JPH0576631B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an image recording device, particularly an image recording device that directly attaches a one-component conductive magnetic developer (hereinafter abbreviated as toner) to a recording medium in response to an image electric signal. The present invention relates to an image recording device that records images.

[Background of the Invention] Conventionally, this type of device is disclosed in US Pat. No. 3,816,840.
There is something disclosed in the specification of No. A very general outline of this conventional device will be explained with reference to FIG. In FIG. 2, 1 is a toner conveying member made of a non-magnetic cylinder provided inside the toner container 2, and 3 is a magnetic roller movably (rotatably) provided inside the toner conveying member 1. Magnetic poles of different polarity are alternately magnetized at approximately equal intervals on the circumference. Reference numeral 8 denotes a large number of recording electrodes, each of which is arranged independently and electrically insulated in the axial direction of the toner conveying member 1, and is made of, for example, permalloy, nickel, iron, or the like.
Reference numeral 5 denotes a recording medium that faces the recording electrode 8 and is transported in the direction of the arrow, and in addition to the illustrated example in which a conductive substrate 5a and an insulating layer 5b are laminated, a commercially available electrostatic recording paper is used. It is also possible. Reference numeral 6 denotes a conductive back electrode disposed opposite the electrode 8 with the recording medium 5 in between, and is in contact with the conductive substrate surface of the recording medium 5.

In the above-mentioned image recording apparatus, the magnetic roller 3 is driven in the direction of arrow A, and the recording medium 5 is driven in the direction of arrow B, respectively, by unillustrated drive sources. The toner T in the container 2 is held on the toner conveying member 1 by the action of the magnetic field and is conveyed in a direction A' opposite to the direction of rotation of the magnet roller 3. The transported toner T is regulated into a uniform thin layer by a doctor blade 7 provided at the outlet of the container, and when it reaches the recording position 10 where the recording electrode 8 and the back electrode 6 face each other, the toner T reaches the recording medium 5. A spike is formed at the tip of the recording electrode 8. At this time, a signal voltage corresponding to the time-series pixel signal of the image selectively applied between the electrodes 8 and 6 from the signal power source 9 (main scanning) and the progress of the recording medium 5 (sub-scanning) are used to generate toner. adheres to the insulating layer 5b of the recording medium to form an image. The toner image T on the insulating layer 5b is sent to a fixing device (not shown), such as a heating or pressurizing device, and is fixed thereon. In this case, the toner image T may be transferred to a transfer material and fixed on the transfer material.

FIG. 3 shows another conventional example of this type of image recording apparatus, which is described in detail in Japanese Patent Laid-Open No. 127578/1983. Portions with the same numbers as in FIG. 2 indicate portions that perform the same functions. In FIG. 3, the recording medium has a structure in which a dielectric layer 5' is provided by alumite treatment on an aluminum cylinder 6, which is a back electrode, but a commercially available electrostatic recording paper or the like may also be used. . Reference numeral 2 denotes a container containing conductive magnetic toner, and inside thereof there is a toner application roller 4 made of a hollow cylinder made of a non-magnetic conductor. A magnet 3 is placed inside the toner application roller 4 . 1
6 is a DC power supply. Reference numeral 8 denotes a recording electrode, which is usually made by arranging a large number of thin wires made of a magnetic material such as iron, permalloy, nickel, etc. in parallel in the axial direction facing the recording medium 5, or by etching from a magnetic sheet. It is created using the technique of Metsuki et al. Although not shown, this is electrically insulated and fixed to the body using an insulating adhesive, and is held between magnets 18. The recording electrodes 8 are each independently connected to a signal generator 9.

The recording medium 5 rotates in the direction of arrow A and passes near the toner application roller 4 . As the toner application roller 4 rotates in the direction of arrow B, the toner T in the container 2, which is attracted to the toner application roller 4 by the action of the magnet 3, is formed into a uniform toner layer by the doctor blade 7. This toner T is
When it comes into contact with the recording medium 5, a DC voltage is applied from the bias power supply 16, so that a charge is obtained and adheres to the recording medium 5.

When the recording medium 5 further rotates in the direction of arrow A and the toner T on it reaches the recording position 10, ears of toner T are formed between the recording medium 5 and the recording electrode 8 due to the influence of the magnetic field emitted from the magnet 18. be done. Since most of the charge of the toner escapes through the dielectric layer 5' before reaching the recording position 10,
At the recording position 10, the adhesion of the toner T to the recording medium 5 is weakened. However, when a recording signal voltage selected according to the image pattern is applied from the character generator 9 to the recording electrode 8 at this moment, the toner T formed between the recording electrode 8 to which the signal voltage was applied and the recording medium 5 is Charges having a polarity opposite to those on the back electrode 6 are injected into the toner T through the ears of the toner T, sandwiching the dielectric layer 5'. This charge provides an electric force sufficient to cause the toner T to adhere to the recording medium 5. On the other hand, in the area to which the recording signal voltage is not applied (non-image area), since there is no charge injection as described above, the adhesion force between the recording medium 5 and the toner T is weakened as described above, and therefore the magnetic field generated from the magnet 18 is generated. , the toner T adheres and accumulates along the recording electrode 8 near the magnet 18 11 .

Although the toner image visualized on the recording medium 5 according to the above-mentioned image pattern is not shown in the figure as in the conventional example described above, it is usually transferred and fixed onto paper by corona discharge/pressure transfer, or by electrostatic transfer. If recording paper or the like is used as the recording medium, the image may be fixed as is.

However, in order to obtain high-resolution images with these image recording devices, the distance between the recording electrode and the recording medium must be extremely narrow, making it difficult to obtain stable images over a long period of time. It was hot. In order to overcome this drawback, a recording device using a back electrode made of a ferromagnetic material facing the recording electrode on the opposite side of the recording medium has been proposed in Japanese Patent Laid-Open No. 173854/1983. However, when the back electrode is made of a magnetic material, the resolution is improved and the distance between the recording medium and the recording electrode can be increased, but the following problems occur. This will be explained using the image recording apparatus shown in FIGS. 2 and 3 as an example.

First, in the case where the back electrode 6 is made of a magnetic material in the image recording device shown in Fig. 2, it is difficult to increase the density due to problems with toner transport. It is difficult to use. In other words, when increasing the amount of magnetic material on the back electrode in the device shown in Figure 2, the back electrode 6 and magnet 3
The magnetic field becomes almost perpendicular to both surfaces between the recording electrode 8 and the recording medium 5, and the toner is attracted to the magnetic field acting on both surfaces between the recording electrode 8 and the recording medium 5. The toner transport direction is
Normally, as shown in FIG. 4, which is a partially enlarged view of FIG. 2, the magnet 3 is
The rotation direction A is opposite to the rotation direction A', but
When there is a magnetic material as the opposing back electrode 6, the toner near the recording electrode 8 is restrained by the magnetic field acting between the back electrode 6 and the magnet 3, and tries to travel in the same direction A as the rotating direction of the magnet 3, Toner is not sufficiently supplied onto 8. In this way, in an image recording apparatus using a toner conveying means as shown in Fig. 2, configuring the back electrode with a magnetic material causes problems in toner supply, leading to a decrease in recorded image density, and stabilizing the density. It becomes very difficult to obtain high-quality images. Therefore, the apparatus shown in FIG. 2 is essentially unsuitable for obtaining high-resolution images by configuring the back electrode with a magnetic material. Therefore, from now on, we will consider only the image recording apparatus of the type shown in FIG. 3 in which the back electrode is made of a magnetic material.

In order to stably record images with high resolution in the apparatus shown in FIG. 3, it is necessary to keep the distance between the recording electrode and the recording medium as constant as possible. To this end, as shown in FIG. 3, the general shape of the device is such that the back electrode and the recording medium are integrated, and a dielectric layer 5', which is the recording medium, is directly coated on the back electrode 6. It is desirable that the Furthermore, in order to record images at a low voltage, which is a feature of this device, it is desirable that the dielectric layer be as thin as possible. For example, in order to reduce the recording voltage to 30 V or less, the thickness of the dielectric layer must be approximately 1 to 2 μm. In this state, if a magnetic iron cylinder is used instead of an aluminum cylinder as the back electrode 6, the resolution will be improved, but because the distance between the recording medium surface and the magnetic material is too short, the magnetic field from the magnetic material that is the back electrode will be Due to the influence, toner that did not participate in recording is transferred to magnet 1.
Due to the magnetic force of 8, it is not smoothly transported to the vicinity 11 of the magnet, and as shown in FIG.
It is difficult to obtain a stable image with good resolution because it accumulates in the image and disturbs the image.

As a modification of the image recording apparatus shown in FIG. 3, the stability of the distance between the recording electrode and the recording medium is somewhat inferior, but as shown in FIG. A device using a dielectric layer 5'b coated on the surface has also been proposed. In this case, by using the iron roller 6' as the back electrode, the resolution at the tip of the recording electrode can be sufficiently increased, and the distance between the magnetic material serving as the back electrode and the surface of the recording medium can be set to about 50 μm. However, because the distance between the magnetic material, which is the back electrode, and the surface of the recording medium is still too short, toner that is not involved in recording accumulates near the recording position 10, as in the case described above, and the image becomes unstable. It is difficult to obtain images with good resolution. It is possible to increase the distance between the magnetic material that is the back electrode and the surface of the recording medium by increasing the thickness of the copper belt 5'a, but in this case too, if the thickness is increased to about 100 μm, the belt becomes stiff and the belt becomes stiff. Since it becomes easily deformed, it becomes impossible to maintain a stable distance between the recording electrode and the recording medium. Therefore, the thickness of the copper belt is at most 100 μm or less, but at this thickness, the distance between the magnetic material that is the back electrode and the recording medium is too short, resulting in stable and high-resolution images. It is not possible to obtain.

Even when electrostatic recording paper is used as a recording medium, the thickness of the paper is approximately 80 μm, so a good quality image cannot be obtained.

As mentioned above, devices in which the back electrode is made of ferromagnetic material have been proposed in order to improve resolution in this type of image recording system. Although the resolution is certainly improved, toner tends to accumulate near the image recording position and the accumulated toner disturbs the recorded image, making it difficult to obtain stable images over a long period of time.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned conventional examples,
This type of image recording can smoothly remove toner near the image recording position, eliminate image disturbances caused by excess toner, make it possible to obtain stable images over a long period of time, and also sufficiently improve resolution. The purpose is to provide equipment.

[Summary of the invention]

The present invention provides a recording medium comprising a recording electrode array, a surface dielectric layer and a conductive layer that closely oppose the recording electrode array and move relative to the recording electrode array, and a conductive magnetic toner applied to the surface of the recording medium. means and
means for applying a recording voltage according to an image pattern between a conductive layer of the recording medium and selected electrodes in the recording electrode array; and a recording electrode for generating a magnetic field between the recording medium and the recording electrode array. In an image recording device comprising opposing magnets arranged so that the same poles face each other with an array in between, magnets are arranged on opposite sides of the recording medium to face the recording electrodes.
It is characterized in that the ferromagnetic material is arranged such that the distance from the surface of the recording medium to the surface of the ferromagnetic material is 200 μm to 2 mm.

[Embodiments of the invention]

FIG. 1 is a side sectional view showing one embodiment of the present invention. Its basic structure and operation are the same as those shown in FIG. 3, and the same reference numerals as in FIG. 3 indicate parts that perform the same functions. As the back electrode 6', a ferromagnetic iron cylinder 6'a having a diameter of 100 mm and a non-magnetic copper plating layer 6'b (200 μm to 2 mm) provided on the surface is used. Furthermore, a dielectric layer 5' is formed on the surface of this back electrode cylinder by dispersing Teflon titanium oxide, etc. in a photocurable resin and curing it with ultraviolet rays.
The material with a thickness of m is uniformly coated.

As toner T, a conductive magnetic toner with a resistance of 10 ¹⁰ Ω-cm or less can be used, but in this example, carbon was externally added to Imaging Powder 355 toner sold by 3M Company to achieve a resistance of 10 ⁵ Ω-cm. I adjusted it accordingly. For the recording electrode 8, 2-permender (alloy of 49% Co, 49% Fe, and 2% V) wires with a diameter of 25 μm are used, and 3360 wires are arranged in parallel over a width of 210 mm, and sold by Cemedine Co., Ltd. It was fixed using epoxy adhesive Hi-Super (trade name). The recording medium 5' and the recording electrode 8 are opposed to each other at a substantially right angle, and the distance between them is maintained at 75±25 μm.

In this embodiment, by providing a non-magnetic layer 6'b on the surface of the ferromagnetic material 6'a of the back electrode using a technique such as plating, the improvement in resolution due to the provision of the ferromagnetic material is preserved. Furthermore, by providing the non-magnetic layer, the magnetic field of the magnet 18 works efficiently to attract the toner toward the magnet, and the toner near the image recording position 10 is smoothly transferred to the magnet 11 near the magnet.
move it to Therefore, according to this embodiment, it is possible to obtain images with good resolution over a long period of time without toner accumulating near the image recording position 10. The thickness of the non-magnetic layer 6'b is at least 200μ
m or more is required.

Here, the relationship between the thickness of the nonmagnetic layer 6'b and the image will be explained once more in an easy-to-understand manner using FIG. From the point of view of improving image resolution, if the magnetic flux density at the tip of the recording electrode is concentrated, the shape of the toner spikes will be sharper, the binding force of the recording electrode on the toner will increase, and fogging will be reduced. This results in a high-resolution image. For this purpose, it is necessary that the opposing magnetic body 6'a be placed as close as possible to the tip of the recording electrode. For this purpose, the distance between the ferromagnetic material 6'a and the surface of the recording medium 5' should be short. However, the toner not used for image recording is pushed out to the area 20 in FIG.
In order to smoothly transfer this toner to the vicinity of the magnet 18, it is necessary to have a large force acting in the direction of moving the toner toward the magnet 18, and this force is proportional to the gradient of the magnetic field. If the distance from the magnet is the same, the gradient of this magnetic field increases as the distance between opposing magnetic bodies increases. Therefore, in order to prevent accumulation in the portion 20, the distance from the magnetic body 6'a to the surface of the recording medium should be large. In this way, in order to concentrate the magnetic field, it is better to keep the distance between the surface of the recording medium and the opposing magnetic body close, but it is possible to smoothly transfer the toner that is not used for image recording to the vicinity of the magnet 18, as shown in FIG. In order to eliminate toner accumulation in the portion 20 and avoid disturbing the image, it is necessary to increase the distance between the opposing magnetic material and the surface of the recording medium as much as possible. Therefore, the optimum value of the distance between the magnetic material and the surface of the recording medium is limited within a certain range. This range is 200μm to 2mm in normal use.
However, in this example, a good image was obtained by setting the thickness to 500 μm.

The optimal value for the distance between the recording medium surface and the magnetic material varies from 200 μm to 2 mm as described above, depending on the residual constraint density of the magnet 18, the magnet configuration, etc.
By adjusting the thickness of the nonmagnetic layer 6'b,
The optimum distance can be easily achieved. In the example described above, this optimum distance was 500 μm, as described above.

In the above embodiment, the non-magnetic layer 6'b was made of a conductive material, but this non-magnetic layer is made of, for example, ceramics with a thickness of 500 μm.
It may be coated with a thickness of m. In this case, a back electrode may be formed by vapor depositing metal on the ceramic surface, and a dielectric layer may be formed on the surface.

FIG. 7 shows another embodiment in which a dielectric layer 5'b is coated on a nickel seamless belt 5'a as a recording medium, and as in the previous embodiment, a back electrode 6' This is a structure in which a non-magnetic nickel plating layer 6'b is formed on the surface of an iron cylinder 6'a, which allows the distance between the recording medium surface and the magnetic material to be adjusted to an arbitrary optimum value of 100 μm or more. . In this case as well, it is also possible to construct the layer 6'b from ceramics. In that case, instead of a metal such as a nickel belt, it is also possible to use a sheet of Mylar with a conductive layer such as ITO or aluminum evaporated on its surface as a seamless belt.

Also, although the accuracy of the distance becomes worse, as shown in FIG.
It may be arranged at an optimal position of 100 μm or more.

〔Effect of the invention〕

As explained above, the ferromagnetic material is placed at least 200 μm to 2 mm from the surface of the recording medium, facing the recording electrode.
By arranging the ferromagnetic material at a distant position, the advantage of improved resolution brought about by arranging the ferromagnetic material is not lost, and the arrangement of the magnetic material also prevents toner from accumulating near the image recording position and disturbing the image. , stable images can be obtained over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG.
FIG. 3 is a sectional view of a conventional example of an image recording apparatus to which the present invention relates, FIGS. 4 and 5 are partially enlarged views of the conventional example, and FIG. 6 is a sectional view showing a modification of the conventional example. 7
8 are sectional views of other embodiments of the present invention. 1... Toner conveying member, 4... Toner application roll, 5... Recording medium, 6, 6'... Back electrode, 1
9...Magnetic material.

Claims (1)

[Scope of Claims] 1. A recording medium comprising a recording electrode array, a surface dielectric layer and a conductive layer that closely oppose and move relative to the recording electrode array, and a conductive magnetic toner on the surface of the recording medium. means for applying a recording voltage according to an image pattern between the conductive layer of the recording medium and selected electrodes in the recording electrode array; and means for applying a magnetic field between the recording medium and the recording electrode array. In an image recording apparatus equipped with opposing magnets that are arranged so that the same poles face each other across a recording electrode array in order to generate an image, a magnet that faces the recording electrodes on the opposite side of the recording medium to the recording electrodes. , the distance from the surface of the recording medium to the surface of the ferromagnetic material is
An image recording device characterized in that the size of the image recording device is 200 μm to 2 mm. 2. Claim 1, wherein the distance between the recording medium surface and the ferromagnetic surface is within the numerical range by configuring a back electrode in which a nonmagnetic conductive layer is provided on the surface of the ferromagnetic material. The image recording device described.