JPS6353546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording device for outputting image signals used in facsimiles, etc., and in particular to a recording device that uses a recording method called powder contrastography and drives recording electrodes and counter electrodes in a matrix manner. Regarding.

Conventionally, a conductive or insulative recording pair is applied to the recording electrode needle, conductive magnetic toner is brought close to the recording medium from the back side, and a voltage corresponding to the image signal is applied between the recording electrode needle and the developing roller sleeve. A method called powder contrastography is known in which toner particles are attached to the powder.

The biggest disadvantage of this method is that it cannot use a multi-stylus electrode with a control electrode, it cannot drive the recording electrode needles in a matrix, and it is necessary to prepare a drive circuit to apply drive voltage for the number of electrode needles. However, there was a problem that the equipment had to be large-scale and expensive.

For this reason, for example, instead of arranging a plurality of counter electrodes in a row at positions facing the recording electrodes with the recording medium in between, as proposed in Japanese Patent Application Laid-open No. 52-149021, , arranged diagonally,
When one counter electrode faces one recording electrode group and generates a high electric field, the other counter electrodes are moved away from the recording electrode group to perform matrix drive without generating an electric field. There is.

However, in this method, in order for the opposing electrode at one end to drive the opposing electrode at the other end, recording of one scanning line ends when the rotating roller to which the opposing electrode is fixed is moved a predetermined distance. , the disadvantage is that the recording speed is extremely slow.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, an object of the present invention is to
It is an object of the present invention to provide a recording device that makes use of various features of the powder contrast recording method and enables selective driving of recording electrode needles in a matrix without reducing the recording speed.

In the recording method of powder contrastography, when insulating magnetic toner is used, the present invention consists of a roller sleeve made of an insulator, on which a plurality of segment electrodes are provided in close contact with each other, and recording electrodes are attached to these electrodes. By selectively applying a voltage with the opposite polarity to the voltage applied to the needle, the toner particles carried onto the selected segment electrode are charged to the polarity applied to each segment electrode, and the toner particles are charged to the recording medium side. It is designed to be adsorbed to.

Furthermore, in the present invention, selective development of the recording electrode needles is possible by utilizing the phenomenon that in order to adhere toner particles onto the recording medium, it is necessary to apply a voltage above a certain threshold to the recording electrode. This is what I did.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the recording principle of the recording apparatus according to the present invention. The recording electrode 1 is a multi-stylus electrode in which a plurality of groups of electrode needles 2 are arranged in a row and fixed with resin 3. A recording body 4 made of an insulator or a two-layer structure of a conductor and an insulator is applied to the recording electrode 1, and a negative voltage 10 is applied to the electrode needle 2 in accordance with an image signal.

On the other hand, a developing device in which a rotating magnet 6 is disposed inside a fixed cylindrical sleeve 5 is provided at a position facing the recording electrode 1 via the recording medium, and this developing device carries a high-resistance magnetic toner 7. By applying zero or a positive bias voltage 11 in the opposite direction to the image signal to the counter electrode 8 provided on the cylindrical sleeve 5, a positive charge is injected into the toner particles 7, and the toner particles become positively charged. 7 is electrostatically attracted to the negative charge applied to the recording medium 4, and a toner image 9 is formed on the back side of the recording medium 4. Normally, this cylindrical sleeve 5 is made of a uniform conductor, but in the present invention, the cylindrical sleeve 5 is made of an insulator or a two-layer structure in which an insulator is formed on a conductor, and a plurality of layers are formed on the cylindrical sleeve 5 along the axial direction. A structure in which the counter electrode 8 divided into segments is arranged in close contact with each other will be explored.

The magnetic toner transferred onto the sleeve 5 is insulating magnetic toner, and conductive magnetic toner is not suitable. This is because the opposing electrodes 8 are arranged very close to each other on the sleeve 5, as will be described later, so that the toner short-circuits the opposing electrodes 8 and causes the toner to adhere to non-selected areas. This is due to the occurrence of

Further, the present invention utilizes the phenomenon that when a high-resistance magnetic toner 7 is used, a threshold voltage of a certain value or more is required for toner image formation.

The recording principle according to the present invention will be explained below with reference to FIGS. 2 and 3.

FIG. 1 shows a simple equivalent circuit of FIG. In the figure, Cd and Rd are the capacitance and equivalent resistance of the recording medium 4, Cg is the capacitance of the empty space, and Ct and Rt are the capacitance and equivalent resistance of the toner layer. Here, if the recording body 4 is considered as an insulator, Rd and Rt have high resistance and can be ignored. It's empty again
is so small that Cg can be ignored. When an electric field V is applied between the sleeve 6 and the recording electrode 1, the toner layer and the recording medium 4 have a charge amount Q. Here, when the coulomb force Fc generated from the amount of charge Q becomes larger than the magnetic attraction force F _M of the magnetic roller 6, the toner particles 7 adhere to the recording medium 4 side. Therefore, the toner image 9 cannot be formed on the recording medium unless the strength of the electric field V applied between the sleeve 6 and the recording electrode 1 exceeds a certain threshold value V ₀ . FIG. 3 is a diagram specifically explaining this from the relationship between voltage V and toner density 0D.

In FIG. 3, the horizontal axis represents voltage (V), and the vertical axis represents toner density (0D). In addition, the threshold value V ₀ and the slope of the graph change depending on the capacity Ct of the toner particles 7 and the capacity Cd of the recording medium, but in the illustrated example, the threshold value V ₀ needs to be -400V or more. This shows that in order to obtain sufficient image density, it is necessary to set the voltage V applied between the two at least to about -800 [V].

From the above phenomena, the following becomes possible. The voltage 10 applied to the recording electrode 1 is switched on and off from zero to -400 [V] depending on the image signal. Further, the voltage 11 applied to the counter electrode 8 is switched on and off from zero to +400 [V] depending on the image signal. By distributing the voltage to the recording electrode and the counter electrode in this way, the electrode needles necessary for image formation are removed only when a voltage is applied to a certain group of recording electrodes 1 and a voltage is applied to the counter electrode 8 facing the group. The voltage between the magnetic toner and the opposing electrode generates an electric field sufficient to attract the magnetic toner on the sleeve. For example, a potential difference of 800 [V] results, and as a result, toner adheres to the recording medium. On the other hand, the potential difference between the other unselected electrode needles and the counter electrode is 400
[V], sufficient coulomb force Fc is not obtained for toner to be transferred, and therefore, toner is not attached to the recording medium side. As described above, according to the present invention, a matrix of recording electrode needles can be selected.

In the above description, the case where the voltage applied to the recording electrode is negative is used, but in the case of positive voltage, the voltage applied to the segment electrode may be made negative.

FIG. 4 shows a specific embodiment of the recording apparatus according to the present invention. The recording electrode 1 is composed of a recording electrode array 2 consisting of a plurality of groups, as will be described later.

Further, a cylindrical sleeve 5 having a plurality of opposing electrodes 8 on its surface is arranged opposite to the recording electrode 1 .
The counter electrodes 8 are each connected to a switching element 14 for selective driving. In the illustrated embodiment, the sleeve 5 is fixed, but even when the sleeve 5 rotates, a ring-shaped counter electrode can be provided on the sleeve 5 and the lead terminal can be taken out using a brush. You can also do it.

FIG. 5 shows an example of the connection between the electrode array 2 of the recording electrode 1 and the counter electrode 8 disposed in close contact with the sleeve 5.
In the figure, 11 is a positive voltage source for applying a predetermined voltage to the recording electrode 1, 12 is a negative voltage source for applying a predetermined voltage to the counter electrode 8, and 13 is a voltage source 1.
1 is a switching element connected between the recording electrode 1 , and 14 is a switching element connected between the voltage source 12 and the counter electrode 8 . Switching element 1
3 and 14 are switched and controlled based on an output signal from a print drive circuit (not shown) that receives an image signal sent from a host device.

As explained above, according to the present invention, the matrix selection drive of the recording electrode needle in the powder contrastography method can be performed using an extremely simple structure, that is,
This can be achieved simply by using insulating magnetic toner, providing multiple opposing electrodes on the insulating sleeve, and applying voltages of opposite polarity to the recording electrode and the opposing electrode, respectively. This makes it possible to significantly reduce the number of circuits, thereby reducing the size and cost of the device, as well as arranging multiple opposing electrodes parallel to the direction in which the recording electrodes are arranged. Matrix driving can be performed without reducing speed.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the recording principle of the recording apparatus according to the present invention, FIG. 2 is an equivalent circuit diagram of FIG. 1, FIG. 3 is a graph showing the relationship between recording voltage and toner concentration, and FIG. FIG. 5 is a diagram showing a specific example of the configuration of the recording device according to the invention, and FIG. 5 is a diagram showing an example of wiring between the recording electrode needle and the counter electrode. In the figure, 1 is a recording electrode, 4 is a recording medium, 5 is a sleeve, 6 is a magnetic roller, 7 is a toner, and 8 is a counter electrode.

Claims (1)

[Scope of Claims] 1. A recording electrode comprising a plurality of electrodes arranged, a magnetic roller provided at a position facing the recording electrode with an insulating recording medium in between, and a magnetic roller surrounding the magnetic roller and forming a surface of the magnetic roller. A magnetic brush comprising an insulating sleeve in which a plurality of counter electrodes are arranged parallel to the arrangement direction of the recording electrodes at a position facing the recording electrodes, and forming a magnetic brush of insulating magnetic toner by rotation of the magnetic roller. a roller; a first voltage source that applies a voltage of positive or negative polarity to the recording electrode; a second voltage source that applies a voltage of opposite polarity to the first voltage source to the counter electrode; and the potential difference between the first and second voltage sources is set to cause the insulating magnetic toner to adhere onto the recording medium, and the voltage of the first voltage source is selectively applied to the recording electrode. By applying the voltage of the second voltage source to a counter electrode on the insulating sleeve arranged at a position facing the recording electrode to which the voltage is applied, the voltage is transferred over the insulating sleeve. A recording apparatus characterized in that an insulating magnetic toner is attached to the insulating recording medium.