JPH09274376A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device for an excellent image quality with a long service life, capable of forming an excellent thin film of the developer on the developer carrier, by stripping off the residual non-magnetic one component developer on the developer carrier, without using developer feeding means laying stress on the developer. SOLUTION: In the device, a toner feeding roller is held in non-contact with the developing roller 2, and allowed to feed only the non-magnetic toner 8. The elastic blade 3 is held in contact with the developing roller 2 in the direction opposing its rotary direction, for forming a minute gap 3d on the downstream side of a contact nip area in which the toner 8 is not filled. The elastic blade 3 is, composed of an insulating elastic layer 3b formed on an elastic thin state substrate 3a, and a conductive plate 3c is provided as electric field generating means, on a surface of the substrate 3a on the side opposite to the developing roller 2, and the conductive plate 3c is arranged while positioned with respect to the minute gap 3d. In the minute gap 3d inside, by the AC electric field formed there, the toner 8 on the developing roller 2 is made stripping-off, soaring, reciprocate-moving and agitating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image with a non-magnetic one-component developer containing no carrier in an image forming apparatus such as an electrophotographic device or an electrostatic recording device. .

[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, a dry type 1
Various component developing devices have been proposed and put into practical use.
However, there is a problem that it is difficult to form a thin layer of the toner of the one-component developer on the developer carrier in any of the developing devices.

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

For example, Japanese Patent Laid-Open No. 54-43038 discloses that
An elastic blade made of rubber or metal is brought into contact with the developing sleeve as the developer carrying member, and the toner layer is configured to pass between the abutting portion of the elastic blade and the developing sleeve. There is described a developing device which regulates the toner, thereby forming a thin layer of the toner on the developing sleeve, and imparting sufficient triboelectric charge (tribo) to the toner by friction at the contact portion.

In this case, when the non-magnetic toner is regulated by the elastic blade, a separate supplying member for supplying the toner onto the developing sleeve is required. 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. .

That is, when the non-magnetic toner is supplied onto the developing sleeve, it becomes necessary to carry the non-magnetic toner on the developing sleeve by the mirroring force, instead of the magnetic force of the magnetic toner. Therefore, it is inevitable that the toner is configured such that the non-magnetic toner has a larger charge amount than the magnetic toner, and that the non-magnetic toner is charged by frictional charging. .

As an example of a developing device which satisfies the above requirements and is capable of favorably supplying the non-magnetic toner onto the developing sleeve, Japanese Patent Application Laid-Open No. 58-11655 previously filed by the present applicant.
There are 9 and so on.

The conventional developing device shown in FIG.
No. 116,559), a fur brush structure in which the developing container 102 in which the non-magnetic toner 106 is stored as a one-component developer is in contact with the developing sleeve 103 at a position upstream of the elastic blade 104 in the rotation direction of the developing sleeve 103. The supply roller 105 for the developing sleeve 103 is installed.
The toner 106, which is not consumed for the above development and remains, is peeled off by the supply roller 105, and the development sleeve 10
3 is supplied with new toner 106.

Developing sleeve 10 by supply roller 105
By the operation of stripping the residual toner on 3, the defective supply of new toner onto the developing sleeve 103 is prevented, and the sleeve ghost is prevented from occurring.

If this peeling operation is not performed, the residual toner on the developing sleeve 103 will pass through the contact portion with the elastic blade 104 many times, and the charge amount thereof will increase (charge up), Since the mirroring force of the residual toner on the developing sleeve 103 increases, the developing sleeve 103
The upper toner area causes a difference in developability between the developing portion area where the residual toner is small and the non-developing portion area where the residual toner is large, and the sleeve ghost is generated. Further, the same toner passing through the elastic blade 104 many times causes a great amount of stress on the toner and causes deterioration of the toner.

Therefore, the operation of peeling off the residual toner from the developing sleeve 103 is recognized as a very important operation in the non-magnetic one-component developing device, and is considered to be essential.

Therefore, the non-magnetic one-component developing device can satisfactorily form a thin layer of non-magnetic toner on the developing sleeve 103 with the above-mentioned structure, and the electrostatic latent image on the image carrier, that is, the photosensitive drum 101 can be formed. The latent image can be developed well, and it is possible to faithfully reproduce a solid black image of high density and a wide area by the development, and always obtain a stable image.
In addition, this developing device, compared to the conventional two-component developing device,
It is possible to provide a developing device that is simple and small in size and has a large toner capacity.

[0014]

By the way, the non-magnetic toner of the one-component developer used in the above conventional developing apparatus is
A toner having a low melting point is used because it has many uses as a color toner and it is necessary to mix and fuse the toners of respective colors in a fixing process. In addition, black toner for black and white image output,
Due to demands for energy saving and quick start, low melting point toner suitable for low temperature fixing has been required.

However, conventionally, a supply roller 105 having a fur brush structure or a sponge roller having a foam skeleton structure is used as a toner supply member, and from the viewpoint of toner supply and peeling, the developing sleeve 103 is provided with a predetermined pressure.
Since it abuts against and rubs against, there was the following problem.

(1) When the toner on the developing sleeve is peeled off by the toner supplying roller 105, an external force (stress) is applied to the toner between the pressure contact portion between the supplying roller and the developing sleeve.
Is added, the toner deteriorates, and the charge acquisition ability gradually decreases. For this reason, when the developing process is repeated many times, the toner is fogged due to a decrease in the charge amount of the toner and the toner adheres to the non-image area of the electrostatic latent image on the photosensitive drum 101.
This fog becomes remarkable especially under high temperature and high humidity.

(2) For example, if the toner supply roller 105 rubs against the developing sleeve 103 for a long time,
The supply roller 105 itself is worn and damaged (fray and wear in the case of a sponge roller, and settling of the brush in the case of a fur brush roller). Therefore, the stress applied to the toner on the developing sleeve can be reduced, but the peeling of the residual toner from the developing sleeve becomes insufficient,
The residual toner charges up. Therefore, the mirroring power of the toner on the developing sleeve increases, the developing property deteriorates, and an image defect such as low density or sleeve ghost occurs in the obtained image.

Alternatively, when the developing device is left in a high temperature environment for a long period of time, the abutting portion of the supply roller 105 with the developing sleeve 103 is locally dented, and this abutting portion may cause a poor contact with the developing sleeve. Invite. Therefore, although the stress applied to the toner can be reduced, the toner is insufficiently peeled off, and similar to (2) above, image defects such as low density of the intervals of the rotation cycle of the supply roller and sleeve ghost occur.

As described above, when the low melting point toner is used in the conventional developing device, the above problems (1) and (2) occur. This is troublesome, as in (1), when stress is applied to the toner for peeling off the toner on the developing sleeve, the toner deteriorates and fogging occurs due to poor charging of the toner. In addition, when the stress applied to the toner is reduced, defective peeling of the toner occurs, which means that the directions of action and effect are contradictory.

Due to the conflicting actions and effects, the life of a non-magnetic one-component developing device using a low-melting point non-magnetic toner, especially a non-magnetic one-component developing device for color, is Compared with the magnetic one-component developing device and the two-component developing device using the magnetic toner, the length was remarkably short.

An object of the present invention is to peel off the non-magnetic one-component developer remaining after development on the developer carrying member without peeling it by means of a developer supplying means which exerts a stress on the developer, and deposit it on the developer carrying member. It is an object of the present invention to provide a developing device with high image quality and long life, which is capable of forming a good thin layer of developer.

[0022]

The above object can be achieved by the developing device according to the present invention. In summary, the present invention is directed to a developer carrier that rotates in opposition to an image carrier, and a non-magnetic one-component developer that supplies non-magnetic one-component developer to the developer carrier and is arranged in non-contact with the developer carrier. In a developing device having: a developer supply unit; and a developer regulating unit that regulates the developer on the developer carrier, which is arranged on the downstream side with respect to the rotating direction of the developer carrier. An electric field generating means is arranged by opening a minute gap with the developer carrying body, and an alternating voltage is applied to the electric field generating means with the developer carrying body to form an alternating electric field in the minute gap. The developing device is characterized in that the developer on the carrier is caused to fly and reciprocate in a minute gap.

According to the present invention, the installation position of the electric field generating means can be located at the developer regulating portion by the developer regulating means or on the downstream side thereof, and the developer regulating member is provided on the developer carrying member. An elastic regulating member that abuts in a direction opposite to the rotating direction, and a conductive plate that constitutes an electric field generating means is provided on the opposite side of the elastic regulating member from the developer carrier.
The conductive plate can be arranged at a position corresponding to a minute gap formed downstream of the contact portion between the elastic regulation member and the developer carrying member.

According to the present invention, the installation position of the electric field generating means is set between the developer regulating means and the facing portion of the developer carrying member and the image carrying member in the rotational direction of the developer carrying member. The electric field generating means may be a conductive plate. The installation position of the electric field generating means may be set at a position from the facing portion of the developer carrying body and the image carrying body to the developer supplying means in the rotational direction of the developer carrying body. In addition, an elastic seal member that abuts a lower portion of the developer carrying member is installed, and the elastic seal member is an insulating member that abuts the elastic conductive plate that constitutes the electric field generating means and the developer carrying member provided thereon. And a flexible elastic layer.

According to the present invention, a developing power source for applying a developing bias between the developer bearing member and the image bearing member is installed, and the developing power source includes at least an AC power source,
An AC voltage can be applied to the electric field generating means by using the AC power supply. Preferably, the shape factor SF-1 of the developer is 100 to 140 and SF-2 is 10.
0 to 120. A part or all of the developer is formed by a polymerization method. The developer has a core / shell structure. The main component of the core is a low softening point substance, the melting point of the low softening point substance is 40 to 90 ° C., the surface of the developer is coated with an external additive, and the coverage is 5 to 99%. is there.

[0026]

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

Embodiment 1 An embodiment of the developing device of the present invention is shown in FIG. FIG. 1 is a cross-sectional view showing a non-magnetic one-component developing device according to an embodiment of the present invention. In FIG. 1, parts such as a drive system not related to the present invention are omitted. This developing device is used as a developing device such as a known electrophotographic image forming apparatus.

As shown in FIG. 1, the non-magnetic one-component developing device 9 of this embodiment has a developing roller 2 facing the photosensitive drum 1 which is an image carrier. The developing container 10 containing the non-magnetic toner 8 as a developer is rotatably installed in an opening facing the photosensitive drum 1. The developing roller 2 is made of a non-magnetic material, and is aluminum in this embodiment. The surface of the developing roller 2 was processed to have a surface roughness Rz of, for example, about 2.5 μm. The photosensitive drum 1 is made of OPC, amorphous Si, or the like.

The developing roller 2 is arranged to face the photosensitive drum 1 in a non-contact manner with a gap of about 300 μm. Of course, the developing roller 2 may be disposed in contact with the photosensitive drum 1, but in this case, it is desirable that the developing roller 2 is formed of an elastic member in order to make the contact state good.

An elastic blade 3 is brought into contact with the surface of the developing roller 2, and the amount of coating and the amount of charge of the non-magnetic toner 8 on the developing roller 2 are regulated at this contact portion. According to the present invention, a great feature is that the toner 8 on the developing roller 2 is caused to have a stirring action by flying and reciprocating at the contact portion where the elastic blade 3 abuts and in the vicinity thereof.

Elastic blade 3 which is one of the features of the present invention
2, the elastic blade 3 is formed on a thin elastic substrate 3a made of a polyethylene terephthalate (PET) film having a thickness of about 100 μm.
An insulative elastic layer 3b made of urethane rubber or the like is formed, and is in contact with the developing roller 2 at a predetermined pressure in a direction opposite to the rotation direction thereof. The width of the elastic layer 3b along the rotation direction of the developing roller 2 is set from the lower end (free end) of the substrate 3a to sufficiently above the portion facing the developing roller 2. In the present embodiment, the material of the elastic layer 3b is a non-magnetic toner 8 having a negative charging polarity, so that it is desirable to use an electron-donating material such as urethane rubber as described above. The surface of the elastic layer 3b can be coated with electron-donating nylon or the like. If the charge polarity of the toner 8 is positive, the elastic layer 3b should be made of an electron-attracting material.

The elastic blade 3 is brought into contact with the developing roller 2 in a direction opposite to the rotation direction thereof, and the width of the elastic layer 3b of the elastic blade 3 is set to the nip width generated at the contact portion between the elastic blade 3 and the developing roller 2. I have taken it long enough than
A gap is formed on the upstream side and the downstream side of the contact nip region in the rotation direction of the developing roller 2. Since the toner 8 is regulated by the contact nip area in the gap on the downstream side of the contact nip area, the minute gap 3d is formed without being filled with the toner 8. Since the gap on the upstream side of the contact nip area is filled with the toner 8 because it is the position before the regulation of the toner 8, no gap is formed there.

According to the present invention, a conductive plate 3c used as an electric field generating means is provided on the surface of the elastic thin substrate 3a of the elastic blade 3 opposite to the developing roller 2, as shown in FIG. The conductive plate 3c is arranged so as to be located in the minute gap 3d downstream of the contact nip region.
In this embodiment, the elastic thin substrate 3a is made of an insulating PET film or the like, but if the substrate 3a is made of a conductive material such as a phosphor bronze plate, the substrate 3a itself can be used as an electric field generating means. Therefore, the conductive plate 3c can be omitted.

However, when the substrate 3a is formed of a conductive plate, if the substrate 3a made of the conductive plate is formed from the portion corresponding to the minute gap 3d to the portion corresponding to the contact nip region, an electric field generated from this will cause This is unsuitable because the contact pressure in the contact nip region increases. Therefore, it is desirable to form the electric field generating means by a conductive plate 3c separate from the substrate 3a in the form shown in FIG.

As shown in FIG. 1, a supply roller 4 of toner supply means is installed in the developing container 10. According to the present invention, the supply roller 4 is arranged so as not to contact the developing roller 2. did. In this embodiment, as an example, the supply roller 4 having a structure in which a fur brush is formed on a rotatable cored bar is used. The material of the fur brush of the toner supply roller 4 is also
Similar to the elastic layer 3b of the elastic blade 3, an electron-donating material is desirable, and nylon is used in this embodiment.

In the present invention, since the toner supply roller 4 is arranged in non-contact with the developing roller 2 as described above, there is no peeling of the residual toner on the developing roller 2 by the toner supply means as in the prior art. . Therefore, the toner 8 is not stressed by peeling itself, and the deterioration due to the stress of the toner prevents the fog caused by the decrease in the charge amount of the toner, thereby solving the above-mentioned problem (1).

As shown in FIG. 1, the developing roller 2 and the toner supply roller 4 rotate in the X and Y directions, respectively, and are arranged to move in opposite directions at the facing portions. By rotating the developing roller 2 and the toner supplying roller 4 in such a rotating direction, the non-magnetic toner 8 in the developing container 10 is supplied to the developing roller 2 as shown by the moving path Z in FIG. It is transported to the contact nip.

As shown in FIG. 1, the developing roller 2 is connected with an AC power source 5 and a DC power source 6 connected in series as a developing power source. In the present invention, as shown in FIG. 2, the conductive plate 3c of the elastic blade 3 is connected between the AC power source 5 and the DC power source 6 so that the AC voltage can be applied to the conductive plate 3c by the AC power source 5. .

In the developing area where the photosensitive drum 1 and the developing roller 2 are opposed to each other, a developing electric field (alternating electric field + electrostatic electric field) is generated by the AC power source 5 and the DC power source 6, and, on the other hand, a small amount on the downstream side of the contact nip area. An alternating electric field is generated by the AC power supply 5 in the void 3d. It is desirable that no electrostatic field be generated in the minute voids 3d. This is because the negatively charged toner 8 may be localized in the minute gap 3d, and the flying and stirring actions of the toner 8 may not work effectively in the minute gap 3d.

In FIG. 1, reference numeral 7 denotes a toner blow-out prevention sheet, which is elastically abutted against the lower portion of the developing roller 2 to prevent a gap therebelow and prevents the toner 8 from blowing out from the developing container 9.

The operation principle and operation of this embodiment will be described below. In FIG. 1, the non-magnetic toner 8 supplied onto the developing roller 2 by the toner supply roller 4 is carried to the contact portion between the elastic blade 3 and the developing roller 2 as the developing roller 2 rotates, and in the contact nip region thereof. It is pressed by the elastic blade 3 and regulated to have a predetermined layer thickness, and is rubbed on the surfaces of the developing roller 2 and the elastic blade 3 to give a predetermined triboelectric charge amount.

Subsequently, the toner 8 passes through the contact nip area as the developing roller 2 rotates and reaches the minute gap 3d on the downstream side of the contact nip area. In this minute gap 3d, an alternating electric field is formed between the developing roller 2 and the AC power source 5 by the AC voltage applied to the conductive plate 3c of the elastic blade 3. As shown in FIG. 3, the conductive plate 3c
When a negative voltage is applied to the developing roller 2, the direction of the electric field formed in the minute gap 3d is in the A direction from the developing roller 2 toward the conductive plate 3c of the elastic blade 3, and the developing roller 2 The negatively charged toner 8 is peeled off from the developing roller 2, flies to the elastic blade 3 as indicated by a dotted arrow C, and adheres to the elastic layer 3b.

Next, when a negative voltage is applied to the conductive plate 3c and a positive voltage is applied to the developing roller 2, as shown in FIG.
The direction of the electric field formed therein is reversed in the B direction from the conductive plate 3c of the elastic blade 3 toward the developing roller 2, the toner 8 is separated from the elastic layer b, and the toner 8 flies to the developing roller 2 and returns. At this time, since the surface of the developing roller 2 is moving in the X direction, the toner 8 returning to the developing roller 2 returns to a position on the upstream side of the developing roller 2 as a trace of a solid arrow C ′.

In other words, due to the alternating electric field formed in the minute gap 3d, the flying and reciprocating movement of the returning position of the toner 8 to the developing roller 2 to the upstream side are repeated, and the toner 8 on the developing roller 2 is The toner layer is agitated from the upper layer to the lower layer.

In this embodiment, the rotation speed of the developing roller 2 is set to 120 mm / sec, and the AC power supply 5 is applied between the developing roller 2 and the conductive plate 3c at a peak-to-peak voltage of 1.6 KVpp and a frequency of 2 KHz. A rectangular bias was applied. The frequency (Hz) of the applied AC voltage is the rotation speed (mm / sec) of the developing roller 2, that is, the moving distance (mm) of the surface of the developing roller 2 per unit moving time of 1 second.
It is desirable to set the value 5 to 30 times.

The reason is that when the frequency of the applied AC voltage is less than 5 times the rotational speed (peripheral speed) of the developing roller 2, the toner on the developing roller 2 is unevenly formed in the toner layer due to the alternating electric field. This is because if it exceeds 30 times, a high-performance high-voltage power source must be used as the AC power source 5, which leads to an increase in cost. It is preferable to use 8 to 20 times.

In the case of the present embodiment, according to the conditions of the frequency and the rotation speed described above, when the length of the minute gap 3d in the rotation direction of the developing roller 2 is about 1 mm, the toner 8 is not contained in the minute gap 3d.
The flight reciprocates about 16 times.

The voltage value of the AC voltage of the AC power supply 5 is 100V.
It is sufficient if it is pp or more, and it is effective in causing the flying reciprocating motion of the toner 8 on the developing roller 2. The upper limit of the voltage value can be applied before the leak occurs. When a leak occurs, the alternating electric field disappears and the reciprocating flight motion is not performed.

In the present embodiment, as described above, the conductive plate 3c of the elastic blade 3 is connected between the AC power source 5 and the DC power source 6 of the developing power source, and the conductive plate 3 is utilized by using this AC power source 5.
Since an AC voltage is applied to c, a new power source for applying an AC voltage to the conductive plate 3c is unnecessary, which is advantageous in terms of cost when implementing the present invention.

As described above, the toner 8 flying and agitated in the minute gap 3d is conveyed to the developing area facing the photosensitive drum 1 by the rotation of the developing roller 2, and the electrostatic charge on the photosensitive drum 1 is maintained as usual. It is used for developing a latent image.

Conventionally, as described in the problem (1), the toner remaining on the developing roller 2 without contributing to the development is peeled off by the rotating supply roller which is in contact with the developing roller 2. For this reason, a large amount of stress is applied to the toner to cause deterioration, and the ability of the toner to acquire a charge is gradually reduced, causing fog.

On the other hand, in the present invention, the developing sleeve 2
3d on the downstream side of the contact nip between the elastic blade 3 and the elastic blade 3
Since an alternating electric field is formed on the developing roller 2, the toner on the developing roller 2 can be stripped off, reciprocating in flight and agitated.
Therefore, the step of stripping off the residual toner by the supply roller in contact with the developing roller can be omitted, the deterioration due to the stress of the toner can be prevented, the charging failure of the toner can be eliminated, and the fog can be prevented from occurring. it can.

Further, as described in the problem (2), when the stress applied to the toner on the developing sleeve by the supply roller is reduced, the toner is not peeled off, resulting in image defects such as low density and sleeve ghost. Occurs. As described above, omitting the stripping step is equivalent to pushing the reduction of the stress applied to the toner to the extreme, and reducing it to zero. Sleeve ghosts etc. will occur.

However, in the present invention, as described above, since the flying and reciprocating motions of the toner are stirred by the alternating electric field in the minute gap 3d on the downstream side of the contact nip, the stripping step by the supply roller is omitted. Even if this occurs, image defects such as low density and sleeve ghost do not occur.

That is, the flying and reciprocating movement of the toner 8 on the developing roller 2 in the minute gap 3d downstream of the contact nip, that is, the flying and reciprocating movement of the toner constituting the toner layer on the developing roller 2, is caused by the toner layer. The upper layer toner and the lower layer toner are moved and agitated, and the same toner is rubbed against the elastic blade 3 less frequently. Therefore, charge-up of the residual toner on the non-image area of the developing roller 2 is prevented, and the difference in the charge amount between the residual toner and the newly supplied toner, and thus the difference in the developability of the toner, can be significantly reduced. it can. For this reason, it is possible to prevent the occurrence of image defects such as low density and sleeve ghost, which would otherwise occur when the stripping step is eliminated.

In summary, according to the present invention, the problem of toner peeling failure due to the stress relaxation of the toner, such as the problem (2), does not occur itself, and the thin density and sleeve ghost caused by this do not occur. The image defects such as "1" are solved.

As described above, according to this embodiment,
High image quality can be obtained by the non-magnetic 1-component developing device,
In addition, the life of the developing device can be extended.

Embodiment 2 FIG. 5 is a constitutional view showing another embodiment of the developing device of the invention.

In the first embodiment shown in FIGS. 1 to 4, the conductive plate 3c as the electric field generating means is provided on the elastic blade 3, but in the present embodiment, as shown in FIG. The feature is that it is provided on the seat 7. 5, the same reference numerals as those given in FIG. 1 denote the same members.

According to this embodiment, the toner blow-out prevention sheet 7 is constructed by disposing the insulating elastic layer 7b on the conductive elastic thin substrate 7a such as phosphor bronze or a conductive film. The elastic thin substrate 7a is used as an electric field generating means. Toner blowout prevention sheet 7
By contacting the developing roller 2 with a predetermined pressure at the elastic layer 7b, a gap formed on the upstream side of the contact nip region between the developing roller 2 and the prevention sheet 7 in the rotation direction of the developing roller 2 A minute gap 7c that is not filled with the residual toner on the developing roller 2 is formed.

The elastic thin substrate 7a is connected between the AC power source 5 and the DC power source 6 connected in series with the developing power source, as in the first embodiment. By applying an AC voltage between the elastic thin substrate 7a and the developing roller 2 by the AC power source 5, an alternating electric field is formed in the minute gap 7c.

Therefore, the residual toner on the developing roller 2 can be peeled off in the minute gap 7c, and the flying reciprocating motion can be agitated. Therefore, the residual toner on the developing roller 2 can be peeled off by the supply roller in contact with the developing roller. Even if it is omitted, it is possible to prevent the occurrence of image defects such as low density and sleeve ghost, and since the peeling by the supply roller is omitted,
Fogging can be prevented by eliminating deterioration of toner due to stress and poor charging.

Example 3 In this example, as shown in FIG. 6, a conductive plate 10 as an electric field generating means was arranged at a predetermined minute distance from the developing roller 2. The positions are the developing roller 2 and the elastic blade 3.
It is located at a position between the contacting part of the developing roller 2 and the facing part of the developing roller 2 and the photosensitive drum 1.

Also in this embodiment, an AC voltage is applied to the conductive plate 10 by the AC power source 5 of the developing power source to generate the conductive plate 10.
By forming an alternating electric field in the minute gap between the developing sleeve 2 and the developing sleeve 2, the toner on the developing roller 2 can be stripped in the minute gap to cause reciprocating flight and stirring.

Therefore, even if the stripping of the residual toner by the supply roller in contact with the developing roller is omitted, the occurrence of image defects such as low density and sleeve ghost can be prevented.
By omitting the stripping by the supply roller, it is possible to prevent deterioration due to stress of toner and charging failure, and prevent fog from occurring.

In the above, the conductive plate 10 is provided between the abutting portion between the developing roller 2 and the elastic blade 3 and between the facing portion between the developing roller 2 and the photosensitive drum 1 and the facing portion between the image roller 2. However, it may be provided between the facing portion between the developing roller 2 and the photosensitive drum 1 and the contact portion between the developing roller 2 and the toner blowing prevention sheet 7.

According to the first to third embodiments described above, a high quality image can be obtained by the non-magnetic one-component developing device 9 and the developing device 9 can have a long life. In the contact nip region between the elastic blade 3 and the developing roller 2, if the stress applied to the toner 8 is reduced and the deterioration of the toner is further reduced, the life of the developing device 9, which is one of the objects of the present invention, is extended. Can be further improved.

According to the study by the present applicants, the spherical toner has higher slipperiness of the toner itself than the irregular toner such as the pulverized toner which has been widely used in the related art, and therefore, the toner in the contact nip region is not easily changed. It was found that the stress of can be reduced.

The spherical degree of the spherical toner can be indicated by using the toner shape factors SF-1 and SF-2.
Toner shape factors SF-1 and SF-2 are FE-SEM (S-800) manufactured by Hitachi Ltd., and 100 toner particle images are sampled at random, and the image information is sampled through an interface. Image analysis device (Lu
It is defined as a value obtained by introducing into ze × 3), performing analysis, and calculating from the following formula.

SF-1 = ｛(MXLNG) ² / ARE
A} × π / 4 × 100 SF-2 = {(PERI) ² / AREA} × 1 / 4π ×
100 However, AREA: Toner projected area, MXLNG: Absolute maximum length of toner, PERI: Perimeter of toner

The shape factor SF-1 indicates the spherical degree,
If this is larger than 140, the shape of the toner gradually changes from a spherical shape to an irregular shape. On the other hand, SF-2 indicates the degree of unevenness,
When it is larger than 120, the unevenness of the toner surface becomes remarkable.

According to the study by the applicants, the shape factor SF
It has been found that, when -1 is 100 to 140 and SF-2 is 100 to 120, the slipperiness is almost doubled as compared with the conventional amorphous toner.

FIG. 7 shows a simple experimental example for comparing the slipperiness of toners.

As shown in FIG. 7, a sample toner 14 is uniformly applied in one layer on an aluminum plate 11 placed horizontally. An aluminum plate 11 'similar to the plate 11 is provided on one surface thereof with an elastic body 12 made of the same material as the elastic layer 3b of the elastic blade 3 of FIG. 14 is placed, and a load W is applied by a weight 13 from the laminated plate. Then, as shown in FIG. 7, a force F is applied to the weight 13 in the horizontal direction so that the weight 13
Was measured in the horizontal direction, and the force F was used to evaluate the slipperiness of the toner 14.

As an example, the elastic body 12 is made of urethane rubber, and the sample toner 14 has a shape factor SF-1.
Of 100 to 140 and SF-2 of 100 to 120, and an irregular toner obtained by crushing the spherical toner. Therefore, the spherical toner and the irregular toner have the same resin. The same amounts of external additives were added to these toners. The load W of the weight 13 is 30 g, 60 g, 100 g,
It was set to 5 of 200g and 300g.

FIG. 8 shows the measurement results of toner slipperiness.
In FIG. 8, the vertical axis represents the force F (g) when the weight 13 starts to move, and the smaller the value, the better the toner slidability. As shown in FIG. 8, the slipperiness of the spherical toner is almost double that of the irregular toner,
It can be seen that the stress on the toner in the contact nip area can be reduced.

The construction and manufacturing method of the spherical toner that can be preferably used in the present invention will be described.

The spherical toner has a weight average particle diameter of about 6 μm, and a toner having a more spherical shape formed by a polymerization method is preferable. In particular, a toner in which the surface portion of the toner is formed by the polymerization method is obtained as a pretoner (monomer composition) particle present in the dispersion medium and a necessary portion is generated by the polymerization reaction, so that the surface is considerably smoothed. be able to.

In the present invention, at the same time, for the purpose of facilitating the production of the spherical toner and saving energy, the spherical toner has a core / shell structure in order to have a low melting point, and the shell portion is formed by polymerization. did. According to the core / shell structure, needless to say, the blocking resistance can be imparted without impairing the excellent fixing property of the toner, and the fact that only the shell portion is polymerized can be compared with a bulk polymerized toner having no core. Then, there is also an advantage that the residual monomer can be easily removed in the post-treatment step of the polymerization step.

The main component of the core portion is preferably a low softening point substance, and a compound having a main component maximum peak value measured in accordance with ASTM D3418-8 of 40 to 90 ° C. is preferable. If the maximum peak is less than 40 ° C., the self-cohesive force of the low softening point substance becomes weak, and as a result, the high-temperature offset property becomes weak, which is not preferable. On the other hand, the maximum peak is 90 ° C
If it exceeds, the fixing temperature becomes high, which is not preferable. Furthermore, when a toner is obtained by a direct polymerization method, granulation and polymerization are carried out in an aqueous system, so when the temperature of the maximum peak value is high, a low softening point substance mainly precipitates during granulation, which interferes with the suspension system. It is not preferable because

In the present invention, for measuring the temperature of the maximum peak value, for example, DSC-7 manufactured by Perkin Elmer Co. is used. The melting point of indium and zinc is used for the temperature correction of the device detection unit, and the heat of fusion of indium is used for the correction of the calorific value.
An aluminum pan was used as a sample, an empty pan was set as a control, and the temperature rising rate was 10 ° C./min. Was measured.

Specific examples of the low softening point substance having a core main component include paraffin wax, polyolefin wax, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax and derivatives thereof, or graft / block thereof. Compounds and the like can be used.

The low softening point substance is preferably added to the toner in an amount of 5 to 30% by weight. With less than 5% by weight,
It takes a burden to remove the residual monomers described above, and 3
When the content exceeds 0% by weight, coalescence of toner particles tends to occur during granulation even in the production by a polymerization method, and a toner having a wide particle size distribution is easily generated, which is not suitable for the present invention.

Furthermore, it is desirable to cover the toner surface with an external additive so that the effect of the photoconductor charging member can be released to some extent by the external additive. The coverage of the external additive on the toner surface is 5 to 99.
%, More preferably 10 to 99%. This external additive coverage is FE-SEM (S-8
00) was used to randomly sample 100 toner particle images, and the image information was introduced into an image analysis device (Luzex3) manufactured by Nikole Co. through an interface, analyzed, and calculated.

From the viewpoint of durability when added to the toner, the particle size of the external additive is 1/10 of the weight average particle size of the toner particles.
The following is preferred. The particle diameter of the external additive means the average particle diameter of the toner particles obtained by observing the surface of the toner particles with an electron microscope. As the external additive, for example, the following ones are used.

Aluminum oxide, titanium oxide, strontium titanate, cerium oxide. Metal oxides such as magnesium oxide, chromium oxide, tin oxide and zinc oxide, nitrides such as silicon nitride, carbides such as silicon carbide, metal salts such as calcium sulfate, barium sulfate and calcium carbonate,
Fatty acid metal salts such as zinc stearate and calcium stearate, as well as carbon black and silica.

The external additive is 0.1% by weight per 100 parts by weight of the toner.
0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight.
Parts by weight are used. The external additives may be used alone or in combination of two or more. An external additive that has been subjected to a hydrophobic treatment is more preferable.

In the present invention, as the non-magnetic toner, the low melting point spherical toner obtained by the above-mentioned polymerization method is used. According to this, it is possible to further improve the life of the non-magnetic one-component developing device of Examples 1 to 3, and to provide a non-magnetic one-component developing device for color having high image quality and high durability. It became possible.

[0089]

As described above, according to the present invention,
The developer carrier of the non-magnetic one-component developing device is provided with an electric field generating means by opening this and a minute gap, and an alternating voltage is applied to this electric field generating means to form an alternating electric field in the minute gap. The non-magnetic one-component developer on the carrier can be agitated by flying and reciprocating in a minute void. Therefore, the residual developer remaining after development on the developer carrier can be stripped off, stirred with the new developer supplied onto the developer carrier, and applied on the developer carrier. A thin layer of well-charged developer can be formed on the agent carrier. As a result, it is possible to prevent the occurrence of image defects such as low density and sleeve ghost. Further, since it is possible to omit the stripping of the residual developer remaining on the developer carrying member by the rotation of the developer supplying means that is in contact with the developer carrying member,
Deterioration due to stress of the developer due to the peeling off and poor charging can be eliminated, and image fogging due to this can be prevented. Therefore, a high-quality image can be obtained and the developing device can have a long life.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a developing device of the present invention.

FIG. 2 is an explanatory diagram showing a contact portion between a developing roller and an elastic blade of the developing device in FIG.

FIG. 3 is an explanatory diagram showing the flight of non-magnetic toner by an electric field in one direction of an alternating electric field formed in a minute gap downstream of the contact nip area in FIG.

FIG. 4 is an explanatory diagram showing flying of non-magnetic toner due to an electric field in the other direction.

FIG. 5 is a sectional view showing another embodiment of the developing device of the invention.

FIG. 6 is a sectional view showing still another embodiment of the developing device of the present invention.

FIG. 7 is an explanatory diagram showing a test method for examining the slipperiness of the toner, which was carried out in the present invention.

FIG. 8 is a graph showing the results of the slipperiness test of FIG. 7.

FIG. 9 is a cross-sectional view showing a conventional developing device.

[Explanation of symbols]

 1 Photosensitive Drum 2 Developing Roller 3 Elastic Blade 3a Elastic Thin Substrate 3b Elastic Layer 3c Conductive Plate 3d Micro Gap 4 Toner Supply Roller 5 AC Power Supply 7 Toner Blow-Out Sheet 7a Conductive Thin Substrate 7b Elastic Layer 7c Micro Gap 8 Non-Magnetic Toner 9 Non-magnetic 1-component developing device 10 Conductive plate

Claims (14)

[Claims] 1. A developer carrying member which rotates so as to face the image carrying member, and a non-magnetic one-component developer is supplied to the developer carrying member.
A developer supply unit arranged in non-contact with the developer carrier and a developer on the developer carrier arranged downstream of the developer supply unit with respect to the rotating direction of the developer carrier. In the developing device having the developer regulating means, the electric field generating means is arranged by opening a minute gap with the developer carrying body, and an alternating voltage is applied between the electric field generating means and the developer carrying body. A developing device characterized in that an alternating electric field is formed in a minute gap to cause the developer on the developer carrier to fly and reciprocate in the minute gap. 2. The developing device according to claim 1, wherein the installation position of the electric field generating means is a developer regulating portion by the developer regulating means or a downstream side thereof. 3. The developer regulating member is an elastic regulating member that is in contact with the developer carrying member in a direction opposite to the rotational direction thereof, and an electric field is provided on the opposite side of the elastic regulating member from the developer carrying member. 3. A conductive plate constituting a generating means is provided, and the conductive plate is arranged at a position corresponding to a minute gap formed downstream of a contact portion between the elastic regulation member and the developer carrying member. Development device. 4. The installation position of the electric field generating means is one place between the developer regulating means and the facing portion of the developer carrying member and the image carrying member in the rotating direction of the developer carrying member. Item 1 of the developing device. 5. The developing device according to claim 4, wherein the electric field generating means is a conductive plate. 6. The installation position of the electric field generating means is located between the facing portion of the developer carrying member and the image carrying member and the developer supplying means in the rotating direction of the developer carrying member. Item 1 of the developing device. 7. The developing device according to claim 6, wherein the electric field generating means comprises a conductive plate. 8. An elastic seal member that abuts a lower portion of the developer carrying member is installed, and the elastic seal member includes an elastic conductive plate that constitutes an electric field generating means, and a developer carrying member provided thereon. 7. An abutting insulating elastic layer
Developing device. 9. A developing power source for applying a developing bias between the developer bearing member and the image bearing member is installed, the developing power source comprises at least an AC power source, and the AC power source is used to generate the electric field. 9. The developing device according to claim 1, wherein an AC voltage is applied to the generating means. 10. The shape factor SF-1 of the developer is 10.
The developing device according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, wherein the developing device has an SF of 0 to 140 and an SF-2 of 100 to 120. 11. The method according to claim 1, wherein a part or all of the developer is formed by a polymerization method.
8, 9 or 10 developing devices. 12. The developing device of claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, wherein the developer has a core / shell structure. 13. The developing device according to claim 12, wherein the main component of the core is a low softening point substance, and the melting point of the low softening point substance is 40 to 90 ° C. 14. The surface of the developer is coated with an external additive, and the coverage is 5 to 99%.
4, 5, 6, 7, 8, 9, 10, 11, 12 or 13
Developing device.