JPH035749B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to color image recording in which a plurality of color toner images are superimposed on an image forming body by repeating electrostatic image formation and development on the image forming body. Regarding the method.

[Prior art]

Conventionally, as a color image recording method as described above, Japanese Patent Application Laid-Open No. 56-144452 and Japanese Patent Application Laid-Open No. 116553-1983
The methods described in Japanese Patent Application Publication No. 2006-119012 and Japanese Patent No. 58-116554 are known. Both of these methods
The image forming body has a photoconductive photoreceptor layer made of Se or the like on its surface, and development is a reversal development process in which a toner triboelectrically charged to the same polarity is attached to an electrostatic image at a low potential compared to the background potential. It is by law. Generally, the electrostatic image forming performance of the photoconductive photoreceptor layer is relatively easily changed by the charging process, and
There are problems in that toner filming occurs and photoreceptor characteristics tend to deteriorate. Development using the reversal development method is a positive development method similar to that used in ordinary electrophotographic copying machines, in which the electrostatic image potential is higher than the background potential, and toner charged with the opposite polarity is attached to the electrostatic image. Compared to conventional development, it is difficult to control toner adhesion, and there are problems such as not being able to obtain a sufficient development density, and the inside of the recording device being easily contaminated due to toner scattering.

On the other hand, methods for forming an electrostatic image on the dielectric layer using an image forming body having a dielectric layer on its surface include those using an electrostatic recording head and those using a screen photoreceptor (Japanese Patent Publication No. 34616), or one using a screen control electrode (Japanese Patent Application Laid-Open No. 137363/1983). These electrostatic image forming methods are excellent in that they separate the electrostatic image forming ability required of the photoreceptor from the toner image forming ability. That is, in these methods, the ability to form an electrostatic image is assumed to be shared by the electrostatic recording head, the screen photoreceptor, or the screen control electrode, and the ability to form a toner image is assumed to be shared by the dielectric layer. Ru. Such a method has the feature that color information is sequentially and independently formed as an electrostatic image on the dielectric layer. However, the toner image created on the dielectric layer could only be monochromatic.

This is because the development method is contact development, and even if an electrostatic image can be further recorded on the previously formed toner image, it may disturb the previous toner image or cause color mixture during development. This is because you will wake up.

[Purpose of the invention]

The present invention was made in order to solve the problems in the conventional color image recording method as described above, and uses a means for forming an electrostatic image on a dielectric layer to stabilize the formation of an electrostatic image. ensure that it is done;
Furthermore, a novel color image recording method is provided by devising a method of overlapping development using dielectric layers.

[Structure of the invention]

That is, in the present invention, on a rotating image forming body having a dielectric layer on its surface, image writing by an image writing means common to charging and non-contact development using dry toner are performed while the image forming body rotates once. The color image recording method is characterized in that the toner images of a plurality of colors are repeatedly formed on the image forming body and then fixed, or the toner images are transferred to the recording body and then fixed.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to illustrated examples.

FIG. 1 is a schematic configuration diagram showing an example of a recording device used in carrying out the method of the present invention, FIG. 2 is a partial sectional view of the recording device showing an example of a developing device, and FIGS. 1 is a flowchart for implementing the method of the invention.

In FIG. 1, 1 is a drum-shaped image forming body which rotates in the direction of the arrow, which is formed by providing a dielectric layer such as a resin on a metal base, 2 is a pre-writing charger, and 3 is an electrostatic charger having a needle-shaped discharge electrode. A recording head, 4 to 7 are developing devices, 8 is a pre-transfer charging device, and 9 is a transfer device for transferring a color image formed by superimposing the color toner images formed on the image forming body 1 onto the recording body P. , 10 is a fixing device for fixing the color image on the recording medium P, 11 and 13 are static eliminators, and 12 is a cleaning member 12a consisting of a fur brush, a blade, etc. that moves towards and away from the surface of the image forming body 1. This is a cleaning device that comes into contact with the surface of the image forming body 1 after color image transfer to remove residual toner.

Note that one of the pre-writing charger 2 and the static eliminator 13 may be omitted, but it is preferable to omit the static eliminator 11.
It is preferable to omit the static eliminator 13 and use it also as the static eliminator 13.
As the pre-writing charger 2, it is particularly preferable to use a scorotron corona discharger as shown in the figure. When the scorotron corona discharger is used, the image forming body 1 can be uniformly charged and neutralized without being affected by the previous charging state. It is preferable to use scorotron corona dischargers for the static eliminators 11 and 13 as well. Furthermore, the pre-transfer charger 8 may be omitted if the transfer device 9 alone can perform sufficient transfer.
The electrostatic recording head 3 forms an electrostatic image of a charged spot distribution on the dielectric layer of the image forming body 1 using needle discharge electrodes arranged in one or more rows.
The developing devices 4 to 7 preferably have a structure as shown in FIG. 2.

In FIG. 2, 31 is a developing sleeve made of non-magnetic material such as aluminum or stainless steel;
2 is a magnet body provided inside the developing sleeve 31 and has a plurality of magnetic poles in the circumferential direction; 33 is a layer thickness regulating blade that regulates the thickness of the developer layer formed on the developing sleeve 31; and 34 is a developing sleeve. 31 is a scraper blade that removes the developer layer after development from above; 35 is a stirring rotor that stirs the developer in the developer reservoir 36; 37 is a toner hopper; 38 is a surface that replenishes toner from the toner hopper 37 to the developer reservoir 36. A toner replenishing roller 39 has a recess into which toner enters, and applies a bias voltage, which may also have a vibrational component, to the developing sleeve 31 via a protective resistor 40 to increase the voltage between the developing sleeve 31 and the image forming body 1. This is a power source for forming an electric field to control the movement of toner, and the figure shows that the developing sleeve 31 and the magnet body 32 rotate in the directions of arrows,
1 may be fixed, the magnet body 32 may be fixed, or the developing sleeve 31 and the magnet body 32 may rotate in the same direction. When the magnet body 32 is fixed, usually in order to make the magnetic flux density of the magnetic pole facing the image forming body 1 larger than the magnetic flux density of other magnetic poles, the magnetization is strengthened or a magnetic pole of the same or different polarity is attached thereto. Two magnetic poles may be provided close to each other.

In such a developing device, the magnetic pole of the magnet body 32 is usually
It is magnetized to a magnetic flux density of 500 to 1500 Gauss,
The developed material in the developer reservoir 36 is attracted to the surface of the developing sleeve 31 by the magnetic force, and the thickness of the adsorbed developer is regulated by the layer thickness regulating blade 33 to form a developer layer, and the developed material is The agent layer moves in the same direction or in the opposite direction to the rotation arrow direction of the image forming body 1 (same direction in the figure), and the image forming body 1 is moved in the developing area where the surface of the developing sleeve 31 faces the surface of the image forming body 1. The remaining electrostatic image is removed from the surface of the developing sleeve 31 by a scraper blade 34 and returned to the developer reservoir 36. The development is performed under non-contact jumping development conditions so that the toner adhered to the image forming body 1 during the previous development, which is repeated to superimpose the color toner images, is not shifted during the subsequent development. I'll do it. FIG. 2 shows a state in which development is performed under non-contact jumping development conditions.

Furthermore, in the developing units 4 to 7, non-magnetic toner is used, which does not require the inclusion of a black or brown magnetic substance in the toner and can obtain a toner with a clear color, and the charging of the toner can be easily controlled. It is preferable to use a so-called two-component developer consisting of a mixture of a magnetic carrier and a magnetic carrier. In particular, when magnetic carriers are used in resins such as styrene resins, vinyl resins, ethyl resins, rosin-modified resins, acrylic resins, polyamide resins, epoxy resins, and polyester resins, triiron tetroxide,
γ-ferric oxide, chromium dioxide, manganese oxide,
A material with low resistivity that is made of dispersed fine particles of ferromagnetic or paramagnetic material such as ferrite, manganese-copper alloy, or the surface of these magnetic material particles is coated with the above-mentioned resin. 10 ^8Ωcm
As mentioned above, it is preferable to use an insulating carrier having a resistance of preferably 10 ¹³ Ωcm or more. If this resistivity is low, when a bias voltage is applied to the developing sleeve 31, charges may be injected into the carrier particles, making it easier for the carrier particles to adhere to the surface of the image forming body. The problem arises that no voltage is applied. In particular, if the carrier adheres to the image forming body 1, it will adversely affect the tone of the color image.

The resistivity was determined by placing the particles in a container with a cross-sectional area of 0.50 cm ² and tapping them, then applying a load of 1 kg/cm ² on the packed particles, and applying a load of 1 kg/cm 2 between the electrode that also served as the load and the bottom electrode. This value is obtained by reading the current value when a voltage is applied that generates an electric field of 1000 V/cm.

In addition, if the average particle size of the carrier is less than 5 μm, the magnetization will be too weak, and if it exceeds 50 μm, the image will not be improved, breakdown or discharge will easily occur, and high voltage will not be able to be applied. The diameter is preferably 5 μm or more and 50 μm or less, and if necessary, a suitable amount of a flow agent such as hydrophobic silica is added as an additive.

The black toner used is the same as that used in conventional two-component developers, the cyan toner is a toner with copper phthalocyanine added instead of black carbon black, and the magenta toner is the same as that used in conventional two-component developers. Those to which tungstophosphoric acid has been added, and yellow ones to which benzidine derivatives have been added are also used. but,
It goes without saying that the toner is not limited to such colored toners using pigments, but may also be colored toners using dyes, and a charge control agent or the like may be added as necessary. The toner has an average particle size of 1 to 20 μm.
Those with an average charge amount of 3 to 3 are preferable.
300 μc/g, particularly 10 to 100 μc/g is preferred. When the average particle size of toner is less than 1 μm, it becomes difficult to separate from the carrier, and when it exceeds 20 μm, the resolution of the image decreases.

When a developer made of a mixture of an insulating carrier and toner as described above is used, the bias voltage applied to the developing sleeve 31 shown in FIG. Settings can be easily performed without fear of leaks. In order to more effectively control the development movement of the toner by applying such a bias voltage, the toner may also contain a magnetic material such as that used in magnetic carriers to the extent that color clarity is not impaired. It's okay.

The above is the structure of the developing device and developer preferably used in the method of the present invention, but the present invention is not limited to this.
58-116553 to 116554 may use the developer, and more preferably, the developing device described in Japanese Patent Application Laid-open No. 59-1989, which was previously filed by the applicant of the present application, may be used.
No. 181362, No. 59-222847, No. 59-222851~3
It is preferable to carry out non-contact jumping development using a two-component developer using a developing device and a developer as described in each publication.

The order in which the colors are developed by the developing units 4 to 7, each using a different color toner developer, must be carefully determined because it affects the tone of the color image.

In the above-described recording apparatus shown in FIG. 1, if the image forming body 1 is made of electrofax paper having a dielectric layer on the surface removably wound on the drum, the pre-transfer charger 8 The transfer device 9, the static eliminator 11, and the cleaning device 12 are no longer necessary.
The image forming body in this case is removed from the drum after color image formation, preferably after color image fixation.

With the recording apparatus as described above, the method of the present invention as shown in the examples of FIGS. 3 to 5 can be carried out. Note that FIGS. 3 to 5 all show up to the stage where the second development has been performed.

In the embodiment shown in FIG. 3, according to the recording apparatus shown in FIG.
From the initial state (the figure shows the charged state), which is cleaned in step 2 and charged negatively or positively if necessary by the pre-writing charger 2, the surface is cleaned by the electrostatic recording head 3. Writing is performed twice to form an electrostatic image with a potential different in polarity from the background potential, and the electrostatic image is developed for the first time in the developing device 4. Then, when the image forming member 1 enters the second rotation, After uniform charging is performed again by the charger 2 as needed, a second writing is performed by the electrostatic recording head 3, and the electrostatic image thus formed is developed for a second time by the developer 5. Writing and development are repeated in the same manner for the third and fourth times, and as a result, the image forming body 1
A color image is formed by superimposing color toner images, and the color image is made easy to transfer by the pre-transfer charger 8, and after being transferred to the recording medium P by the transfer device 9, it is transferred to the fixing device. The image is fixed on the recording medium P by 10. Then, the surface of the image forming body 1 to which the color image has been transferred is neutralized by a static eliminator 11, residual toner is removed by a cleaning device 12, and if necessary, the static eliminator 13 is further removed to record a color image. 4 shows the method of the present invention in which one cycle of is completed.

The embodiment shown in FIG. 4 is an example using the recording apparatus shown in FIG. 1, and differs from the embodiment shown in FIG. This shows the method of the present invention, which is performed in the same manner as the embodiment shown in FIG. 3, except that the image forming body 1 is neutralized by a static eliminator 11.

The embodiment shown in FIG. 5 also shows an example based on the recording device shown in FIG.
This embodiment differs from the embodiment shown in FIG. 3 in that the embodiment operates as follows.

Note that T and T' in FIGS. 3 to 5 are toners of different colors attached to the image forming body 1.

In the method of the present invention, development is performed under the non-contact jumping development conditions as described above, so that the developing devices other than those used for each development are
Even without removing the developer layer from the developing sleeve 31, the developing sleeve 31 can be disconnected from the power source 39 and placed in a floating state, or grounded, or the developing sleeve 31 can be actively set to the same polarity as the electrostatic image. That is, by applying a DC bias voltage with a polarity opposite to that of toner charging, it can be easily maintained in an inactive state. Among these, it is preferable to maintain the developing device in an inoperative state by applying a bias voltage having a polarity opposite to that of the toner.

Next, the third
The examples shown in FIGS. 7 to 5 will be described more specifically as Examples 1 to 3, respectively.

Example 1 A recording apparatus as shown in FIG. 1 was used. The image forming body 1 had an insulating layer of 20 μm on an Al base, and its peripheral speed was 180 mm/sec. The surface of this image forming body 1 is charged to -100V by a pre-writing charger 2 using a scorotron corona discharger,
Next, the tip of the needle electrode is approximately
The first writing was performed with an electrostatic recording head 3 spaced 30 μm apart at a distribution density of 10 spots/mm. As a result, an electrostatic image was formed on the image forming body 1 in which the potential of the writing part was +200V while the potential of the background part was -100V. This electrostatic image was first developed using a developing device 5 as shown in FIG. The developing device 5 contains 50wt% of magnetite dispersed in the resin with an average particle size.
A non-magnetic toner with an average particle size of 10 μm, which is made by adding a carrier having a magnetization of 20 μm, a magnetization of 30 emu/g, and a resistivity of 10 ¹⁴ Ωcm or more, and 10 parts by weight of copper phthalocyanine as a cyan pigment and other charge control agents to a styrene-acrylic resin. A developer consisting of was used under the condition that the ratio of toner to carrier was 10 wt%. Also,
The outer diameter of the developing sleeve 31 is 30 mm, and its rotation speed is
The magnetic flux density of the N and S magnetic poles of the 100 rpm magnet body 32 is
1000 Gauss, rotation speed is 1000 rpm.Thickness of the developer layer in the developing area is 0.7 mm.Gap between the developing sleeve 31 and the image forming body 1 is 0.8 mm.The developing sleeve 31 has a DC voltage component of 0V, 1.5KHz, and an AC of 1000V. A non-contact jumping development condition was used in which a bias voltage consisting of a voltage component was applied.

The surface of the image forming body 1 that has been subjected to the first development is transferred to the same electrostatic recording head 3 again without operating the pre-transfer charger 8, the static eliminators 11 and 13, the cleaning device 12, and the pre-write charger 2. The first
In the second writing, the spot position was shifted and the second writing was performed with the same spot density so that the potential of the writing part was +300V. Next, a toner in which polytungstophosphoric acid was added as a magenta pigment instead of a cyan pigment was used as a developer toner, and a bias voltage consisting of a 100 V DC voltage component and a 1.5 KHz, 1000 V AC voltage component was applied. is developed by the developing device 5 under the same conditions as the developing device 4.
I developed it twice. Similarly, the potential of the writing section is +
During the third writing to 400V, using a developer toner containing a benzidine derivative as a yellow pigment, the developing bias was set to 200V DC component.
A third development was carried out using the same conditions as developer 4 except that the alternating current component was 1.5KHz and 1000V.Furthermore, the fourth writing was performed so that the potential of the writing part was +500V, and a black pigment was added to the toner of the developer. A fourth process was performed using developer 7 under the same conditions as developer 4, except that toner containing carbon black was used and the developing bias was 300 V for the DC component and 1.5 KHz and 600 V for the AC component.
I developed it twice. The color image thus formed on the image forming member 1 was transferred and fixed onto the recording member P as described with reference to FIG. Further, the surface of the image forming body 1 to which the color image was transferred was charged with electricity removed by a static eliminator 11, and residual toner was removed by a cleaning device 12.

The recorded image obtained in the above manner was a very clear color image with little color mixing of color toners.

In this embodiment, the spot position of the subsequent writing may be overlapped with the spot position of the previous writing, or the electrostatic recording head may be adjusted so as to adjust the development density of each color during writing and development. The voltage value, frequency, and selection time of the DC component or AC component of the discharge voltage or the voltage applied to the developing sleeve may be changed. Overlapping writing spot positions tends to cause color mixing and muddying of the colors, but it is possible to increase the spot density and improve the tone. In this case, the order of colors to be developed is particularly important. Further, by adjusting the development density of each color as described above, a color image with a changed tone can be obtained.

Example 2 Using the same recording device as in Example 1, charging was not performed using the pre-writing charger 2 before the first writing in Example 1, and the potential was +150 V with respect to the background potential of 0 V in the first writing. The electrostatic image was formed, and during development, a +50V DC voltage was applied to the developing sleeve 31.
The weight voltage of 3KHz, 2000V AC voltage is applied as the bias voltage, and the static electricity is removed by the static eliminator 11 before the second and subsequent writing, so that the background potential is 0V even in the second and subsequent writing. Te+
Color image recording was carried out under the same conditions as in Example 1 except that an electrostatic image of 150V was formed.

The recorded image obtained was a color image with excellent clarity, similar to that in Example 1.

Example 3 Using the same recording device as in Example 1, charge to -300V with the charger 2 before the first write, and form an electrostatic image with a potential of +50V against the background potential of -300 in the first write. During development, a superimposed voltage of -200V DC voltage and 2KHz, 1KV AC voltage was applied as a bias to the developing sleeve 31, and the pre-writing charger 2 was used before the second and subsequent writing. The conditions were the same as in Example 1 except that
Color images were recorded. The recorded image obtained was a color image with excellent clarity, similar to that in Example 1.

[Effects of the Invention] According to the present invention, by using an image forming means that separates electrostatic image forming ability and toner image forming ability, the tone etc. of a color image can be easily changed, and the clarity is improved. The excellent effects of being able to record high-tone color images and stable recording can be obtained.

The present invention can be applied to a belt-shaped image forming body, or an image forming body is attached to a substrate such as electrofax paper, and the image forming body is applied to a belt-shaped image forming body. It may be one that fixes a color image using toner without transferring it. In that case, although it is necessary to consider the order in which the color toner images are superimposed, a pre-transfer lamp, a transfer device, a cleaning device, etc. are not necessary. Of course, the pre-transfer lamp and static eliminator are
It can also be omitted when the toner is transferred with a specific polarity and charge amount. Also,
In addition to corona transfer, the transfer may be bias roller transfer, adhesive transfer, direct pressure transfer, or transfer via an intermediate transfer member, and fixing is not limited to hot roller fixing.

Furthermore, although an electrostatic recording head is used as the writing means in the embodiments of the present invention, other means may be used as long as they form an electrostatic image on the dielectric layer. In other words, there are methods in which an electrostatic image is formed on a dielectric layer by controlling the amount of corona ion flow passing through with a control electrode, and a method in which an electrostatic charge pattern formed on the photoreceptor is controlled by a method using a screen photoreceptor to form an electrostatic image on a dielectric layer by controlling the amount of the corona ion flow. A method of forming an electrostatic image on a dielectric layer for controlling the amount of passage can be similarly applied.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a recording device used to carry out the method of the present invention, FIG. 2 is a partial sectional view of the recording device showing an example of a developing device, and FIGS.
Each figure is a flowchart for implementing the method of the invention. DESCRIPTION OF SYMBOLS 1... Image forming body, 2... Pre-writing charger, 3... Electrostatic recording head, 4-7... Developing device, 8... Pre-transfer charger, 9... Transfer device, 10... Fixing device, 11... Static eliminator,
12...Cleaning device, 31...Developing sleeve,
32... Magnet body, 33... Layer thickness regulating blade, 34...
Scraper blade, 35... Stirring magnet, 36...
Developer reservoir, 37... Toner hopper, 38... Toner replenishment roller, 39... Power supply, 40... Protection resistor.

Claims (1)

[Claims] 1 A rotating image forming body having a dielectric layer on its surface,
Charging, image writing by a common image writing means, and non-contact development using dry toner are repeated every time the image forming body rotates once, and toner images of multiple colors are formed on the image forming body. A color image recording method characterized by fixing the image or transferring it to a recording medium and then fixing it.