JPH0384577A - Developing device - Google Patents

Abstract

PURPOSE:To obtain a stable image by providing a magnetic field producing means between the abutting part between a developer control means and a developer carrier and the slide contact part between the developer carrier and a developer supply means. CONSTITUTION:A supply roller 5 rotates in the same direction with a developing sleeve 3 to supply a developer to the developing sleeve 8 and also comes into elastic contact to peel toner 8 off the developing sleeve 3. On the downstream side of the slide contact part S between the supply roller 5 and developing sleeve 3 in the rotating direction of the developing sleeve 3, the elastic blade 6 is arranged abutting on the developing sleeve 3 at the abutting part T to control the passage of the developer 8 on the developing sleeve 3. At least one magnetic pole of a magnet 4 is arranged between the slide contact part S and abutting part T and magnetic particles 7 are held by a small amount on the upstream side of the elastic blade 6 in the rotating direction of the sleeve and on the downstream side of the supply roller 5. Consequently, even when the toner 8 decreases in particle size, a charging-up phenomenon and toner blocking are precluded and the excellent image is stably obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device that performs development using a dry developer.

[Prior Art] Various types of dry-component developing devices have been proposed and put into practical use. However, in any development method, it is extremely difficult to form a thin layer of dry one-component developer. However, as improvements in the clarity and resolution of developed images are required, the development of a thin layer-forming dry single-component developer and its equipment has become essential, and in response to this, several measures have been taken. is proposed.

For example, there is a device as shown in Japanese Patent Application Laid-Open No. 54-43038. In this device, a rubber or metal elastic blade, which is a developer regulating means, is brought into contact with a developing sleeve, which is a developer carrier, and the developer (hereinafter referred to as toner) is allowed to enter and pass through the abutting portion onto the developing sleeve. A thin toner layer is formed on the toner, and an electric charge (hereinafter referred to as triboelectric charge) due to triboelectric charging is applied to the toner at the contact portion.

In such an apparatus, when using magnetic toner, if a magnet is provided in the developing sleeve, the toner can be supplied onto the developing sleeve by the magnetic force of the magnet. However, there is a problem in that using non-magnetic toner requires additional mechanical supply means. Therefore, the present applicant proposed the developing device shown in FIG.
59). In such a device, a supply roller serving as a developer supplying means is disposed upstream in the rotational direction of the developing sleeve from the contact portion between the elastic blade and the developing sleeve so as to be in contact with the developing sleeve. The undeveloped toner is removed. With such a simple configuration, it has become possible to faithfully reproduce high-density, wide-area solid black images and to always provide stable images.

[Problems to be Solved by the Invention] However, with the recent trend toward smaller particle diameters of developer accompanying the improvement in the quality of copied images, it is no longer possible to obtain sufficiently good images even with the above-mentioned conventional apparatus. . It is true that by making the particle size small, the triboelectricity of the toner tends to increase, and images with high resolution and clarity can be obtained, but due to the tendency for the triboelectricity to increase, the following problems arise. was.

If you continue to develop documents with a small image ratio (those with many blank areas) under conditions of low humidity, the toner that is not used for development on the development sleeve will not be sufficiently peeled off after development and will repeatedly come into contact with the elastic blade. As the sliding contact is repeated, the amount of charge due to frictional charging becomes excessive (hereinafter referred to as charge-up).

Then, the adhesion to the developing sleeve becomes stronger, and the remaining toner that has not been subjected to the development becomes increasingly difficult to peel off, further causing charge-up. On the other hand, since the newly supplied toner comes into contact with the toner adhered to the developing sleeve, it is charged to the opposite polarity and is not given sufficient triboelectric charge. In this way, fogging and image density fading occur due to insufficient triboelectricity.

Another problem caused by reducing the particle size of the toner is an increase in the degree of aggregation. Particularly under high humidity conditions, the degree of agglomeration of the negative layer increases, causing toner clogging (blocking) near the elastic blade.As a result, shearing between toner particles occurs at the contact area of the elastic blade. This makes it difficult for the toner to enter between the elastic blade and the developing sleeve, resulting in uneven coating and loss of density. Various configurations have been developed to prevent toner from blocking near the elastic blade. For example, a rotating roller may be provided near the elastic blade to disturb the aggregated toner layer, or a magnetic piece may be provided near the elastic blade facing the developing sleeve to prevent the rotation of the magnet within the developing sleeve. An attempt has been made to prevent blocking by swinging this magnetic piece. However, such a configuration complicates the device and is not sufficient to prevent blocking.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a developing device that can obtain stable images without causing toner charge-up or blocking even when using toner with a small particle size. It is said that

[Means for Solving the Problems] According to the present invention, the above object is achieved by: a developer supply container having an opening at the front and storing a developer for -a; and a developer supply container rotatably disposed in the opening. a developer carrier for carrying and transporting developer; and a developer carrier disposed behind the developer carrier so as to be in sliding contact with the developer carrier at a sliding contact portion, and rotating in the same direction as the developer carrier, and rotating in the same direction as the developer carrier. a developer supply means for supplying the developer to the developer carrier;
A developing device comprising an elastic developer regulating means for regulating the passage of the developer on the developer carrier at a contact portion that abuts the developer carrier; A magnetic field generating means having at least one magnetic pole is provided externally between the sliding contact portion and the contact portion, and magnetic field generating means is provided on the surface of the developer carrier between the sliding contact portion and the contact portion. Distantly related to particles that carry particles.

[Function] The present invention provides magnetic field generating means between the contact portion between the developer regulating means and the developer carrying member and the sliding contact portion between the developer carrying member and the developer supplying means. Magnetic particles are supported on the surface of the developer carrier between the contact portion and the sliding contact portion. The magnetic particles are
As the developer carrier rotates, the magnetic particles are transported to the abutting part, but the magnetic particles are bounced off by the abutting part, fall to the sliding contact part, and return to the abutting part. and is transported.

In this way, a circulating flow of magnetic particles is formed, and the particles are mixed with the developer and disturbed repeatedly. Therefore, the developer adhering to the surface of the developer carrier is peeled off near the sliding contact area, and the developer adhering to the surface of the developer carrier is peeled off near the contact area. , the developer is disturbed to break up the agglomeration of the developer.

[Embodiment] Hereinafter, a first embodiment of the present invention will be described based on FIGS. 1 and 3 of the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a photosensitive drum as a latent image carrier that rotates in the direction of arrow A. Examples of the photosensitive drum 1 include a so-called xerographic photosensitive material on which an electrostatic latent image is formed by the Carlson process, and a photosensitive material having an insulating layer on the surface on which an electrostatic latent image is formed using the NP process described in Japanese Patent Publication No. 42-23910. , an insulator on which a latent image is formed by an electrostatic recording method, an insulator on which an electrostatic latent image is transferred by a transfer method, an electrostatic latent image (or potential latent image) or a magnetic latent image formed and retained by other appropriate methods. It is a member that has been installed.

A developing device is arranged opposite to the photosensitive drum l,
The developing device includes a developer supply container (hereinafter simply referred to as a container).
2, a developing sleeve 3 as a developer carrying member, an elastic blade 4 as a developer regulating means, and a supply roller 5 as a developer supplying means.

The container 2 has an opening extending in the longitudinal direction of the developing device (direction perpendicular to the paper surface), and the developing sleeve 3 is inserted into the opening.
is installed. The developing sleeve 3 is made of a non-magnetic material such as aluminum.

The developing sleeve 3 is horizontally installed in the opening in FIG. 1, with its right half-circumferential surface protruding into the container 2, and its left half-circumferential surface exposed outside the container 2, and rotatably supported on a bearing. Arrow B
rotationally driven in the direction. The developing sleeve 3 has a cylindrical body (
It is not limited to a sleeve), but may be in the form of an endless belt driven to rotate, or may be a conductive rubber roller.

The surface of the developing sleeve 3 exposed outside the container faces the surface of the photosensitive drum 1 with a eugenic gap.

Inside the developing sleeve 3, there is a magnet 4 as a magnetic field generating means.
is fixedly placed. The magnet 4 is a permanent magnet having an N pole and an S pole, but an electromagnet may also be used.

At the rear of the developing sleeve 3, a supply roller 5 is disposed so as to rotate in sliding contact with the surface of the developing sleeve 3 entering the container at a sliding contact portion S. The supply roller 5 rotates in the same direction as the developing sleeve 3 and supplies the developer to the developing sleeve 3.
The toner on the developing sleeve 3 is peeled off by supplying the toner to the developing sleeve 3 and making elastic contact with the developing sleeve 3. The above-mentioned supply roller 5 may be one made of a urethane foam with a low degree of foaming (high density), a rubber skin layer covered over a sponge, or one with an uneven surface on the skin layer. Preferably, it is an elastic body.

An elastic blade 6 is disposed in contact with the developing sleeve 3 at a contact portion T downstream of the sliding contact portion S between the supply roller 5 and the developing sleeve 3 in the rotational direction of the developing sleeve 3. , the passage of the developer on the developing sleeve 3 is restricted at the corresponding contact portion T.

For example, the material of the elastic blade has a JIS hardness of 40~
80'' rubber, preferably 50 to 70'', is suitable for stable formation of a thin layer of developer. The thickness of the elastic plate 6 is preferably set to a certain degree in order to prevent the magnetic particles 7 from riding on the back surface of the elastic blade 6, and according to the inventor's experiments and considerations, the thickness is preferably 11I11 or more. It is 2.0 mm or more.

At least one magnetic pole of the magnet 4 is arranged between the rubbing part S and the contact part T, and the contact part T is located downstream in the rotational direction of the developing sleeve 3 from the arrangement position of the magnetic pole. The sliding contact portion S is located upstream in the rotational direction of the developing sleeve 3 from the position where the magnetic pole is arranged.

Further, a small amount of magnetic particles 7 and non-magnetic toner 8 are placed inside the container 2, and the magnetic particles 7 are restrained on the surface of the developing sleeve 3 by the action of the magnetic field of the magnet 4, forming a magnetic brush. ing. Here, a small amount is an amount that exists only in the area between the elastic blade 6 and the supply roller 5 with respect to the surface of the developing sleeve 3 at the opening of the container 2, and more specifically, 50% of the surface of the developing sleeve 3 at the opening of the container 2. Above developing sleeve 3
The surface is covered with magnetic particles 7, and the developing sleeve 3
This is an amount that can be circulated by the magnetic field of the inner magnet 4 and the rotation of the developing sleeve 3.

Further, it is preferable to provide the surface of the developing sleeve 3 with minute irregularities rather than a mirror surface from the viewpoint of circulation and vibration of the magnetic particles 7.

As the magnetic particles 7, iron powder, ferrite powder, etc. can be used. Furthermore, it is even more preferable to coat these with a resin in accordance with the charging polarity of the toner 8.

The magnetic particles 7 may have a particle size of 50 to 2001 Lys. If the thickness is less than 50, the fluidity of the magnetic particles 7 is poor;
It was confirmed that sufficient circulation and vibration were not obtained, the amount of toner 8 taken in was reduced, and a stable thin layer of toner 8 was not formed. Further, in the case of a particle size of 200 ILm or more, although the toner 8 is sufficiently supplied, the frictional charging is not sufficient, which is not preferable. Within this range, 80 to 150 p-ta is particularly preferred in order to obtain sufficient circulation and vibration of the magnetic particles 7.

The developing method in this embodiment is, for example,
32375, that is, by applying an alternating current with a superimposed direct current between the photosensitive tram 1 and the developing sleeve 3, a thin layer of toner on the developing sleeve 3 is transferred to an electrostatic latent image on the photosensitive tram l in an image form. Although a so-called non-contact development method can be used to transfer the toner, a contact development method may also be used.

Next, the operation of the apparatus of this embodiment as described above will be explained.

First, when the developing sleeve 3 rotates in the direction of arrow B, the magnetic particles 7 are conveyed in the rotating direction of the developing sleeve 3 while being restrained by the magnetic field formed by the magnet 4. However, the magnetic particles 7 are transported by the end of the elastic blade 6 and do not come out of the container 2, and due to gravity and magnetic force, the magnetic particles 7 are brought into contact with the contact portion T of the elastic plate 6 where the N and S magnetic poles are arranged. It circulates between the sliding contact portions S of the supply roller 5.

On the other hand, the toner 8 supplied near the developing sleeve 3 by the rotation of the supply roller 5 is conveyed to the area where the magnetic particles 7 exist near the sliding contact portion S of the supply roller 5 due to the rotation of the developing sleeve 3, and is transported between the magnetic particles 7. After that, it enters the contact portion T between the elastic plate 6 and the developing sleeve 3, and is carried on the surface of the developing sleeve 3.

As the magnetic particles 7 circulate, the toner 8 inside the container 2
is stirred and at the same time rubbed against the magnetic particles 7, thereby receiving frictional electrification.

Further, when the toner 8 passes through the contact portion T between the elastic blade 6 and the developing sleeve 3, it comes into sliding contact with the surface of the developing sleeve 3 by the elastic blade 6, and is further subjected to frictional charging. In this way, the toner 8 can receive sufficient triboelectric charging.

As a result, image density can be ensured in the developed image, and background fogging can be further reduced.

The toner 8 that has been sufficiently triboelectrically charged in this manner passes through the contact portion T and is formed as a thin layer of toner on the developing sleeve 3, and is transferred to the developing portion F facing the photosensitive drum 1 on the developing sleeve 3. carried. In the developing section F, some toner is consumed by the developing operation, and other toner is collected from the lower part of the developing sleeve 3 as the developing sleeve 3 rotates. A sealing member 10 is provided in this recovery portion to allow the toner that has not been consumed during development to pass into the container 2, and to prevent the toner 8 in the container 2 from leaking from the lower part of the container 2. The collected toner on the developing sleeve 3 comes into elastic contact (and is scraped off) at the sliding contact S between the supply roller 5 and the developing sleeve 3. However, when the toner has a small particle size, it has a higher charge than one with a normal particle size. The amount tends to increase (hereinafter referred to as charge-up), and as a result, the adhesion to the developing sleeve becomes strong, and there are cases where the sliding contact portion S cannot completely scrape off the developing sleeve. This phenomenon occurs noticeably when a large amount of toner is conveyed to the sliding contact area S between the roller 5 and the developing sleeve 3.In other words, the frequency of contact between toner particles at or near the sliding contact area S increases, and the degree of charge-up increases. This is because a large amount of excessively charged toner adheres to the developing sleeve 3, making it difficult to scrape it off at the sliding contact portion S. Therefore, the toner that has not been scraped off will be removed again. The toner passes through the contact portion T between the developing sleeve 3 and the elastic blade 6, and as it passes, it is further charged up, creating a vicious cycle.The toner firmly adhered in this way is not easily transferred to the photosensitive drum l. This is particularly noticeable when non-contact development is used as in this embodiment.
Nearby, toner tends to stick together in a high humidity environment. In some cases, so-called blocking occurred. This blocking causes the image density to become low and toner to be applied unevenly. Moreover, in the above-mentioned conventional example, the amount of toner conveyed to the sliding contact portion S is not only large but also non-uniform.
This caused variations in the image quality, which adversely affected the image. Furthermore, the newly supplied toner cannot rub against the surface of the developing sleeve 3 because of the toner that continues to adhere to the developing sleeve 3 as described above, but instead undergoes friction with the adhered toner.

As a result, the polarity may be reversed or triboelectricity may not be sufficiently applied. Therefore, there are problems in that image density becomes low, fogging occurs, and toner scatters.

However, in the device of this embodiment, the supply roller 5
Since the magnetic particles 7 are arranged near the sliding contact part S and circulated between the sliding contact part S and the contact part T of the elastic blade 6, the toner 8 and the magnetic particles 7 are actively mixed and stirred together. . Therefore, since the toner not consumed during development is scraped off by the supply roller 5 and magnetic particles, old toner is constantly replaced with new toner, preventing charge-up and producing good images without so-called sleeve ghosts. can get.

Further, since the load when scraping off toner by the supply roller 5 is reduced, the accuracy of the mounting position of the supply roller 5 can also be increased.

Furthermore, the agitation between the toner and the magnetic particles loosens the aggregated toner and prevents so-called blocking from occurring.

Next, the positional relationship between the elastic blade 6 including the magnetic particle circulation layer, the magnetic poles of the magnet 4 in the developing sleeve 3, and the supply roller 5, and the respective members will be described in detail.

FIG. 2 is a sectional view showing the above positional relationship.

Since the elastic blade 6 is pressed against and in contact with the surface of the developing sleeve 3, it is deformed as shown in the figure. Thereby, the end of the elastic plate 6 is urged to come into contact with the developing sleeve 3. Note that the end of the blade herein refers to the tip of the plate, the vicinity including the tip, or the vicinity of the tip not including the tip.

In the embodiment shown in FIG. 2, the elastic plate 6 is inclined from the end toward the downstream side in the rotational direction of the developing sleeve. The broken line indicates the state of the elastic blade 6 assuming that the developing sleeve 3 does not exist. A straight line m is a vertical line passing through the center of the developing sleeve 3, and a straight line n is a vertical line passing through the center of the developing sleeve 3.
A straight line passing through the abutting portion T and the center of the developing sleeve 3 is a straight line passing through the center of the developing sleeve 3 and the center of the N pole. Let the angle between the straight line 41m and the straight line n be 01, and the angle between the straight line n and the straight line be 02. Surface U is the bottom surface of the first elastic blade 6 when the elastic blade 6 is in contact with the developing sleeve 3 and is not deformed. Point R is the cross section of the line of intersection between the surface U and the surface of the developing sleeve 3, and the angle O8 is a point. The distance d2, which is the angle formed by the tangent line of the developing sleeve 3 passing through R and the surface U, is the length by which U enters the inside of the developing sleeve 3. The straight line p is a straight line that passes through the most downstream point in the rotating direction of the developing sleeve of the sliding contact portion S between the supply roller 5 and the developing sleeve 3 and the center of the developing sleeve 3 . Further, the dotted line q is a straight line passing through the center of the developing sleeve 3 and the center of the S pole. Let the angle between the sentence and p be 03, and the angle between q and p be 04.

The distance *di is the nip width of the sliding contact portion between the developing sleeve 3 and the supply roller 5. vl rotates counterclockwise (positive) at the circumferential speed of the developing sleeve 3. v2 is the circumferential speed of the supply roller 5, which also rotates counterclockwise.

The angle θ5 is from 0 to 40", preferably 2, in order to prevent problems such as the elastic plate 6 returning due to frictional force when the developing sleeve 3 rotates.
to 20″.

Further, the amount of deflection d2 of each elastic blade 6 is preferably 0.5 to 2 mm, and it is preferable that the edge portion of the tip of the elastic blade 6 is in contact with the developing sleeve 3. This is because if the edge of the tip of the elastic blade 6 is separated from the surface of the developing sleeve 3, the magnetic particles 7 may enter this gap, impairing the uniformity of contact pressure and potentially damaging the surface of the developing sleeve 73. This is because something has become clear.

Furthermore, it is preferable that the angles θ, θ2, and θ3 satisfy the first-order condition.

θ, ≧O θ2+θ, <90' 0 θ2<90"0<θ1<90" θ, +02<90" Regarding the angle θ, when θ1<0, at the tip of the elastic blade 6 , because the direction of gravity is toward the elastic blade 6, the magnetic particles 7 tend to stay near the tip of the elastic plate 6, and due to the zero gravity relationship, it was found that the magnetic particles 7 tend to stay near the tip of the elastic plate 6. The preferred range of θ1 is 5×θ, <40@.

- Regarding the angle (θ2+03), if θ2 is 10, >90", the space that should exist will be too large relative to the amount of magnetic particles 7, and the effect of putting the magnetic particles will be lost. Also, if the developing sleeve 3 and the supply roller 5 are located in the fourth quadrant of the coordinate system with the center of the developing sleeve 3 as the coordinate center. Therefore, depending on the circumferential speed of the supply roller, the magnetic particles 7 may According to experiments, it has been confirmed that the more preferable condition is 3'<θ, +0:I<90'.

Regarding the angle θ2, it has been found that when θ2≦0″, the magnetic particles 7 stick to the vicinity of the tip of the elastic plate 6 and circulation is not performed, which is not preferable.

Furthermore, in the case of 306〈θ, <60@, particularly good circulation was achieved, which was confirmed to be preferable.

In this range, particularly, the magnetic particles 7 are sufficiently circulated, and the vicinity of the tribo and scraping are effectively performed.

Note that if another magnetic pole is provided between the first elastic blade 6 and the supply roller 5, the effect of holding the magnetic particles 7 will be increased. This is because if there is one magnetic pole between the elastic blade 6 and the supply roller 5, the above θ2+03 is close to 90@, or
Or, if it becomes larger than 90", the conveyance of the magnetic particles may deteriorate, and depending on the position of the N pole, the magnetic particles 7 may pass through the sliding contact between the developing sleeve 3 and the supply roller 5 and fall downward. However,
By providing an S pole, which is another magnetic pole, upstream of the N pole in the rotational direction of the developing sleeve, conveyance performance is improved and θ2+
Even if 03 becomes larger, the magnetic particles 7 do not pass through the above-mentioned sliding contact portion and continue to be held securely.

As a further effect, by arranging another S pole near the sliding contact between the developing sleeve 3 and the supply roller 5, the S pole causes the magnetic particles 7 to stand up in the vicinity of the sliding contact. is vibrated by the rotation of the developing sleeve 3, thereby making it possible to disturb the toner adhering to the supply roller 5 and scrape it off.

In FIG. 2, when the angle θ3 is θ3≦0, the magnetic particles 7 stick to the wedge-shaped space downstream of the sliding contact portion between the supply roller 5 and the developing sleeve, and circulation is not performed.
Furthermore, it has been found that depending on the circumferential speed of the supply roller 5, the magnetic particles 7 may pass through the sliding contact portion to the upstream side, which is an undesirable result. Furthermore, 10” <θ
It was confirmed that good circulation was achieved in the case of 3<60°, which is preferable.

Regarding the angle θ1+02, if θ1+02〉9'',
The magnetic particles 7 are not transported well on the developing sleeve 3 to the position of the elastic blade 6, and the magnetic particles 7 are dispersed within the developing sleeve 3 due to gravity, and the magnetic particles 7 circulating and vibrating just before the elastic blade 6 no longer exist. It turned out to be something I didn't like.

Based on the above considerations, more preferable ranges are as follows.

Oo<θ, <40” 300 <θ2 + θ, <90@10°<θ3<60” 30@<θ2<60° θ1+02<90° The preferred range for θ4 is 0 and θ4<60°. In this range, sufficient circulation of the magnetic particles can be obtained, and the effects of toner stirring, scraping, triboading, and blocking prevention can be improved.

In FIG. 2, vl is the circumferential speed of the developing sleeve 3 (positive in the counterclockwise direction), and v2 is the circumferential speed of the supply roller 5 (positive in the counterclockwise direction). Considering this, it is preferable that V and v2 are in opposite directions to each other at the sliding contact portion between the developing sleeve and the supply roller, and that the relative speed does not become zero. Also, the arrows in Figure 2 (Vo,
When the counter touches the sliding part as shown in V2),
If 1v21 is faster than 1v,1, there is a possibility that magnetic particles will pass through the sliding contact portion as the supply roller rotates. Therefore, in addition to the above formula, it is more preferable that 1v21≦I v, I.

In addition, in the case of counter contact, the circumferential speed ratio of 1v, 1 and 1v21 is 30%≦(l V+ l / l V21
) It is more preferable that X100%≦IO05%.

Next, an example of an experiment conducted under the following conditions based on this embodiment will be described with reference to FIG.

In this experimental example, an aluminum developing sleeve with a diameter of 20 mm was used, and one surface of the sleeve was subjected to irregular sand blasting using alundum abrasive grains.

As the magnet 4, one with a peak value of magnetic flux density of 800 Gauss and a half value @so'' was used.

Next, as the elastic blade 6, urethane rubber (rubber hardness JIS 65°, thickness 2 mm) was used. The pressure (linear pressure) of the elastic blade on the developing sleeve is set at 20 to 200 g.
/Otori is preferable, and in the experimental example, it was set to 60 g/m.

In addition, as the supply roller 5, Everlite (trade name manufactured by Brideston Co., Ltd.) is placed on a stainless steel core metal with a diameter of 7 openings.
Using a roller with a diameter of 18 mm wrapped around a sponge, rotate it in the same direction as the developing sleeve (the counter direction is at the sliding contact with the developing sleeve), and set the relative speed to the developing sleeve at 50 to 300 amlsec. I did it.

The mounting positions of the above components are θ5=IO", d2=1
．． 0 am, θ, =15", θ2=40", 6
1. ==30"d, =3.0 mm.

The magnetic particles have a particle size of 100 to 80 ILm (Is5
200 mesh iron particles (maximum magnetization = 190 parts mu/g) coated with acrylic and fluorine resin are used at an areal density of 0.3 to 0.6 g/c1, and styrene/acrylic resin is used as the toner. A red toner was used in which 1.0% of colloidal silica was externally added to toner powder having an average particle size of 13 g, which was composed of 100 parts of a copolymer of styrene-butadiene resin and 5 parts of a perylene red pigment.

The above device was installed in a Canon Co., Ltd. NP1215 copying machine, and a frequency of 1800H was used as a bias power source.
z, -2 to AC voltage with peak-to-peak voltage of 1300V
Using a superimposed DC current of 50V, the surface potential of the latent image on the photosensitive drum l was set to -540V in the dark area and -150V in the bright area, and the distance between the developing sleeve 3 and the photosensitive drum l was set to 250V.
Development was carried out by non-contact development with the setting at L■.

As a result, a uniform coating layer of about 30 μm was obtained on the developing sleeve, and when the amount of charge on this layer was measured by the blow-off method, the amount of charge was +12 Bc/g. This amount of charge is sufficient to obtain a good image.

Moreover, the obtained image was a good red image with a reflection density of 1.3.

Furthermore, after being left in a high-humidity environment for one week, the area around the elastic plate in the developing device was observed after development, and it was found that toner blocking was prevented. Furthermore, in a low humidity environment, the same type of toner as mentioned above has an average particle size of 8 wells.
When developing was carried out using toner with a small particle size, 1
There was no abnormal increase in the amount of triboelectric charge of the toner until 1,000 images were formed, and images without thinning of density or fogging could be obtained.

Next, a second embodiment of the present invention will be described using FIG. 4. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

This embodiment differs from the first embodiment in that the elastic blade 6 is brought into contact with the developing sleeve 3 in the forward direction relative to the rotating direction.

In the case of this embodiment, it is preferable that the contact position of the elastic blade 6 to the developing sleeve 3 be as close as possible to the intersection V of the vertical line m drawn from the center of the developing sleeve 3 and the developing sleeve 3. Preferably, a magnetic particle circulation limiting member 12 is provided to prevent the magnetic particles 7 from clogging the wedge-shaped space between the elastic slide roller and the developing sleeve 3.

In this example, as the supply roller 5, an elastic roller having a rubber skin layer covered with an uneven surface was used as the supply roller 5.

In this way, the first elastic plate 6 is not limited to being brought into contact with the rotational direction of the developing sleeve 3 in the opposite direction, but even if it is brought into contact with the developing sleeve 3 in the forward direction as in this embodiment, the same effect as in the first embodiment can be obtained. play.

Next, a third embodiment of the present invention will be described using FIG. 5. Note that the same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

This embodiment differs from the first embodiment in that the magnet 4 is disposed not inside the developing sleeve 3, but on the opposite side of the contact lower side of the elastic blade 6, or on the free end surface of the elastic blade 6.

In this example, the surface of the developing sleeve is
It is better to make it rougher than in the embodiment and second embodiment.

Further, the elastic blade 6 may be made of a magnetic material such as a rubber magnet or rubber in which magnets are dispersed.

In this way, the position of the magnetic field generating means is not limited to the inside of the developing sleeve, and even if it is placed outside as in this embodiment, the same effects as in the first embodiment can be achieved.

In the above-mentioned apparatuses of the first and second embodiments, if the number of magnetic poles of the magnet in the developing sleeve is further increased and magnetic poles are also provided on the photosensitive drum side, the magnetic poles will pass under the elastic blade as the developing sleeve rotates. A small amount of magnetic particles may be conveyed and collected into the developing container.Also, in the third embodiment, a magnet may also be provided within the developing sleeve to perform the collection as described above.

[Effects of the Invention] As explained above, the present invention uses a non-magnetic component toner, and uses an elastic blade and a supply roller to apply the toner onto the developing sleeve and control the stripping of the toner from the developing sleeve. In the developing device, a small amount of magnetic particles is held at a position upstream of the elastic blade in the rotational direction of the sleeve and downstream of the supply roller. therefore,
Even in situations where the toner tends to charge up due to the smaller particle size of the toner, the disturbance of the magnetic particles improves the effect of stripping off the toner on the developing sleeve, so the toner does not charge up, reducing density fading and reverse fogging. It is now possible to prevent such incidents. Also, due to the above disturbance,
It is also effective in preventing toner blocking near the elastic blade in a high humidity environment, and good images can be stably obtained.

Furthermore, the presence of the magnetic particles makes it possible to reduce the burden of toner stripping by the supply roller, and it is possible to provide flexibility in the accuracy of the position and circumferential speed setting of the supply roller.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a first embodiment of the present invention;
FIG. 2 is an enlarged view showing the positional relationship between the developer regulating means, developer supply means, and developer carrier of the apparatus shown in FIG. 1, and FIG. 3 is a schematic diagram of an experimental example apparatus based on the first embodiment of the present invention. 4 is a sectional view showing a schematic structure of a second embodiment of the present invention, FIG. 5 is a sectional view showing a schematic structure of a third embodiment of the present invention, and FIG. 6 is a conventional device. FIG. 2...Developer supply container (container) 3...
Developer carrying member (developing sleeve) 4 -------- Magnetic field generating means (magnet) S -------- Developer supplying means (supply roller) 6 ---
-----Developer regulating means (elastic blade) 7...
・Magnetic particle 8...Developer (toner) S...Sliding contact part T...Contact part

Claims (4)

[Claims] (1) A developer supply container having an opening in the front and storing a one-component developer, a developer carrier rotatably disposed in the opening to carry and transport the developer, and the developer carrier. a developer supply means disposed at the rear of the body so as to be in sliding contact with the developer carrier at a sliding contact portion, and rotating in the same direction as the developer carrier to supply the developer to the developer carrier; and a developer regulating means made of an elastic body that regulates the passage of the developer on the developer carrier at a contact portion that abuts the developer carrier, A magnetic field generating means having at least one magnetic pole is provided internally or externally between the sliding contact part and the contact part, and the surface of the developer carrier between the sliding contact part and the contact part. A developing device characterized in that magnetic particles are supported on the surface of the developing device. (2) The developing device according to claim (1), wherein the developer regulating means is made of an elastic body. (3) The developing device according to claim (2), wherein the developer regulating means is a magnetic material. (4) The developing device according to claim (1), wherein the developer supply means is made of an elastic body.