JPH1026861A - Multi-color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent toner from scattering and falling from a developing device on the upstream side, and to prevent toner from staining and entering a developing device, an exposure device, a potential sensor, and an electrifying device, etc., on the downstream, side. SOLUTION: This device is provided with a developing sleeve 32a on which plural kinds of areas for coping with the toner falling from the developing sleeve 32a are provided on a toner thin layer area on a side close to both ends part with respect to the central part of a toner applying area in the shaft direction of the sleeve 32a of the developing device 4 on the upstream side, ducts 71 and 72 making air flow guiding falling toner flow in/out, and a toner collecting member 61 collecting the falling toner. The surface roughness of the sleeve 32a becomes small stepwise toward both ends, the speed of the air flow is changed in accordance with the surface roughness, and an interval between the member 61 and a photoreceptor drum 1 is similarly changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type multicolor image forming apparatus such as a color copying machine or a color printer.

[0002]

2. Description of the Related Art In recent years, an electrophotographic or electrostatic recording type image forming apparatus which forms a multicolor image using a plurality of colors has been desired.

FIG. 1 shows such a multicolor image forming apparatus.
The image forming process of the two-color image forming apparatus shown in FIG. FIG. 17 shows the surface potential of the photosensitive drum in each step of the two-color image formation.

In FIG. 16, a two-color image forming apparatus has, for example, a photosensitive drum 1 as an electrostatic latent image carrier, and the photosensitive drum 1 has a photoconductive layer such as OPC on the surface thereof, and an arrow R1.
Rotated in the direction. The surface of the photosensitive drum 1 is uniformly charged to, for example, -600 V by the first primary charger 2 (FIG. 17A). Next, a first image exposure 3 based on the first image signal is performed. The first image exposure 3 emits a laser beam modulated by the first image signal from the first semiconductor laser 20a, polarizes the laser beam with the rotary polygon mirror 28 rotated by the motor 55, and converts the polarized laser beam. The light is reflected by the turning mirror 17 via the coupling lens 56 and raster-scanned by the photosensitive drum 1.

The first image exposure 3 causes the photosensitive drum 1
The surface potential of the upper exposed portion is attenuated to, for example, -100 V, and a first latent image corresponding to the first image signal is formed on the photosensitive drum 1 (FIG. 17B).

Next, the first latent image is developed by a first developing device 4 which is a red two-component developing device, and is visualized as a red toner image. The first developing device 4 uses, for development, a two-component developer in which a negatively charged red toner and a magnetic carrier such as ferrite are mixed. At the time of development, the first developing device 4 applies, for example, an AC voltage of 1600 Hz and 1800 Vpp to -500 V
Then, a developing bias on which the DC voltage is superimposed is applied to reversely develop the first latent image (FIG. 17C). The potential (first toner image potential) on the surface of the obtained first toner image rises by about -100 V to about -200 V with respect to the photosensitive drum surface potential of the first image portion of -100 V due to the toner charge.

Next, the photosensitive drum 1 is uniformly charged again by the second primary charger (recharger) 5 to increase the first toner image potential. At this time, the non-image portion potential also slightly increases. The potential of the non-image portion after recharging is -650 V, and the potential of the first image portion is about -600 V (FIG. 17D). The second image exposure 6 is performed on the photosensitive drum 1, the surface potential of the exposed portion on the photosensitive drum 1 is attenuated to, for example, -100 V, and a second latent image is formed according to the second image signal (FIG. 17 (E)). The second image exposure 6 includes the second semiconductor laser 2
0b, a laser beam modulated by the second image signal is emitted, polarized by the rotary polygon mirror 28, and the polarized laser beam is passed through the coupling lens 56 to the photosensitive drum 1.
This is the result of raster scanning above.

Thereafter, the second developing device 7 uses a one-component developer composed of, for example, black toner, which is negatively charged, for example, to an AC voltage of 1600 Hz, 1300 Vpp and -500 V.
Then, a developing bias in which the DC voltage is superimposed is applied to reversely develop the second latent image (FIG. 17F). Thus, a two-color image of a red toner image and a black toner image is formed on the photosensitive drum 1.

The above is the image forming process called negative recharge. Another method for forming a two-color image on a photosensitive drum is a negative-positive process (Japanese Patent Laid-Open No. 55-137).
No. 538) and a three-value process (JP-A-52-81855).
No.).

The two-color image formed on the photosensitive drum 1 is subjected to a pre-transfer process using a charger 41 as necessary (usually, a corona is applied by DC or AC, or a combination of the corona is applied and the light is applied. After the charge amounts of the two-color toner images are prepared so as to be easily transferred, the toner images are transferred onto the transfer material P supplied to the photosensitive drum 1 by the transfer charger 8. Thereafter, the transfer material P is sent to the fixing device 12 to fix the toner image, thereby obtaining a two-color image of red and black.

On the other hand, the photosensitive drum 1 removes toner remaining on the photosensitive drum 1 by a cleaning device 13 to prepare for the next image formation.

A developing device using a non-magnetic one-component developer is frequently used in copiers and printers because of its simplicity and low cost.

The developing device is configured such that a non-magnetic toner, which is a developer contained in a developing container, is supplied onto a rotating developing roller to form a thin toner layer, and the toner layer faces the photosensitive member. After developing the electrostatic latent image by transporting it to the developing area, the toner remaining on the developing roller is collected again in the developing container. A seal member made of a soft material such as a sponge is attached to the collecting portion for collecting the residual toner to prevent the toner in the developing container from flowing out and to collect the residual toner without spilling out of the developing container. I have.

Such a developing device is used as a first developing device for visualizing with a developer containing a chromatic dye.

[0015]

However, in the above-mentioned prior art, since the first developing device and the second developing device use developers of different dyes, the second developing device uses the developing device from the first developing device. The mixing of toner due to scattering or leakage of the agent greatly affects the development color.

In order to prevent the toner from being scattered due to scattering, a shutter member which can be opened and closed is provided on a toner carrying and conveying sleeve of the second developing device, or the entire developing device is moved away from the photosensitive drum. It has been proposed to provide such a mechanism, or it has already been commercialized. However, these mechanisms are limited to the case of using non-simultaneous developing devices of various colors. By providing such a mechanism, the size and cost of the apparatus are increased, and the reliability is reduced due to the complexity of the mechanical mechanism. In addition, there was a possibility of occurrence of troubles such as shock and noise during operation.

In particular, when a non-magnetic toner, which is a latent image visualizing particle of a drum, is used as a developer of the first developing device, the scattered toner and the like are deposited on a certain portion. Is difficult to restrain electrostatically, and because it is non-magnetic, it is impossible to restrain it magnetically. In other words, if the amount of scattered and deposited toner exceeds the amount of toner that can be deposited at the portion where a large amount of non-magnetic toner is deposited, it falls downstream (downward) in the direction of gravity, and a charger and the like disposed below , And fall on the second developing device.

Obviously, the greater the number of components disposed below the first developing unit, the greater the obstacle. For example, when charging is performed again on the toner developed on the drum, recharging is performed. Toner on the inner surface of the shield case and dirt on the corona wire for
Unevenness in potential and unevenness in distribution of the amount of toner charge occur, causing unevenness in density in an image.

Further, even when an exposure light path including image information is formed, if there is a toner deposit in the light path, the light path is blocked, and unevenness such as streaks is generated on an image.

Further, when a potential detector or the like for detecting the drum surface potential is provided, the accumulation of toner on the potential detector lowers the detection accuracy and corrects the normal drum surface potential. An obstacle arises in that the image cannot be formed by the control and an optimum output image cannot be obtained.

As the developing method using the non-magnetic toner described above, a typical one is a two-component magnetic brush using a magnetic particle carrier and a non-magnetic toner as a developer.
There are a developing method and a non-magnetic one-component developing method using only non-magnetic toner. In both cases, the deposited toner after the toner is scattered fouls the inside of the apparatus and causes an image failure. However, the two-component system can electrostatically restrain the non-magnetic toner on the surface of the magnetic particles, and the magnetic particles Since the upper portion can be magnetically constrained, the amount of scattered toner is relatively small, and the toner is re-constrained by the carrier even on the upper surface of the lower cover portion of the developing container at the end of the sleeve where the scattered and leaking toner tends to accumulate. To prevent excessive deposition
A large amount of toner does not drop from the developing device, and a small amount of toner can be dropped under specific conditions.

On the other hand, in the non-magnetic one-component developing system, after the powder is deposited on the sleeve or any portion near the outside of the developing container due to scattering or leakage, the force for electrostatically restraining the developing material is not sufficient. Weak, difficult to re-restrain,
If the sedimentation continues, the sedimentation capacity will eventually be exceeded,
It will fall to the bottom.

If toner scattering continues, excessive accumulation and toner drop will be repeated intermittently, causing a large amount of toner scattering and dropping to cause contamination in the apparatus and image failure. Of these, particularly, the portion where the toner scatters and accumulates continuously is large and it is difficult to cope with the scatter, and a description will be given with reference to the developing device shown in FIG.

In FIG. 18, the developing device is provided with a developing sleeve (material:
A non-magnetic toner T is accommodated in the developing container 35. The toner T comes into contact with the developing sleeve 32 and
The roller 33 is supplied onto the developing sleeve 32 by a supply roller (material: silicon sponge or the like) 34 which rotates in the same direction as that of the developing roller 32, and is fixed by a blade 33 (material: silicon rubber, urethane rubber or the like) having elasticity and abutting on the developing sleeve 32 The toner is applied on the developing sleeve while being regulated by the toner layer thickness.

The toner is triboelectrically charged when rubbed onto the developing sleeve 32 by the blade 33, and is an electrostatic attraction acting between the developing sleeve 32 and the toner. The toner applied on the developing sleeve 32 is conveyed to a developing area facing the photosensitive drum with the rotation of the developing sleeve 32, and adheres to an electrostatic latent image formed on the photosensitive drum 1 in advance to form a visible image. . The toner remaining on the developing sleeve 32 without adhering to the latent image is conveyed as it is and collected from the collecting section R into the developing container 35.

FIG. 18 shows a conventional configuration in the vicinity of the toner collecting section R in the image forming area of the developing device.

The toner T in the developing container 35 is supplied to the supply roller 3
4, the toner is supplied onto the developing sleeve 32 along the arrow A, is applied to the developing sleeve 32 by the blade 33, and is sent to the developing area. The toner remaining on the developing sleeve 32 after the developing process is transported to the collecting section R. A sealing member 36a made of a flexible elastic material such as a sponge having substantially the same length as the developing sleeve 32 is attached on the container wall 36b near the collecting section along the rotation axis direction of the developing sleeve 32. A thin sheet member 36c made of PET or the like is attached to the lower portion of the container wall 36b over the same length as the developing sleeve 32, and its free end is in contact with the contact portion between the developing sleeve 32 and the seal member 36a. It is sandwiched. The sheet member 36c has the elasticity so that the developing sleeve 3
The two sides are in contact with very light pressure.

The seal member 36a prevents the toner in the developing container 35 from leaking to the outside along the arrow C, and the sealing member 36a and the developing sleeve 2 which lightly contact the residual toner on the developing sleeve 32. The residual toner can be satisfactorily collected in the developing container 35 by being conveyed in the direction of arrow B while rubbing through the gap.

However, when the developing device 4 is used for a long time, the toner in the developing container 35 enters the inside of the seal member 36a, and the sheet member 36c is thermally deformed and hardened by the rubbing heat with the developing sleeve 32. Accordingly, the pressing of the seal member 36 against the sheet member 36c is increased, and the sheet member 36c is pressed strongly against the developing sleeve 32. Thus, the residual toner is dammed in the sheet member 36c portion of the residual toner T ₁ is so spill in the direction of arrow D is not recovered. Spilling the toner T ₁ has become a cause of image contamination by contaminating the machine and deposited on the malfunction or the transfer material of the other parts.

At both ends of the developing sleeve, shielding members (not shown) made of an elastic member (sponge or felt) are provided so as to prevent toner from leaking outside at the inner surface of the side wall of the developing container. At this end, the toner which has been conveyed by the rotation of the developing sleeve or the stirring rod flows and is pressed, so that the toner particles tend to leak out from a small gap. Fall downward showing the toner T ₁ scattered from leaking toner and the sleeve by the sleeve rotation force and the developing sleeve applied bias of the WAS Kazutsu exceeds the capacity of the collection deposited deposited its ends by an arrow D, the charge The device, the optical path portion, the potential sensor, the developing device installed below, and the like are soiled, causing potential unevenness, density unevenness and color unevenness due to mixing of different color toners.

Accordingly, an object of the present invention is to prevent toner scattering and toner falling from an upstream or preceding developing device, and to prevent toner contamination of a downstream or subsequent charging device, exposure device, potential sensor, etc. An object of the present invention is to provide a multi-color image forming apparatus capable of preventing mixing.

[0032]

The above object is achieved by a multicolor image forming apparatus according to the present invention. In summary, the present invention provides a first image information potential distribution forming means for forming a latent image corresponding to a first color on an electrostatic latent image carrier, and the first image information potential distribution forming means. First developing means for visualizing the formed latent image with a developer having a first dye,
The above process is performed a plurality of times according to the number of color types, or in a multicolor image forming apparatus having a plurality of the units, an axial direction of a developer carrying conveyance member of a developing unit that performs upstream or preceding development. In the developer thin layer area close to both ends with respect to the center of the developer application area, a plurality of types of handling areas are provided in the axial direction to deal with the developer that easily falls off from the developer carrying member. A multicolor image forming apparatus comprising: a developer carrying and conveying unit; a developer guiding unit; and a developer collecting unit.

There is provided a means for dealing with dropped developer for dealing with the developer which has fallen off from the developer carrying / transporting member, and the means for dealing with dropped developer correspond to an area where the developer carrying / transporting member can easily fall off. Are preferably different. It is preferable that the developer handling area of the developer carrying / transporting member includes a plurality of areas where the amount of developer applied per unit area varies in the axial direction of the developer carrying / transporting member.

It is preferable that the developer application amount per unit area on the developer carrying and conveying member decreases stepwise from the axial center of the developer carrying and conveying member toward both ends. The developer-carrying / transporting member has a surface roughness that decreases stepwise from its axial center toward both ends, and has the minimum surface roughness at both end positions of the developer thin-layer coating regulating member. Is preferred. The visualized particles as a developer are preferably non-magnetic agents.

In the developer thin layer application area near the both ends with respect to the center of the developer application area in the axial direction of the developer carrying member, the surface roughness in the axial direction of the developer carrying member is reduced in the axial direction. Relatively coarse, roughly equivalent to that of the image corresponding area,
The developer guiding means forms a relatively strong air flow from the downstream direction toward the developer carrying member on the downstream side in the direction of gravity corresponding to the image corresponding area, and The developer carrying-off member is guided in a direction away from the carrier, and the surface roughness of the developer carrying member is smaller than that of the image corresponding region in the developer thin layer coating area relatively near both ends in the axial direction. The developer guide means is smaller and forms a relatively weak air flow downstream from the downstream direction toward the developer carrying member in the direction of gravity corresponding to the area, and It is preferable that the means has a different distance from the electrostatic latent image carrier in accordance with a plurality of levels of surface roughness of the developer carrying member. The developing means preferably includes a non-magnetic one-component developer and a flexible developer thin-layer coating regulating member.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a multicolor image forming apparatus according to the present invention will be described in more detail with reference to the drawings. Note that members having the same functions as those described above are denoted by the same reference numerals.

Embodiment 1 FIG. 1 is a schematic structural view showing Embodiment 1 of a two-color image forming apparatus according to the present invention. The photosensitive drum 1 serving as an electrostatic latent image carrier has a photoconductive layer provided on a cylindrical conductive substrate.
It is rotatably supported in the direction of arrow R1 in the figure. Around the photosensitive drum 1, a first scorotron charger 2 for uniformly charging the surface of the photosensitive drum 1 in order along the rotation direction, a document is read, and one color plane image is separated into two colors. A first exposure device for exposing the photosensitive drum 1 with a laser beam 3 based on a first image signal proportional to the density of the photosensitive drum 1 to form a first electrostatic latent image, and attaching toner to the first electrostatic latent image A first developing device 4 for forming a first toner image is arranged.

Further, a second scorotron charger 5 for charging the photosensitive drum 1 after carrying the first toner image, and a laser beam 6 based on a second image signal proportional to the density of the other color image separated. A second exposure device which forms a second electrostatic latent image by forming a second toner image by adhering toner to the second electrostatic latent image, and a second exposure device which forms a second toner image by adhering toner to the second electrostatic latent image. Transfer charger 8 for transferring the overlaid color image onto a transfer sheet P as a transfer material, the transfer sheet P on which the overlaid image is transferred
, A cleaning device 13 for removing the residual toner on the photosensitive drum 1 after transferring the color superimposed image, and a pre-exposure (lamp) for removing the residual charge on the photosensitive drum 1 30 are arranged.

The transfer paper P on which the color superimposed image has been transferred is
After being separated from the photosensitive drum 1, the sheet is conveyed to a fixing device 12, where a toner image on the surface is fixed, a desired print image is formed, and the image is discharged outside the image forming apparatus main body.

The image scanner section 18 scans the original 15 placed on the original glass table 14 by scanning with an illumination lamp 16 and converts image information into an electric signal by a photoelectric conversion element 19. The reflected light from the original 15 scanned by the mirror 16 is reflected by mirrors 17a and 1a.
7b, 17c, led by lens 17d,
Photoelectric conversion element 1 with built-in green and blue filters
9 is formed.

The electrical signals output by the photoelectric conversion element 19 for each of the red, green, and blue components are A / A
After being digitized by the D converter 21, it is sent to a signal processing unit 22 as a color separation unit, and is converted into an image signal of 256 gradations in proportion to the image density of each of the red and black components.

The red image signal (first image signal) and the black image signal (second image signal) are sent to a laser driver 24 as a signal generator, and a laser is generated according to the red and black image signals. Modulate the luminescence of 20.
The laser beam 3 modulated according to the red signal writes a first electrostatic latent image on the photosensitive drum 1 via the polygon mirror 28 and the mirror 17e as first image information, and the laser beam 6 modulated according to the black signal. Writes a second electrostatic latent image on the photosensitive drum 1 via the polygon mirror 28 and the mirrors 17f and 17g as second image information.

FIG. 2 shows the overall structure of the first developing device 4 of this embodiment. A developing sleeve (material: metal such as stainless steel or aluminum) 32 is disposed facing the photosensitive drum 1 with a predetermined gap from the photosensitive drum 1, and a non-magnetic toner T is contained in a developing container 35. The toner T is supplied onto the developing sleeve 2 by a supply roller (material: silicon sponge or the like) 34 which comes into contact with the developing sleeve 32 and rotates in the same direction as the developing sleeve 32, and has a blade (having elasticity and coming into contact with the developing sleeve 32). (Material: silicon rubber, urethane rubber, etc.) 33 is applied to the developing sleeve 32 while being regulated to a predetermined toner layer thickness.

The toner T is frictionally charged when being rubbed on the developing sleeve 32 by the blade 33, and is held on the developing sleeve 32 by a mirroring force, which is an electrostatic attraction acting between the developing sleeve 32 and the toner. The toner applied on the developing sleeve 32 is conveyed to the developing area facing the photosensitive drum 1 with the rotation of the developing sleeve 32, adheres to the electrostatic latent image formed on the photosensitive drum 1 in advance, and forms a visible image. I do. The toner remaining on the developing sleeve without adhering to the latent image is conveyed as it is and is collected in the developing container 35 in the collecting section R.

When the toner in the developing container 35 is consumed and becomes small, the toner is replenished from a toner storage unit (not shown) along the arrow F, and is conveyed to the supply roller 34 by the toner conveying members 37 and 38.

Next, the structure of the first developing device 4 will be further described with reference to FIGS.

First, in FIG. 3, the first developing device 4 includes:
The developing sleeve 3 is brought into contact with the developing sleeve 32 from below.
2. An elastic seal roller 39 rotating in a direction opposite to the direction 2.
Is provided. The peripheral speed Vd of the seal roller 39 is set to be equal to or higher than the peripheral speed Vs of the developing sleeve 32.
And the residual toner can be collected in the developing container without spilling. The collected toner is removed from above the seal roller 39 by a scraper 39a in contact with the seal roller 39, and is conveyed along the arrow E into the developing container 35.

According to the above configuration, the toner in the developing container 35 is not blocked by the scraper 39a and the seal roller 39 and does not leak to the outside. Also, the seal roller 39
At the contact portion with the developing sleeve 32
2 rotates in the direction of transporting the residual toner on the inside of the container, the residual toner can pass through the contact portion and be collected in the developing container 35 without being blocked by the seal roller 39. Further, in the present configuration, even if the developing device is used for a long time, the seal roller 39 is constantly rotated and the residual toner is taken into the developing container 35, so that the toner does not spill.

The seal roller 39 is a rubber roller made of silicon rubber, urethane rubber, fluorine rubber, or the like, or
The rubber roller is made of an elastic roller coated with a fluororesin, so that the toner does not intrude even when used for a long time. The scraper 39a uses a urethane rubber blade or a PET sheet.

FIG. 4 is a sectional view showing a toner shielding member at the end of the sleeve of the first developing device. Smoothing processing of the area outside the thin toner layer coating part (Rz less than 1.8 μm)
A toner shielding member 45 made of an elastic member (such as a sponge or a felt member) is provided on the sleeve surface thus formed. The toner shielding member 45 is in pressure contact with the peripheral surface of the sleeve 32 and the peripheral surface of the seal roller 39a from the developing container 35 side. Thereby, leakage of toner from the end of the sleeve 32 is suppressed.

However, the G1 region, that is, the blade 3
3, the free end area and the G2 area, ie, the scraper 39
In the front end region a, even if any elastic member 45 is used, the toner having an average particle diameter of about 3 to 15 μm may leak out little by little, accumulate, and fall from the developing device when the accumulation capacity exceeds the allowable capacity. is there. In particular, the frequency of this drop is high in the toner not containing the toner magnetic substance and in the non-magnetic one-component developing system.

The elastic blade 33 of the developing device 4 shown in FIG.
2 was brought into counter contact with a linear pressure of 15 to 20 g / cm. As the toner of the developing device 4, a styrene acrylic nonmagnetic toner colored with a pigment and having an average particle diameter of 8 μm was used, and silica was externally added to impart fluidity.

The developing sleeve has a surface roughness Rz of 1.8 to 1.
Glass beads of # 400 abrasive grains or arundum alumina particles which had been blasted to about 0 μm were used.

At this time, the amount of triboelectric charge of the toner is about 25 to
30 μC / g, application amount is about 0.4-0.8 mg / cm ²
Met. This charge amount is 15 to 2 of the magnetic toner charge amount.
Although it is higher than 0 μC to 20 μC / g, there is no problem because the magnetic toner is attracted to the developing sleeve by the magnetic force, but the non-magnetic toner used in the experiment adheres to the developing sleeve only by the reflection force. Therefore, unless the charge amount is increased to increase the mirroring power, the photosensitive drum easily flies and fogging occurs.

The above-mentioned developing device 4 is set so that the gap between the developing sleeve 32 and the photosensitive drum 1 is about 280 μm with respect to the photosensitive drum 1.
And the developing sleeve 32 was rotated in the same direction as the photosensitive drum 1 at a peripheral speed of about 1.5 times.

FIG. 5 which best illustrates the features of the present invention will be described below.
Will be described. The figure mainly shows the image area of the photosensitive drum, and mainly describes the surface treatment of the upstream, upper, or preceding developing sleeve, the air flow opening, and the longitudinal positional relationship of the toner particle collecting member. This is shown in relation to a developing device position setting member, a downstream, lower or subsequent developing sleeve, a cleaning member, an exposure area, a charging area, a potential detection area, and the like of the photoconductor.

First, the state of stepwise surface treatment formation in the longitudinal direction of the upstream, upper, or preceding developing sleeve will be described.

The upper, upstream, or preceding developing sleeves are located on both outer sides (closer to both ends) of the image area I in the areas L, M,
N, and these areas L, M, and N have their surface roughness (Rz) gradually increased in the order of the areas L, M, and N from the surface roughness (Rz) of the area corresponding to the image area I. It is configured to be smaller.

That is, the relationship of the roughness (Rz) corresponding to each region is set as I ≧ L>M> N. This developing sleeve is obtained by performing the above-described blast processing while performing masking in each of the regions L, M, and N, and has a roughness (Rz) of I
When the area is 3 to 5 μm, the L area is 3 to 2 μm,
The area is set to less than 2 μm and 1 μm or more, and the N area is set to 1 μm or less, and the surface treatment is performed.

The amount of toner applied and the amount of charge on the developing sleeve in each area are 0.5 to 1.
0 mg / cm ² , 25 to 26 μC / g, 0.4 in L region
^{~0.5mg / cm 2, 25~27μC / g} , in M region, at 0.2 mg / cm ² or more and less than 0.4 mg / cm ^2, greater than 27 28μC / g or less, 0.2 N region
mg / cm ² , larger than 28 μC / g.

As described above, the surface of the developing sleeve is subjected to the surface treatment, and the corresponding toner coating characteristics are obtained.
By gradually decreasing the amount of toner that reaches the portions D ₁ and D ₂ near the toner shielding member 45 where toner leakage is most likely to occur, toner leakage due to toner stagnation from the inner edge of the toner shielding member 45 is prevented. be able to. The areas S corresponding to both ends of the developing sleeve are almost mirror-finished, and the toner shielding member is rubbed in contact. The relationship between the toner application amount and toner leakage will be described later.

Next, the air flow below the first developing device will be described. First, with reference to FIG. 2 again, the arrangement of the duct and the like for sucking the dropped toner will be described. As shown in FIG. 2, below the first developing device 4, an air flow outlet 0 ₀ and a suction port O _i facing the photosensitive drum surface.
Outflow duct 71 and suction duct 72 each having
However, the suction duct 72 is arranged so as to overlap the outflow duct 71, and further, a blowing fan 71 a and a suction fan 72 a are provided behind the outflow duct 71 and the suction duct 72, respectively. Have been.

[0063] By the action of the blowing fan 71a, the air flow A flowing out of the outflow duct 71 as the outlet 0 _0
m1 collides with the photosensitive drum surface, and its direction is changed to the intake air flow A _m2
Change direction. This, by the suction fan 72a and the suction duct 72, there is due to suction is being performed, the toner T _m scattered is directed along the intake air flow A _{m @ 2,} through suction the suction opening O _i And is carried to a collection member (not shown) such as a dust collection filter.

[0064] opening width is the outlet O _o and inlet O _i of the outflow duct 71 and suction duct 72, as shown in FIG. 5, the region on the developing sleeve L, M, corresponding to the N L
_a , M _a , and N _a, and the relationship between the opening widths is
I _a ≦ L _a <there is a M _a <N _a.

[0065] Naturally, the narrower is the flow velocity of the air flow is larger aperture width, wherein the flow rate of the I _a region on the photosensitive drum peripheral surface 1.2 m / s (sec), is L _a region 1.0 1.2m /
s, M _a region 0.8~1.0m / s, N _a region is 0.
It is set to about 6 to 0.8 m / s.

In the image area I shown in FIG. 5, the toner is set so that the flow velocity is increased so as not to adversely affect the image area of the transfer-related members of the downstream installation elements and the rechargeable member. As the position approaches the shielding member and the areas D ₁ and D ₂ , the flow velocity is reduced to prevent toner contamination in the apparatus due to the turbulent flow of the scattered toner in the area where the toner leakage is relatively large.

Next, the toner particle collecting member will be described. As shown in FIG. 2, the toner particle collecting member 61 is provided below the airflow forming members, that is, the ducts 71 and 72, as a member for coping with a large amount of leakage of toner.

As shown in FIG. 5, the gap I with the drum corresponds to the areas I, L, M, and N of the developing sleeve.
By setting _g , L _g , M _g , and N _{g such} that _Ig ≧ L _g > M _g > N _g , in the event that toner leakage should occur, the D ₁ and D ₂ regions with large leakage amounts should be used. It is configured to receive the toner leaking and prevent toner contamination of downstream element members.

As an example, I _g : 2.0 mm, L _g :
_{1.8mm, M g: 1.4mm, N} g: If set to 1.0mm or the like, a high collection efficiency of leak toner D _1, D ₂ parts.

It is most effective as the toner receiver that the tip of the toner collecting member 61 enters the position overlapping the downstream side of the drum in the direction of gravity. The toner receiver (toner collecting member) may be located upstream of the airflow forming member, and may directly receive the toner dropped from the developing device.

FIGS. 6 to 6 show that the developing device constructed as described above is effective in preventing toner scattering.
A description will be given based on the phenomenon data shown in the graph of FIG.

FIG. 6 is a graph showing the relationship between the amount of applied toner on the developing sleeve and the amount of toner falling off and scattered. As shown in FIG. 11, the properties and phenomena of the scattered toner are different in the image areas I, L and M with respect to the area N. In the area N where the toner shielding member is installed, most of the scattered A scattering phenomenon occurs in which the toner drops, and conversely, in the other image areas I and the areas L and M, most of the scattering is caused by powder cloud-like floating toner.

For this reason, as shown in FIG. 6, the scattering amount differs for each region. However, the tendency that the scattering amount increases as the toner application amount increases is the same. Also, image area I,
When the application amount is 0.6 mg / cm ² or less in the regions L and M,
It can be seen that the scattering in the form of a powder ground is reduced, and in the area N, the scattering is drastically reduced at a toner application amount of 0.2 to 0.3 mg / cm ² , but this reaches the toner shielding member and is blocked. This is probably because the amount of toner scraped or scraped becomes extremely small.

Further, the toner application amount is 0.1 to 0.3 mg.
/ Cm ² is difficult to suppress, and the characteristics tend to fluctuate due to environmental fluctuations and the like. If the toner coating amount as shown in FIG. 6 has been set to S _n as an example, a small amount side in low humidity environment, varies a large amount side in a high humidity environment, it varies with a width of about [Delta] S _n. That is, in the region N, _Sn is the toner application amount of 0.2.
It is important to keep a value of about mg / cm ² at the center.

As shown in FIG. 7, the sleeve surface roughness (R
In z), the toner application amount M / S can be almost set to a desired amount, but the toner application amount in the image area I is 0.5 to
When 1.0 mg / cm ² is set to be rapidly reduced outside the image area, as shown in FIG. 8, powder cloud-like scattering increases at the boundary between adjacent application amount differences, and the adjacent toner application amount is It is understood that the difference needs to be changed stepwise or continuously with the difference being about 0.1 to 0.2 mg / cm ² . However, it is difficult to manufacture the sleeve surface by continuously changing the surface roughness Rz to set the sleeve surface roughness. Therefore, it is difficult to form the sleeve surface roughness (Rz) step by step. Becomes effective. In other words, a sleeve that effectively divides the area from the image area I to the area N where the toner shielding member abuts into several steps to reduce the surface roughness Rz and the amount of applied toner is effective.

Next, FIG. 9 will be described. Here, a toner collecting receiver having a uniform longitudinal shape, that is, a toner collecting member is installed at the lower part of the developing device, and scattering when the distance (collecting member gap) between the photosensitive drum and the tip of the toner receiving at that time is changed. It shows the collection and collection rate of toner. According to this graph, it can be seen that there is a large difference in the relationship between the collection gap and the toner collection rate due to the scattering of the bulk toner and the powder cloud-like toner.

Here, according to FIG. 11, the drop of the massive toner is concentrated between the sleeve areas N and S, and the image area I
It can be seen that the L and M areas are almost powder cloud-like toner scattering. That is, the N and S regions of the sleeve are
It is effective for toner recovery to reduce the gap of the toner collecting portion and increase the gap in the image areas I, L, and M areas.

However, the size of the gap needs to be determined in consideration of the relationship between the sleeve region shown in FIGS. 6 and 7 and its surface roughness. That is, when the surface property of the sleeve is changed stepwise in each region, setting the gap amount of the collecting member in each region in accordance with the step is the best method for improving the amount of collected toner. However, since the toner scattered to the toner collecting member is diffused to some extent and falls, it is not necessary that the toner collecting member always form a stepwise shape at the longitudinal position completely at the same position as the sleeve region section. However, even if the trapping member gap is formed continuously, the same effect as described above can be obtained.

Next, FIG. 10 shows that an air flow is formed under development.
FIG. 6 shows a relationship between the total amount of toner collected by a filter on the downstream side of the air flow by the toner collecting member under a certain condition and the air flow velocity. This also shows that the collection performance differs between the bulk toner and the powder cloud toner.
In both cases, the collection rate is improved up to a flow rate of 0.75 m / sec. However, if the flow rate is larger than that, the lumpy toner is scattered around by the strong wind, so that the toner cannot be collected efficiently. The trapping rate will drop sharply.

In other words, as a method for effectively collecting and collecting both the powder cloud-like scatter and the mass toner fall, as shown in FIG. 11, the priority is given to the collection of the powder cloud-like scatter in the image area I. In addition, the image area I forms a relatively strong air flow of about 1.0 to 1.5 m / sec in the sense that the collection efficiency of the lump toner at the end of the sleeve is secured to some extent. As the distance approaches, the flow velocity is reduced stepwise in accordance with the area where the surface treatment of the sleeve is different. 6 ~
It can be seen that a configuration in which an air flow of about 0.9 m / sec is supplied has the highest scattering toner collection ability.

As described above, as shown in the graphs of FIGS. 6 to 11, the longitudinal lengths of the upper, upstream, and preceding developing sleeves and the developer application areas are those of the lower, downstream, and subsequent developing sleeves. When the toner particles are larger than each other, even if toner scattering occurs, it is possible to prevent toner from being mixed into the second development area.

The above experimental results are experimental data when the peripheral surface moving speed of the photosensitive drum is 150 mm / s to 300 mm / s, and the peripheral speed of the developing sleeve is 150 mm / s to 450 mm / s. Although the absolute values of the data are different, it has been confirmed that they have the same tendency as the present data, and it goes without saying that the same technical idea can be applied.

The same tendency can be applied to a two-component developing system using a non-magnetic toner and a magnetic carrier, and the present concept can be applied.

In FIG. 1, the first latent image was developed by the first developing device 4 and visualized as a red toner image. Next, the photosensitive drum 1 is charged again by the recharger 5, and the first image portion (the portion to which the red toner is attached) is about -600V, and the non-image portion is about -65V.
It became 0V. Next, a second image exposure 6 is performed on the photosensitive drum 1 to form a second latent image.
To form a black toner image to form a two-color image of red and black.

Here, the second developing device 7 used in this embodiment will be further described.

As shown in FIG. 12, the second developing device 7 contains a magnetic toner (one-component magnetic developer) therein, and the toner is stirred by stirring members 71a and 71b.
It is configured to supply to the developing sleeve 72.

The toner supplied to the developing sleeve 72 is
The developing sleeve 72 is conveyed in the same direction by the rotation of the developing sleeve 72 in the direction of arrow B and the magnetic force of the magnet roller 73 arranged non-rotatably inside the developing sleeve 72. During the conveyance, the toner is regulated by the regulating member 74 and applied in a thin layer on the developing sleeve 72, and then reaches the developing area 75 in the vicinity where the developing sleeve 72 is closest to the photosensitive drum 1.

The magnetic toner is insulative and is charged by friction with the non-magnetic developing sleeve 72. Second developing device 7
Is negative in order to reverse develop the second latent image (negative latent image) on the photosensitive drum 1. The amount of triboelectric charge of the toner is determined by the prescription and particle size of the toner, the addition of a charge control agent, the surface properties of the developing sleeve 72, the distance between the regulating member 74 and the developing sleeve 72, the strength of toner packing (toner density ) And so on. In this embodiment, a styrene-acrylic magnetic toner having an average particle diameter of 4 to 8 μm was used, and silica was externally added to impart fluidity.

The developing sleeve 72 was used by subjecting a surface of a non-magnetic stainless steel sleeve base material to blasting with about # 400 glass beads. The regulating member 74 is made of magnetic stainless steel and has a thickness of 0.3 to 1.2 mm. The distance between the regulating member 74 and the developing sleeve 72 is 200 to 400 μm.
m. At this time, the amount of triboelectric charge of the toner is about 15
２０20 μC / g, and the application amount is about 0.8-1.2 mg-1.
It was 2 mg / cm ₂ .

The magnet roller 73 is magnetized to four poles, and the developing pole located in the developing area 75 faces the photosensitive drum 1, and raises the magnetic toner on the developing sleeve 72 with a magnetic force of about 800 to 1200 gauss. Let it. In this state, the jumping development is performed by the action of the alternating electric field of the development bias. The gap between the closest position between the developing sleeve 72 and the photosensitive drum 1 is 300 μm, the rotation of the developing sleeve 72 is in the same direction as that of the photosensitive drum 1 in the developing area 75, and the peripheral speed thereof is about 1. 5 times.

In the long-term use experiment with the above configuration, an image was formed in which the image ratio of the first toner image (red toner image) was 6%, and then the image ratio of the second toner image (black toner image) was 6%. In the two-color image formation in which the image formation is carried out, there is no defective color mixture on the image of the red toner as the first toner and the black toner of the second toner even when the number of formed images is 100,000. A good two-color image was obtained without obstruction of density unevenness of the image and the like.

Embodiment 2 Next, Embodiment 2 of the image forming apparatus according to the present invention will be described. Note that members having the same functions as those described above are denoted by the same reference numerals.

FIG. 13 is a configuration diagram of a multi-color or full-color image forming apparatus according to the second embodiment employing the present invention. Exposure to the photosensitive drum 1 by a pre-exposure (lamp) 30;
Primary charging is performed on the entire surface by the primary charger 2, exposure with the laser light 3 a according to image information is sequentially performed, first development is performed by the first developing device 4 a, and the repetition is repeated by secondary charging by the recharger 5 a and laser light 3 b The third and fourth developing units 4c and 4d perform the tertiary and quaternary development as in the secondary image exposure by the second developing unit 4b and the second developing unit 4b.

Thereafter, the charged state of the toner image on the drum is substantially uniformly adjusted for each color by charging by the post charger 41.
The toner image is transferred onto the fed transfer paper P by the electric field applied from the back of the transfer belt 8a, and is fixed on the paper by the fixing roller 12. The surface of the drum is cleaned by a cleaner 13 to prepare for the next image formation.

Here, the developing devices 4a, 4b, 4c, 4d
Indicates that the sleeve, the air flow, and the toner collecting member of the present invention are N
(N is 1, 2, 3, 4) (N +
1) It is wider than the longitudinal charging area and the exposure area of the first charger.

The cleaning members 113a, 113b, 11
3c and 113d are configured to clean the spacer rollers for setting the distance between the sleeve and the drum and to clean the drum surface in the area corresponding to these rollers immediately before each developing area. As the cleaning member, a sponge material such as malt plain, or a fiber or cloth member such as wool felt is used.

The toner in the developing device is supplied to the developing device 4
a, 4b, 4c, and 4d, for forming a multicolor image containing red (R), green (G), blue (B), and black (BK) toners, or yellow (Y), magenta (M ), Cyan (C), and black (BK) toners, and can be used for full-color images.

With the above configuration, a good multi-color or full-color image without color mixture or image unevenness can be obtained.

Embodiment 3 Next, Embodiment 3 of the image forming apparatus will be described with reference to FIG.

The multi-color or full-color image forming apparatus shown in FIG. 14 obtains a multi-color image by rotating the photosensitive drum 1 many times. In other words, the development is performed up to the first developing device 4a in the same manner as in the above-described embodiment, but after that, the paper is not passed through the transfer separation regions 8 and 9 without performing the next development, and the cleaner 13 is also moved by the arrow M. As shown by the arrow, the photosensitive drum is moved away from the photosensitive drum, exposure by the pre-exposure 30 for the second color, charging by the charger 2 and image exposure are performed. It is developed in the container 4b. Similarly, after repeating up to the third and fourth developing units 4c and 4d, the transfer paper P is fed, the transfer by the transfer device 8 and the fixing by the fixing unit 12 are performed, and the multicolor image is formed. Form.

In this configuration, similarly to the second embodiment, the colors of the toner in the developing device are sequentially changed to R, G, B, BK or Y,
M, C, and BK can be applied. These developing devices 4a, 4
b, 4c, 4d, the sleeve of the invention, the air flow,
By forming the toner collecting member, no toner leakage or toner fall occurs in the image area, so that it is possible to obtain a good image free of color mixture and image unevenness over a long period of time.

Embodiment 4 Next, Embodiment 4 of the image forming apparatus will be described with reference to FIG.

The multi-color image forming apparatus shown in FIG. 15 is a multi-color image forming apparatus using an intermediate transfer member 50 capable of performing various multi-color image modes.
Y, M, and C toners are stored therein, respectively.
R, G, B, and BK toners are respectively stored in a to 4d.

The photosensitive belt 1a is formed by forming a photosensitive layer on a transparent material belt. After irradiation from the inside by pre-exposure 30, charging by the charger 2 and image exposure by the laser beam 3a are performed.

First, in the full-color mode, the developing device 4e
After the development, the other process passes, and when the photosensitive belt 1a moves to a region where the transfer charger 8 is installed at a position facing the intermediate transfer body 50, the transfer paper P is supplied in synchronization with the movement. Is transferred onto the transfer paper P electrostatically attracted to the intermediate transfer body 50 by the attraction charger 8a, and the transfer paper P stays on the intermediate transfer body 50. This is repeated, and the developing device 4f,
After the development of 4 g and 4 d is completed, the transfer paper P is separated from the intermediate transfer body 50, and fixing by the fixing device 12 is performed.

In the multi-color or single-color image mode, the pre-exposure 30
5a, the image exposure 3b, and the image exposure 3b in accordance with each color developing device specified in the same manner as in the process of exposure by the charger 2, charging by the charger 2, image exposure by the laser beam 3a, and development by the developing device 4a. Development 4b, charging 5b,
Image exposure 3c, development 4c, charging 5c, image exposure 3
The multi-color toner image on the photosensitive belt is collectively transferred onto the transfer paper by the transfer charger 8 and the fixing 12 is performed.

Here, the developing units 4e, 4f, 4g, 4a,
Reference numerals 4b, 4c, and 4d denote a sleeve, an air flow, and a toner collection member of the present invention, that they are wider than the longitudinal width of the downstream charger and the exposure area of each developing device, and that the photosensitive layer area is further larger. With a wide configuration, the developing gap with the photosensitive belt can be set optimally, there is no mixing of color toner, and there is no unevenness in charging and exposure, so it is possible to supply good images without color mixing, density unevenness, pitch unevenness, etc. Becomes

[0108]

As is apparent from the above description, according to the present invention, at both ends with respect to the center of the axial developer application area of the developer carrying member of the developing means for performing upstream or specialized development. In the developer thin layer area on the near side, a plurality of types of handling areas provided in the axial direction to deal with the developer that easily falls off from the developer carrying transport member, the developer carrying transport member,
By having a developer guiding unit and a developer collecting unit, a downstream charger or an exposing unit, a potential sensor, a potential sensor, a downstream charger, an exposing device due to scattering of the developer from an upstream or preceding developing unit or dropping of the developer. The developing means does not cause toner contamination or contamination, and it is possible to prevent image defects such as image unevenness, color change of two-color or multi-color image and color unevenness, and obtain a good multi-color image. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a multicolor image forming apparatus according to a first embodiment.

FIG. 2 is an explanatory diagram illustrating a first developing device of the multicolor image forming apparatus of FIG. 1;

FIG. 3 is an enlarged explanatory view of a main part of the first developing device of FIG. 2;

FIG. 4 is an explanatory view showing a sleeve end of the first developing device of FIG. 2;

5 is an explanatory diagram showing a positional relationship in a longitudinal direction with respect to components of the photosensitive drum and the developing device of FIG. 1;

FIG. 6 is a graph showing a relationship between a toner application amount on a sleeve and a toner scattering amount.

FIG. 7 is a graph showing the relationship between sleeve surface roughness and toner application amount.

FIG. 8 is a graph showing a relationship between a toner application amount step difference and a toner scattering amount at a step portion.

FIG. 9 is a graph showing a relationship between a distance between a toner collecting member and a photosensitive drum and a toner collecting rate.

FIG. 10 is a graph showing a relationship between an air flow velocity and a toner collection rate.

FIG. 11 is a graph showing a sleeve region and a toner falling scattering amount distribution rate.

FIG. 12 is a configuration diagram illustrating a second developing device according to the first exemplary embodiment.

FIG. 13 is a configuration diagram illustrating an image forming apparatus according to a second embodiment.

FIG. 14 is a configuration diagram illustrating an image forming apparatus according to a third embodiment.

FIG. 15 is a configuration diagram illustrating an image forming apparatus according to a fourth embodiment.

FIG. 16 is a configuration diagram illustrating an example of a conventional two-color image forming apparatus.

17 is a schematic diagram illustrating a surface potential of a photosensitive drum in each step of forming a two-color image by the two-color image forming apparatus of FIG. 16;

18 is an explanatory diagram illustrating a developing device of the two-color image forming apparatus of FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photosensitive drum (electrostatic latent image carrier) 2 charger 3 image exposure (first) 4 developer (first developing means) 5 second charger 6 image exposure (second) 7 developer (second) (Developing unit) 8 Transfer charger 13 Cleaner 32 Developing sleeve (developer carrying member) 33 Blade (developer thin layer regulating member) 39 Seal roller 45 End toner seal 61 Toner particle collecting member (Developer collecting unit) 71 Outflow duct (developer guiding means) 72 Inhalation duct (developer guiding means)

Claims (8)

[Claims] 1. A first image information potential distribution forming means for forming a latent image corresponding to a first color on an electrostatic latent image carrier, and a first image information potential distribution forming means formed by the first image information potential distribution forming means. A first developing means for developing a latent image with a developer having a first dye, and a multicolor image forming method comprising performing the above steps a plurality of times in accordance with the number of color types or a plurality of said means In the apparatus, the developer-carrying and conveying member is provided in a developer thin-layer area nearer to both ends with respect to the center of the developer-applying and conveying member of the developing means that performs upstream or preceding development. The developer carrying and conveying member, the developer guiding means, and the developer collecting means, which are provided with a plurality of types of handling areas for handling the developer that easily falls off the developer, are provided. Color image forming apparatus. 2. A device according to claim 1, further comprising means for dealing with a developer which has fallen off from said developer carrying member, wherein said means for dealing with said developer fall away from said developer carrying member. 2. The multicolor image forming apparatus according to claim 1, wherein the image forming apparatus is different depending on the image forming apparatus. 3. The developer handling area in which the developer carrying / transporting member easily falls off includes a plurality of areas where the amount of developer applied per unit area is different in the axial direction of the developer carrying / transporting member. 3. The multicolor image forming apparatus according to claim 2, wherein: 4. The developing device according to claim 1, wherein the amount of developer applied per unit area on the developer carrying member decreases stepwise from the axial center of the developer carrying member toward both ends. 3. A multicolor image forming apparatus. 5. The developer-carrying / transporting member has a surface roughness stepwisely reduced from its axial center toward both ends, and has a surface roughness at both end positions of the thin-film developer regulating member. The multicolor image forming apparatus according to claim 3, wherein the multicolor image forming apparatus has a minimum area. 6. The multicolor image forming apparatus according to claim 1, wherein the visualized particles as a developer are non-magnetic agents. 7. The developer carrying member has a surface roughness in the axial direction of the developer carrying member in a developer thin layer applying region near both ends with respect to the center of the developer carrying region in the axial direction. The developer guiding means is relatively coarse roughly equivalent to that of the axial image corresponding area, and is relatively downstream from the downstream direction in the direction of gravity corresponding to the image corresponding area toward the developer carrying conveyance member. A strong air flow is formed, and the developer that has come off is guided in a direction away from the electrostatic latent image carrier, and the developer carrying conveyance member is located in a developer thin layer coating area relatively close to both ends in the axial direction. The surface roughness is smaller than that of the image corresponding area, and the developer guiding means is compared to the developer carrying member from the downstream direction in the gravity direction corresponding to the area. Form a weak air flow, 7. The developer collecting device according to claim 1, wherein a distance from the electrostatic latent image carrier varies according to a plurality of levels of surface roughness of the developer carrying member. One multicolor image forming apparatus. 8. A multicolor image forming apparatus according to claim 1, wherein said developing means includes a non-magnetic one-component developer and a flexible developer thin-layer coating regulating member. .