JPH06324571A - Method and device for development and multicolor image forming device using same - Google Patents

Abstract

PURPOSE:To secure a sufficient developing property in forming a multicolor image, without distorting a toner image that is already formed. CONSTITUTION:In a developing method that uses a developer carrier 1 having a magnetic roller 3 installed in place inside a rotatable nonmagnetic sleeve 2, for developing without contact a latent image Z which is formed on a latent image carrier 4 using a two-component developer G carried on the developer carrier 1, the effective development area (m) of the developer carrier 1 opposite to the latent image carrier 4 is acted upon by a horizontal magnetic field component SH which extends in the circumferential direction of the developer carrier 1 with respect to the developer G on the developer carrier 1, and part of the effective development area (m) of the developer carrier 1 is acted upon by a partial behavior-accelerating magnetic field component SF for partially retreating the developer G on the developer carrier 1 and for causing the chains of the carrier C of the developer G on the developer carrier 1 in this developer retreat area K to slide along the circumferential direction of the developer carrier 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method used in an image forming apparatus such as an electrophotographic copying apparatus or a printer for forming a monochromatic or multicolor image, and a developing apparatus therefor. The present invention relates to a developing method for forming a thin layer of a magnetic brush on a latent image carrier and developing a latent image on a latent image carrier in a non-contact state, an improvement of the apparatus, and a multicolor image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, in a copying machine or the like in which an electrostatic latent image formed on a photoconductor is developed by a developing device and then transferred onto a recording paper, a developer is brought into contact with the surface of the photoconductor to electrostatically charge it. A number of developing methods using a two-component magnetic brush for visualizing a latent image have been proposed. This method is a mainstream developing method from the viewpoints of image quality characteristics, maintainability, etc., though it has problems of complicated toner density control and enlargement of the apparatus.
However, in recent years, with the improvement in image quality and multicolor recording, a multicolor image forming process has been proposed in which toner images of a plurality of colors are simultaneously formed on a photoconductor and these are collectively transferred to a recording paper. However, when the contact type two-component magnetic brush developing method described above is adopted for the second and subsequent developing processes of such a multicolor image forming process, the toner image already formed on the photoreceptor is destroyed, The technical problem that other color toners are mixed or other color toners are mixed in the developing device has already been found.

In order to solve such technical problems,
Many so-called non-contact developing methods have been proposed in which development is performed without contacting the surface of the photoreceptor with a developer. As a non-contact developing method of this type, for example, as disclosed in JP-A-56-144452, a thin layer (developing magnetic brush) composed of toner and magnetic carrier is formed on a developing roll to form a photosensitive member. Magnetically in the developer layer with the developing magnetic brush in a non-contact state,
It is known to provide a disturbing effect by an electric or mechanical means to develop. According to this method, when a multicolor image is formed, it is possible to form a good image without disturbance and color mixture due to mechanical contact of the magnetic brush in the developing process located after the first toner image. In particular, JP-A-60
As disclosed in Japanese Patent Publication No. 176069, the magnetic poles of the magnet roll are arranged so as to avoid the position where the developing sleeve and the photoconductor are closest to each other, and development is performed under an oscillating electric field while applying a horizontal magnetic field component to the developer layer. In this method, since a thin and uniform developer layer can be obtained, in the development process located after the first toner image during multicolor image formation, there is no disturbance and color mixing due to mechanical contact of the magnetic brush. A good image that does not exist can be obtained more reliably. Incidentally, these developing methods can be applied not only to the multicolor image forming process but also to the developing technology for monochromatic recording, and since the magnetic brush is not in contact with the latent image on the photoconductor, Faithful image reproduction can be expected.

[0004]

However, in the developing method disclosed in JP-A-60-176069, although a thin and uniform developer layer can be obtained because the horizontal magnetic field component acts on the developer layer, When a multicolor image is formed, it is impossible to sufficiently enhance the developability of the toner itself so as not to disturb the toner image already formed on the photoconductor, and a technical problem that the so-called developability is deteriorated has been found. .
With respect to the technical problem of deterioration of the developability in this non-contact developing method, particularly, the developing magnetic pole is arranged so as to avoid the position where the sleeve and the photoconductor are closest to each other, and the developing layer is developed while the horizontal magnetic field component is applied. Various studies were conducted on the method. As a result, when a horizontal magnetic field component is applied to the developer layer, the developer particles are magnetically arranged along the lines of magnetic force to form a high density and uniform thin layer on the developing sleeve surface,
It was found that the developer contributing to the development was only one or two surface layers. It is considered that this is because the developer layer is placed in a state of being strongly packed along the lines of magnetic force, so that the toner particles in the developer near the developing sleeve cannot move to the surface layer.

The present invention has been made in order to solve the above technical problems, and ensures sufficient developability without disturbing a toner image that has already been formed when a multicolor image is formed. The present invention provides a novel non-contact developing method and apparatus, and a multicolor image forming apparatus using the same.

[0006]

That is, the present invention is
As shown in FIG. 1, a rotatable non-magnetic sleeve 2 has a developer carrier 1 on which a magnet roll 3 is fixedly installed, and a developer carrier 1 is composed of a toner T and a magnetic carrier C. In the developing method, which carries the component developer G and develops the latent image Z formed on the latent image carrier 4 with the two-component developer G on the developer carrier 1 in a non-contact state, In the effective developing region m of the developer carrier 1 facing the latent image carrier 4, a horizontal magnetic field component SH along the circumferential direction of the developer carrier 1 is applied to the developer G on the developer carrier 1. At the same time, in a part of the effective developing area of the developer carrying member 1, the developer G on the developer carrying member 1 is locally repelled, and the carrier C chain of the developer G is held in the developer repelling area K. At least a local behavior promoting magnetic field component that slides along the circumferential direction of the developer carrying member 1. It is characterized by causing SF to act.

In such technical means, the invention of the present application is directed to non-contact development, and usually, the latent image Z formed on the latent image carrier 4 is a two-component image on the developer carrier 1. It means that the developing is performed in a non-contact state with the developer G. In the present application, the gap between the surface of the latent image carrier 1 and the surface of the developer carrier 1 is the developer at least when the non-magnetic sleeve 2 is stationary. As long as it is wider than the layer thickness of the developer layer on the carrier 1, a wide range of objects include those in which a part of the developer G is in light contact with the surface of the latent image carrier 1 in dynamic behavior. Let's assume.

The magnetic flux density of the magnetic poles (two magnetic poles having different polarities) for causing the horizontal magnetic field component SH to act on the effective developing area m contributing to the development is in the range of 300 to 1500 gauss. The magnetic angle formed by the line connecting the centers of the magnet rolls 3 (m-center of the effective developing area) is 3
It is in the range of 0 to 180 degrees. The magnetic flux density and the magnetic angle are determined by the curvature (outer diameter) when the developer carrier 1 and the latent image carrier 4 are cylindrical.

Further, as the behavior promoting magnetic field component SF, the developer G on the developer carrier 1 is locally rejected, and the developer G on the developer carrier 1 in the developer reject area K is changed. As long as the carrier C chain is slid, for example, vertical and horizontal magnetic field components along the radial direction and the circumferential direction of the developer carrying member 1 may be appropriately selected.

On the other hand, as a carrier constituting the developer, it is preferable that the magnetic force per unit volume is small from the viewpoint of layer formation and image characteristics (carrier particle size is about 20 to 50 μm). Further, it is possible to form a more uniform layer by removing fine powder particles of 10 μm or less among the carrier particles and sharply controlling the particle size distribution. Further, in order to further improve the developability, it is preferable to apply an AC bias VCB between the surface of the latent image carrier 4 and the non-magnetic sleeve 2.

As shown in FIG. 1, an apparatus invention embodying such a method invention has a developer carrier 1 in which a magnet roll 3 is fixedly installed in a rotatable non-magnetic sleeve 2. A two-component developer G composed of toner T and a magnetic carrier C is carried on the developer carrier 1, and a latent image formed on the latent image carrier 4 by the two-component developer G on the developer carrier 1. In a developing device that develops Z in a non-contact state, the magnet roll 3 has a developer G relative to the developer G on the effective development area m of the developer carrier 1 facing the latent image carrier 4. The magnetic pole pairs 5 and 6 of different polarities for exerting the horizontal magnetic field component SH along the circumferential direction of the carrier 1 and the magnetic pole pairs 5 and 6 for the horizontal magnetic field components are provided at an intermediate position between the developer carrier and the developer carrier. In a part of the effective developing area m of No. 1, the developer G on the developer carrier 1 is locally At least one of which is locally displaced and in which the carrier C chain of the developer G slides at least along the circumferential direction of the developer carrying member 1 in the developer retreat region K, causing a local behavior promoting magnetic field component SF to act. A pair of magnetic pole pairs 7 and 8 for behavior promoting magnetic field components having different polarities are included.

In such a technical means, as a method of producing the magnetic pole pairs 5 and 6 for the horizontal magnetic field component and the magnetic pole pairs 7 and 8 for the behavior promoting magnetic field component, a usual magnetizing method may be used. The design may be changed as appropriate by adopting a method of embedding a magnet. In this case, from the viewpoint of easily creating the behavior promoting magnetic field component magnetic pole pairs 7 and 8, as the different polarity behavior promoting magnetic field component magnetic pole pairs 7 and 8, the different polarity horizontal magnetic field component magnetic pole pair 5 is used. , 6 influences the vicinity of the polarity reversal portion of the vertical magnetic field component, secures a local developer repelling region K on the developer carrier 1 in the vicinity of the polarity reversal portion, and the horizontal magnetic field component magnetic pole pair 5, The behavior promoting magnetic field component SF containing the vertical magnetic field component smaller than the peak value of the vertical magnetic field component 6 may be selected according to one criterion. It should be noted that the method of creating the behavior promoting magnetic field component magnetic pole pairs 7 and 8 is merely an example, and it goes without saying that creation by another method is not limited.

Further, the behavior promoting magnetic field component magnetic pole pair 7,
When creating 8, magnetic pole pairs 5 and 6 for horizontal magnetic field components
It is necessary to set the magnetic field strength and the magnetic field pattern of the behavior promoting magnetic field component magnetic pole pairs 7 and 8 in consideration of the magnetic field strength and the magnetic field pattern. In this case, the magnetic flux density of the magnetic pole pairs 7 and 8 for the behavior promoting magnetic field component is such that the developer G arranged along at least the horizontal magnetic field component SH is locally displaced at the inter-magnetic pole portion, Is determined so as to provide a vertical magnetic field component that is not released and a horizontal magnetic field component that causes the developer G to slide along the circumferential direction of the developer carrier 1 in the developer retreat region K.

Further, the horizontal magnetic field component of the behavior promoting magnetic field component SF must be an inverted horizontal magnetic field component in the opposite direction to the horizontal magnetic field component SH by the horizontal magnetic field component magnetic pole pairs 5, 6. In this case, in order to make the sliding motion of the developer G smoother, the reverse horizontal magnetic field component in the opposite direction to the horizontal magnetic field component SH by the horizontal magnetic field component magnetic pole pairs 5 and 6 is generated, and the reverse is performed. It is preferable that the horizontal magnetic field component acts only on the surface portion of the developer carrying member 1. At this time, the reverse horizontal magnetic field component of the behavior promoting magnetic field component SF acts on the surface portion of the developer carrier 1 to overcome the horizontal magnetic field component SH by the magnetic pole pairs 5 and 6 for the horizontal magnetic field component. In the portion radially separated from 1, the horizontal magnetic field component SH due to the horizontal magnetic field component magnetic pole pairs 5 and 6
Acts to overcome the reverse horizontal magnetic field component of the behavior promoting magnetic field component SF.

Further, the behavior promoting magnetic field component SF may be any one as long as it acts on a part of the effective developing area m of the developer carrier 1, but the developer G is applied at the location where the behavior promoting magnetic field component SF acts. From the standpoint of facilitating the adjustment of the gap between the spike amount of the developer G and the latent image carrier 4 when the carrier C chain rises, a portion other than the portion closest to the latent image carrier 1, Specifically, the behavior-promoting magnetic field component magnetic pole pairs 7 and 8 are arranged near the upstream or downstream region of the effective developing area m of the developer carrier 1 (one magnetic pole 7 or 8 is arranged outside the effective developing area m). However, it is preferable that the behavior promoting magnetic field component SF acts on the upstream region or the downstream region of the effective developing region m.

Further, although the developing performance is improved by disposing the magnetic pole pairs 7 and 8 for the behavior promoting magnetic field component, on the other hand, the developer G using the carrier (microcarrier) C having a small particle size is present. For carrier C,
In particular, there is a technical problem that micro carry over easily occurs between lines of a high frequency line image. From the viewpoint of effectively avoiding this micro-carryover, the magnetic pole 6 located on the rotational direction side of the developer carrier 1 of the horizontal magnetic field component magnetic pole pairs 5 and 6 is set as an effective developing area of the developer carrier 1. Is preferably arranged in the vicinity of the downstream area of the latent image carrier 4 in this case. In this case, the magnetized portion of the magnet roll 3 in the downstream area of the effective developing area m attracts and collects the carrier C transferred to the latent image carrier 4 side. Is also preferable in that it functions effectively. The effective development area m
By appropriately adjusting the magnetic force of the magnetic pole 6 in the vicinity of the downstream region of, it is possible to more effectively avoid the micro carryover.

Furthermore, the action-promoting magnetic field component SF does not necessarily have to be a single action point, and from the viewpoint of improving the developing performance, the behavior-promoting magnetic field component SF is applied to a plurality of points in the effective developing area m. It is preferable to let SF act.

Further, as an effective application example of such a developing device, a plurality of latent images Z are sequentially formed on the latent image carrier 4, and each formed latent image Z is a toner T of a corresponding color system. In the multi-color image forming apparatus in which the toner images of a plurality of color systems formed on the latent image carrier 4 are collectively transferred to the transfer medium, at least the second and subsequent latent images are developed. It is preferable to use the developing device of the present invention.

In such a technical means, as a multicolor image forming apparatus, latent image formation and development for each color component are sequentially repeated while the latent image carrier 4 is rotated once, and then collectively transferred to a transfer medium. Alternatively, the latent image carrier 4 may be rotated multiple times to form a latent image of each color component for each rotation.
After the development is sequentially repeated, a type such as batch transfer to the transfer medium may be appropriately selected. Further, the developing device of the present invention is effective as a device for developing the second and subsequent latent images of the multicolor image forming device, but the developing parameter such as the developing bias voltage value is changed to develop the first latent image. It can be used as a product.

[0020]

According to the above-mentioned technical means, the polarities for forming the horizontal magnetic field component SH are different in the area where the developer carrying member 1 and the surface of the latent image carrying member 4 face each other (effective developing area m). When the magnetic pole areas of the two magnetic poles 5 and 6 are opposed to each other, the developer G carried on the non-magnetic sleeve 2 is arranged along the lines of magnetic force to form a high-density and uniform thin layer on the surface of the non-magnetic sleeve 2. Form.

Further, in a part of the effective developing area m, for example,
Two magnetic poles 7 and 8 having different magnetic forces and different polarities are opposed to the two magnetic poles 5 and 6 for generating the horizontal magnetic field component SH, and the vertical and horizontal magnetic field components (horizontal magnetic field components (horizontal When a reverse horizontal magnetic field (opposite to the magnetic field component SH) is applied, the developer G is locally rejected due to the influence of the vertical magnetic field component, and the carrier C chain of the developer G rises. Under the influence of the components, the carrier C chain of the developer G slides on the surface of the non-magnetic sleeve 2 in the developer retreat area K, and falls down along the circumferential direction of the developer carrier 1. Depending on the regulated amount of the developer G layer thickness and the direction and size of the horizontal magnetic field component at the portion radially separated from the developer carrying member 1, the tip end side of the carrier C chain may follow the magnetic field along the developer carrying member 1. It may fly along the circumferential direction.

At this time, due to the rising of the carrier C chain of the developer G, the sliding and falling of the carrier C chain, the upper layer portion and the lower layer portion of the developer layer are exchanged, or the carrier C flies. The carrier collides with the developer G on the downstream side, and the toner is knocked out. Therefore, the behavior promoting magnetic field component SF of the effective developing area m
The behavior of the developer G is accelerated around the working area (the movement of the carrier C particles of the entire developer G becomes active), and the latent image carrier 4 of the toner T particles from the surface of the carrier C particles under the developing electric field. The transfer to the side is promoted, and as a result, high developability is obtained under the same developing conditions (for example, developing electric field strength, developing sleeve rotation speed, toner concentration in the developer, etc.).

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the accompanying drawings. Example 1 FIG. 2 shows an example of a multicolor image forming apparatus using the developing method according to the present invention. In the figure, 11 is a negatively charged photoreceptor that rotates in the a direction, 12 and 13 are first and second chargers (scorotron in the embodiment) that charge the photoreceptor 11, 1
Reference numerals 4 and 15 are first and second Rs made of, for example, a semiconductor laser.
OS [abbreviation of Raster Output Scannor] (optical writing device: resolution 400 spots per inch), 16 and 17 are first and second developing devices having the same charging polarity but different colors, and 18 is formed on the photoconductor 11. A transfer pretreatment lamp that radiates light to the two-color toner images to make the potentials uniform, 19 is a transfer charger that collectively transfers the two-color toner images on the photoconductor 11 onto the recording paper 20, and 21 is a photoconductor after the transfer. Recording paper 2 from body 11
Reference numeral 22 denotes a peeling charger for peeling 0, 22 is a cleaner for removing the residual toner on the photoconductor 11, and 23 is a discharging lamp for removing the residual charge on the photoconductor 11.

In this embodiment, the first developing device 16 uses the contact magnetic brush developing method, and the second developing device 17 uses the non-contact magnetic brush developing method according to the present invention. The details of the second developing device 17 are shown in FIG. In the figure, the second developing device 17 has a developing roller 171 having a magnet roller 173 in a rotatable non-magnetic sleeve 172 having an average surface roughness of 10 to 50 μm and a non-magnetic sleeve 172 and a constant gap. A developer regulating member 17 composed of a non-magnetic member provided
4. Further, the paddle 175 and the auger 176 are configured as main constituent parts.

The magnet roll 173, as shown in FIG.
Pre-development stage magnetic pole S1 for applying a horizontal magnetic field component for developer packing to the effective development area m that contributes to development
And a post-development stage magnetic pole N1, and between the pre-development stage magnetic pole S1 and the post-development stage magnetic pole N1, a behavior promoting magnetic field component that functions to promote the behavior of the developer in the upstream region (entrance side region) of the effective developing region m. And a development-promoting post-stage magnetic pole S1 ′ and a development-promoting post-stage magnetic pole N1 ′ having different polarities for forming a toner, and further, the developer after passing through the effective developing region m is transferred to the sleeve 1
72, a pick-off magnetic pole S2 for peeling from above, and a pickup magnetic pole S3 for adsorbing the developer to the sleeve 172.
And trimming pole N2 for forming a thin layer of developer
Is provided. In this embodiment, the magnetic poles S1 to S3 and N1 to N except the development promoting magnetic poles S1 'and N1' are used.
2 is formed by magnetizing the corresponding portions of the magnet roll 173, while the development promoting magnetic poles S1 'and N1' are magnets 17 in the grooves formed in the corresponding portions of the magnet roll 173.
It is formed by embedding 8,179.

Further, FIG. 5 shows a magnet roll 17 according to the embodiment.
3 shows the magnetic force distribution of No. 3 in the radial direction. In the figure, a region where the developing roll 171 faces the photoconductor 11 (effective developing region m)
In the upstream region, development promoting magnetic poles S1 'and N1' having different polarities are provided.
The magnetic field distribution of the post-development magnetic pole N1 is mainly shown in the downstream area of the effective development area m. In particular, in this embodiment, the development promoting magnetic poles S1 'and N1' having different polarities are the development magnetic poles N having different polarities.
1, S1 influences the vicinity of the polarity reversal portion of the magnetic force in the radial direction (vertical magnetic field component), and secures a local developer repelling region K described later on the developing roll 171 near the polarity reversal portion and develop The magnetic force including the magnetic force in the radial direction (perpendicular magnetic field component) smaller than the peak value of the magnetic force in the radial direction of the magnetic poles N1, S1 is applied. In this magnetic force distribution, the magnetic forces of the developing magnetic poles N1 and S1 are 300 to 1200.
Gauss, and the magnets 178 and 179 have a height of 4 m.
The magnetic force of the development promoting magnetic poles S1 ', N1' formed by the magnets 178, 179 is 50 to m.
It is 400 gauss. A specific example of this is shown in FIG. In the figure, radial is the radial component of the magnetic force distribution.
Indicates the circumferential direction component of the magnetic force distribution. As shown in FIG. 4, the vertical direction of the D-cut surface of the support shaft 173a of the magnet roll 173 is set as the reference position (0 °), and the pre-development magnetic pole S1 (40 ° from the reference position). The radial component of the magnetic force of (deviation) is 420 gauss, the radial component of the magnetic force of development promoting magnetic pole N1 ′ (deviation of 15 ° from the reference position) is 240 gauss, and the development promoting magnetic pole S1 ′.
Set the radial component of the magnetic force (deviation of 355 ° from the reference position) to 1
70 Gauss, the radial component of the magnetic force of the post-development magnetic pole N1 (deviation of 330 ° from the reference position) was 820 Gauss.

In this case, the development promoting magnetic pole S
Things to note when setting the magnetic force of 1 ', N1' are:
As shown in FIG. 7, when the developing roll 171 is in the static state, a predetermined gap is provided between the photoconductor 11 and the spiked tip of the developer G that rises along the vertical magnetic field of the development promoting magnetic poles S1 ′ and N1 ′. It is to ensure δ. In particular, in this embodiment, since the bristling position of the developer G rising by the vertical magnetic field of the development accelerating magnetic poles S1 'and N1' is displaced to the front side from the position closest to the photoconductor 11, the developer regulating member is formed. Even if the layer thickness adjustment accuracy of the developer G by 174 is made rough to some extent, the gap δ can be easily set in a form including the variation amount of the spike amount of the developer G.

Further, in this way, the development promoting magnetic poles S1 ', N
If the magnetic force of 1'is set, in the static state of the developing roll 171, there is a developer withdrawal region K where the developer G is locally withdrawn between the development promoting magnetic poles S1 'and N1'.
In the dynamic state in which the developing roll 171 rotates, as shown in FIG. 8, the carrier of the developer G is between the development promoting magnetic poles S1 ′ and N1 ′ in the effective developing region m of the developing roll 171 (developer retreat region K). C chain is developing roll 171
The behavior of sliding along the rotation direction (circumferential direction) and falling down was confirmed. Incidentally, it was observed that a part of the carrier located on the tip end side of the carrier C chain flies in the circumferential direction of the developing roll 171, and collides with the developer G located on the downstream side.

Further, in the front region of the development promoting magnetic poles S1 ', N1', that is, the front region entering the effective developing region m (between the pre-development magnetic pole S1 and the development promoting magnetic poles S1 ', N1'), FIG. As shown in (4), the behavior of the carrier C chain of the developer G reaching the development accelerating magnetic poles S1 ′ and N1 ′ while rotating (the behavior presumed to cause a disturbance in the developer G) was also confirmed. Note that, in FIG. 9, the alternate long and short dash line indicates the general surface of the developer layer. The behavior of the carrier C chain of the developer was confirmed by observing with an optical microscope while slowly rotating the developing roll 171 incorporating the magnet roll 173 having the magnetic force distribution described above.

Further, the developing roll 171 according to this embodiment.
Further analysis of the circumferential component of the magnetic force distribution of
The magnetic circumferential component on the surface of the developing roll 171 changes as shown by the solid line in FIG. 10, while the magnetic circumferential component on the surface of the developing roll 171 at a position 1 mm away from the surface of the developing roll 171 in the radial direction is shown in FIG. It was confirmed that the change occurred as shown by the broken line. In FIG. 10, + on the vertical axis indicates the rotation direction of the sleeve, and − indicates the opposite direction. Furthermore, when the magnetic force line directions around the magnet roll 171 were plotted, the results shown in FIG. 11 were obtained. 10 and 11
According to the above, although the circumferential magnetic force component on the surface of the developing roll 171 is the reverse horizontal magnetic field component N in the opposite direction to the other portion in the developer repelling region K between the development promoting magnetic poles S1 'and N1'. On the other hand, 1 m from the surface of the developing roll 171 in the radial direction.
It is understood that the horizontal magnetic field components at the positions separated by m are directed in the same direction, and it is considered that the reversed horizontal magnetic field component M is a factor that gives the above-described sliding and falling behavior of the carrier C chain. .

In the figure, the depth h of the groove of the magnet roll 173 is changed or the mutual magnets 178, 1 are changed.
By changing the magnetic force of 79, it is possible to control the magnetic forces of the development promoting magnetic poles S1'N1 'having different polarities.
Furthermore, the individual magnetic forces S and N of the front and rear development magnetic poles S1 and N1
The angle formed by the poles 1, 1 and the development promoting magnetic poles S1 ', N
It is also possible to control the angle formed by 1 '.

The developer regulating member 174 is arranged so as to face the magnetic pole N2 and maintain a minute gap. In addition, paddle 1
Reference numeral 75 has a function of sending the developer separated from the sleeve 172 to the auger 176 side by the pickoff magnetic pole S2. Further, the auger 176 has a function of stirring the peeled developer and stirring the toner supplied from a toner hopper (not shown) and the developer in the developing device.

Next, the image forming process of the multicolor image forming apparatus according to this embodiment will be described with reference to FIG. In the charging step a, the surface of the photoconductor is uniformly charged (first initial charging potential VDDP
1) In the first exposure step b, after forming a first latent image corresponding to the original information (the image portion potential of the original is VL1 and the non-image portion potential VH1), the reverse development is performed in the first developing step c. The image portion of the first latent image is developed with (developing bias potential VB1). Next, in the recharging step d, the surface of the photoconductor is uniformly recharged (second initial charging potential VDDP2), and in the second exposure step e, the second latent image (of the original document) corresponding to other information of the original document. After the image portion potential is set to VL2 and the non-image portion potential VH2), a second developing step f (developing bias potential V) having a color different from that of the first developing step is formed.
In B2), the image portion of the second latent image is reversely developed. Through these steps, two color toner images are formed on the photoconductor.

Images were formed according to the above-mentioned image forming process under the following experimental conditions. ● Photoreceptor Organic photoreceptor (negative charging type) Drum outer diameter 84mm ● Process speed 160mm / sec ● First developer (toner concentration 3.0%) ・ Two-component system (negatively charged red toner) ・ Carrier average Ferrite carrier having a particle size of 100 μm ・ Red toner 90 parts of styrene-n-butyl methacrylate copolymer, 8 parts of red pigment resole scarlet (BASF), and 2 parts of charge control agent (E-84, manufactured by Orient Chemical Co., Ltd.) After mixing, melt-kneading, and finely pulverized to an average particle size of 12 μm, the carrier is negatively charged. ● Second developer (toner concentration 8.0%) ・ Two-component system (negatively charged black toner) ・ Carrier Polymethylmethacrylate copolymer (35 parts) and magnetite (65 parts) are mixed, melt-kneaded, and then finely pulverized. Powder-dispersion type, average particle diameter 45 μm, density 2. 2g / cm ³ Black toner 93 parts of styrene-n-butyl methacrylate copolymer and 7 parts of carbon black are mixed, melt-kneaded, and then finely pulverized to have an average particle size of 11 μm, which is negatively charged to the carrier. ● Parameters of first developing device (contact type development) ・ DRS (gap between photoconductor and transfer member) 0.6 mm ・ MSA (set angle of main development pole) + 5 ° ・ TG (gap between layer thickness control member and sleeve) 0. 50 mm ・ Development sleeve outer diameter 20 mm ・ Development sleeve rotation speed 480 mm / sec ・ Development sleeve rotation direction With (same direction as photoconductor) ● Second developing device parameter (non-contact development) ・ DRS 0.5 mm ・ MSA magnetic pole・ TG 0.65mm ・ Development sleeve outer diameter 24.5mm ・ Development sleeve rotation direction With ● Voltage applied to transfer charger AC400HZ. VP-P
8.5 KV. DC + 2.5 KV Further, the potential conditions for latent image formation shown in FIG. 12 are as follows: the first image has the first initial charging potential VDDP1 of −600 V, the first non-image portion potential VH1 of −600 V, and the first image portion potential VL1. −
100V, first developing bias potential VB1 is DC-500V
On the other hand, as the second image, the second non-image portion potential VH2 is −
The second image portion potential VL2 was set to 600V, the second developing bias potential VB2 was set to DC-500V. When an image was formed under the above conditions, there was no color mixing of the second developing toner in the first image, and the second image also had a reflection density of 1.2 or more. In addition, a high-frequency line image (2 l in this embodiment)
Almost no carrier adhesion was observed between the lines of [p [line pair] / mm).

Comparative Example When an image was formed on the magnet roll 173 of the second developing device 17 under the same conditions as in Example 1 with a pattern without the development accelerating magnetic poles S1 'and N1', the image in the first image was Although there was no color mixing of the second developing toner, the second image could only obtain a density of 1.0 or less.

Example 2 The bias condition of the second developing device 17 was set to AC 2.5 KHz, V
An experiment was conducted in the same manner as in Example 1 except that P-P was 1.0 KV, VDC-500 V, and other conditions were the same, and there was no color mixture of the second developing toner in the first image and the second image was 1.4. The above reflection densities were obtained. Further, carrier adhesion was hardly observed between the lines of the high frequency line image (2 lp / mm in this example) as in Example 1.

Example 3 This example is substantially the same as Example 2 except that the developer carrying amount is increased as compared with Example 2. At this time, the behavior of the developer on the developing roll 171 was examined. As the sleeve 172 rotates, the developer slides and falls in the developer retreat area K near the sleeve 172. It was confirmed that in the developer withdrawal region K at a position radially away from, more carriers flew to the downstream side along the circumferential direction of the developing roll 171 than in Example 1. Also in this embodiment, similarly to the second embodiment, there is no color mixing of the second developing toner in the first image, and the second image can also obtain a reflection density of 1.4 or more, but the developer is conveyed. When the amount was set too high, a relatively large amount of carrier adhesion was observed between the lines of the high frequency line image. It is considered that this is because the upper layer portion of the developer is more likely to come into contact with the surface of the photoconductor 11 as the flight phenomenon of the carrier is activated.

Example 4 In this example, as shown in FIGS. 13 and 14, substantially the center of the pre-development-stage magnetic pole S1 and the post-development-stage magnetic pole N1 (in this embodiment, at the center of the effective development area m, the photoconductor 11). (Corresponding to the position closest to) with the second developing device 17 having a built-in magnet roll 173 in which the development promoting magnetic poles S1 ′ and N1 ′ are arranged,
When an image was formed under the same conditions as in Example 2, there was no color mixture of the second developing toner in the first image and the second image was 1.4.
The above reflection densities were obtained. In this example, a relatively large amount of carrier adhesion was observed between the lines of the high frequency line image (2 lp / mm in this example).

Fifth Embodiment In this embodiment, as shown in FIGS. 15 and 16, a second magnet roll 173 having development promoting magnetic poles S1 'and N1' disposed therein is provided downstream of the effective developing area m. When an image was formed using the developing device 17 under the same conditions as in Example 2, there was no color mixing of the second developing toner in the first image and a reflection density of 1.4 or more was also obtained in the second image. . In this embodiment also, a high frequency line image (2 lp / mm in this embodiment)
A relatively large amount of carrier adhesion was observed between the lines.

Example 6 In this example, as shown in FIG. 17, the effective developing area m
The first development promoting magnetic poles S11 'and N11' in the upstream region of the second development promoting magnetic pole S1 in the downstream region of the effective developing region m.
When an image was formed under the same conditions as in Example 1 using the second developing device 17 having the magnet roll 173 in which 2'and N12 'were arranged, the color mixture of the second developing toner in the first image was found. In addition, the second image also had a reflection density of 1.4 or more. In addition, a high-frequency line image (2 lp / mm in this embodiment)
As in the case of Example 1, almost no carrier adhesion was observed between the lines. When an image was formed in this example under the same conditions as in Example 2, it was obtained that the second image had a higher reflection density.

Example 7 In the magnet roll 173 according to this example, as shown in FIG. 18, N1 is arranged on the upstream side and S1 is arranged on the downstream side as a developing magnetic pole pair for developer packing. Also,
In the upstream area of the effective developing area m, S1 ′ is arranged on the upstream side and N1 ′ is arranged on the downstream side as a development promoting magnetic pole, and further, the developer after passing through the effective developing area m is transferred from a sleeve (not shown). Pickoff magnetic pole N2 for peeling, pickup magnetic pole N for adsorbing the developer to a sleeve (not shown)
3 and trimming pole S for forming a thin layer of developer
2 is provided. Note that FIG. 19 shows the radial component of the magnetic force of the magnet roll 173 according to this embodiment.

In this example, when an image was formed under the same conditions as in Example 1, there was no color mixture of the second developing toner in the first image and the second image also had a reflection density of 1.2 or more. Was given. In addition, a high-frequency line image (2 l in this embodiment)
Almost no carrier adhesion was observed between the lines of [p [line pair] / mm).

In this embodiment, the bias condition of the second developing device is AC 1.5 KHz, VP-P 1.0 KV, VD.
An experiment was conducted in the same manner as in Example 1 under the conditions of C-500V and other conditions. As a result, there was no color mixing of the second developing toner in the first image and the second image also had a reflection density of 1.4 or more. Was given. In addition, a high frequency line image (2 lp / in this embodiment)
As in Example 1, almost no carrier adhesion was observed between the lines (mm).

[0044]

As described above, according to claims 1 and 4,
According to the invention as set forth in claim 12, in the non-contact developing method using a two-component developer, a horizontal magnetic field component is applied to the effective developing area to secure a thin and uniform developer layer, and further, the effective developing area. A partial behavior promoting magnetic field component is caused to act on a part of the surface of the developer to cause the developer to slide and fall on the surface of the developer carrier, thereby increasing the amount of toner contributing to the development. In some cases, mechanical rubbing against an existing toner image can be completely eliminated in the subsequent developing process, and it is possible to surely avoid a situation in which an image quality defect such as color mixing or image disturbance occurs, and a sufficient developing density can be obtained. Therefore, it is possible to obtain a good multicolor image having no image quality defect.

According to the second aspect of the present invention, since the vertical and horizontal magnetic field components along the radial direction and the circumferential direction of the developer carrying member act as the behavior promoting magnetic field components, magnets having different polarities are used. The behavior-promoting magnetic field component can be easily created by using this. Furthermore, according to the third aspect of the present invention, the amount of toner contributing to the development can be further increased by the AC bias, so that the development density can be further increased.

Furthermore, according to the invention of claim 5,
Since the layout for the behavior promoting magnetic field component magnetic pole pair and one criterion by which the behavior promoting magnetic field component is easily determined are clarified, the behavior promoting magnetic field component magnetic pole pair can be easily created. According to the sixth aspect of the present invention, by optimizing the magnitude of the vertical magnetic field component of the behavior promoting magnetic field component magnetic pole pair along the radial direction of the developer carrier, the developer on the developer carrier is optimized. Can be locally rejected, and the developer can be started up without causing the developer to be released from the developer carrier, and the behavior of the developer can be promoted while the carry-over phenomenon of the developer is suppressed. Can be secured.

According to the inventions of claims 7 and 8,
The horizontal magnetic field component of the magnetic pole pair for the behavior promoting magnetic field component along the circumferential direction of the developer carrier is set as a reversing horizontal magnetic field component in the opposite direction to that of the magnetic pole pair for the horizontal magnetic field component, particularly, the surface portion of the developer carrier. If the inversion horizontal magnetic field component is made to act only by itself, the carrier chain of the developer can be surely slid and fallen in the developer retreat area on the developer carrier, and the developer can The behavior of can be easily promoted.

According to the invention of claim 9, the behavior promoting magnetic field component is caused to act on the upstream region or the downstream region of the effective developing region, so that the action region of the behavior promoting magnetic field component in the developer carrier is Even if the layer thickness deviates from the position closest to the latent image carrier and the layer thickness regulation accuracy of the developer is roughly rough, the spikes of the carrier chain of the developer that rise due to the vertical component of the behavior promoting magnetic field component The variation in the amount can be effectively absorbed.

According to the tenth aspect of the invention, among the magnetic roll magnetic pole portions for forming the horizontal magnetic field component,
Since the non-magnetic sleeve on the rotational direction side is arranged in the downstream area of the effective developing area, there is a concern that the carrier may be transferred to the latent image carrier side in the case of a developer using a carrier having a small particle diameter. However, the carrier transferred to the latent image carrier side can be adsorbed and collected to the developer carrier side by the magnetic pole part in the downstream area of the effective developing area, and the image quality deterioration due to the micro carryover can be effectively avoided by that much. be able to. Further, the magnetic poles arranged in the downstream area of the effective developing area can also seal the toner cloud generated in the effective developing area, and effectively prevent stains inside the machine.

According to the eleventh aspect of the invention, since the behavior promoting magnetic field component is made to act on a plurality of positions in the effective developing area, the developing performance can be further improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a developing method and an apparatus therefor according to the present invention.

FIG. 2 is an explanatory diagram showing a multicolor image forming apparatus of Embodiment 1 using the developing device according to the present invention.

FIG. 3 is an explanatory diagram illustrating a configuration of a second developing device according to the first exemplary embodiment.

FIG. 4 is an explanatory diagram showing a magnet roll configuration of a second developing device.

FIG. 5 is an explanatory diagram showing a radial component of a magnetic force distribution of a magnet roll.

FIG. 6 is an explanatory diagram showing a specific example of magnetic force distribution of a magnet roll.

FIG. 7 is an explanatory diagram showing the behavior of the developer in a static state of the developing roll.

FIG. 8 is an explanatory diagram showing a behavior of a developer in an effective developing region in a dynamic state of a developing roll.

FIG. 9 is an explanatory diagram showing the behavior of the developer before the effective developing area in the dynamic state of the developing roll.

FIG. 10: Surface portion of developing roller and 1 mm from the surface
It is explanatory drawing which shows the circumferential direction component of the magnetic force distribution of the part which left | separated.

FIG. 11 is an explanatory diagram showing the directions of magnetic lines of force around the magnet roll.

FIG. 12 is an explanatory diagram illustrating an image forming process of the multicolor image forming apparatus according to the first embodiment.

FIG. 13 is an explanatory diagram illustrating a magnet roll configuration of a second developing device according to a fourth exemplary embodiment.

14 is an explanatory diagram showing a magnetic force distribution of the magnet roll of FIG.

FIG. 15 is an explanatory diagram illustrating a magnet roll configuration of a second developing device according to a fifth exemplary embodiment.

16 is an explanatory diagram showing a magnetic force distribution of the magnet roll of FIG.

FIG. 17 is an explanatory diagram showing a magnet roll configuration of a second developing device according to a sixth embodiment.

FIG. 18 is an explanatory diagram showing a magnet roll configuration of a second developing device according to a seventh embodiment.

19 is an explanatory diagram showing radial components of magnetic force of the magnet roll of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Developer carrier, 2 ... Non-magnetic sleeve, 3 ... Magnet roll, 4 ... Latent image carrier, 5.6 ... Horizontal magnetic field component magnetic pole pair,
7, 8 ... Magnetic pole pairs for behavior promoting magnetic field component, G ... Two-component developer, C ... Magnetic carrier, T ... Toner, Z ... Latent image, VCB ...
AC bias, SH ... Horizontal magnetic field component, SF ... Behavior promoting magnetic field component, m ... Effective development area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Ken Inagawa, 2274 Hongo, Ebina, Ebina, Kanagawa Prefecture, Fuji Xerox Co., Ltd. ) Inventor Heiwa Koren, 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (12)

[Claims] 1. A non-rotatable rotatable sleeve (2) has a developer carrier (1) on which a magnet roll (3) is fixedly installed, and a toner (T) is provided on the developer carrier (1). ) And a magnetic carrier (C) are carried on the latent image carrier (4) by the two-component developer (G) on the developer carrier (1). In the developing method in which the latent image (Z) is developed in a non-contact state, in the effective developing area (m) of the developer carrier (1) facing the latent image carrier (4), the developer carrier is carried. With respect to the developer (G) on the body (1), a horizontal magnetic field component (S
H) acts, and in a part of the effective developing area (m) of the developer carrying member (1), the developer (G) on the developer carrying member (1) is locally rejected and The carrier (C) chain of the developer (G) slides at least along the circumferential direction of the developer carrying member (1) in the agent repelling region (K) to exert a local behavior promoting magnetic field component (SF). A developing method characterized by the above. 2. The behavior according to claim 1, wherein the behavior promoting magnetic field component magnetic pole pair (7, 8) comprises vertical and horizontal magnetic field components along the radial direction and the circumferential direction of the developer carrier (1). A developing method characterized by generating an accelerating magnetic field component (SF). 3. The developing method according to claim 1, wherein an AC bias (VCB) is applied between the surface of the latent image carrier (4) and the non-magnetic sleeve (2). 4. A rotatable nonmagnetic sleeve (2) has a developer carrier (1) on which a magnet roll (3) is fixedly installed, and a toner (T) is provided on the developer carrier (1). ) And a magnetic carrier (C) are carried on the latent image carrier (4) by the two-component developer (G) on the developer carrier (1). In the developing device adapted to develop the latent image (Z) in a non-contact state, the magnet roll (3) has an effective developing area (1) of the developer carrier (1) facing the latent image carrier (4). m) the developer (G) on the horizontal magnetic field component (S) along the circumferential direction of the developer carrier (1).
H) acting magnetic pole pair for horizontal magnetic field component of different polarity (5,
6) and this horizontal magnetic field component magnetic pole pair (5, 6), and is provided on the developer carrier (1) in a part of the effective developing area (m) of the developer carrier (1). Of the developer (G) is locally displaced, and the carrier (C) chain of the developer (G) slides at least along the circumferential direction of the developer carrier (1) in the developer displacement area (K). At least one pair of magnetic poles (7,
8) and a developing device. 5. The magnetic pole pair (7, 8) for behavior promoting magnetic field components of different polarities according to claim 4, wherein the polarities of vertical magnetic field components by the magnetic pole pairs (5, 6) for horizontal magnetic field component of different polarities. It affects the vicinity of the reversal portion, secures a local developer repelling region (K) on the developer carrier (1) of the polarity reversal portion, and is perpendicular to the horizontal magnetic field component magnetic pole pair (5, 6). A developing device characterized in that a behavior promoting magnetic field component (SF) containing a vertical magnetic field component smaller than the peak value of the magnetic field component is applied. 6. The behavior promoting magnetic field component (7, 8) according to claim 4, wherein the behavior promoting magnetic field component (7, 8) includes a vertical magnetic field component along a radial direction of the developer carrier (1). And a peak value of the vertical magnetic field component is set so that the developer (G) is not released from the developer carrier (1). 7. The magnetic pole pair for behavior promoting magnetic field component (7, 8) according to claim 4, wherein the magnetic pole pair (5, 6) for horizontal magnetic field component extends along the circumferential direction of the developer carrying member (1). ) Is a device for generating a behavior promoting magnetic field component (SF) including an inverted horizontal magnetic field component in the opposite direction to the horizontal magnetic field component (SH) by the above). 8. The magnetic pole pair for behavior promoting magnetic field component (7, 8) according to claim 4, wherein the magnetic pole pair (5, 6) for horizontal magnetic field component extends along the circumferential direction of the developer carrying member (1). ), A behavior-promoting magnetic field component (SF) containing a reverse horizontal magnetic field component in the opposite direction to the horizontal magnetic field component (SH) is generated, and the reverse horizontal magnetic field component is applied only to the surface portion of the developer carrier (1). A developing device characterized by being made to act. 9. The magnetic pole pair (7, 8) for behavior promoting magnetic field component according to claim 4, wherein the magnetic pole pair (7, 8) is arranged in the vicinity of an upstream region or a downstream region of the effective developing area (m) of the developer carrier (1). A developing device characterized in that a behavior promoting magnetic field component (SF) is caused to act on an upstream region or a downstream region of the effective developing region (m). 10. The non-magnetic sleeve (2) according to claim 4, wherein the magnetic pole pair (5, 6) for the horizontal magnetic field component.
The developing device, wherein the magnetic pole (6) on the rotation direction side is disposed near the downstream region of the effective developing region (m). 11. The magnetic recording medium according to claim 4, wherein a plurality of pairs of magnetic poles for behavior promoting magnetic field components (7, 8) are arranged and arranged at a plurality of positions in an effective developing area (m) of the developer carrier (1). A developing device characterized in that a behavior promoting magnetic field component (SF) is applied. 12. A plurality of latent images (Z) are sequentially formed on a latent image carrier (4), and each formed latent image (Z) is sequentially developed with toner (T) of a corresponding color system. After that, in a multicolor image forming apparatus in which toner images of a plurality of color systems formed on the latent image carrier (4) are collectively transferred to a transfer medium, as a developing device for developing at least the second and subsequent latent images. A multicolor image forming apparatus using the one according to claim 4.