JPH02181180A - Recorder - Google Patents

Abstract

PURPOSE:To obtain images of high densities by specifying the volume average grain size of the 1st magnetic toner and forming this toner to the volume average grain size larger than the volume average grain size of the 2nd magnetic toner. CONSTITUTION:The volume average grain size of the 1st magnetic toner T1 which contains a magnetic material having the magnetic characteristics to allow permanent magnetization and forms the master images 52 by developing the electrostatic latent images formed on an image carrier 14 is specified to >=10mum. In addition, the same is formed to the volume average grain size larger than the volume average grain size of the 2nd magnetic toner T2 which develops the magnetic latent images formed on the master images 52 consisting of the 1st magnetic toner T1. The images of the practicably high densities are obtd. on paper in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a recording device used as a copying machine or a printer.

(Prior Art) Electronic copying machines and plate-making/printing devices are conventionally known as devices for copying originals.

In general, electronic copying machines are easy to set up for copying operations and are easy to handle. In contrast, plate making/printing equipment can create an original plate from a manuscript and use this master plate to repeatedly transfer onto recording paper, so it is possible to print at high speed after creating the original plate, and it is also possible to make copies from the same original. There is an advantage that the higher the number of sheets, the lower the printing cost.

By the way, with conventional plate-making and printing devices, when the number of copies made from the same manuscript is less than the same document, the original plate accounts for a large proportion of the cost, so the printing cost is higher than that of an electronic copying machine, and furthermore, a process to create the original plate is required. Therefore, it takes time and effort to set up the work.

On the other hand, electronic copying machines repeat processes such as charging, exposure, development, and neutralization each time they copy a single original, so the cost per copy does not decrease even if the number of copies made from the same original increases. However, the copying speed is considerably slower than that of a printing machine.

To address these problems, electric copying machines, as an extension of conventional technology, are capable of copying at a speed closer to that of printing, and do not require the skilled work and setup required for printing machines. is being put into practical use.

However, in order to further increase the copying speed, the electric power required for exposing the original, fixing the developer, and charging becomes extremely large. There is a problem that image quality may be sacrificed due to unreasonableness in the image quality, etc.

Therefore, the inventors of the present invention have developed a method that uses a permanent magnetizable first magnetic l.
A toner image is formed, this is magnetized by a magnetizing means to form a master image which is a printing original plate, and a magnetic latent image formed on this master image is developed with a second magnetic toner to form a master image on the master image. He invented and proposed a recording device that obtains a second toner image identical to the image (first toner image) and transfers this toner image to a transfer material (Japanese Patent Application Laid-Open No.
29273).

This recording apparatus has the advantage that it can perform high-speed duplication of multiple sheets from the same document in the same way as a printing machine, with the same simple operation as a conventional electronic copying machine, and has the advantage of low power consumption.

(Problems to be Solved by the Invention) However, the two-record recording device had the following major problems.

That is, in the recording apparatus described above, a master image formed by a magnetic latent image is developed with magnetic toner.
The amount of magnetic toner that adhered to the master image during this development was not sufficient, and as a result, the density of the final reproduced image on paper was much lower than, for example, with electrophotography. .

The above-mentioned problem is caused by the weak strength of the magnetic latent image of the mask image, and an improvement has been desired.

This invention was made in view of the above circumstances, and it is possible to obtain high-density images equivalent to that of an electrophotographic copying machine, and it is also possible to produce images from the same original using a simple process, similar to a printing machine. It is an object of the present invention to provide a recording device that can perform high-speed copying of a large number of sheets.

[Structure of the Invention (Means for Solving the Problems) A recording device according to the present invention includes an electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, and a magnetic property capable of permanent magnetization. a first developing means for developing the electrostatic latent image with a first magnetic toner containing a magnetic material; a fixing means for fixing onto the carrier; a magnetic latent image forming means for forming a magnetic latent image on the fixed first toner image; and a second magnetic latent image forming means for developing the magnetic latent image with a second magnetic toner. A recording device comprising a developing means and a transfer means for transferring a second toner image obtained on the first toner image by the second developing means to a transfer material, wherein the first magnetic The toner has a volume average particle size of 10 lt m or more and is larger than the volume average particle size of the second magnetic toner.

(Function) As described above, the present invention includes a magnetic material having magnetic properties capable of permanent magnetization, and develops an electrostatic latent image formed on an image carrier to form a master image. The volume average particle size of the magnetic material of the first magnetic toner is 10 μm or more, and is larger than the volume average particle size of the second magnetic toner that develops the magnetic latent image formed on the master image made of the first magnetic toner. do. This allows a practically high density image to be obtained on paper. That is, the first magnetic toner is
The toner is made of conductive magnetic l.su~ that is charged by charge injection during development, and its volume average particle size is 10 μm or more, which is larger than normal triboelectric insulating toner, resulting in a toner image with a large amount of adhesion. The master image obtained by fixing the toner image on the image carrier becomes a thick film-like image. The magnetic latent image formed when this master image is magnetized has high intensity and is uniform. On the other hand, since the first toner is a conductive magnetic toner as described above, there is practically no decrease in resolution due to increasing the particle size. By developing such a magnetic latent image with a second magnetic toner, which is an insulating magnetic toner that has a smaller volume average particle diameter than the first toner and can be electrostatically transferred to plain paper, etc., The amount of toner adhesion (development amount) on the master image increases significantly, and as a result, the image density on the paper increases, making it possible to obtain an image with a practical density. The upper limit of the volume average particle size of the first toner is preferably 50 μm, and the upper limit of the volume average particle size of the second toner is preferably 4 to 20 μm.

(Example) This invention will be explained in detail based on examples.

FIG. 1 is a schematic configuration diagram showing a recording apparatus according to an embodiment of the present invention. This recording device uses an electrophotographic method to obtain a first toner image (master image) made of a first magnetic toner, forms a magnetic latent image thereon, and then develops this magnetic latent image with a second magnetic toner. A second toner image is obtained, and this second toner image is transferred to a transfer target for recording.

In FIG. 1, a drum 1 is surrounded by a charger 2, an exposure optical system 3 for forming an electrostatic latent image, a first developer 4 containing a first magnetic toner T1 (not shown), and a plugger. A master image fixing device 5 equipped with a lamp, a second developing device 6 containing a second magnetic toner T2, a pre-transfer charger 7, a transfer charger 8, and a magnetic latent image on the master image (first toner image). A magnetic head 9 serving as a magnetic latent image forming means is sequentially arranged.

A photoreceptor belt 14 serving as an image carrier is provided on the outer periphery of the drum 1 so as to surround the outer periphery of the drum 1 . The photoreceptor belt 14 includes a photoreceptor layer 14a for forming an electrostatic latent image on its surface. The photoreceptor layer 14a is made of a dielectric material such as zinc oxide, which has been sensitized to long wavelengths with a dye such as rose bengal in order to have sensitivity in the visible range, for example. Formed with this photoreceptor] 4 is
Each time the document to be printed changes, a new document of a predetermined size is fed out from the supply port roll 15 onto the drum 5, and the used portion is wound onto the winding port 16.

The drum 1 can be rotated in the direction of the arrow shown in the figure at least at a first speed V1 and a second speed 2 by a drive mechanism (not shown). For example, the first speed V1 of the peripheral surface of the drum 5 is 10-50 mm/s.
ee and the second speed V2 of 500 mm/see or more is selected and driven.

The exposure optical system 3 irradiates the photoreceptor belt 14 with light reflected from the light source and reflected by the original.

The magnetic head 9 is constituted by, for example, a single track head having a length corresponding to the entire width of the photoreceptor belt 14. This magnetic head 9 is disposed so as to be movable in the force direction indicated by the arrow CD, and is set so as to move in the direction indicated by the arrow C and approach the photoreceptor belt 14 during the master image forming process described later. During the process, it moves in the direction of the arrow d shown in the figure and waits away from the photoreceptor belt 1.4.

Further, a paper P, which is a transfer material, is fed by a paper feed roller 11 and guided to the drum 1 by a pair of registration rollers 12 at a certain timing.

In the figure, 13 is a turn roller, and 10 is a fixing device that fixes the toner image on the paper P.

The first developing device 4 containing the first magnetic toner Tl (magnetic toner of the present invention) is a magnetic] component developing device, and a non-magnetic sleeve [7] rotating in synchronization with the drum 1 and a sleeve] 7 and rotates in the same direction as the drum] 8 and the doctor blade 1
It is composed of two parts. The second developing device containing the second magnetic toner T2 is also composed of a non-magnetic sleeve 20, a magnet roll 21, and a doctor blade 22, or the magnetic field of this magnet roll 21 is the master. In order to reduce the influence on the magnetic latent image formed in the image, the magnet roll 22 is fixedly arranged so as to be midway between the north and south poles or coincident with the development position.

The first toner Tl is mainly composed of a magnetic material having magnetic properties capable of permanent magnetization and a resin binder. This first toner has a volume average particle size of 10 μm.
m or more, and is configured to be larger than the volume average particle diameter of second toner T2, which will be described later. Further, the volume average particle size of the first 1.sup. is preferably 50 μm or less in practical terms. The magnetic particles included in the first toner and constituting the permanently magnetizable magnetic material are preferably those having a coercive force of 300 oersteds or more, and γ-
Examples include iron oxide magnetic materials such as Fe2O3, co-γ-Fe2O3, barium, ferrite, lead ferrite, cobalt ferrite, and nickel ferrite, or CrO2.

In addition, the resin for the binder]1 in the first magnetic l-ner may be appropriately selected depending on the fixing method, for example, ethylene-vinyl acetate copolymer, ethylene acrylic acid copolymer, low molecular weight polypropylene, styrene, Waxes such as evoquine, polyester, polyamide, carba wax, paraffin wax, polyethylene wax, and amide wax can be used.

Furthermore, in the first magnetic toner, in addition to the above-mentioned magnetic material and binder resin, an electrical resistance adjusting agent (for example,
carbon black, etc.) or other additives are added in appropriate amounts depending on the required performance of the toner.

The content of the magnetic material particles contained in the first magnetic toner is preferably higher in terms of magnetic properties, but there is a limit in terms of fixing properties. A magnetic toner with favorable magnetic properties is obtained.

Further, the electrical resistance, that is, the volume resistivity, of the first magnetic layer 1.sup.1 is preferably ]012 Ω.am or less;
More preferably, it is 9Ω·cm or less. In this way, the first toner] 2 is made conductive, and the conductive magnetic toner is supplied to an electrostatic latent image formed on an image bearing member such as a photoreceptor, and the electric field created by the electrostatic latent image causes this electrostatic latent image to become conductive. By injecting charge into the magnetic toner for development, the toner itself functions as a development electrode. Therefore, the electrostatic latent image can be developed faithfully,
A toner image with extremely high resolution and excellent density can be obtained on the image carrier without edge effects. Therefore, as described above, even if the volume average particle diameter of the magnetic H is larger than 10 μm, which is larger than that of an insulating magnetic toner that develops a normal electrostatic latent image, there is little decrease in resolution. On the other hand, by using the first magnetic toner having such a large particle size, a thicker master image can be obtained.

The second magnetic toner T2 is a high-resistance magnetic toner in which a binder resin contains a magnetic material with small residual magnetization or coercive force, such as macnetite (Fe204), and has a volume average particle diameter between 4 μm and 20 μm. It is set.

Next, the operation of the recording apparatus configured as described above will be explained in detail with reference to FIGS. 2 to 10.

The recording process in this recording apparatus is roughly divided into two processes: a master image creation process and a printing process. First, the master image creation process will be explained. In FIG. 2, the photoreceptor belt 14 is rotationally moving in the direction of the arrow shown in the figure at a speed V1, and the photoreceptor layer 14a of the photoreceptor belt 14 is uniformly negatively charged (for example, -600V) by the charger 2.
be done. Next, as shown in FIG. 3, imagewise exposure is performed by the optical system 3, and the charges on the irradiated portion disappear, forming a dielectric latent image corresponding to the image on the photosensitive layer 14a.

As shown in FIG. 4, the electrostatic latent image thus obtained is developed by a first developing device 4 with a first magnetic 1.S-T1, or this first magnetic toner T1 is a conductive magnetic toner. Therefore, charges are induced in the first magnetic toner T1 by the latent image charge of the photosensitive layer 14a, and the first magnetic toner T1 is charged and attached to the photosensitive layer 1.48 by Coulomb force and developed. Furthermore, the fifth
As shown in the figure, the first magnetic material attracted onto the photosensitive layer 14a is melted by a flash lamp of the fixing device 5, and is thermally fixed on the photosensitive layer 14a to form the first magnetic material. It becomes I. Na statue 51.

The first toner image 5 made of the first magnetic toner T1 formed on the photoreceptor belt 14 in this way includes the sixth
As shown in the figure, a magnetic head 9 serves as a magnetic latent image forming means.
A magnetic latent image is formed. Formation of this magnetic latent image = l
The second stage will be discussed in detail later.

The magnetic properties of the first toner image formed in this way will be explained. FIG. 15 is a graph showing an example of the hysteresis loop of the first magnetic toner T, in which the coercive force He is approximately 175° Oersted.

Therefore, as a matter of course, the first toner image 5 formed on the photoreceptor belt 4 also has the same coercive force.

A master image 52 in which a magnetic latent image is formed is obtained through the master image forming steps shown in FIGS. 2 to 6 above. Note that in this master image creation step, the photoreceptor belt 1
The movement speeds of 4 are all performed sequentially and continuously at the speed of Vl.

Next, the influence of the volume average particle diameter of the first magnetic toner on the thickness of the master image will be explained. Figure 13 shows the first
2 is a graph showing experimental results of the relationship between the volume average particle diameter of the magnetic toner T1 and the average thickness and resolution of the obtained master image.

It can be seen from this figure that the average thickness of the master image increases as the volume average particle size of the first magnetic toner increases. On the other hand, it has been shown that the resolution deteriorates as the volume average particle size increases, but essentially this first magnetic toner is a conductive magnetic toner (the one used here has a volume resistivity of about 10 Ω・cm), the resolving power is originally extremely good, and almost good resolving power can be obtained even when the volume average particle diameter is about 40 μm.

Next, the printing process will be explained. After the previous master image creation process is performed for one revolution of the drum, the second speed ■
2 allows it to rotate at high speed. First, as shown in FIG. 7, the second magnetic toner T2 is attached to the master image 52 on which the magnetic latent image is formed by magnetic attraction, and the same @2 as the mask image 52 is deposited on the master image 52. A toner image 53 is obtained.

Then, as shown in FIG. 8, this second toner image 53 is charged to a negative polarity by the pre-transfer charger 7, and further transferred to the paper P by the transfer charger 8 (FIG. 9), and then by the fixing device 1o. The image is fixed (FIG. 10), and a duplicate image is obtained on the paper P.

Here, among the above recording steps, the magnetic latent image forming step and the second
The developing process will be explained in detail using FIG. 11 and FIG. 12.

In the recording apparatus of the present invention, an important point in order to obtain a uniform image without missing prints is to apply a second toner image on the mask image (first toner image) 52 over the entire surface of the mask image 52.
This is to uniformly adhere the second magnetic toner T2 on the master image 52, which forms a --like magnetic latent image on the master image 52 without removing it. Leak magnetic field (leak magnetic flux) that adheres uniformly
It is to form a pattern.

As a result of various experiments conducted by the present inventors, we found that by magnetizing the master image (first toner image) 52 so that the magnetization direction is alternately reversed by a constant length Ω, on this master image 52, It has been found that it is possible to obtain a leakage magnetic field that causes the second magnetic toner T2 to adhere uniformly.

The above-mentioned magnetization direction is magnetized in such a way that it is alternately reversed over a certain length. When the magnetization direction is magnetized in the in-plane direction of the master image 52 (longitudinal direction magnetization), and when the magnetization direction is magnetized in the thickness direction of the mask image 52 (perpendicular direction magnetization) It was found that a uniform leakage magnetic field pattern could be obtained for both directions (magnetization direction).

FIG. 11 is a side view of the magnetic head '9, which includes a core 31 having a single recording track width and a coil 32 wound around the core 3. There is a gap g opposite to the first toner image of the core 3.
is formed, and the magnetic flux generated in this gap g magnetizes the first 1.sub.image 5].

E is a power source for passing a current through the coil 32, and the coil 32 is supplied with a constant frequency alternating rectangular wave voltage W outputted from the power source E]8. FIG. 12 shows the master image 5 formed by the longitudinal magnetization magnetic head 9 shown in FIG.
2 schematically shows development in which the second magnetic toner T2 adheres to the magnetic latent image on the second magnetic latent image. As mentioned above, a temporally alternating magnetic field is generated near the front gear g of the magnetic head 9, and as the photoreceptor belt 4 moves and passes under the magnetic head 9 at a constant speed V1, the master statue 52
A magnetic latent image whose magnetization direction is alternately reversed at a constant length in the plane direction of the master image 52 is formed on the master image 52 . This twelfth
As shown in the figure, leakage magnetic flux is generated from the magnetization transition part M,
Generates an external magnetic field.

The leakage magnetic flux forms a loop between each magnetization transition portion M, and the second magnetic toner T2 conveyed to the vicinity of the master image 52 by the second developing device 6 forms a toner along the loop of the leakage magnetic flux. A second toner image 53 identical to the master image 52 is obtained by forming a chain, uniformly depositing it on the master image 52, and developing it.

Here, the constant length Ω, that is, the distance between the magnetization transition parts M, is the frequency of the voltage W of the alternating rectangular wave, I゛ (肚),
The moving speed of the photoreceptor belt 14 (more precisely, the relative speed between the magnetic head 30 and the photoreceptor belt 14) is V l
(mm/see), simply, ρ-V
1. /2 f (mm).

For example f = 1 kllz, Vl = 60mm
/see, then ρ-0.03mm5, that is, 30
It becomes μm.

On the other hand, if the explanation is not made using drawings, or the same applies to the case of perpendicular magnetization, the master 1
The magnetization may be performed in a magnetization direction that is alternately reversed in the thickness direction of the image 52.

By forming the magnetic latent image on the master image as explained above, a uniform image can be obtained.

FIG. 14 shows the master Ig! when mask images 52 obtained by varying the volume average particle diameter of the first magnetic toner TI are magnetized at a recording pitch of Ω-30 μm! 52
The relationship between the average thickness of P and the image density of an image obtained on paper P in the printing process is shown. Since the practical image density is about 1.0, in order to obtain a practical image density, from Fig. 14,
The average thickness of the mask image 52 is about 5 μm or more, preferably 8 μm
It turns out that anything above that is good. The thickness of the master image is
Since it is known that the volume average particle size of the first magnetic toner is about half of the volume average particle size of the first toner, the volume average particle size of the first magnetic toner forming the master image 52 is preferably 10 μm or more, and preferably 2 μm or more.
0μm or more, and if you want high resolution, 50μm
The thickness is preferably 30 μm or less, and more preferably 30 μm or less.

The advantage of the recording device of this invention is that it can make multiple copies from the same original at high speed. Development process (Figure 7), pre-transfer charging process (Figure 8), transfer process (Figure 9), fixing process (Figure 10)
This is because it can be easily realized if the printing process consisting of is performed at high speed.

This is because there is no step of forming an electrostatic latent image or a magnetic latent image, which is an obstacle to speeding up.

Note that the present invention is not limited to the above embodiment. That is, in the above embodiment, the photosensitive layer 14a is made of zinc oxide, but the photosensitive layer 14a is not limited to this, but a photosensitive material such as an organic photoconductor may be used, or a dielectric material may be used as an image carrier instead of the photosensitive material, and a static photosensitive material may be used. An electrostatic latent image may be formed by an electrographic method.

Further, as the image exposure means for the photosensitive layer 14a, a laser beam may be irradiated instead of irradiating the reflected light from the original as in the above embodiment.

Furthermore, any means for forming a magnetic latent image, such as a magnetic head, may be used as long as it does not depart from the gist of the invention.

It goes without saying that the magnetic toner of the present invention can be applied to all recording devices that magnetize and use images formed with this magnetic toner.

[Effects of the Invention] As explained above, according to the present invention, it is possible to obtain uniform and clear images with high density, and to print the same original in the same way as a printing machine with the same simple operation as a conventional electronic copying machine. Accordingly, it is possible to provide a recording apparatus that can copy a large number of sheets at high speed, reduce power consumption, and obtain uniform and clear images.

[Brief explanation of the drawing]

All drawings relate to embodiments of this invention, and the first
The figure is a schematic diagram showing the configuration of the recording device, Figures 2 to 10 are diagrams for explaining the recording process, Figure 11 is a schematic sectional view of the magnetic head, and Figure 12 shows the state of the magnetic island image. Figure 13 is a graph showing the relationship between the volume average particle diameter of the magnetic toner in item 1- and the average thickness and resolution of the obtained master image, and Figure 14 is a graph showing the relationship between the average thickness of the master image and the image a degree. FIG. 15 is a graph showing the magnetic characteristics of the first magnetic layer 1. 2... Charger, 3... Image exposure optical system/light,
4... First developing device, 5... Flash fixing device, 6
...Second developer, 8...Transfer charger, 9...
Magnetic head (magnetic latent image forming means), ]4... Photoreceptor belt (image carrier), T1... First magnetic toner T2...
- Second magnetic toner 52... Master image (first toner image), 53... Second toner image. 771

Claims (1)

[Claims] (1) Developing this electrostatic latent image using an electrostatic latent image forming means that forms an electrostatic latent image on an image carrier, and a first magnetic toner containing a magnetic material having magnetic properties capable of permanent magnetization. 1st
a developing means, a fixing means for fixing the first toner image obtained on the image bearing member by the first developing means on the image bearing member, and a fixing means for fixing the first toner image obtained on the image bearing member by the first developing means; a magnetic latent image forming means for forming a magnetic latent image; a second developing means for developing the magnetic latent image with a second magnetic toner;
A recording device comprising a transfer means for transferring a second toner image obtained on the first toner image by a developing means to a transfer material, wherein the volume average particle diameter of the first magnetic toner is , 10 μm or more and larger than the volume average particle diameter of the second magnetic toner.