JPH05158338A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of fogging caused by the deterioration of a developer and to prolong the life of a member by moving an elastic roller as a developer supplying member so as to obtain a noncontact state with a developing sleeve at the time of nondeveloping. CONSTITUTION:The bearing 9 of the elastic roller 5 is projected from a container side surface, and supported by the fork parts of the top end of the supporting member 11 provided freely rockably around the center of the rotation B, on a device main body. Therefore, the elastic roller 5 in non-contact with the developing sleeve 3, in a nondeveloping action, obtains a contact state with the developing sleeve 3, in such a manner that a solenoid 12 is turned on, and the bottom end of the supporting member 11 is supported by output from the device main body at the time of developing. Thus, the solenoid 12 is turned off at the rime of nondevelopment, and turned on at the time of developing action, so that the developing sleeve 3 and the elastic roller 5 are kept in a non-contact state at the time of nondevelopment, and the developing sleeve 3 and the elastic roller 5 are abutted and rotated only at the time of developing action. Thus, rubbing time is kept to an irreducible minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type copying apparatus, an image recording apparatus, a printer, a facsimile or other image forming apparatus, and more particularly to an electrophotographic photoreceptor or an electrostatic recording apparatus. A developing device which develops an electrostatic latent image formed on an image carrier made of a recording dielectric or the like into a visible image (toner image), and is characterized by a one-component developer containing no carrier. It can be suitably embodied in a developing device used for development.

[0002]

2. Description of the Related Art Copiers, image recorders, printers,
In an image forming apparatus such as a facsimile, an electrostatic latent image formed on an image carrier made of an electrophotographic photosensitive member or an electrostatic recording dielectric is developed by a developing device to form a toner image. As one of such developing devices, various dry one-component developing devices have been proposed and put into practical use. However, it is difficult to form a thin layer of toner, which is a one-component developer, on the developer carrier with any of the developing devices.

However, at the present time when improvements in image resolution and sharpness are required, development of a toner thin layer forming method and its apparatus is indispensable, and some measures are proposed for this. Has been done.

For example, in Japanese Unexamined Patent Publication No. 54-43038, an elastic blade made of rubber or metal is brought into contact with a developing sleeve as a developer carrying member, and a toner layer is formed at a contact portion between the elastic blade and the developing sleeve. And a toner layer thickness is regulated so that a thin layer of toner is formed on the developing sleeve and a sufficient tribo is imparted to the toner by friction at the contact portion. The device is described.

In this case, when the non-magnetic toner is regulated by the elastic blade, a toner supply member for supplying the toner onto the developing sleeve is required separately. This is because in the case of the magnetic toner, the toner can be supplied onto the developing sleeve by the magnetic force of the magnet in the developing sleeve, but in the case of the non-magnetic toner, the toner cannot be supplied by the magnetic force. The applicant of the present invention has proposed a developing device having the structure shown in FIG. 7 attached to the present application in Japanese Patent Laid-Open No. 58-116559.

In the conventional developing device disclosed in Japanese Patent Laid-Open No. 58-116559, the developing sleeve 3 is contained in the developing container 2 containing the non-magnetic toner 6 as a one-component developer rather than the elastic blade 4.
An elastic roller 5 having a fur brush structure that comes into contact with the developing sleeve 3 is installed at a position on the upstream side in the rotation direction of, and the toner 6 remaining on the developing sleeve 3 that is not consumed for the development is peeled off by the elastic roller 5. New toner 6 is supplied onto the developing sleeve 3.

With this configuration, a thin layer of non-magnetic toner can be satisfactorily formed on the developing sleeve 3, and the electrostatic latent image on the image carrier, that is, the photosensitive member 1 can be satisfactorily developed. By developing, it became possible to faithfully reproduce a high density, wide area solid black image and always obtain a stable image. Further, this developing device can provide a developing device which is simple and small in size and has a large toner capacity as compared with the conventional two-component developing device.

[0008]

However, in the developing device proposed in Japanese Patent Laid-Open No. 58-116559, an elastic roller having a fur brush structure or a sponge roller having a foam skeleton structure is used as a toner supply member. The roller is in contact with and rubs against the developing sleeve with a predetermined pressure from the viewpoint of supplying and removing the toner, so that the following problems occur. When the toner for low temperature fixing is used in the developing device having the above-mentioned structure for the purpose of quick start of copying operation, when the copying operation is repeated many times, the charge amount of the toner on the developing sleeve decreases, and A phenomenon (fogging) in which toner adheres to the non-image area of the electrostatic latent image occurs.

This phenomenon is caused by applying an external force to the toner between the elastic roller and the developing sleeve when supplying and stripping the toner from the elastic roller by the elastic roller, and when this is repeated many times, the toner is gradually applied with the tribo. It occurs due to a decrease in the ability, and becomes remarkable especially under high temperature and high humidity. If the elastic roller rubs against the developing sleeve for a long time, the elastic roller itself will be worn or damaged (fray and wear in the case of a sponge roller, the brush will be worn in the case of a fur brush roller, etc.), and the toner will be supplied and removed. Taken inadequately. When the developing device is left in a high temperature environment for a long period of time, the abutting portion of the elastic roller is locally dented, resulting in poor contact with the developing sleeve at this portion, and toner supply and peeling. Becomes insufficient, and image defects such as density density and ghost occur at the elastic roller cycle.

Particularly, in order to prevent the above-mentioned problem as much as possible, it is desirable to minimize the driving time of the developing sleeve and the elastic roller. Specifically, the toner on the developing sleeve is placed on the photosensitive member. The developing sleeve and the elastic roller may be rotationally driven only during the developing operation for developing. However, in a relatively small and low cost image forming apparatus,
Since the photoconductor and the developing sleeve are driven from the main drive motor via the gear train, the developing sleeve is
It is not preferable because it rotates in synchronism with the photoconductor and the time during which the developing sleeve and the elastic roller rub against each other becomes longer.

Therefore, it is an object of the present invention to configure a developer supply member such as an elastic roller so as not to contact a developer carrier such as a developing sleeve during non-developing operation. The rubbing time between the developer supply member and the developer carrying member is suppressed to a necessary minimum to prevent the occurrence of fog due to the deterioration of the developer, and also to prevent the developer supply member itself from being damaged,
An object of the present invention is to provide an image forming apparatus capable of extending the life of the developer supply member.

Another object of the present invention involves local deformation of the developer supplying member which occurs when the developer supplying member is in pressure contact with the developer carrying member and is left for a long time in a high temperature environment. An object of the present invention is to provide an image forming apparatus capable of preventing image defects and providing a high-density image that is stable and free of fog for a long period of time.

[0013]

The above object can be achieved by an image forming apparatus according to the present invention. In summary, the present invention
In an image forming apparatus that forms an electrostatic latent image on an image carrier and makes the electrostatic latent image into a visible image by a developing device, the developing device contains a developer and opposes the image carrier. A developing container having an opening in the opening, a developer carrying body arranged laterally in the developing container opening, and a developer carrying body in proximity to or in contact with the developer carrying body to form a thin developer layer on the developer carrying body. It has a regulating member and a developer supplying member which is disposed in the developing container and is rotatable by contacting with the developer carrying member, wherein the developer supplying member is in a non-developing operation, The image forming apparatus is characterized in that it is maintained in a non-contact state with the developer carrying member. Preferably, the developer is a non-magnetic one-component developer, and the developer supplying member is a sponge rubber having a foam skeleton structure, or a roller having a fur brush structure in which nylon or rayon is flocked. According to another embodiment, scraping means is provided in the developing container, and the developer supplying member is rotated by contacting with the scraping means from the end of the developing operation of the developer supplying member to the end of the image forming operation. It

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

FIG. 1 is a side view of the image forming apparatus of the present invention. In particular, the developing device is shown in FIG. 1 during a developing operation and in FIG. 2 during a non-developing operation.

In the present embodiment, the image forming apparatus is an electrophotographic image forming apparatus, and its entire configuration is well known to those skilled in the art, and therefore, it will be briefly described here.

That is, in FIG. 1, a drum-shaped electrophotographic photosensitive member 1 serving as an image bearing member is rotatably supported in the direction of arrow a, and a primary member for uniformly charging the photosensitive member 1 is provided around the electrophotographic photosensitive member 1. The charger 100, the exposure unit 102 for irradiating the photoconductor 1 with the optical image for forming the electrostatic latent image, which will be described in detail later,
A developing device 103 for converting the latent image on the photoconductor 1 into a visible image (toner image), a transfer charger 104 for transferring the toner image on the photoconductor 1 onto the transfer material P, and a photoconductor 1 on the photoconductor 1. A cleaning device 105 for removing the residual toner is arranged.

Next, the developing device 103 constructed according to the present invention will be described in more detail. Referring to FIG. 5, the developing device 103 includes a developing container 2 that contains a non-magnetic one-component developer (hereinafter referred to as “toner”) as the developer 6, and the container 2 faces the photoconductor 1. The developing sleeve 3 as a developer carrying member is provided in the opening.

In FIG. 5, the developing sleeve 3 has a right half-peripheral surface projecting into the container 2 in the opening, and a left half-peripheral surface exposed to the outside of the container 2 and rotatably supported in the direction of arrow b. It is installed horizontally. Further, as will be understood with reference to FIG. 3, the developing sleeve 3 is rotationally driven via the developing sleeve drive gear 15 that meshes with the drive gear 14 of the photoconductor 1.

Further, the outer exposed surface of the developing sleeve 3 faces the surface of the photoconductor 1 with a small gap, or contacts the surface of the photoconductor 1.

The developing sleeve 3 having such a structure is, for example, SU.
Made of metal materials such as S and aluminum, and
In order to increase the probability of rubbing with the toner 6 and to improve the transportability of the toner 6, appropriate irregularities are formed on the surface. Alternatively, a conductive rubber roller may be used as the developing sleeve 3.

In this embodiment, an elastic blade 4 is provided on the upper side of the developing sleeve 3 so as to contact the outer surface of the developing sleeve 3,
In addition, the developing sleeve 3 is inclined toward the downstream side in the rotation direction, that is,
The developing sleeves 3 are arranged so as to face each other in the rotation direction of the developing sleeve 3. The elastic roller 5 is a roller made of sponge rubber having a foamed skeleton structure or a fur brush structure roller having flocked nylon, rayon or the like, and contacts the developing sleeve 3 during the developing operation (see FIG. 5). It is provided so as to be movable so as to be in a non-contact state (a dotted line position in FIG. 5) during a non-developing operation.

The elastic roller 5 has its contact point with the developing sleeve 3 located upstream of the elastic blade 4 in the rotational direction of the developing sleeve 3 during the developing operation, and is rotationally driven in the direction of arrow c.

More specifically, as shown in FIGS. 1 and 2, the rotating shaft 8 of the elastic roller 5 is supported by a bearing 9, and the bearing 9 is an elongated hole-shaped guide provided on the side surface of the container 2. It is movable in the lateral direction in the figure along 10. Further, in order to prevent the toner 6 in the container 2 from leaking out from the gap between the guide 10 and the bearing 9, an elastic seal member 13 such as polyurethane foam is provided in the gap portion. The bearing 9 projects from the side surface of the container 2 and is supported by the upper end bifurcated portion of a support member 11 which is swingably provided around the rotation center O in the image forming apparatus main body. The lower end of the support member 11 is connected to the solenoid 12.

At the time of non-developing operation, as shown in FIG. 2, the elastic roller 5 not in contact with the developing sleeve 3 is
During the developing operation, the solenoid 12 is turned on by the output from the apparatus main body and the lower end of the support member 11 is moved to the arrow d.
By moving in the direction, as shown in FIG. 1, it is brought into contact with the developing sleeve 3.

3 and 4, the photoconductor 1 and the elastic roller 5 are shown.
And gears 14, 15 and 17 provided at the side ends of the developing sleeve 3 are in mesh with each other. As shown in FIG. 4, during the non-developing operation, even if the developing sleeve 3 rotates in synchronization with the photoconductor 1, the elastic roller 5
The gear 17 of the elastic roller 5 is in a free state.
Is not rotating, but the elastic roller 5 moves during the developing operation, so that as shown in FIG.
5, the elastic roller gear 17 meshes with the idler gear 16 meshing with the gear 5. As a result, with the rotation of the photoconductor 1 driven by the apparatus main body, the drive is transmitted to the elastic roller gear 17 via the photoconductor gear 14, the developing sleeve gear 15, and the idler gear 16, and the elastic roller 5 is indicated by the arrow c.
Rotate in the direction.

Therefore, referring to FIG. 5, during the developing operation, the elastic roller 5 in contact with the outer surface of the developing sleeve 3 rotates in the direction of arrow c, and this rotation causes the toner 6 to rotate.
Is carried to the vicinity of the developing sleeve 3, and the toner 6 carried on the elastic roller 5 at the contact portion between the developing sleeve 3 and the elastic roller 5 is rubbed against the developing sleeve 3 to be rubbed and charged. It adheres on the developing sleeve 3.
Thereafter, as the developing sleeve 3 rotates, the toner 6 penetrates into the contact portion between the elastic blade 4 and the developing sleeve 3, and when passing therethrough, the toner 6 is rubbed against both the surface of the developing sleeve 3 and the blade 4 and sufficiently charged by friction. Receive

The thus charged toner 6 escapes from the contact portion, is formed as a thin toner layer on the developing sleeve 3, and is sent to the developing portion facing the photoconductor 1.
The developing sleeve 3 and the photoconductor 1 have a minute gap in the developing portion, and an AC voltage having a direct current superposed between them is applied to remove the toner 6 formed in a thin layer on the developing sleeve 3 from the photoconductor 1. The toner image is formed as a visible image by being transferred corresponding to the electrostatic latent image.

The undeveloped toner that has not been consumed in the developing section is collected from the lower portion of the developing sleeve 3 as the developing sleeve 3 rotates. A seal member 7 is provided in this collecting portion to allow passage of undeveloped toner into the container 2 and prevent the toner 6 in the container 2 from leaking from the lower portion of the developing sleeve 3. The collected undeveloped toner on the developing sleeve 3 is peeled off from the developing sleeve 3 at the contact portion between the elastic roller 5 and the developing sleeve 3. Most of the peeled toner is conveyed as the elastic roller 5 rotates and mixes with the toner 6 in the container 2 to disperse the charge of the charged toner. At the same time, new toner is supplied onto the developing sleeve 3 by the rotation of the elastic roller 5, and the above-described operation is repeated.

As described above, the elastic roller 5 has both the functions of supplying the toner 6 to the developing sleeve 3 and stripping the undeveloped toner, and it is important that the elastic roller 5 is in stable contact with the developing sleeve 3. Becomes If this contact is insufficient, toner supply and peeling defects occur, and image defects such as density and ghost images occur.

As described above, according to the present invention, the developing device turns off the solenoid 12 during the non-developing operation and turns on the solenoid 12 during the developing operation, so that the developing sleeve 3 and the elastic roller during the non-developing operation. 5, the developing sleeve 3 and the elastic roller 5 can be brought into contact with each other and rotated only during the developing operation, and the time during which the elastic roller 5 rubs against the developing sleeve 3 can be minimized. As a result, it is possible to prevent the deterioration of the ability of the toner to impart tribo and the damage to the elastic roller 5 itself, and to extend the life of the elastic roller 5.

According to the above construction, the elastic roller 5 is
It is also possible to prevent an image defect due to local deformation of the elastic roller 5 that occurs in a state of being pressed against the developing sleeve 3 and left for a long time in a high temperature environment.

Next, a more specific embodiment of the developing device will be described.

In this embodiment, as the developing sleeve 3, an aluminum sleeve having a diameter of 16 mm was used, and the surface thereof was subjected to a standard blast treatment with glass beads.
The elastic blade 4 is made of urethane having a JIS hardness of 40 ° to 80 °, preferably 50 ° to 70 °, a rubber such as silicon, or a metal thin plate such as SUS or phosphor bronze for stable formation of a thin developer layer. And the hardness is 65 ° in this embodiment.
The urethane rubber blade was used, and the end of the elastic blade 4 was urged so as to make surface contact with the developing sleeve 3. The setting pressure of the elastic blade 4 at this time is 5 to 200 g /
cm (line pressure in the developing sleeve generatrix direction) is effective, and in this embodiment, 30 g / cm. In addition, the measuring method of the linear pressure is
Three thin plates having a coefficient of friction of 1 were stacked and inserted into the elastic blade contact portion, and the central thin plate was pulled out by a spring backer, and the pulling force at that time was defined as the linear pressure.

As the material of the elastic roller 10, a sponge roller having a skeletal structure having a relatively low degree of foaming (having a relatively high density) is preferable. In this embodiment, the wall thickness is 3 mm
The urethane foam ( ¹ ) having a density of 0.025 g / cm ³ was wound around a core rod was used. The sponge roller softly abuts on the developing sleeve 3, and a contact width of 1 to 10 mm is effective. In this embodiment, the sponge roller is 3 mm. In order to improve the peeling of the undeveloped toner on the developing sleeve 3, it is preferable that the sponge roller peripheral speed and the developing sleeve peripheral speed have a relative speed, and the relative speed is 5 to 600 mm / sec. It is effective, and in this embodiment, it is set to 80 mm / sec.

As a developer, in this embodiment, styrene /
A copolymer of acrylic resin and styrene-butadiene resin,
A toner obtained by externally adding 1.5% of colloidal silica to a toner powder composed of a pigment and having an average particle diameter of 12 μm was used.
A uniform coating layer of μ was obtained.

The above-mentioned developing device is an F manufactured by Canon Inc.
C-3, or FC-5 frequency 1800H _Z as intrinsic bias power supply to that remodeled copying machine, V _PP 1200
By using a DC voltage of -300V superimposed on an AC voltage of V, the surface potential of the latent image on the photoconductor is set to -600V for the dark part and -150V for the light part, and the distance between the developing sleeve 3 and the photoconductor 1 is set to 250 μm. The toner layer on the developing sleeve 3 is initially set when 2000 sheets are formed under the high temperature and high humidity environment by using the low melting point toner and controlling the solenoid 12 to be turned on only during the developing operation. In contrast to the charge amount by the blow-off method of +15 μc / g, the charge amount after 2,000 sheets remains approximately the same value as +12 μc / g, and it is possible to stably obtain a good image with a reflection density of 1.3 without fog. It was

In the present embodiment, the elastic roller 5 is
In the non-contact state with the developing sleeve 3, the structure is not rotated, but the structure may be rotated. Furthermore,
The drive of the elastic roller 5 can be received from the main body, and when the elastic roller 5 is driven and comes into contact with the developing sleeve 3, the drive is transmitted from the elastic roller 5 side to the developing sleeve 3. It is also possible to stop both the developing sleeve 3 and the elastic roller 5 during the non-developing operation.

FIG. 6 shows another embodiment of the developing device.

In this embodiment, the elastic roller 5 moves to the dotted line position in the figure during the non-developing operation as in the case of the first embodiment.
From the end of the developing operation to the end of the copying operation, the elastic roller 5 is configured to continuously rotate in a non-contact state with the developing sleeve 3, and further, the toner scraping means 18 provided in the developing container 2 is provided. The elastic roller 5 rotates while contacting the tip 18a. As a result, the toner attached to the surface of the elastic roller 5 is peeled off.

As described above, the toner deterioration due to the friction between the elastic roller 5 and the developing sleeve 3 is promoted by the following phenomenon.

That is, when the toner 6 is clogged in the elastic roller 5, the roller 5 is further hardened, the pressure on the toner 6 at the contact portion with the developing sleeve 3 is increased, and the toner deterioration is promoted. Therefore, in this embodiment, the toner on the elastic roller 5 is stripped from the end of the developing operation to the end of the copying operation to prevent acceleration of toner deterioration due to hardening of the elastic roller. is there.

In this embodiment, a toner feeding member 19 is provided in order to reliably supply the toner to the elastic roller 5 and the developing sleeve 3 and is rotated in the direction of arrow e.

As the toner scraping means 18,
In this embodiment, the tip of the PET plate is in contact with the elastic roller 5. However, when the elastic roller 5 is in a non-contact state with the elastic roller 5, a member such as a malt brain or a brush is attached to the elastic roller 5. It is also effective as a structure that abuts.

[0045]

As described above, the image forming apparatus according to the present invention is, as a developing device, a developing container that contains a developer and has an opening at a portion facing the image carrier, and a lateral side of the container opening. A developer carrying member such as a developing sleeve arranged,
A developing device having a regulating member that is close to or in contact with the developer carrying member and forms a thin developer layer on the carrying member is used, and is brought into contact with the developer carrying member in the developing container. , A developer supply member such as an rotatably provided elastic roller, and the developer supply member is not in contact with the developer carrier during non-developing operation, so that the developer supply member It is possible to suppress the rubbing time between the developer carrier and the developer carrier to the minimum necessary, prevent the occurrence of fogging due to the deterioration of the developer, prevent the developer supply member itself from being damaged, and prolong the life of the member. It is also possible to prevent an image defect due to local deformation of the roller that occurs when this developer supply member is in pressure contact with the developer carrier and is left for a long time in a high temperature environment, and for a long time. Stable, high density images without fog Be subjected, it may exhibit the effect that.

[Brief description of drawings]

FIG. 1 is a side view showing the configuration of an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a side view showing a developing device portion of the image forming apparatus of FIG. 1, showing a non-developing operation.

3 is a side view showing a drive gear system portion of the developing device of the image forming apparatus of FIG.

FIG. 4 is a side view showing a drive gear system portion of the developing device similar to FIG. 3, showing a non-developing operation;

FIG. 5 is a sectional side view of an embodiment of a developing device configured according to the present invention.

FIG. 6 is a cross-sectional side view of another embodiment of a developing device constructed in accordance with the present invention.

FIG. 7 is a sectional side view of a conventional developing device.

[Explanation of symbols]

 1 image carrier (photoreceptor) 3 developer carrier (developing sleeve) 4 regulating member (elastic blade) 5 developer supply member (elastic roller) 6 developer (toner)

Claims (3)

[Claims] 1. An image forming apparatus in which an electrostatic latent image is formed on an image carrier and the electrostatic latent image is formed into a visible image by a developing device,
The developing device accommodates a developer and has a developing container having an opening at a portion facing the image carrier, a developer carrier laterally arranged at the opening of the developing container, and a proximity to the developer carrier. Alternatively, a restricting member that abuts and forms a thin developer layer on the developer carrying member, and a developer supplying member that is disposed in the developing container and that abuts on the developer carrying member and is rotatable. The image forming apparatus is characterized in that the developer supply member is maintained in a non-contact state with the developer carrying member during a non-developing operation. 2. The image forming apparatus according to claim 1, wherein the developer supply member is a sponge rubber having a foam skeleton structure, or a roller having a fur brush structure in which nylon or rayon is flocked. 3. A scraping means is provided in the developing container, and the developer supplying member abuts on the scraping means and rotates from after the developing operation of the developer supplying member ends to when the image forming operation ends. Claim 1 or 2 characterized by
The image forming apparatus described.