JPH09146334A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of an image caused by re-transfer and the color mixture of toner in a developing device caused by simultaneous recovery with development without spoiling high-speed performance by specifying the contact angle of the surface of a 2nd latent image carrier to water. SOLUTION: A magenta toner image is formed on the photoreceptor drum 10M of a magenta unit UM, and transferred on transfer paper 18 carried by a transfer carrying belt 30 by transfer electric field formed by a transfer blade 25M. Next, the transfer paper 18 having the magenta toner image is moved as the belt 30 is moved and a cyan toner image is multiply transferred on the transfer paper 18 by the next cyan unit UC. In the same manner, multiple transfer is performed and the toner image is finally fixed by a fixing device 38. In such a case, by setting the contact angle of the surface of the photoreceptor drum 10 to the water to >=85 deg., the releasing property of the surface of the drum 10 becomes high, the toner is easily peeled from the surface of the drum 10 at the time of transferring, and peeling discharge is reduced, so that re-transfer is hardly caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus utilizing an image forming process such as an electrostatic recording system or an electrophotographic system, and in particular, multiple transfer of visualized images on a plurality of image information carriers. The present invention relates to a multicolor image forming apparatus capable of obtaining a multicolor image, and is used not only in an electrophotographic copying apparatus but also in a printer or a facsimile.

[0002]

2. Description of the Related Art In recent years, image forming apparatuses such as electrophotographic apparatuses have been reduced in size, enhanced in function, and colorized.
On the other hand, there are increasing demands for improved reliability, system deployment, maintenance-free, and friendly to people and the environment, and various image output devices have been proposed to meet those demands.

For example, JP-A-53-74037 (corresponding US Pat. No. 4,162,843) discloses that
There has been proposed an image forming apparatus in which a plurality of photoconductors are stacked and a transfer material is conveyed by a belt-like conveying unit to sequentially transfer multiple toner images in order to speed up color image output.

On the other hand, recently, in particular, downsizing of the entire apparatus, ecology support by eliminating waste toner, extension of life of photoconductor,
In order to reduce the toner consumption per page, copying machines and printers that employ a cleanerless, so-called simultaneous development cleaning system that collects and reuses transfer residual toner have been put into practical use. In particular, when such a system is adopted, it is preferable to use the spherical toner produced by the polymerization method.

Therefore, even in the image forming apparatus described in Japanese Patent Laid-Open No. 53-74037, in which a plurality of photoconductors are stacked and the toner images are sequentially transferred onto the transfer paper, the size of the entire apparatus is reduced, It is desired to adopt the simultaneous development cleaning method in consideration of ecology support by eliminating waste toner, longer life of the photoconductor, and reduction of toner consumption per page.

However, when the simultaneous developing and cleaning system is adopted in an image forming apparatus in which a plurality of such photoconductors are stacked and a toner image is sequentially transferred onto a transfer sheet in a multiple transfer manner, the following problems may occur. .

For example, an image forming unit having a photoreceptor as a latent image carrier, a primary charger as a charging unit, an image exposure unit as a latent image forming unit, a developing unit as a developing unit and a transfer unit is used for cyan toner. , For magenta toner,
In a full-color image forming apparatus in which four toner images are used for yellow toner and black toner, and a toner image is sequentially multi-transferred by a transfer unit of an image forming unit for each color toner on a transfer material conveyed by a transfer belt, for example, two colors are used. In the mode (magenta, cyan), the transfer material supported on the transfer belt sequentially passes through the magenta unit, the cyan unit, the yellow unit, and the black unit, but only the desired magenta unit and cyan unit. It suffices that the image forming section of is operating.

However, as described above, the transfer material is sequentially sent to the magenta unit, the cyan unit, the yellow unit, and the black unit, and passes through the gap between the transfer belt and the photosensitive drum. If all operations of the image forming process of the yellow unit and the black unit) are stopped, the transfer material is already formed on the transfer material when passing through the gap between the drum and the belt of each of the magenta and cyan units as described above. In addition, the magenta image and the cyan image are rubbed by the photoconductor drums of the yellow unit and the black unit, respectively, resulting in a problem that the images are significantly damaged.

Further, in such a case, when the transfer material passes through the gap between the drum and the belt, a transfer material jam (jam) is likely to occur.

Therefore, it is possible to avoid these problems by operating an undesired unit, but by doing so, unnecessary operation shortens the life of parts, increases running costs, and wastes extra power. Will be done.

At this time, the magenta toner and the cyan toner transferred onto the transfer material are electrostatically attracted to the transfer material, but the transfer material passes through the gaps between the yellow and black photosensitive drums and the belt. At that time, a part of the magenta toner and the cyan toner forming the magenta image and the cyan image may be retransferred to these photosensitive drums, in which case the image is significantly deteriorated, that is, the image unevenness is caused. There is also a problem that the density is lowered, and the color balance is deviated.

In order to solve such a problem, for example, as described in Japanese Patent Application Laid-Open No. 2-20866, the biasing and releasing of the transfer belt to the photosensitive drum used for image formation is selectively performed. It is conceivable to use a method of controlling so as to perform the above. However, when such a method is used, since a pressure contact releasing mechanism for the photosensitive drum of the image unit which is not desired is required for each unit, Various mechanical vibrations are generated during the operation of these release mechanisms, which tend to have an adverse effect at the time of transfer, and in order to avoid them, when they are operated at the time of non-image formation, high speed is hindered.

Further, even when a full-color image is formed by using all the image forming units, the toner already transferred onto the transfer paper at the time of multiple transfer of the second and subsequent colors may be retransferred to the drum.

If the retransfer as described above occurs, that is, if the magenta toner and the cyan toner are retransferred to the yellow and black photoconductor drums,
Since the photoconductor drum cleaner is not used, it is collected by the developing device at the time of development, which causes a problem of toner color mixing in the developing device. The color mixture in the developing device is a serious problem in multicolor image formation.

Generally, as a countermeasure for the retransfer phenomenon,
It is possible to set a continuous charge amount in which the charge amount of the toner sequentially decreases from the first color, over a wide range, assuming that the toner on the transfer paper is attracted by the electric field from the charged region of the photoconductor. Are known.

However, this method has a problem that the prescription of the developer and the charging method must be changed for each color toner, and the constitution of the developer and the developing device cannot be made common.

In Japanese Patent Application Laid-Open No. 1-273076, the toner on the transfer paper is also charged to the transfer polarity by the transfer, and it is assumed that the toner is repulsed by the same polarity as the charging of the belt. It is proposed to contact and transfer.

However, in this method, the charging condition of the belt must be constantly monitored and controlled so that proper charging can be performed, and in addition, the apparatus configuration becomes complicated, and the simplification and cost reduction are achieved. Not good for

[0019]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of preventing image deterioration due to retransfer and toner color mixture in a developing device due to simultaneous recovery of development without impairing high speed. It is in.

An object of the present invention is to provide an image forming apparatus in which chromaticity change hardly occurs when a large number of images are formed.

[0021]

The present invention comprises: (i) a first latent image carrier for carrying a first electrostatic latent image; (ii)
First latent image forming means for forming a first electrostatic latent image on the first latent image carrier, (iii) developing the first electrostatic latent image with a first toner, A first developing unit for forming a first toner image on the first latent image carrier, and (i
v) a first image forming unit having a first transfer means for transferring the first toner image on the first latent image carrier onto an image receiving member; and (i) a second image forming unit. A second latent image carrier for carrying an electrostatic latent image, (ii) second latent image forming means for forming a second electrostatic latent image on the second latent image carrier, ( iii) second developing means for developing the second electrostatic latent image with a second toner to form a second toner image on the second latent image carrier, and (iv) the second developing means. Second transfer means for transferring the second toner image on the second latent image carrier onto the image receiving member having the first toner image formed by the first image forming unit. , And the second developing means is a cleaning means for collecting and cleaning the toner existing on the second latent image carrier after the transfer. An image forming apparatus having at least a second image forming unit having a function as well, wherein the surface of the second latent image carrier has a contact angle with water of 85 degrees or more. It relates to the device.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The mechanism of occurrence of retransfer and the present invention, which are the problems to be solved by the present invention, will be described below.

As described above, when the developing simultaneous cleaning type developing method is used, the phenomenon of retransfer causes a problem that toner of another color is mixed in the developing device.
The present inventors have conducted various studies on this retransfer phenomenon, and as shown in FIG. 2, a peeling discharge generated between the photoconductor drum and the transfer paper (including the transfer belt) as the image receiving member. It was found that the cause was. As described above, the toner image Tm formed on the photosensitive drum 10M as a latent image carrier of the magenta unit by the well-known electrophotographic process is carried on the transfer belt 30,
A transfer blade 25M as a transfer unit that is in close contact with the transfer material 18 supplied in synchronization with the rotation of the photoconductor drum 10M and is in contact with the transfer belt 30 from the back side thereof in order to transfer the toner image Tm. At, the positive transfer charge Qb is supplied to the transfer belt 30. This transfer charge Q
b exerts an electrostatic attraction on the toner image Tm having a negative charge, and the toner image Tm is attracted to the transfer material 18. On the other hand, the positive transfer charge Qb induces a negative charge on the photoconductor drum 10M, and an electrostatic attractive force acts on the transfer material 18 and the photoconductor drum 10M by both of them, so that the transfer paper 18 and the photoconductor drum 10M are separated from each other. In close contact.

At the next moment, the photosensitive drum 10
Due to the curvature of M, the toner image Tm is held on the transfer belt 30 while being attracted to the transfer paper 18.
8 and the transferred toner image Tm on the transfer paper 18 is peeled off from the photoconductor drum 10M. Due to this peeling, an air gap is formed between the photoconductor drum 10M and the toner image Tm, and the electrostatic charge at that portion is formed. The peeling discharge occurs due to the sudden decrease in the capacity and the increase in the potential difference.

Most of the positive and negative charges generated by the peeling discharge are generated by a slight air grab surrounded by the photosensitive drum 10M and the toner image Tm, but the positive charge Qb applied to the transfer belt 30. And according to the electric field formed by the negative charge induced on the photoconductor drum 10M, the positive charge jumps to the photoconductor drum 10M, and the negative charge jumps to the toner image Tm and the transfer paper 18. But some positive charges
The toner, which has jumped into the toner image Tm and has its charge polarity reversed by the positive charge, repels the positive charge Qb of the transfer belt 30 and is transferred to the photoconductor drum 10M to cause retransfer. However, at this time, most of the remaining toner whose charge polarity has not been reversed by the positive charge is imparted with a negative charge due to the peeling discharge, the charge amount increases, and the toner is transferred to the transfer material 18.

Actually, the change in the charge amount of the magenta toner transferred to the transfer material 18 after the transfer and the change in the charge amount of the toner remaining on the photosensitive drum after being retransferred onto the photosensitive drum 10M are
FIG. 3 shows the measurement results obtained by changing the transfer bias.
From this graph, it can be seen that the absolute value of the charge amount of the transfer toner is larger than that before transfer (-20 μC / g in this example), and the charge amount of the retransfer toner on the photosensitive drum is reversed. Further, it is shown that as the transfer bias is increased, the degree thereof is increased and the peeling discharge is increased.

The relationship between the transfer current and the transfer efficiency and the retransfer amount will be described with reference to FIG. 4. The transfer efficiency rapidly increases as the transfer current increases as shown by the transfer efficiency curve in FIG. A saturation tendency is seen. On the other hand, the retransfer amount tends to increase monotonously as shown in FIG. Therefore, in consideration of reducing the retransfer amount, the transfer current should be small. However, in the actual setting, the point where the transfer efficiency is saturated is used as the value of the transfer current, while paying attention to the problem that occurs when the transfer current such as scattering of the transferred toner image is too strong.

As described above, since the transfer current does not pay attention to the retransfer amount and a current suitable for the transfer efficiency is used, the retransfer is likely to occur in an actual apparatus.

Next, the image forming apparatus of the present invention has a developing unit as a developing unit which also has a function as a cleaning unit for collecting and cleaning the toner existing on the latent image carrier. The image forming unit will be described with reference to FIG.

Image forming unit (magenta unit) U
On M, a cylindrical photosensitive drum 10M as an electrostatic latent image carrier is rotationally moved in the direction of arrow a. 12M is a primary charger as a charging means, which is installed in non-contact with the photosensitive drum 10M. Reference numeral 14M is an image exposure device as a latent image forming means, and the photosensitive drum 10 is connected to the primary charger 12M.
The photosensitive drum 10M is exposed on the downstream side of the rotational direction of M to form an electrostatic latent image. 16M is a developing device as a developing means,
The photoconductor drum 10M is installed further downstream than the exposure position so as to be adjacent to the photoconductor drum 10M. 25
M is a transfer blade, which is installed so as to sandwich the transfer material at the transfer position during transfer and to face the photoconductor drum 10M. 13M is a pre-exposure lamp, which is installed between a transfer blade 25M as a transfer unit and the primary charger 12M.

In the image forming unit UM, the primary charging device 12M uniformly primary-charges the photoconductor of the photoconductor drum 10M, and then the image exposing device 14M forms an electrostatic latent image on the photoconductor by exposing the photoconductor to the developing device. The electrostatic latent image is developed with magenta toner at 16M, and the developed toner image is transferred to a transfer material as an image receiving member by supplying a transfer charge from a transfer blade 25M at a transfer position. Is discharged by the pre-exposure lamp 13M, and the primary charging by the primary charging device 12M, the latent image formation by the image exposing device 14M, and the development by the developing device 16M are performed again. The development by the developing device 16M uses, for example, a two-component developer composed of toner and carrier, and
A magnetic brush formed of this two-component developer can be brought into contact with M and toner can be made to fly to the side of the photoconductor drum for development, and at the time of this development, for example, a frequency of 2 KHz as a development bias. By applying an AC voltage of peak = peak voltage of 2 KV and DC of −500 V, the toner existing on the photoconductor after the transfer is collected by the developing device.

The present invention comprises a plurality of image forming units using a developing means which also has a function as a cleaning means for collecting and cleaning the toner existing on the latent image carrier. The toner images formed by the image forming unit are sequentially transferred onto an image receiving member that is a transfer material.

When this magenta unit is used for the first color, the toner color mixture in the developing unit due to the simultaneous development cleaning does not occur even if the image is deteriorated to some extent by the retransfer.

A cyan unit, a yellow unit, and a black unit having the same structure as this magenta unit are sequentially arranged following the magenta unit, and the cyan toner image is transferred onto the transfer material on which the magenta toner image has been transferred.
When the yellow toner image and the black toner image are sequentially transferred in multiplex, after the second color, peeling discharge occurs and retransfer occurs at the time of transfer according to the same principle as the first color, but in this case, the first color Toner is easy to retransfer. It is considered that this is because, as described above, the charged state of the toner on the transfer material changed during transfer, which facilitated retransfer. When retransfer occurs after the second color, the toner of the previous image forming unit including the toner of the first color mixes into the developing unit of the image forming unit that forms the image of the second and subsequent colors, and The image deteriorates due to the imbalance.

As described above, the retransfer is caused by the peeling discharge generated between the photoconductor drum and the transfer paper, and this peeling discharge has a great correlation with the releasability of the photoconductor drum, and the toner is removed from the photoconductor. When the toner is transferred, the peeling discharge tends to occur largely when the toner is difficult to peel off.

The reason for this is that the transfer of toner causes the transfer of electric charges, and the potential difference between the photoconductor and the transfer material decreases, but when the transfer is difficult, the potential difference does not decrease.
Discharge may occur.

Therefore, in the present invention, since the contact angle of water on the surface of the photoconductor is 85 degrees or more, the releasability of the photoconductor surface is high, so that the toner is peeled off from the photoconductor surface during transfer. The peeling discharge is less likely to occur and retransfer is less likely to occur.

In the present invention, the contact angle of water on the surface of the photoconductor is 85 ° or more, preferably 90 ° or more, more preferably 100 ° or more. It is good in that it can be more difficult to cause.

The contact angle of water on the surface of the photoreceptor is 85.
If it is less than 100 ° C., the releasability of the surface of the photoconductor becomes low, so that there is substantially no effect of suppressing retransfer.

In the present invention, the contact angle of water on the surface of the latent image carrier is Kyowa Kagaku Co., Ltd. Kyowa contact angle meter CA-
It was measured using DS.

In the present invention, in order to obtain a latent image carrier surface having a water contact angle of 85 degrees or more, a surface resin of the latent image carrier may be a base resin such as a polycarbonate resin or a photocurable acrylic resin. This can be performed by using a fluororesin such as Teflon dispersed in a specific amount.

The content of the fluororesin in this surface layer is preferably 1 to 1 with respect to 100 parts by weight of the base resin.
50 parts by weight, more preferably 5 to 100 parts by weight, still more preferably 10 to 50 parts by weight.

When the content of the fluororesin is less than 1 part by weight, the contact angle of water on the surface of the latent image carrier is 85.
If it is less than 150 parts by weight, and if it exceeds 150 parts by weight, the dispersibility of the fluororesin is lowered and the durability of the latent image bearing member is apt to be lowered.

Further, as the toner used in the image forming apparatus of the present invention, the surface of the toner is more uneven than that of a so-called crushed toner obtained by melting, kneading, crushing and classifying a toner material which is generally used conventionally. It is particularly preferable to use a spherical toner having a surface shape with a small amount of sphere or a sphere having a shape close to sphere, because the occurrence of retransfer can be suppressed.

The reason why the occurrence of retransfer can be suppressed by using the spherical toner will be described with reference to FIG. 5 from the viewpoint of the adhesive force between the toner and the photosensitive member.

The main forces acting on the toner in contact with the surface of the photoconductor are a mirror image force and a van der Waals force. The mirror image force largely depends on the amount of electric charge and its distance. The surface shape of pulverized toner generated by general pulverization is uneven, and the convex portions are intensively charged by frictional charging.

On the other hand, for example, a spherical polymerized toner obtained by a polymerization method has a spherical surface or a shape close to a spherical surface, so that the surface is uniformly charged. In the pulverized toner, the convex portions are in contact with each other, and a large amount of electric charge exists in a very close region, so that the mirror image force is increased. On the other hand, when the toner has a spherical shape like the polymerized toner, the contact state becomes almost point-like, the amount of charge in the adjacent region is small, and the mirror image force is smaller than the above. The Van der Waals force is very large in the state where the contact is made in a plane due to the influence of the region closest to the van der Waals.

When a toner having an uneven surface is used, many of the toners come into contact with each other in the state shown in FIG. 5 as described above. The Wars force becomes very large. On the contrary,
Since the spherical toner has a spherical surface shape, the toner comes into contact with the toner at almost points. Therefore, the van der Waals force is also smaller for the spherical toner.

For the above reason, in the case of a spherical toner whose surface shape is spherical or nearly spherical, the mirror image force, van der Waals force, that is, the adhesive force to the photoconductor is small, and as described above, the adhesion between the photoconductor and the toner is small. If the adhesive force becomes small and peeling from the photoconductor is easy, peeling discharge is unlikely to occur. Therefore, such a spherical toner having a weak adhesive force is unlikely to cause peeling discharge and retransfer is unlikely to occur.

In addition to this, the spherical toner, which has a small adhesive force to the photosensitive member, has less transfer residual toner after transfer, and has a large toner collecting effect at the time of simultaneous cleaning at the time of development, thus improving the simultaneous cleaning at the time of development. .

In the present invention, a spherical or nearly spherical toner has a toner shape factor SF-1 of 100 to 1.
80, preferably 100-140, more preferably 10
0 to 130, SF-2 is 100 to 140, preferably 1
A toner in the range of 00 to 120, more preferably 100 to 115 is preferable.

SF-indicating the shape factor used in the present invention
1 and SF-2 are Hitachi FE-SEM (S-8
00) is used to randomly sample 100 toners, and the image information is introduced into an image analysis device (Luzex3) manufactured by Nireco Co. through an interface for analysis.
In the present invention, the shape coefficients SF-1 and SF-2 are defined as the values calculated by the following equation.

[0053]

(Equation 1) (AREA: toner projection area, MXLNG: absolute maximum length, PERI: circumference)

The shape factor SF-1 of the toner indicates the degree of sphere, and when it is larger than 180, the shape factor gradually changes from spherical to irregular. SF-2 indicates the degree of unevenness, and when it is larger than 140, the unevenness of the surface area of the toner becomes remarkable. Therefore, SF-1
Of more than 180 or SF-2 of more than 140, retransfer may not be suppressed, transfer efficiency may be lowered, fog may be further increased, and durability may be slightly deteriorated.

The function and effect of the toner shape is to reduce the influence of the photosensitive member charging member on the toner surface as much as possible and suppress the formation of reactive low molecular weight components in the toner. That is, it is preferable that the toner and the spherical surface have a surface area as small as possible.

The effect of the present invention can be enhanced by using a toner in which a part or the whole of the toner is formed by a polymerization method. In particular, for the toner formed by polymerization method on such a portion of the toner surface, the necessary portion is generated by the polymerization reaction by existing as pre-toner (monomer composition) particles in the dispersion medium, so the surface property is considerably smooth. It is possible to obtain the one that is converted.

Further, in the present invention, in addition to the toner formed by the above-mentioned polymerization method as a spherical toner, a pulverized toner obtained by melting, kneading, pulverizing and classifying a toner raw material is heated, and the toner particle surface is It is possible to use a spherical toner that has been subjected to a spheroidizing treatment such as imparting impact force to the toner.

Further, in the present invention, the toner used in the image forming apparatus of the present invention can be manufactured more easily by giving the toner a core / shell structure and forming the shell portion by polymerization. In this sense,
In the present invention, a toner having a core / shell structure is preferably used. It goes without saying that the action of the core / shell structure can impart anti-blocking property without impairing the excellent fixing property of the toner.

The toner having a volume average particle diameter of 4 to 15 μm can be preferably used. Here, the volume average particle diameter of the toner is, for example, a value measured by the following measuring method.

As a measuring device, a Coulter counter T
A-II type (manufactured by Coulter, Inc.)
Interface to output volume average distribution (made by Nikkaki)
And CX-i personal computer (Canon) are connected, and the electrolyte is 1% Na using primary sodium chloride.
An aqueous Cl solution is prepared.

The measuring method is as follows:
0.1 to 5 ml of a surfactant (preferably alkyl sulfonate) as a dispersant is added to 150 ml, and 0.5 to 50 mg of a measurement sample is further added.

The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the particle size of particles of 2 to 40 μm was measured using a 100 μm aperture as a rear aperture by the Coulter Counter TA-II type. Measure the distribution and obtain the volume distribution. The volume average particle diameter of the sample is obtained from the obtained volume distribution.

Further, it is desirable that the surface of the toner is coated with an external additive so that the influence of the photoconductor charging member can be released to a partial external additive.

The external additive used in the present invention preferably has a particle size of 1/10 or less of the weight average particle size of the toner particles from the viewpoint of durability when added to the toner. The particle size of the additive means an average particle size obtained by observing the surface of the toner particles with an electron microscope. Examples of the external additive include aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide,
Metal oxides such as chromium oxide, tin oxide and zinc oxide, such as nitrides such as silicon nitride, carbides such as silicon carbide, metal salts such as calcium sulfate, barium sulphate and calcium carbonate, zinc stearate and calcium stearate. Such fatty acid metal salts, carbon black, and silicidity can be mentioned.

The external additive is used in an amount of 0.01 to 10 parts by weight, preferably 100 parts by weight, based on 100 parts by weight of the toner particles.
05-5 parts by weight are used. These external additives may be used alone or in combination. Those subjected to a hydrophobic treatment are more preferable.

Next, preferred embodiments of the image forming apparatus of the present invention will be described in detail in the following first to third embodiments.

(First Embodiment) FIG. 1 is an explanatory view showing a first embodiment of the image forming apparatus of the present invention. The UM is an image forming unit (magenta unit) having a developing unit as a developing unit that also has a function as a cleaning unit that collects and cleans the toner existing on the latent image carrier. A cyan unit, a yellow unit, and a black unit, each having a cyan toner, a yellow toner, and a black toner, respectively, having the same configuration, are sequentially provided following the magenta unit.

A transfer belt, which is a transfer material conveying means, is disposed vertically through each of the image forming units. Reference numeral 18 denotes a transfer material (copy paper) as an image receiving member. Reference numeral 20 denotes a paper feeding unit for feeding the transfer paper 18. A transfer belt 30 is in contact with the photosensitive drum 10M as a latent image carrier and is driven in the b direction. 31 is a drive roller,
Reference numeral 32 is a driving unit that stretches and drives the transfer belt 30 with a support roller. 38 is a fixing device, which is the transfer / conveyance belt 3.
It is arranged adjacent to the drive roller 31 of 0. A transfer blade 25M as a transfer unit, which is installed so as to face the photoconductor drum 10M at the transfer position, transfers the transfer between the transfer conveyance belt 30 and the transfer paper 18 conveyed by the transfer conveyance belt 30 at the time of transfer. It is something to do.

The operation of image formation with the above configuration will be described.

First, a magenta toner image is formed on the photosensitive drum 10M of the magenta unit UM, and the magenta toner image is transferred by the transfer transfer belt 30 on the transfer paper 18 by the transfer electric field formed by the transfer blade 25M. Is transcribed to.

Next, as the transfer / conveyance belt 30 moves,
The transfer paper 18 having the magenta toner image moves, and the next cyan unit UC multiple-transfers the cyan toner image onto the transfer paper 18.

Similarly, the yellow toner image and the black toner image are multi-transferred onto the transfer paper 18 by the yellow unit and the black unit, and finally fixed on the fixing device 38 to form an image.

In the 4-drum full-color copying machine having the above-described structure, for example, in the case of the two-color mode (magenta, cyan), the transfer paper 18 supported on the transfer belt 30 is
The image forming section sequentially passes through the magenta unit UM, the cyan unit UC, the yellow unit UY, and the black unit UBk, but the image forming section may be a desired unit, for example, only the magenta unit and the cyan unit. In this case, the undesired units (in this case, the yellow unit and the black unit) may be separated from the transfer belt without being operated, but may be operated normally for the sake of simplicity of the configuration.

(Second Embodiment) FIG. 6 is an explanatory view showing a second embodiment of the image forming apparatus of the present invention.

Also in this embodiment, as in the first embodiment, an image forming unit in which charging, exposure, development, and pre-exposure are integrated around the photoconductor drum is used as U for each toner color.
It is configured to have four M, UC, UY, and UBk. A spherical toner is used as the toner, and an image is formed by a process in which the toner on the photosensitive drum is collected by a developing device at the same time.

However, the difference from the first embodiment is that a transfer material as an image receiving member is carried and conveyed on the transfer belt,
Rather than multiple transfer of toner images of respective colors onto a transfer material, an intermediate transfer member 50 as an image receiving member is stretched by a driving roller 31, a support roller and a backup roller 27 instead of the transfer belt. The toner images of respective colors are multi-transferred (primary transfer) onto the toner image 50, and the multi-transferred toner images are transferred to the copy paper 19 as the final transfer material fed by the paper feed roller 20, the backup roller 27 and the secondary roller. The image is transferred by the transfer roller 26 and fixed by the fixing device 38.

As the intermediate transfer member, urethane rubber (10
PTFE as a dielectric layer on the surface of ³ to 10 ⁴ Ωcm)
It is preferably composed of a flexible endless belt on which a (polytetrafluoroethylene) layer (10 ¹⁴ Ωcm or more) is formed. The other components are almost the same as those in the first embodiment.

The operation of image formation with the above arrangement will be described below. First, a magenta toner image is formed on the photosensitive drum of the magenta unit UM by the same process as described above, and the magenta toner image is primarily transferred onto the intermediate transfer member 50 by the transfer electric field formed by the transfer blade.

Next, the magenta toner image on the intermediate transfer member 50 is conveyed as the intermediate transfer member 50 rotates, and the cyan toner image is multi-transferred (primary transfer) by the next cyan unit UC.

Similarly, charge adjustment and multiple transfer (primary transfer) are performed by the yellow unit and the black unit, and finally they are collectively transferred onto the copy paper 19 by the secondary transfer roller 26 and fixed by the fixing device 38. By this, an image is formed.

(Third Embodiment) FIG. 7 is an explanatory view showing a third embodiment of the image forming apparatus of the invention. In this embodiment, as in the first embodiment, an image forming unit that integrates charging, exposure, development, and pre-exposure centering on the photosensitive drum is used for each of the toner colors UM, UC, UY, and UBk. Although each unit has a configuration, the arrangement of each unit is characterized by the order of the yellow unit UY, the magenta unit UM, the cyan unit UC, and the black unit UBk.

The order of arranging the image forming units is determined in consideration of the characteristic of the change in chromaticity due to the color mixture of toners of respective colors, which will be described later, and the change in chromaticity in the image forming units of each color is minimized. By arranging the image forming unit as described above, it is possible to minimize the change in chromaticity of the final output image due to color mixture.

By taking such an arrangement order of the image forming units, a developing device as a developing device means also having a function as a cleaning means for collecting and cleaning the toner present on the latent image carrier of the present invention. Re-transfer can be suppressed by using a spherical toner and a latent image carrier having a surface having a contact angle with water of 85 degrees or more in combination in an image forming apparatus using a plurality of image forming units having It is possible to obtain a remarkable effect that it is possible to maintain a larger number of effects that the image forming apparatus has, that is, color mixing is less likely to occur and color balance deviation is less likely to occur until after the endurance.

Chromaticity change characteristics due to color mixing of toners of respective colors will be described. The change in chromaticity due to the mixing of different color toners depends not only on the color type of the mixed toner but also on the color type of the mixed toner. FIG. 8 shows the difference in chromaticity when different color toners are mixed in 7% by weight based on each of yellow toner, magenta toner, and cyan toner. According to this, when the yellow toner is used as the base, the change in the chromaticity is larger than when the magenta toner and the cyan toner are used as bases, regardless of whether the magenta toner or the cyan toner is mixed. Therefore, by arranging the yellow image forming unit in the most upstream part in the transfer material conveyance direction where color mixing does not occur in principle in the image forming apparatus, a large change in chromaticity due to color mixture of different color toner in the yellow toner is caused. Can be prevented.

The largest change in chromaticity due to color mixing among toners other than yellow is when yellow toner is mixed with cyan toner. If the cyan image forming unit is located immediately after the second image forming unit, i.e., the yellow image forming unit, only the yellow toner is mixed in the cyan image forming unit.If the third image forming unit is arranged, the magenta toner is added to the yellow toner. Is clearly mixed in. FIG. 9 shows changes in chromaticity when two color toners, a cyan toner as a base and a yellow toner and a magenta toner, are mixed. This figure shows that the change in chromaticity is smaller when the yellow toner is mixed with the magenta toner than when the yellow toner is mixed based on the cyan toner. Next, FIG. 10 shows changes in chromaticity when two color toners, a yellow toner and a cyan toner, are mixed based on magenta toner. In this case, the mixing ratio of the second color toner suppresses the increase rate of chromaticity, but does not tend to decrease.
Therefore, from the viewpoint of minimizing the chromaticity change in each image forming unit, it is most preferable to arrange the magenta image forming unit in the second place and the cyan image forming unit in the third place. I understand.

Toners mixed into the fourth image forming unit by retransfer are yellow toner, magenta toner, and cyan toner. It is well known that when these three color toners are mixed, a color close to black is obtained due to the characteristics of the subtractive color mixing method. That is, even if these toners are mixed in black, they are hardly noticeable. Therefore, if the black image forming unit is arranged at the fourth position, the change in chromaticity due to color mixture is minimized.

For the above reasons, the order of the image forming units of each color is set in order from the transfer material transport direction to yellow, magenta,
By using cyan and black, it is possible to minimize the change in chromaticity due to the color mixture of the output image.

The present invention has at least a first image forming unit and a second image forming unit, and the second image forming unit collects the toner existing on the latent image carrier after transfer. In the image forming apparatus having the developing unit also having a function as a cleaning unit for cleaning, the second unit used in the second image forming unit
Since the contact angle of the surface of the latent image carrier with water is 85 degrees or more, the first image formed by the first image forming unit is
When the second toner image formed by the second image forming unit is transferred onto the image-receiving member on which the toner image has been transferred, the first toner of the first toner image carries the second latent image. Retransfer to the body is less likely to occur, mixing of the first toner into the second developing unit is suppressed, color balance is less likely to be disturbed, and chromaticity change during multi-image formation can be suppressed. It is possible.

The image forming apparatus of the present invention will be described in detail below with reference to the examples, but the examples do not limit the present invention at all.

[0090]

EXAMPLES Preparation of Cyan Toner A Polymerization of suspended particles formed by adding a monomer composition containing a polymerizable monomer and a cyan colorant to an aqueous medium and suspending and dispersing the mixture by stirring Cyan polymerized toner A was obtained.

The cyan polymerized toner A thus obtained had a weight average particle size of 8 μm, SF-1 was 108 and SF-2 was 1.
It was 08 and had a spherical shape.

Magenta toner A, yellow toner A, and
Manufacture of Black Toner A Except for the cyan toner A, except that a magenta colorant, a yellow colorant, and a black colorant are used in place of the cyan colorant used in the manufacture of the cyan toner A. Magenta toner A, yellow toner A, and black toner A having the physical properties shown in Table 1 in the same manner as in production
Was manufactured respectively.

Production of Cyan Toners B and C Binder resin and cyan colorant were melted, kneaded, pulverized and classified to obtain pulverized cyan toner B.

The crushed cyan toner B thus obtained had a weight average particle size of 8 μm, SF-1 was 150 and SF-2 was 14
It was 5 and had a non-spherical shape.

The crushed cyan toner B was heat-treated to obtain a spherical cyan toner C.

The obtained cyan toner C had a weight average particle size of 8 μm, SF-1 of 110 and SF-2 of 110, and had a spherical shape.

Magenta toner B and C, yellow toner
Manufacture of B and C, and black toners B and C , instead of the cyan colorant used in the manufacture of cyan toners B and C, a magenta colorant, a yellow colorant, and a black colorant, respectively. Magenta toners B and C and yellow toner B having the physical properties shown in Table 1 in the same manner as cyan toners B and C except that they are used.
And C and black toners B and C, respectively.

Production of Cyan Toners D to F In the production of cyan toner A, the stirring conditions of the monomer composition in the aqueous medium were changed to obtain polymerized cyan toners D to F having the physical properties shown in Table 1.

[0099] change the agitation conditions of the monomer composition in an aqueous medium in the production of manufactured magenta toner A magenta toner D~F obtain a polymer magenta toner D~F having physical properties as shown in Table 1.

[0100] was changed agitation conditions of the monomer composition in an aqueous medium in the production of manufacturing the yellow toner A yellow toner D~F obtain a polymer yellow toner D~F having physical properties as shown in Table 1.

[0102] was changed agitation conditions of the monomer composition in an aqueous medium in the production of manufacturing the black toner A black toner D~F obtain a polymer black toner D~F having physical properties as shown in Table 1.

Production of Cyan Toner G Cyan Toner B produced in the production of Cyan Toner B was heat-treated for a shorter time than Cyan Toner C to obtain Cyan Toner G having the physical properties shown in Table 1.

Manufacture of Magenta Toner G Magenta Toner B manufactured in Magenta Toner B was heat-treated for a shorter time than Magenta Toner C to obtain Magenta Toner G having the physical properties shown in Table 1.

Production of Yellow Toner G The yellow toner B produced in the production of the yellow toner B was subjected to a heat treatment for a shorter time than that of the yellow toner C to obtain a yellow toner G having the physical properties shown in Table 1.

Production of Black Toner G The black toner B produced in the production of the black toner B was subjected to a heat treatment for a shorter time than that of the black toner C to obtain a black toner G having the physical properties shown in Table 1.

[0106]

[Table 1]

Manufacture of Photosensitive Drum A A drum base made of aluminum having a diameter of 30 mm has an undercoat layer as a first layer, and is a conductive layer having a thickness of 20 μm for preventing generation of moire due to reflection of exposure. The second layer is a positive charge injection layer, and has a role of preventing the positive charges injected from the drum substrate from canceling out the negative charges charged on the surface of the photoconductor. ^The thickness adjusted to about ⁶ Ωcm is about 0. It is a medium resistance layer of 1 μm. The third layer is a charge generation layer and has a thickness of about 0.3 μm in which a disazo pigment is resin-dispersed.
Layers that generate positive and negative charge pairs upon exposure. The fourth layer is a charge transport layer, which is a polycarbonate resin in which hydrazone is dispersed, and is a p-type semiconductor. The fifth layer is a layer thickness 2 formed of a polycarbonate resin.
It is a surface layer of μm. The contact angle of water on the surface of the photosensitive drum A was 80 degrees.

Production of Photoreceptor Drums B to F Instead of the surface layer of the fifth layer formed in the production of photoreceptive drum A, 2 parts by weight of Teflon (PTFE under the trademark of DuPont) is added to 100 parts by weight of the polycarbonate resin. (Photosensitive drum B), 5 parts by weight (photosensitive drum C), 7 parts by weight (photosensitive drum D), 10 parts by weight (photosensitive drum E), 11
Photosensitive drums B to F were manufactured in the same manner as the photosensitive drum A, except that a surface layer of 2 μm in which each part by weight (photosensitive drum F) was dispersed was formed. The contact angles of water on the surfaces of the photosensitive drums B to F are 85 degrees (photosensitive drum B), 92 degrees (photosensitive drum C), 95 degrees (photosensitive drum D), and 100 degrees (photosensitive body, respectively). Drum E) and 103 degrees (photoreceptor drum F).

Photoreceptor Drum G Instead of the surface layer of the fifth layer used in the photoreceptor drum A, a photoreceptor drum G having a surface layer formed of a photocurable acrylic resin as the fifth layer is manufactured. did. The contact angle of water on the surface of the photosensitive drum G was 82 degrees.

Production of Photoreceptor Drums H and I Instead of the surface layer of the fifth layer formed in the production of photoreceptive drum G, 100 parts by weight of photocurable acrylic resin was added to SnO _2.
Photoreceptor drums H and I having layers in which 200 parts by weight and 30 parts by weight and 35 parts by weight of fluororesin particles such as Teflon were respectively dispersed were obtained.

The contact angles of water on the surfaces of the photosensitive drums H and I were 102 ° and 103 °, respectively.

Example 1 In the image forming apparatus of the first embodiment shown in FIG. 1, four color toners of cyan toner A, magenta toner A, yellow toner A and black toner A were mixed with a carrier. Using the prepared four-color two-component developer in combination with the photoconductor drum B, continuous image formation on 7,000 sheets was performed under the following development and transfer conditions, and retransfer efficiency and chromaticity change due to toner mixing and full color The chromaticity of the image was evaluated.

Development conditions AC bias: V _PP = 2 kV, f = 2 kHz, DC component:
A developing waveform having a driving waveform of _VDC = -500V was used.

The toner existing on the photoconductor after the transfer was collected and cleaned at the time of development with a magnetic brush composed of the toner of the developing device and the carrier.

Transfer conditions: + 2.0k for the blade that contacts the back of the transfer belt.
V was applied.

As shown in Table 2, the evaluation result shows that the retransfer efficiency is low, a good image in which the image deterioration, the density decrease, and the color balance shift are suppressed is obtained, and the toner color mixture in the developing device is caused by the simultaneous development collection. I was able to suppress it. further,
Cyan toner consumption is 0.05g / sheet (A4 size), 8% compared to the case with conventional cleaner
It was a small value.

The retransfer rate was 3.5% at the initial stage and 70,000.
After the endurance of the sheets, it was 6.5%. The change in chromaticity of cyan single color due to remixing of magenta toner onto the cyan developing device after formation of 70,000 full-color images had a color difference of 8.
With a color difference of about 8, sufficiently good color reproduction can be obtained.

(1) The retransfer rate was determined by the following method.

A solid magenta image is formed by the first-color image forming unit (magenta unit), this solid magenta image is transferred onto the image receiving member, and the magenta toner of the solid magenta image transferred onto this image receiving member is transferred. The amount (W ₁ ) of magenta toner transferred and collected by a suction device provided with a filter is obtained.

Next, a solid magenta image is formed by the first color image forming unit (magenta unit), this solid magenta image is transferred onto the image receiving member, and then the second color image forming unit (cyan unit). To form a solid white image (a cyan toner image is not formed on the photoconductor drum), and the solid white image is transferred onto the image receiving member to which the solid magenta image is transferred (actually,
Only the transfer operation is performed because a cyan toner image is not formed), and the magenta toner existing (transferred again) on the photosensitive drum of the second color image forming unit after transfer is collected by a suction device provided with a filter. Then, the re-transferred magenta toner amount (W ₂ ) is obtained.

From the values of the transferred magenta toner amount (W ₁ ) and the retransferred magenta toner amount (W ₂ ) obtained above, the retransfer ratio of the magenta toner was calculated according to the following formula, and based on the following evaluation criteria. evaluated.

Retransfer rate (%) = {(W ₂ ) / (W ₁ )} × 100

-Evaluation Criteria-Retransfer Rate <5.0: Virtually No Retransfer 5.0 <Retransfer Rate <7.0: Almost No Retransfer 7.0 <Retransfer Rate <8.0: Retransfer Slightly 8.0 ≦ Retransfer rate <9.0: Retransfer is present 9.0 ≦ Retransfer rate: Retransfer is considerable

(2) The chromaticity change of a single-color image is caused by the re-transfer of the magenta toner, which is the first color image forming unit, to the cyan unit, which is the second color image forming unit. Was evaluated by the color difference (ΔE) obtained as described below.

X-Rite 404 manufactured by X-Rite was used to obtain a color difference (ΔE) from the color data (lightness (L ^* ) and chromaticity (a ^* , b ^* )) of the original image and the copied image based on the following equation. ) Was obtained and evaluated based on the following evaluation criteria.

ΔE = {(L ₁ ^* -L ₂ ^* ) ² + (a ₁ ^* -
^{_{a 2 *) 2 + (b}} 1 * -b 2 *) 2} 1/2 (L 1 *, a 1 *, b 1 *: original color data of the ^{_{image) (L 2 *, a 2}} *, b 2 ^* : Color data of copied image)

-Evaluation Criteria-ΔE ≦ 6.0: Better 6.0 <ΔE ≦ 8.0: Good 8.0 <ΔE ≦ 10.0: Good 10.0 <ΔE ≦ 12.0: Not good 12 0.0 <ΔE: Not better

(3) The chromaticity evaluation of a full-color image corresponds to the chromaticity change of a single color.
How faithfully the copied image was reproduced with respect to the original image was evaluated according to the following evaluation criteria.

-Evaluation Criteria- A: Reproduced extremely faithfully to the original image B: Reproduced almost faithfully to the original image C: Color balance is slightly degraded, but it is in a sufficiently practical area D: Color balance Is slightly broken E: The color balance is considerably broken

(Examples 2 to 18 and Comparative Examples 1 to 7)
The cyan toner A, the magenta toner A, the yellow toner A, and the black toner A used in the examples were replaced by the respective color toners shown in Table 1, and the photosensitive drum B was replaced by the photosensitive drum shown in Table 1. Image formation was performed and evaluated in the same manner as in Example 1. Table 2 shows the evaluation results.

Comparative Example 8 In the image forming apparatus of the first embodiment shown in FIG. 1 used in Example 1, the toner existing on the photoconductor after being transferred to the cyan unit is brought into contact with the surface of the photoconductor drum. When a cleaner having a cleaning grade was provided and images were collected and collected, the consumption amount of the cyan toner was 0.055 g / sheet (A4 size), which was about 8% higher than that in the first embodiment.

[0132]

[Table 2]

(Example 9) In the image forming apparatus of the second embodiment shown in FIG. 6, the spherical polymerized toner A and the contact angle of water are 103.
Image forming was performed on 70,000 sheets under the following developing conditions and primary transfer conditions by using the photosensitive drum F in combination.

Development conditions AC bias: V _PP = 2 kV, f = 2 kHz, DC component:
A developing waveform having a driving waveform of _VDC = -500V was used.

The toner present on the photoconductor after the transfer was collected and cleaned at the time of development with a magnetic brush composed of the toner of the developing device and the carrier.

Primary transfer conditions: +2.0 kV was applied to the transfer blade.

As a result, an excellent image without image defects due to retransfer was obtained, and color mixing of toner in the developing device due to simultaneous recovery during development was suppressed. The full-color image after running a large number of sheets had less color balance deviation than the initial full-color image.

(Embodiment 20) In the image forming apparatus of the third embodiment in which the color order of the image forming units shown in FIG. 7 is changed,
When the same combination as in Example 5 was used, a spherical polymerized toner A and a photosensitive drum F having a contact angle of water of 103 degrees were used in combination, and image formation was carried out under the same development and transfer conditions as in Example 5. As shown in Table 3, the full-color image after 100,000 durability had less change in chromaticity than that in Example 5, and color shift was less likely to occur.

[0139]

[Table 3]

(Embodiment 21) The black unit is removed from the image forming apparatus used in Embodiment 1, and the image forming apparatus is modified into a three-color image forming unit of a cyan unit, a magenta unit and a yellow unit, and three color toners are used. When images were formed in the same manner as in Example 1 except that a full-color image was formed, black reproducibility of black characters and the like was slightly deteriorated as compared with Example 1, but overall good results were obtained. Was obtained.

[0141]

As described above, according to the present invention,
By using a photoconductor having a contact angle of water of 85 degrees or more on the surface, it is possible to realize a very simple and compact color printer that can obtain a high-quality image without retransfer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a model diagram illustrating retransfer of the first color.

FIG. 3 is a graph showing data obtained by measuring the charge amounts of the transferred toner after transfer and the toner remaining on the drum by retransfer.

FIG. 4 is an explanatory diagram showing the relationship between transfer current, transfer efficiency, and retransfer.

FIG. 5 is an explanatory diagram of a relationship among a toner shape, a mirror image force, and a van der Waalsca.

FIG. 6 is a schematic configuration diagram of an image forming apparatus according to a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an image forming apparatus according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram of chromaticity change due to color mixture of magenta toner, yellow toner, and cyan toner.

FIG. 9 is an explanatory diagram of chromaticity change when yellow toner and magenta toner are mixed with cyan toner.

FIG. 10 is an explanatory diagram of chromaticity change when yellow toner and cyan toner are mixed with magenta toner.

FIG. 11 is a schematic configuration diagram of a conventional image forming apparatus.

[Explanation of symbols]

 UM Magenta image forming unit UC Cyan image forming unit UY Yellow image forming unit UBk Black image forming unit 10 Photoreceptor drum (latent image bearing member) 12-Next charger 13 Pre-exposure lamp 14 Image exposure unit 16 Developer 18 Transfer paper ( Image receiving member) 20 Paper feed roller 25 Transfer blade 26 Secondary transfer roller 27 Backup roller 30 Transfer belt 31 Belt drive roller 38 Fixer 50 Intermediate transfer body 51 Belt cleaner Tm Magenta toner image Tc Cyan toner image Qb Transfer charge

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 18, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a model diagram illustrating retransfer of the first color.

FIG. 3 is a graph showing data obtained by measuring the charge amounts of the transferred toner after transfer and the toner remaining on the drum by retransfer.

FIG. 4 is an explanatory diagram showing the relationship between transfer current, transfer efficiency, and retransfer.

FIG. 5 is an explanatory diagram of a relationship among a toner shape, a mirror image force, and a Van der Waals force.

FIG. 6 is a schematic configuration diagram of an image forming apparatus according to a second embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of an image forming apparatus according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram of chromaticity change due to color mixture of magenta toner, yellow toner, and cyan toner.

FIG. 9 is an explanatory diagram of chromaticity change when yellow toner and magenta toner are mixed with cyan toner.

FIG. 10 is an explanatory diagram of chromaticity change when yellow toner and cyan toner are mixed with magenta toner.

[Description of Reference Signs] UM Magenta Image Forming Unit UC Cyan Image Forming Unit UY Yellow Image Forming Unit UBk Black Image Forming Unit 10 Photosensitive Drum (Latent Image Carrier) 12 Primary Charger 13 Pre-exposure Lamp 14 Image Exposure Unit 16 Developer 18 Transfer Paper (Image Receiving Member) 20 Paper Feed Roller 25 Transfer Blade 26 Secondary Transfer Roller 27 Backup Roller 30 Transfer Belt 31 Belt Drive Roller 38 Fixing Device 50 Intermediate Transfer Body 51 Belt Cleaner Tm Magenta Toner Image Tc Cyan Toner Image Qb Transfer charge

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location G03G 15/08 507 G03G 9/08 381 (72) Inventor Hiroyuki Suzuki 3 chome Shimomaruko, Ota-ku, Tokyo 30 No. 2 Canon Inc.

Claims (31)

[Claims] 1. (i) a first latent image carrier for carrying a first electrostatic latent image, and (ii) a first latent image carrier for the first latent image carrier.
First latent image forming means for forming an electrostatic latent image of
ii) first developing means for developing the first electrostatic latent image with a first toner to form a first toner image on the first latent image carrier, and (iv) the first developing means. A first image forming unit having a first transfer means for transferring the first toner image on the first latent image carrier onto an image receiving member; and (i) a second electrostatic latent unit. A second latent image carrier for carrying an image, (ii) second latent image forming means for forming a second electrostatic latent image on the second latent image carrier, (iii) Second developing means for developing the second electrostatic latent image with a second toner to form a second toner image on the second latent image carrier, and (iv) the second developing means. The first toner image formed on the latent image carrier by the first image forming unit is transferred to the second toner image.
Second transfer means for transferring the toner image on the image receiving member having the toner image, and the second developing means recovers the toner existing on the second latent image carrier after the transfer. However, the image forming apparatus includes at least a second image forming unit that also has a function as a cleaning unit for cleaning, and the surface of the second latent image carrier has a contact angle with water of 85.
An image forming apparatus characterized by being at least once. 2. The contact angle of water on the surface of the second latent image carrier is 90 degrees or more.
An image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein a contact angle of water on the surface of the second latent image carrier is 100 degrees or more. 4. The SF-1 of the first toner is 100 to 100.
The image forming apparatus according to any one of claims 1 to 3, wherein 180 and SF-2 have a shape factor of 100 to 140. 5. The SF-1 of the first toner is 100 to 100.
The image forming apparatus according to claim 1, wherein 130 and SF-2 have a shape factor of 100 to 120. 6. The image forming apparatus according to claim 1, wherein the first toner has a spherical shape. 7. The first toner has SF-1 of 100 to 100.
180, SF-2 has a shape factor of 100 to 140, and the second toner has SF-1 of 100 to 180,
The image forming apparatus according to any one of claims 1 to 3, wherein SF-2 has a shape factor of 100 to 140. 8. The SF-1 of the first toner is 100 to 100.
130, SF-2 has a shape factor of 100 to 120, and the second toner has SF-1 of 100 to 130,
The image forming apparatus according to claim 1, wherein SF-2 has a shape factor of 100 to 120. 9. The image forming apparatus according to claim 1, wherein the first toner has a spherical shape, and the second toner has a spherical shape. 10. The first toner is obtained by polymerizing a monomer composition containing at least a polymerizable monomer and a colorant in a dispersion medium. The image forming apparatus according to any one of 1. 11. The first toner is obtained by subjecting toner particles obtained by melting, kneading, pulverizing and classifying a toner raw material containing at least a binder resin and a colorant to a spheroidizing treatment. The image forming apparatus according to claim 1, wherein: 12. The image forming apparatus further includes a third image forming unit in addition to the first image forming unit and the second image forming unit, and the third image forming unit. Is (i) a third latent image carrier for carrying a third electrostatic latent image, and (ii) a third latent image carrier for forming a third electrostatic latent image on the third latent image carrier. Third latent image forming means, (iii) a third toner for developing the third electrostatic latent image with a third toner to form a third toner image on the third latent image carrier. Developing means, and (iv) forming the third toner image on the third latent image carrier by the first toner image formed by the first image forming unit and the second image forming unit by the second image forming unit. A third transfer means for transferring the formed second toner image onto the image-receiving member, and the third developing means includes a transfer means. To collect the toner present on the latent image bearing member the third, also has a function as a cleaning means for cleaning, third
12. The image forming apparatus according to claim 1, wherein the surface of the latent image carrier has a contact angle with water of 85 degrees or more. 13. The first toner, the second toner and the third toner are any of magenta toner, cyan toner and yellow toner, and the magenta toner, cyan toner and yellow toner. 13. The image forming apparatus according to claim 12, wherein a combination of three color toners is formed, and a full color image can be formed by the combination of the three color toners. 14. The first toner is a yellow toner, the second toner is a magenta toner, the third toner is a cyan toner, and the yellow toner, the magenta toner and the cyan toner are The image forming apparatus according to claim 12, wherein a full-color image can be formed by combination. 15. The contact angle of water on the surface of the second latent image carrier is 90 degrees or more, and the contact angle of water on the surface of the third latent image carrier is 90 degrees or more. The image forming apparatus according to any one of claims 12 to 14, which is characterized in that. 16. The contact angle of water on the surface of the second latent image carrier is 100 degrees or more, and the contact angle of water on the surface of the third latent image carrier is 100 degrees or more. The image forming apparatus according to any one of claims 12 to 14, which is characterized in that. 17. The first toner has an SF-1 of 100.
.About.180, SF-2 has a shape factor of 100 to 140, and the second toner has SF-1 of 100 to 18
0, SF-2 has a shape factor of 100 to 140, and the third toner has SF-1 of 100 to 180 and S
The image forming apparatus according to claim 12, wherein F-2 has a shape factor of 100 to 140. 18. The SF-1 toner of the first toner is 100.
˜130, SF-2 has a shape factor of 100˜120, and the second toner has SF−1 of 100˜13.
0, SF-2 has a shape factor of 100 to 120, and the third toner has SF-1 of 100 to 130 and S
The image forming apparatus according to claim 12, wherein F-2 has a shape factor of 100 to 120. 19. The first toner is spherical and the second toner is spherical.
17. The image forming apparatus according to claim 12, wherein the toner is spherical and the third toner is spherical. 20. The image forming apparatus further comprises a third image forming unit and a fourth image forming unit in addition to the first image forming unit and the second image forming unit, The third image forming unit includes (i) a third latent image carrier for carrying a third electrostatic latent image, and (ii) a third electrostatic latent image carrier on the third latent image carrier. Third latent image forming means for forming an image, (iii) developing the third electrostatic latent image with a third toner, and forming a third toner image on the third latent image carrier. Third developing means for forming, and (iv) the first toner image and the first toner image formed by the first image forming unit on the third toner image on the third latent image carrier. A third transfer means for transferring onto the image receiving member having the second toner image formed by the second image forming unit. Developing means said third toner present on the latent image bearing member third recovered after the transfer, also has a function as a cleaning means for cleaning, third
The surface of the latent image carrier has a contact angle with water of 85 degrees or more, and the fourth image forming unit includes (i) a fourth latent image carrier for carrying a fourth electrostatic latent image. Body, (ii) fourth latent image forming means for forming a fourth electrostatic latent image on the fourth latent image carrier, and (iii) the fourth electrostatic latent image with a fourth toner. Developing means for forming a fourth toner image on the fourth latent image carrier, and (iv) the fourth toner image on the fourth latent image carrier. The first toner image formed by the first image forming unit, the second toner image formed by the second image forming unit, and the first toner image formed by the third image forming unit. 3 has a fourth transfer means for transferring onto the image receiving member having the toner image, and the fourth developing means has the fourth latent image carrier after the transfer. It also has a function as a cleaning means for collecting and cleaning the toner present above, and the surface of the fourth latent image carrier has a contact angle with water of 85 degrees or more. The image forming apparatus according to any one of claims 1 to 11. 21. The first toner, the second toner, the third toner, and the fourth toner are magenta toner,
Any one of cyan toner, yellow toner, and black toner, and forms a combination of four color toners of the magenta toner, the cyan toner, the yellow toner, and the black toner, and a combination of the four color toners. The image forming apparatus according to claim 20, wherein a full color image can be formed by 22. The first toner is a yellow toner, the second toner is a magenta toner, the third toner is a cyan toner, the fourth toner is a black toner, and the fourth toner is a black toner. 21. The image forming apparatus according to claim 20, wherein a full color image can be formed by combining a yellow toner, the magenta toner, the cyan toner and the black toner. 23. The contact angle of water on the surface of the second latent image carrier is 90 degrees or more, and the contact angle of water on the surface of the third latent image carrier is 90 degrees or more. 23. The image forming apparatus according to claim 20, wherein a contact angle of water on the surface of the fourth latent image carrier is 90 degrees or more. 24. The contact angle of water on the surface of the second latent image carrier is 100 degrees or more, and the contact angle of water on the surface of the third latent image carrier is 100 degrees or more. Fourth
23. The image forming apparatus according to claim 20, wherein a contact angle of water on the surface of the latent image carrier is 100 degrees or more. 25. The first toner has an SF-1 of 100.
.About.180, SF-2 has a shape factor of 100 to 140, and the second toner has SF-1 of 100 to 18
0, SF-2 has a shape factor of 100 to 140, and the third toner has SF-1 of 100 to 180 and S
F-2 has a shape factor of 100 to 140, and the fourth toner has SF-1 of 100 to 180 and SF-2 of 1
The image forming apparatus according to any one of claims 20 to 24, having a shape factor of 00 to 140. 26. The first toner has SF-1 of 100.
˜130, SF-2 has a shape factor of 100˜120, and the second toner has SF−1 of 100˜13.
0, SF-2 has a shape factor of 100 to 120, and the third toner has SF-1 of 100 to 130 and S
F-2 has a shape factor of 100 to 120, and the fourth toner has a shape factor of 100 to 130 for SF-1 and 100 to 120 for SF-2. The image forming apparatus according to claim 20. 27. The first toner is spherical, and the second toner is spherical.
Toner is spherical and the third toner is spherical,
3. The fourth toner is spherical in shape.
The image forming apparatus according to any one of 0 to 24. 28. The image forming apparatus according to claim 1, wherein the image receiving member is a recording material. 29. The image receiving member is an intermediate transfer material member, and the image forming apparatus transfers the first toner image and the second toner image transferred onto the intermediate transfer member onto a recording material. The image forming apparatus according to any one of claims 1 to 12, further comprising a secondary transfer unit for performing secondary transfer collectively. 30. The image receiving member is an intermediate transfer material member, and the image forming apparatus is configured such that the first toner image, the second toner image and the third toner image transferred onto the intermediate transfer member. 20. An image forming apparatus according to claim 13, further comprising a secondary transfer unit for secondarily transferring the toner images of 1. to the recording material collectively. 31. The image receiving member is an intermediate transfer material body, and the image forming apparatus is configured such that the first toner image, the second toner image, and the third toner image transferred onto the intermediate transfer body. 29. The image according to any one of claims 20 to 28, further comprising a secondary transfer unit for collectively secondary-transferring the toner image of 4 and the fourth toner image onto a recording material. Forming equipment.