JPH0556503B2 - - Google Patents

Abstract

PURPOSE:To reduce contamination by toner at the inside of a picture image recorder and to obtain stable picture images for a long period, by making the width of a back electrode made of a magnetic substance wider than that of a magnet. CONSTITUTION:The figure shows the vicinity of a recording electrode viewed from the direction of the contacting surface of a recording medium 1. Since the width of a back electrode 17 made of a magnetic substance is made wider than that of a magnet 9, end faces of the back electrode 17 are positioned on the outside of the sides of the recording medium 1. Therefore, magnetic fields are not concentrated on the end faces of the recording medium 1 and toner 8 accumulation does not occur on the surface of the recording medium 1. Moreover, the toner 8 is not scattered to the inside of this device even if the recording medium 1 moves.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an image recording device, and in particular to an image recording device in which an image is obtained by directly controlling toner using an electric signal corresponding to the image and making it adhere to a recording medium. Regarding equipment.

[Background of the invention]

An example of a conventional image recording device of this type is disclosed in U.S. Patent No.
It is disclosed in No. 3914771.

An example of this conventional image recording apparatus will be explained with reference to the cross-sectional view shown in FIG. Move in the direction of the middle arrow. As the recording medium 1, it is also possible to use a generally commercially available electrostatic recording paper. Reference numeral 4 denotes a conductive roller-shaped back electrode, which is in contact with the conductive material 2 of the recording medium 1 that is fed in the direction of the arrow. Reference numeral 5 denotes electrode members for applying an image signal voltage, and a large number of electrode members 5 are arranged in a row on a cylinder 6 described below and are fixed insulated from each other. This electrode member 5 is made of a conductive magnetic material such as permalloy, nickel, iron, etc., and its tip is bent to form an electrode protrusion. Reference numeral 6 denotes a non-magnetic stationary cylinder serving as a means for transporting the toner to a recording position, and is immersed in monocomponent conductive magnetic toner 8 in a toner container 7 . The cylinder 6 and the electrode member 5 are electrically insulated. A rotating magnet 9 is provided inside the toner conveying member 6 made of a non-magnetic cylinder, and this magnet 9 is magnetized with magnetic poles of different polarity alternately. Due to the action of the magnet 9, the toner 8 moves on the toner conveying member 6 in the rotation direction A of the magnet 9.
transported in the opposite direction. The transported toner is formed into a uniform thin layer by the action of the doctor blade 10 and reaches the recording position 11 . Here, the toner adheres to the recording medium 1 and forms an image when a signal voltage corresponding to the image is applied from the signal power source 12 between the electrode member 5 and the back electrode (therefore, the recording medium 1 in contact with it). be done. The toner image deposited on the recording medium 1 is fixed by means such as heating or pressure.

FIG. 3 shows another example of this type of image recording apparatus, which is described in detail in Japanese Patent Application Laid-Open No. 127578/1983. The same numbers as in FIG. 1 indicate elements that perform the same functions. In this example, recording medium 1 is cylindrical and
Rotate in direction A′. The conductive magnetic electrode 5 is opposed to the recording medium 1 at a slight distance, and is penetrated by the magnetic flux of the magnet 9 surrounding it. 13 is a toner application roller made of a non-magnetic cylinder, and inside is a rotating magnet 16 which is rotated by a drive system (not shown).
is installed. When the rotating magnet 16 rotates in the direction of the arrow C, the conductive magnetic toner 8 moves from the toner container 7 in the direction of the arrow D on the application roller 13 and is conveyed to the recording medium 1 . In this case, a voltage is applied between the recording medium 1 and the toner application roller 13 from the power source 14, and thereby the toner 8 is applied onto the recording medium 1 in a thin layer. When the applied toner 8 reaches the recording electrode 5, the toner 8 forms a toner chain on the tip of the recording electrode 5, and the charge injected by the coating roller escapes through the toner chain, so that the recording medium 1 and the toner 8, no adhesive force will work between it and 8. On the other hand, when an image signal voltage is applied between the recording medium 1 and the recording electrode 5 from the signal power supply 12, electric charges are generated on the recording medium 1 through the toner chains in the same way as shown in FIG. A force that adheres to the recording medium 1 acts. Next, the toner 8 that has no adhesion force is removed by a toner removing device 15 (for example, means using a magnetic field or air suction) to the extent that the toner 8, which has been charged in the image pattern, is not disturbed. A visible image corresponding to the image signal appears on 1.

By the way, in the images obtained by these conventional image recording devices, the magnetic field generated by the magnet 9 spreads near the recording medium 1, so that when the toner 8 on the recording electrode 5 comes into contact with the surface of the recording medium 1, it moves along this magnetic field. Because it spreads, it becomes wider than the width of the recording electrode 5, and the recorded image obtained becomes blurred. As a solution to this problem,
173854 and Japanese Patent Application Laid-Open No. 57-19762, a method has been proposed in which a back electrode made of a magnetic material is used on the opposite side of the recording medium 1 at a position facing the recording electrode 5, and FIG. This method is illustrated, and numeral 17 is a back electrode made of a ferromagnetic material such as iron or nickel, and the other configurations are the same as the conventional device described above. The width of the back electrode 17 (the length in the left-right direction in the figure) extends over the width of the magnet 9. In this configuration, the magnetic field generated by the magnet 9 extends substantially perpendicularly to the recording medium 1 through the recording electrode 5, so that a clear recorded image without widening of the dot diameter can be obtained.

However, in this method, since the magnetic field generated by the magnet 9 is more concentrated on the end face of the back electrode 17, the toner 8 tends to collect on the end face of the back electrode 17, and when the recording medium 1 moves, the toner 8 tends to collect on the end face of the back electrode 17. The accumulated toner 8 was transferred as the recording medium 1 moved and contaminated the inside of the apparatus, which was undesirable.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned conventional examples,
It reduces the spread of the magnetic field from the recording electrode to the recording medium to ensure the clarity of the recorded image, and also prevents toner accumulation near the edges of the recording width, making it possible to obtain stable images over a long period of time. An object of the present invention is to provide an image recording device of this type.

[Summary of the invention]

The present invention provides an image recording device of the type described above, in which a magnetic field applying means (magnet 9 in the above example) which applies a magnetic field between the recording electrode and the recording medium has a width wider than the width in the width direction of the recording medium. The feature is that the magnetic material is placed on the opposite side of the recording medium, facing the recording electrode.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, in which the vicinity of the recording electrodes is viewed in the direction of the tangential plane of the recording medium. In this embodiment, the width of the back electrode 17 made of a magnetic material is made longer than the width of the magnet 9, so that the end surface of the back electrode 17 is located outward from the width of the recording medium 1. As a result, the magnetic field is not concentrated on the end face, the toner 8 does not accumulate, and even if the recording medium 1 moves, the toner 8 does not scatter into the apparatus. When applied to the image recording device shown in FIG. 2, the back electrode 17 may also serve as the back electrode 4 shown in the same figure, and when applied to the image recording device shown in FIG. It may be placed on the opposite side (inside) of the recording medium 1.

Figure 5 shows a part of another type of image recording apparatus, in which the recording medium is not cylindrical but belt-shaped in the image recording apparatus shown in Figure 3, and a magnetic body rotating at the same circumferential speed is used. A rear electrode 17 made of aluminum is placed opposite the recording electrode group 5, and its operation is essentially the same as that shown in FIG.

Conventionally, in FIG. 5, the back electrode 17 using a magnetic material extends across the width of the magnet 9, and the toner 8 adheres to the end face of the magnet 9 due to magnetic flux concentration.
As this toner 8 moves along with the rotation in the direction of arrow E, more unnecessary toner 8 is carried than in the case of FIG. This is undesirable as it causes stains. However, according to an embodiment of the invention, the width of the back electrode 17 in FIG. 5 is made wider than that of the magnet 9. This eliminates the drawbacks mentioned above. Moreover, by making the linear velocity of the recording medium 1 and the back electrode 17 the same, the back electrode 1
7 is eliminated, a constant distance is always maintained between the recording electrode 5 and the recording medium 1, and a stable image can be obtained for a long time.

In addition, as another embodiment, a ferromagnetic drum may be used as the back electrode 17, and the dielectric layer 3 may be coated on the upper surface thereof. A similar effect can also be obtained by providing a curved surface on the end surface of the back electrode 17 from the non-recording position.

〔Effect of the invention〕

As explained above, with a simple configuration in which the width of the back electrode made of magnetic material is made wider than the width of the magnet, it is possible to reduce toner stains inside the device and obtain stable images over a long period of time. becomes.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing one embodiment of the present invention;
2 and 3 are schematic sectional views showing conventional examples of image recording devices to which the present invention is applied, FIG. 4 is a diagram showing a conventionally proposed back electrode, and FIG. 5 is a diagram showing a conventional example of an image recording device to which the present invention is applied. FIG. 3 is a partial cross-sectional view of another type of image recording device. DESCRIPTION OF SYMBOLS 1... Recording medium, 4... Back electrode, 5... Electrode member, 6... Toner conveying cylinder, 8... Toner...
9...Magnet, 10...Doctor blade, 11...
...recording position, 12...image signal voltage source, 13...
Application roller, 14... Voltage source, 15... Toner removal device, 16... Rotating magnet, 17... Back electrode.

Claims (1)

[Scope of Claims] 1. A recording electrode group, a recording medium that is close to and moves relative to the recording electrode group, and means for supplying conductive magnetic toner into a gap between the recording electrode group and the recording medium; In an image recording apparatus comprising a magnetic field applying means for applying a magnetic field to the gap, and a means for applying an image recording voltage to selected electrodes of the recording electrode group according to an image pattern, the magnetic field applying means in the width direction of the recording medium is provided. An image recording device characterized in that a ferromagnetic material having a width wider than the width of the means is disposed on the opposite side of the recording medium, facing the recording electrode group. 2. The image recording device according to claim 1, wherein the ferromagnetic material has an endless surface that moves at the same circumferential speed as the recording medium.