so that it is possible to easily prevent the generation of roundness at the both end portions 18c and 18d, and the developer supply portion 25 is provided near the developer supply portion 25. It is possible to prevent the image forming apparatus from being stained or defective due to toner scattering from the image forming apparatus.

(Third Embodiment) The amount of untransferred toner passing through the gaps S, S depends on the size of the original image, the state of transfer of the toner image to the sheet 26, or the outer peripheral surface 1a of the photosensitive member 1.
It is very difficult to control the amount, depending on the condition of Therefore, as shown in FIG. 10, between the downstream side of the cleaning blade 41 in the rotation direction A and the developer shielding member 18, the portion facing the gap S in the circumferential direction can be brought into contact with the outer peripheral surface 1 a. In the third embodiment, the elastic members 60 are provided. These elastic members 60 are made of polyurethane, and are mounted on the support member 19 such that their tips 60a are lightly pressed against the outer peripheral surface 1a. Since the elastic member 60 only needs to have an elastic force enough to regulate the layer thickness of the toner bands 49, 49, the elastic member 60 does not need to be pressed so strongly that all the transfer residual toner constituting each toner band is scraped off. Alternatively, each of the elastic members 60 may be supported such that the distal end 60a has a slight gap with respect to the outer peripheral surface 1a.

When the elastic members 60 are provided in this manner, when the toner bands 49, 49 formed through the gaps S pass below the elastic members 60, the layer thicknesses t thereof are made uniform. Alternatively, as shown in FIG. 11, the width D of each toner band 49 in the axial direction of the photoconductor 1 is the width D1.
Respectively. For this reason, the transfer residual toner acting as a lubricant is supplied to a wider range near the contact portion 70, and the effect of preventing both ends 18 c and 18 d of the developer shielding member 18 from being sharpened can be further enhanced. Further, since the supply range of the transfer residual toner is widened by the increase in the width of the toner bands 49, 49, the occurrence of the extreme waving of the ridge line of the contact portion 70 is suppressed. Each width D of the toner bands 49, 49 is widened by the elastic members 60, 60, but it is preferable that the enlarged width D1 does not invade the image forming area 1d in order to perform good development.

[0023]

According to the first aspect of the invention, the entire length of the developer shielding member of the developing device in the longitudinal direction is longer than the entire length of the image carrier in the axial direction, and both ends of the developer shielding member are provided. By setting the positional relationship so that the projections protrude from both end surfaces of the image carrier, both ends of the developer shielding member do not come into contact with the image carrier, so that the both ends of the developer shielding member generate dust. Is prevented, and the device can be prevented from being soiled or defective due to toner scattering from the vicinity of the developer supply unit.

According to the second aspect of the present invention, the entire length of the cleaning blade is set to be equal to or slightly shorter than the entire length of the developer shielding member, and both ends of the cleaning blade are aligned with both longitudinal ends of the developer shielding member. When a predetermined gap is provided between both ends of the cleaning blade and the developer shielding member, a part of the transfer residual toner that reaches the cleaning blade passes through the gap and the developer is removed. Since the toner band is formed on the outer peripheral surface opposite to both ends of the shielding member, the transfer residual toner from the toner band can be used as a lubricant, and it is possible to more reliably prevent the developer shielding member from being damaged. For this reason, it is possible to more reliably prevent the device from being stained or defective due to toner scattering from the vicinity of the developer supply unit.

According to the third aspect of the present invention, if an elastic member is provided upstream of the developer shielding member and in contact with the image carrier near the end of the developer shielding member, the elastic member provides a toner. Since the layer thickness of the band is regulated and the width of the toner band is widened, the toner spread in the band shape can be more effectively used as a lubricant, and the effect of preventing the developer shielding member from being sharpened can be further enhanced.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view showing a configuration of a developing device and its vicinity.

FIG. 3 is an enlarged view showing a configuration of a cleaning device and its vicinity.

FIG. 4 is an exploded perspective view showing a relationship between an attached state of a developer shielding member according to the first embodiment of the present invention and an image carrier.

FIG. 5 is an enlarged view showing a contact state between a developer shielding member and an image carrier according to the first embodiment of the present invention.

FIG. 6 is an enlarged perspective view illustrating an attached state of a cleaning blade and a barrier member according to a second embodiment of the present invention.

FIG. 7 is a developed view showing a relationship among a cleaning blade, a barrier member, a developer shielding member, and an image carrier.

FIG. 8 is an enlarged perspective view showing an operation by a gap between a cleaning blade and a barrier member.

FIG. 9 is an enlarged view showing a contact state between a developer shielding member and an image carrier according to a second embodiment of the present invention.

FIG. 10 is an enlarged view showing a configuration of an elastic member according to a third embodiment of the present invention and its vicinity.

FIG. 11 is a partially broken plan view showing a change of a toner band caused by an elastic member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 1a Outer peripheral surface 10 Developing device 18 Developer shielding member 25 Developer supply part 41 Cleaning blade 41a, 41b Both ends 47A, 47B of cleaning blade Barrier member 60 Elastic member O Axis line of image carrier L1 Image carrier Total length L2 Total length of developer shielding member L3 Total length of cleaning blade S Predetermined gap

Continued on the front page F term (reference) 2H034 AA06 BF01 BF06 2H077 AB04 AC02 AC03 AD06 AD13 BA10 CA04 CA12 EA21 FA21 GA14

Claims (3)

[Claims] A developer supply section of the developing device and an outside thereof are separated from each other;
A flexible developer shielding member that contacts the outer peripheral surface of the image carrier in the trailing direction with respect to rotation during image formation of the image carrier, and is provided so as to be able to contact the surface of the image carrier; An image forming apparatus comprising: a cleaning blade for collecting toner remaining on the outer peripheral surface; and rotating the image carrier in a direction opposite to a rotation direction at the time of image formation when the image formation is completed. An image forming apparatus, wherein the total length of the image carrier in the longitudinal direction is set longer than the total length of the image carrier in the axial direction. 2. A developer supply unit of a developing device, which is separated from the outside,
A flexible developer shielding member that contacts the outer peripheral surface of the image carrier in the trailing direction with respect to rotation during image formation of the image carrier, and is provided so as to be able to contact the surface of the image carrier; An image forming apparatus comprising: a cleaning blade for collecting toner remaining on an outer peripheral surface of the image carrier; and rotating the image carrier in a direction opposite to a rotation at the time of image formation at the end of image formation. The entire length of the blade in the longitudinal direction is set to be equal to or shorter than the entire length of the developer shielding member in the longitudinal direction. An image forming apparatus, wherein barrier members for preventing toner from leaking to the downstream side in the rotation direction of the image carrier are provided with predetermined gaps from the both end portions. 3. The image forming apparatus according to claim 2, wherein each of the gaps is located between a downstream side of the cleaning blade in a rotation direction of the image carrier during the image formation and the developer shielding member. An image forming apparatus, wherein an elastic member is provided at a portion opposed in a circumferential direction so as to be able to contact an outer peripheral surface of the image carrier.