JPH0310313B2 - - Google Patents

Abstract

PURPOSE:To enable to obtain an image with high resolution, by a method wherein a magnetic brush of a magnetic toner is provided on a linear form member by a magnet provided in a non-magnetic sleeve, and an image signal pulse voltage is impressed on stripe form electrodes to produce a toner image on a recording member. CONSTITUTION:The toner 17 is supplied to the linear form member 18 by rotating a magnet roller 11, and while rotating an electrode drum 19, pulse voltages are impressed selectively on annular stripe electrodes 20, whereby electric charges are induced in a belt form magnetic brush provided on the member 18 at tip parts located on the stripe electrodes 20, a toner image is formed on an insulating layer 28, is transferred by a transferring device 23 onto a paper provided in a paper-supplying tray 22 synchronized with the rotation of the drum 19, and residual toner is cleaned by a device 24. In this case, the electric charges are induced only in the toner present at the magnetic brush part on the electrodes on which the pulses are impressed, and no electric current is leaked to the toner present on the insulating layer. Accordingly, an image with resolution approximately equal to the density of the stripe electrodes can be obtained without any lowering in the toner concentration, and the device can be constructed in a highly reliable simple construction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image recording apparatus that obtains a toner image by applying a voltage pulse signal between a magnetic brush and a counter electrode.

Prior art A voltage pulse signal is applied between a magnetic brush and a counter electrode to generate a signal on the counter electrode (or on a recording paper on the counter electrode).
Compared to recording methods that use other types of toner, such as those used in electrostatic printing, which require an applied voltage of several hundred volts, the recording method that obtains toner images can produce images with sufficient image density with an applied voltage of several tens of volts. Since this can be obtained, technological development for simple printers has been progressing in recent years.

For example, a conventional recording apparatus using this type of magnetic brush was constructed as shown in the sectional view of FIG. A symmetrical magnet roller 1 having alternating north and south poles is rotatably placed in a fixed non-magnetic sleeve 2 and rotated by a suitable drive source. On the sleeve 2, fine recording electrodes 3 are arranged in a row in the axial direction of the sleeve 2 to form a recording electrode group. Each electrode 3 is connected so that a voltage pulse corresponding to an image signal generated from a voltage pulse application device 4 is applied thereto. A counter electrode 5 is arranged at a constant distance from the recording electrode 3. A recording medium 6 is placed on this counter electrode. This recording body 6 may be made of paper or the like and used as a final recording body, or the recording body 6 may be used as an intermediate recording body and further transferred to another paper or the like. Then, due to the rotation of the magnet roller 1, the conductive or semi-conductive magnetic toner 7 rotates in a direction opposite to the rotation direction of the magnet roller 1, and is thereby continuously deposited onto the recording electrode 3. Supplied.

In such a recording device, the toner 7 conveyed onto the recording electrode 3 separates into ears of toner in the circumferential direction of the sleeve, as shown in FIG.
Furthermore, the ears are formed in a separate needle-like state in the axial direction of the sleeve.

As a result, the voltage pulse applied from each electrode 3 of the recording electrode group induces an electric charge in the tip of the acicular toner chain located on the electrode to which the voltage pulse is applied, and the electric charge The electrostatic force acting on the magnetic toner particles overcomes the magnetic force acting on the magnetic toner particles and the magnetic toner particles adhere to the recording medium 6.

However, if the magnetic brushes on the recording electrodes 3 are not separated in the recording electrode arrangement direction, that is, in the axial direction of the sleeve, but have a strip-shaped brush shape, a pulse voltage is applied to a certain recording electrode of the recording electrode group. When the voltage is applied, the voltage pulse leaks through the current path created by the conductive or semiconductive toner between the energized electrode and the unenergized electrode. As a result, the density of the toner image on the recording medium in front of the electrode to which the voltage pulse was applied may decrease, or charges may be induced not only in the toner on the electrode to which the voltage is applied, but also in the toner in the vicinity. Toner in a wider area than the area to which the voltage is applied adheres to the recording medium, causing damage such as a significant decrease in resolution compared to the electrode density.

Therefore, in the recording device of this method, the recording electrode 3
It is essential to form the upper magnetic brush into a needle-like magnetic brush that is separated in both the circumferential direction and the axial direction of the sleeve. However, in order to achieve this, high precision is required in the shape of the recording electrode, the magnetic force distribution of the magnet roller, etc., and the shape of the acicular brush is deformed due to unevenness in the rotation speed of the magnet roller. The resolution of simple printers has not been fully satisfactory due to problems with productivity and reliability, such as reduced image quality.

OBJECT OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its purpose is to form a magnetic brush in a shape that is required in conventional recording devices.
A toner image with satisfactory resolution can be obtained even by development using a magnetic brush with a shape that is easy to maintain.A toner image is obtained by applying a pulse signal between the magnetic brush and a counter electrode. The present invention aims to provide an image recording device.

Structure of the Invention That is, according to the present invention, a non-magnetic sleeve having a rotatable magnet inside is provided facing a recording member having a large number of striped electrodes on a base and an insulating layer covering the stripe-like electrodes. A conductive and magnetic linear member is arranged on the non-magnetic sleeve on the opposing surface so as to intersect with the striped electrode, and a magnetic brush of magnetic toner is formed on the linear member by the magnet in the non-magnetic sleeve. An image recording apparatus is provided that forms a toner image on a recording member by applying a pulse voltage to a shaped electrode according to an image signal.

When the development is carried out as described above, strip-shaped magnetic brushes are formed on the linear member of the sleeve that are separated only in the circumferential direction of the sleeve and continuous in the axial direction of the sleeve, and striped electrodes in the recording member are formed. When a voltage pulse corresponding to an image signal is selectively applied to the stripe electrode group, charges are induced at the tips of the toner spikes on the electrodes to which the voltage pulses have been applied among the band-shaped magnetic brushes that intersect with the stripe electrode group, and the toner particles are transferred onto the recording member. A toner image can be formed. Then, if necessary, the toner image on the electrode member can be transferred and fixed onto a final recording medium such as plain paper.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a sectional view of the image recording apparatus of the present invention.

A magnet roller 11 similar to the magnet roller of FIG. 1 is rotatably placed within a non-magnetic sleeve 12 and rotated by a suitable drive source.
A conductive and magnetic linear member 18 extending in the axial direction of the sleeve is provided on the sleeve 12 to form a band-shaped magnetic brush. A striped electrode group 2 is arranged opposite to the linear member 18.
0 is placed parallel to the axis of the sleeve 12. A shaft 21, which also serves as a rotation axis of the electrode drum 19 and a wiring path for applying voltage to each striped electrode 20, is rotatably supported. And around the electrode drum,
A recording paper supply tray 22, a transfer device 23, a cleaning device 24, and a fixing device 25 are arranged.

FIG. 3 shows the linear member 1 on the non-magnetic sleeve 12.
FIG. 8 shows a cross-sectional view of No. 8. The cross-sectional shape of the linear member 18 may be triangular as shown in FIG. 3A, or trapezoidal as shown in FIG. 3B. Furthermore, the linear member 18 may be made of aluminum, for example, and protrude from the non-magnetic sleeve 12 as shown in FIGS. 3A and 3B, or it may be inserted into the non-magnetic sleeve 12 as shown in FIG. 3C. It may be embedded in the plastic coating layer 26 covering the non-magnetic sleeve 12 as shown in FIG. 3D, or it may be embedded in the plastic coating layer 26 and protrude as shown in FIG. 3E. You can do it like this. The linear member 18 may protrude from the surface of the sleeve 12 by a maximum of about 10 mm;
It may also be in the same plane as the sleeve 12 or the plastic covering layer 26. This linear member 18
The toner brush must have magnetism so that the toner brush can be formed efficiently, and must have conductivity so that charge can be reliably injected into the toner in contact with the linear member 18 of the toner brush. As such materials, metals such as iron, nickel, and cobalt can be used.

Sleeve 1 with a built-in rotating magnet formed in this way
When a conductive or semiconductive magnetic toner 17 is supplied to the toner 2, it rotates and is conveyed onto the linear member 18 as the magnet roller 11 rotates. On this linear member 18, the toner is formed into a band-shaped magnetic brush that is continuous in the axial direction of the sleeve, instead of the needle-shaped brush required in the device shown in FIG. 1 used to explain the conventional example. . That is, in the present invention, the magnetic brushes do not need to be separated into needles. Therefore, the accuracy required for the magnetic force distribution of the linear member or the magnet roller, its rotation speed, etc. is reduced, and reliability is improved.

Furthermore, in the case of the sleeve 12 described above, the linear member 18 is different from the conventional recording apparatus in which it was necessary to provide a large number of wires on the sleeve for guiding pulse voltage to the recording electrode on the developing sleeve. The structure is simple just by holding the linear member 1.
By holding the sleeve 8 on a side plate that holds a sleeve, a magnet roller, etc., the sleeve can be easily rotated if necessary.

4 and 5 are a perspective view of the electrode drum 19 and an enlarged sectional view of section A in the perspective view.

As shown in FIG. 4, the electrode drum 19 has a stripe electrode 20 formed by closely arranging annular electrode wires in parallel to the circumferential direction on a cylindrical support drum 27, and a recording layer 28 on the stripe electrode 20. It is coated with a dielectric material. Each of the annular stripe electrodes 20 is connected to the voltage pulse applying device 14 by a wire connection 25 and a wiring provided in the shaft 21.

The resin used to form the recording layer 28 may be acrylic resin, alkyd resin, vinyl chloride resin, polystyrene, polycarbonate, vinylidene chloride, styrene-butadiene copolymer, or a combination thereof. Appropriate. Furthermore, in order to improve the static elimination performance on the electrode drum, it is also possible to slightly lower the resistance by adding a portion of a conductive material such as ZnO, SnO ₂ or carbon.

The toner 17 to be used is conductive or semiconductive such that a charge is quickly induced by the application of an electric field, that is, the toner 17 has a specific resistance of 10 ⁷ to 17.
Preferably, the toner is in the range of 10 ¹² Ωm.

In the above device, the magnet roller 1
1 to supply the toner 17 to the linear member 18, and while rotating the electrode drum 19, selectively applying a pulse voltage to the annular stripe electrode 20 causes the linear member intersecting the stripe electrode at right angles to Charge is induced in the tip of the band-shaped magnetic brush 18 located on the stripe electrode to which the pulse voltage is applied, toner adheres to the recording layer 28, and a toner image is formed on the recording layer 28. Ru. The toner image is transferred by the transfer device 23 to the paper in the paper feed tray 22 that is fed in synchronization with the rotation of the electrode drum 19 carrying the toner image, and then,
The image is fixed by the fixing device. On the other hand, residual toner on the electrode drum is removed by a cleaning device 24.

The image thus obtained has a sufficiently satisfactory resolution. That is, among the striped electrodes of the electrode drum, charges are induced only in the toner in the magnetic brush portion located on the electrode to which the pulse is applied, and almost no voltage is induced in the toner in the vicinity. On the other hand, since the recording layer 28 is non-conductive, there is no leakage of current from the stripe electrodes to the toner, and the concentration of the adhered toner does not decrease. Therefore, an image with approximately the same resolution as the density of the stripe electrodes can be obtained without a decrease in toner density.

FIG. 6 is a perspective view showing another type of electrode drum, in which, unlike the electrode drum of FIG.
It is covered in This spiral electrode is made by winding the electrodes around the entire surface of the support drum at an angle parallel to the diagonal line of the rectangle obtained by expanding the support drum, so that each electrode comes into contact with the band-shaped magnetic brush at one point. This results in a state where To connect each electrode to the voltage pulse application device, each spiral electrode is brought out from the end of the drum as a contact point, and a number of external contact terminals corresponding to each electrode are fixedly arranged so as to make contact with it, and the electrode drum is rotated. At the same time, contact may be made intermittently in sequence. Alternatively, like the annular stripe electrode described above, the connection may be made through the shaft 21a.

Effects of the Invention As described above, according to the present invention, since the linear member having conductivity and magnetism is provided in the non-magnetic sleeve, magnetic flux is concentrated at the portion of the linear member to form a stable magnetic brush. In addition, since the stripe electrodes are arranged on the recording medium so as to intersect with the linear members, the electric field is concentrated at the intersecting portions, thereby improving resolution.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional image recording device;
3A to 3E are partial sectional views showing the shape of the linear member of the sleeve with a built-in rotating magnet used in the device of FIG. 4. The figure is a perspective view of the electrode drum used in the device of Figure 2, Figure 5 is a partially enlarged sectional view of section A in Figure 4, and Figure 6 shows a modified example of the electrode drum. FIG. 1, 11... Magnet roller, 2, 12...
Non-magnetic sleeve, 3... Recording electrode, 4, 14...
Voltage pulse application device, 5... Counter electrode, 6... Recording body, 7, 17... Toner, 18... Linear member,
19... Electrode drum, 20, 20a... Stripe electrode, 21, 21a... Shaft, 22... Paper feed tray, 23... Transfer device, 24... Cleaning device, 25... Fixing device, 26... Covering layer,
27...Support drum, 28...Recording layer.

Claims (1)

[Claims] 1. A non-magnetic sleeve having a rotatable magnet inside is provided facing a recording member having a large number of striped electrodes on a substrate and an insulating layer covering the electrodes, and striped electrodes are formed on the non-magnetic sleeve on the opposing surface. A conductive and magnetic linear member is arranged to intersect with the electrode, and a magnet in a non-magnetic sleeve forms a magnetic brush of magnetic toner on the linear member, and a pulse voltage is applied to the striped electrode according to the image signal. An image recording apparatus characterized in that a toner image is formed on a recording member by applying a toner image.