JPH04363263A - Electrostatic recording head - Google Patents

Abstract

PURPOSE:To provide an electrostatic recording head which is high in ion beam density by a method wherein an ion beam dot is prevented from broadening and blurring and decrease of an ion beam quantity passing through an ion outflow opening is reduced by bringing the ion beam passing through the ion outflow opening into convergence effectively. CONSTITUTION:An ion beam converging means provided to control electrodes 25, 42 of an electrostatic recording head generates so-called electric force line of a barrel type to bring an ion beam into convergence by increasing a diameter of an opening of the control electrodes 25, 42 from an ion generating source side toward an ion discharge side. Then, an image is prevented from expanding and blurring and decrease of ion beam density is lessened by decreasing diffusion of the ion beam by the ion beam converging means.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an electrostatic recording head, specifically an ion flow type electrostatic recording head for forming an electrostatic latent image by flying corona ions onto the dielectric surface of an image carrier. Regarding recording heads.

0002

[Prior Art] Generally, in this type of electrostatic recording system, an electrostatic latent image is formed on the dielectric surface of an image carrier, and the latent image is developed with toner to obtain an image. . Various methods have been proposed for forming a latent image in this case, one of which is to generate ions using corona discharge, extract and control the flow of ions, and then immerse them on the surface of the dielectric material. There is a method to form an image, for example,
This is shown in Japanese Patent No. 1348.

[0003] This method uses two devices separated by a dielectric member.
A high-frequency voltage is applied between two electrodes to generate a discharge, and ions generated by the discharge are extracted in accordance with a print signal and controlled by a control electrode to form a latent image on an image carrier.

According to this method, an electrostatic latent image can be formed on the image carrier without contact, and recording can be performed at high speed. Therefore, it is possible to meet the needs for high speed and high reliability required of recent recording devices.

However, in the electrostatic latent image formed by the ion flow, the electric field is distorted as the latent image potential becomes higher.
An electric field is formed that diffuses the ion flow flowing from the electrostatic recording head 1. The situation of the lines of electric force L and the equipotential surface E in the vicinity of the image carrier 2 holding this electrostatic latent image is as shown in FIG.

[0006] Due to the electric field in such a situation, the ion flow flowing later is diffused, and the recorded dots are enlarged. This may cause the image to expand or become blurred. In addition, since the diffusion of the ion flow occurs in directions other than the aperture, the density of the ion flow passing through the aperture becomes small, making it impossible to increase the recording density and, therefore, the recording speed. There was a problem.

An improved system for solving these problems is disclosed in Japanese Patent Laid-Open No. 62-3965. That is, in addition to the structure of the ion flow type recording head described above, an insulating spacer having an opening and a second control electrode having an opening are provided, and a variable distance between the first and second control electrodes is provided. This method applies a bias voltage to focus the ion flow.

[0008]

However, this method of adding the second control electrode has the disadvantage that the structure and manufacturing process of the electrostatic recording head become quite complicated. As the structure and manufacturing process become more complex, there is a higher possibility that geometrical defects and positional deviations will occur, and if these occur, variations in discharge will occur. Further, in this method, although it is possible to converge the ion flow, there is also a drawback that when the bias voltage is applied, the ion flow tends to be sucked into the first control electrode, and the amount of ion current tends to decrease.

The present invention has been made in view of the above-mentioned problems, and it solves the drawbacks of the prior art, efficiently converges the ion flow passing through the ion outflow aperture, and eliminates the spreading and blurring of the ion flow dots. It is an object of the present invention to provide an electrostatic recording head that can prevent the ion flow, reduce the amount of ion current passing through the ion outflow openings, and perform printing with high precision and high ion current density.

0010

Means for Solving the Problems and Operations In order to solve the above problems, in the present invention, the control electrode of the electrostatic recording head has an ion flow focusing means. As a first example of this means, the aperture shape of the control electrode is such that its diameter increases from the ion source side toward the ion emission side to generate a so-called barrel-shaped electric field and converge the ion flow. As a second example, a second control electrode is provided sandwiching the semiconductor layer, a bias voltage is applied between the first control electrode and the second control electrode, and a so-called barrel-shaped electric field is generated. A cylindrical magnetic field is generated by a current-carrying means that causes a current to flow from the ion-generating part side to the ion-emitting side inside the semiconductor layer, and the ion flow is efficiently converged by the electric field and the magnetic field. The ion focusing means reduces the diffusion of the ion flow, prevents expansion and blurring of the image, and reduces the decrease in the density of the ion flow.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show a first embodiment of the present invention. FIG. 1 shows an enlarged view of one charge dot implantation element in a recording head device 11 that forms charge dots using an ion flow according to the present invention, and FIG. 2 shows a drum type transfer method using the recording head device 11. The configuration of an example of an image recording device 12 is schematically shown.

As shown in FIG. 1, the recording head 20 of the recording head device 11 includes a first dielectric layer 21, a line electrode 22 as a first discharge electrode sandwiching this, and a line electrode 22 as a second discharge electrode. The finger electrodes 23 are provided with apertures 23a located at portions facing the line electrodes 22, respectively.

Furthermore, the recording head 20 is provided with a control electrode 25 with a second dielectric layer 24 interposed between it and the finger electrode 23, thereby forming an ion control section. This control electrode 25 is formed with apertures 25a located corresponding to the apertures 23a of the finger electrode 23, respectively. Further, in the second dielectric layer 24, openings 24a are formed in positions corresponding to the openings 23a of the finger electrodes 23, respectively, and having a diameter larger than each of the openings 23a and 25a. ing.

The recording head 20 as a whole has electrodes 22, 23, 25 and dielectric layers 21, 24 stacked on top of each other to form an integral laminate. The openings 23a, 24a, and 25a of the body layer 24 and the control electrode 25 extend coaxially through the body layer 24 and the control electrode 25, and constitute an ion flow path 26 corresponding to the recording dots.

Furthermore, an AC voltage source 27 is connected to the line electrode 22 and the finger electrode 23, and the electrodes 22,
23, an alternating current voltage is applied at regular intervals. A signal voltage corresponding to image information is applied to the finger electrode 23 from a signal voltage source 29 through a switching circuit 28 that operates in accordance with the timing of the alternating current voltage. Further, a constant bias voltage with a polarity opposite to that of the ion flow is applied to the control electrode 25 from a control voltage source 30.

Furthermore, as shown in FIG. 1, the control electrode 25 of the electrostatic recording head 20 is formed with an opening 25a whose diameter gradually increases from the ion generation source side to the ion emission side. In other words, this opening 25
a has a so-called trumpet-shaped inner circumferential surface that expands from the ion source side to the ion emitting side, thereby constituting a means for converging the ion flow passing through the opening 25a, as described later. There is.

Furthermore, in order to further improve the effect of converging the ion flow, the control electrode 33a is made thicker in the direction of the ion flow than conventional control electrodes. For example, like the line electrode 22 and finger electrode 23, its thickness is in the range of 9 to 30 microns, but if it is larger than that,
For example, it is formed with a thickness of 40 to 100 microns.

Furthermore, a dielectric layer 36 having an opening 36b is provided overlappingly on the image carrier surface side of the control electrode 25. Opening hole 3
6b is provided coaxially with the aperture 25a of the control electrode 25 corresponding to this, and the aperture 25 of the control electrode 25
The diameter is equal to or larger than the maximum diameter of a.

In FIG. 2, reference numeral 31 denotes a solid dielectric drum (hereinafter simply referred to as a drum) as an image carrier which is rotationally driven at a predetermined frequency in the direction of the arrow. It is formed by forming a body layer 31b. Around the drum 31, following the recording head 20 along the rotational direction of the drum 31, a developing device 32,
A transfer charger 33, a cleaner 34, and a static eliminator 35 are arranged in this order.

Next, the electrostatic recording operation in this embodiment will be sequentially explained. First, the electrostatic latent image forming operation of the recording head 20 on the image bearing surface of the drum 31 whose charge has been removed by the charge remover 35 is performed as follows. An AC voltage source 27 is connected between the line electrode 22 and the finger electrode 23.
AC voltage with a constant period, for example, frequency 1 MH
When an AC voltage with a peak-to-peak voltage of 2.5 KVP-P is applied, positive and negative ions are generated in the vicinity of the aperture 23a. At this time, -600V is applied to the control electrode 25.
voltage is applied.

Now, when a signal voltage corresponding to the image information, for example a voltage of -620V, is applied to the finger electrode 23 from the signal voltage source 29 through the switching circuit 28 in synchronization with the timing of the alternating current voltage, a voltage of -620 V, for example, is applied to the finger electrode 23 at the opening 23a. A certain negative ion is connected to the finger electrode 23 and the control electrode 25.
Because of the potential difference between recorded as a latent image. This is the finger voltage on state.

On the other hand, when recording is not performed, the finger electrode 23 is grounded (0V) or at least a voltage higher than the voltage applied to the control electrode 25 (
For example, -420V) is applied. As a result, ions are not released. This is the finger voltage off state.

Therefore, by selecting the signal voltage to be applied to the finger electrodes 25 according to the image information, it is possible to form a charge pattern (latent image) on the image carrier surface of the drum 31 according to the image information.

Therefore, the voltages applied to the finger electrodes 25 of the individual charge dot implanting elements arranged along the longitudinal direction of the recording head 20 are not shown in correspondence with the time-series pixel signals of the target image to be formed. The control circuit selectively performs main scanning control, and by relatively moving the recording head 20 and drum 31 in the sub-scanning direction in a direction perpendicular to the main scanning direction, the electrostatic charge of the target image is applied to the image carrier surface of the drum 31. A latent image is sequentially formed as a charge pattern using charge dots as pixels.

In order to improve the convergence of the ion flow, it is better to have a smaller gap distance between the control electrode 25 and the image bearing surface of the solid dielectric drum 31 as an image carrier, but on the other hand, as the gap distance becomes smaller, If foreign matter adheres to the periphery of the aperture 25a or if the aperture 25a has a shape defect, electric discharge is likely to occur between the control electrode 25 and the surface of the image carrier. For example, if the voltage of the control electrode 25 is -600V, discharge may occur between the control electrode 25 and the surface of the image carrier when the gap distance is 150 μm or less.

Therefore, in this embodiment, an opening 36b is formed on the image carrier surface side of the control electrode 25 in order to prevent discharge in the gap.
The dielectric layers 36 having . This may cause foreign matter to adhere to the periphery of the opening 25a or
Discharge can be prevented when there is a shape defect in a.

As shown in FIG. 1, when the finger voltage is on, among the lines of electric force from the generation end of the ion generation source, the line of electric force at the center is connected to the opening of the finger electrode 23 and the control electrode 25. along the center. The lines of electric force located at the periphery expand once in the gap between the finger electrode 23 and the control electrode 25, but the lines of electric force tend to intersect perpendicularly to the opening circumferential surface of the aperture 25a of the control electrode 25. Therefore, after being narrowed down into a so-called barrel shape within the aperture 25a of the control electrode 25, it heads toward the image carrier surface of the drum 31. Ions flow along the electric field lines. Note that E indicates an equipotential line.

Incidentally, ions in the atmosphere repeatedly collide due to thermal motion, but when an electric field is applied thereto, they drift macroscopically in the direction of the electric field. The magnitude of the diffusion of the ion current that causes the spread of dots on the image carrier surface is determined by the ratio of the drift velocity in the direction of the electric field and the thermal velocity. In this example, the ion drift velocity and thermal velocity are not significantly different, and the motion of the charged particles is strongly constrained by the electric field. Therefore, as shown in FIG. 1, if the electric lines of force are narrowed into the barrel shape, the ion flow can be focused according to the barrel-shaped electric lines of force, and the static Even when the electric field is distorted due to the electric latent image,
This makes it possible to reduce the diffusion of ion currents.

In this embodiment, it is possible to converge the ion flow without adding any components that cause variations in discharge, and the amount of ion current decreases little. In addition, it is possible to sufficiently remove defects in the shape of the opening and foreign matter attached to the periphery of the opening. Furthermore, if the discharge can be prevented, the ion flow can be focused even without the dielectric layer 24.

With respect to the image bearing surface of the drum 31 from which static electricity has been removed,
The recording head 20 described above sequentially forms an electrostatic latent image according to an image signal, for example, as a charge pattern of charge dots of negative polarity. The charge pattern recorded on the drum 31 is developed with toner having positive polarity from a developing device 32.

Next, the toner image on the drum 31 is sequentially transferred by a transfer charger 33 onto a transfer material 37 fed between the image transfer charger 33 and the drum 31 from a paper feed section (not shown). Ru.

After this transfer, the drum 31 is cleaned by removing the residual toner after transfer by a cleaner 34, and is then neutralized by a static eliminator 35 and used repeatedly for image formation as described above. On the other hand, the toner image on the transfer material 37 is fixed by the fixing device 38 and is discharged outside the machine.

FIG. 3 shows a second embodiment of the invention. Note that the same components as in the first embodiment shown in FIG. 1 are given the same reference numerals. In FIG. 3, a semiconductor layer 41 having an opening 41a is provided on the image carrier surface side of the first control electrode 25 having an opening 25a. An opening 4 is provided on the image carrier surface side of this semiconductor layer 41.
A second control electrode 42 having a diameter of 2a is provided in an overlapping manner. The openings 23a, 24a, 25a, 41a, and 42a of the finger electrode 23, the second dielectric layer 24, the first control electrode 25, the semiconductor layer 41, and the second control electrode 42 are in coaxial communication with each other. It is set in.

Furthermore, a control voltage source 30 is connected to the second control electrode 42 for applying a constant voltage having a polarity opposite to that of the ion flow. Further, a bias voltage source 44 is connected to the first control electrode 25 and the second control electrode 42 via a second switching circuit 43, and the second control electrode 42 is connected to the first control electrode 25. A negative bias voltage is selectively applied to. As shown in the figure, this second switching circuit 43 has two states: a state where a negative bias voltage is applied to the second control electrode 42 with respect to the first control electrode 25, and a state where a negative bias voltage is applied to the second control electrode 42 with respect to the first control electrode The state in which the control electrode 42 is electrically conductive can be selected.

Therefore, a constant voltage having a polarity opposite to that of the ion flow is applied to the second control electrode 42 by the control voltage source 30, and the second switching circuit 43 applies a second control voltage to the first control electrode 25. In the state in which a negative bias voltage is applied to the electrode 42, the bias voltage source 4
4 applies a negative bias voltage to the second control electrode 42 with respect to the potential of the first control electrode 25 . Also, the second
When the switching circuit 43 conducts the first control electrode 25 and the second control electrode 42 , the bias voltage source 44 causes the first control electrode 25 and the second control electrode 4 to be connected to each other.
2, a constant voltage of opposite polarity to the ion flow is applied at the same potential.

When a bias voltage is applied between the first control electrode 25 and the second control electrode 42 by the voltage source 30, and a voltage is applied to the finger electrode 23 to turn it on, as shown in FIG. Barrel-shaped lines of electric force are formed. Further, a current i flows inside the semiconductor layer 41 in a direction from the first control electrode 25 to the second control electrode 42.
A control magnetic field B is generated by the current i caused by this energizing means. FIG. 4 schematically shows the state of the aperture 41a and the control magnetic field B around it as seen from the image carrier side. That is, due to the current flowing inside the semiconductor layer 41, a clockwise cylindrical magnetic field B is formed in the opening 41a when viewed from the image carrier side. Negative ions passing through the aperture 41a are subjected to a Lorentz force directed toward the center of the aperture 41a due to the magnetic field B. This Lorentz force provides convergence of the ion flow.

[0037] In this way, the negative ions are subjected to a force in the direction of convergence due to the electric field and magnetic field, and the ion flow is efficiently converged. This can prevent the charge dots from blurring and spreading, and the current density of the ion flow can be increased. In addition, in this second embodiment, since the ion flow is controlled by the magnetic field B in addition to the electric field, the ion flow is controlled by the first and second control electrodes 25, compared to a means that controls the ion flow by only the electric field. , 42 can be set small. Therefore, even if the ion flow is focused, the decrease in the amount of ion current can be reduced.

In the first and second embodiments, the ion source is located on the side of the line electrode 22 (first discharge electrode) and control electrodes 25 and 42 arranged in a matrix with the dielectric layer 21 in between. finger electrode 23 (second
However, even if the ion source is one corotron common to all the openings of the control electrodes 25 and 42, the same ion flow as in the first and second embodiments can be achieved. By providing a control unit, the ion flow can be focused.

FIG. 5 shows an example in which a corotron is used as the ion source and an ion control section similar to that of the first embodiment is provided. Ions generated from the corona wire 52 to which a DC voltage is applied by the DC power supply 51 are diffused in all directions, some of which are absorbed by the casing 53, and the ion flow toward the opening 25a of the control electrode 25 is similar to that in the first embodiment. Converges as in the example. The present invention is not limited to the embodiments described above, and various other modifications are possible.

[0040]

As explained above, according to the electrostatic recording head of the present invention, the ion flow passing through the ion outflow aperture is efficiently converged, the ion flow dots are prevented from spreading and blurring, and the ion outflow is prevented. The amount of ion current passing through the aperture is less likely to decrease, and the ion current density can be increased.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a recording head device showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing the configuration of an example of a drum-type transfer type image recording apparatus using the recording head device.

FIG. 3 is a sectional view of a recording head device showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram schematically showing the state of a control magnetic field when the aperture of a recording head is viewed from below, also showing a second embodiment of the present invention.

FIG. 5 is a sectional view showing a modification of the recording head device of the present invention.

FIG. 6 is an explanatory diagram showing the state of electric lines of force and equipotential surfaces in the vicinity of an image carrier from a recording head in a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11... Recording head device, 12... Image recording device, 20... Recording head, 21... First dielectric layer, 22... Line electrode,
23... Finger electrode, 25... Control electrode, 26... Ion flow path, 27... AC voltage source, 28... Switching circuit,
29... Signal voltage source, 36... Dielectric layer.

Claims (5)

[Claims] 1. In an electrostatic recording head having an ion generation source and an ion control section, a control electrode having an opening corresponding to a recording dot is provided on the ion emission side of the ion generation source, and the control electrode has an ion emission side. An electrostatic recording head comprising means for converging ions. 2. The electrostatic recording head according to claim 1, wherein the ion focusing means is in the form of an opening in a control electrode whose diameter increases from the ion source side toward the ion emitting side. 3. The ion focusing means is an energizing means that causes an ion focusing effect using an electromagnetic field generated by passing a current from the ion generating section side to the ion emitting side in the ion control section. The electrostatic recording head described in . 4. An ion generation source is constituted by a first discharge electrode arranged in a matrix with a dielectric material in between and a second discharge electrode located on the control electrode side;
4. The electrostatic recording head according to claim 2, further comprising apertures for generating ions at matrix intersections of the electrodes. 5. The electrostatic recording head according to claim 2, wherein the ion source is one corotron common to all the apertures of the control electrode.