JPH0872292A - Ion write head - Google Patents

Abstract

PURPOSE: To provide an ion write head which has high ion utility efficiency in a small size. CONSTITUTION: An ion write head 16 forms an electrostatic image by selectively adhering charged particles on a latent image carrier 28 formed of dielectric unit, and comprises a plurality of individual electrodes 21 formed on a board 17, an electron emitting unit 22 which is formed on the electrodes 21 and can emit electrons to form the particles by heating, a heater 24 for heating the unit 22, and a gate electrode 26 for accelerating the electrons emitted from the unit 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording apparatus for forming electrostatic latent images by selectively attaching charged particles corresponding to an image from the outside onto a latent image carrier composed of a dielectric material. And an ion writing head suitable for.

[0002]

2. Description of the Related Art In recent years, the latent image carrier has a higher mechanical strength and is more stable with respect to temperature and repetition than the photoreceptor used as a latent image carrier in the conventional electrophotographic system. In addition to using a latent image carrier formed of a dielectric material, an ion writing printer that uses charged particles (ions) instead of conventional light to form an electrostatic latent image can print at high speed. It is widely used in commercial high-speed printers, etc., which have a large number of maintenances and require little maintenance. Since the ion writing type printer is easier to control the latent image potential than the electrophotographic printer using the photoconductor, it is possible to control the density level by controlling the adhesion amount of the developer such as toner. It is suitable for printing with tones, and is suitable for a full-color printing device in which reproducibility of density gradation is important.

Hereinafter, such a conventional ion writing head will be described.

22A and 22B show an example of a conventional ion writing head. FIG. 22A is a perspective view showing the overall shape, and FIG. 22B is a vertical cross-sectional view showing the structure of the main part.
(C) is an explanatory view showing an arrangement state of the line electrodes and the finger electrodes.

As shown in FIG. 22 (a), the conventional ion writing head 1a has a screen electrode 2 on one surface.
Are provided, and a plurality of openings 3 are formed on the surface thereof in an array in a sawtooth shape, and have a substantially flat plate shape as a whole.
Then, as shown in FIG. 22B, the screen electrode 2, the finger electrode 4 having the opening 3, and the line electrode 5
Are disposed with an insulating layer 6 made of a desired dielectric material interposed therebetween. Further, as shown in FIG. 22C, the openings 3 of the finger electrodes 4 and the line electrodes 5 are arranged in a matrix. Then, as shown in FIG. 22B, the ion writing head 1 a is arranged so that each opening 3 faces the latent image carrier 7.

Such a conventional ion writing head 1a
In the above, a high frequency voltage having a frequency of 1 MHz and a voltage of about 1 kV is applied between the finger electrode 4 and the line electrode 5 by a desired drive circuit (not shown), and the atmosphere around the finger electrode 4 is charged by discharge. Ions 8 as particles ((b) in FIG. 22) are generated. Further, as shown in FIG. 22C, a plurality of line electrodes 5 are provided, and a high frequency voltage is sequentially applied to one of them. Then, a DC voltage of -600 V is applied to the screen electrode 2,
-700V on the finger electrode 4 at standby, at printing-
A voltage of 400V is applied. Further, the pulse width at the time of printing is set to, for example, about 20 μS, and, for example, the negative polarity ions 8 generated in the atmosphere around the finger electrodes 4 are controlled by the screen electrode 2, and FIG. As shown in FIG. 3, the latent image carrier 7 is made to collide with the opening 3 through the opening 3.

The latent image carrier 7 is a so-called dielectric drum 11 having a desired dielectric layer 10 formed on the surface of a metal drum 9, as shown in FIG. Is grounded. And, as mentioned above,
By causing ions 8 of negative polarity as charged particles to collide with the surface of the dielectric drum 11, an electrostatic latent image corresponding to a desired image (not shown) is formed on the surface of the dielectric drum 11. .

FIG. 23 shows another example of a conventional ion writing head 1b. In this conventional ion writing head 1b, a corotron 12 is used to generate ions 8 as charged particles, and the front surface thereof is used. Two control electrodes 14 and 14 having a plurality of desired openings 13 are arranged in the drive circuit and driven by an appropriate drive circuit 15. Then, depending on the polarity of the voltage applied between the two control electrodes 14 and 14, whether or not the ions 8 generated in the corotron 12, for example, the positive polarity ions 8 reach the latent image carrier 7 from the opening 13. Is controlled. The distance between the two control electrodes 14 and 14 is
For example, the diameter is about 100 μm, and the diameter of the opening 13 is 20.
It is set to about 0 μm. Furthermore, the resolution of the ion writing head 1b is set to about 8 dots / mm. The openings 13 are arranged in a sawtooth shape like the openings 3 of the head 1a shown in FIG.

[0009]

However, in the above-described conventional ion writing head 1 (the reference numerals collectively refer to the conventional ion writing heads 1a and 1b), only the amount of ions 8 necessary for latent image formation is real-time. Since it is impossible to generate an electrostatic latent image, a large amount of ions 8 are constantly generated, and a part of the ions 8 is guided onto the latent image carrier 7 by the screen electrode 2 or the two control electrodes 14 and 14, etc. It is designed to form an image. Therefore, the utilization efficiency of the generated ions 8 is low, the ozone generated at the same time as the ions 8 is processed, the power consumption is increased, the head 1 is increased in size, and the drive circuit 15 for the control electrode for controlling the high voltage is increased in size. There were various problems such as high price and high price.

Further, the conventional ion writing head 1 has a problem that the lower limit of the size of the openings 3 and 13 through which the ions 8 pass is limited. One of the restrictions is to increase the utilization efficiency of the generated ions 8.
The other is that the processing accuracy and withstand voltage of the screen electrode 2 or the control electrode 14 to which a high voltage is applied must be maintained.

That is, the problem of using the screen electrode 2 or the control electrode 14 having the large openings 3 and 13 is that the absolute value of the control voltage becomes large and that the ion writing head 1 moves toward the latent image carrier 7. Flowing ions 8
The point is that the diameter of one dot of the electrostatic latent image formed when the (ion flow) is narrowed does not become sufficiently small. When narrowing the ion flow, the diameter of the ion flow is controlled by the voltage applied to the electrodes 2 and 14 so that the diameters of the openings 3 and 13 of the control electrodes 2 and 14 are small.
It is focused to a fraction of the diameter of. Therefore, the diameter of one dot of the electrostatic latent image formed is smaller than that when the ion flow is increased. However, due to the limit of the focusing rate, the potential of the electrostatic latent image when the ion flow is narrowed becomes an intermediate value, and a halftone is reproduced by the potential.

Further, when the density gradation is reproduced by the toner adhesion amount, the reproducibility in the case of area gradation is good, but the reproducibility in the case of density gradation depends on factors such as variations in the charge amount of toner. Reproducibility is not very good. Generally, it is said that the conventional ion writing head 1 is superior in reproducibility of density gradation as compared with other writing methods. Strictly looking at this reproducibility, although the reproducibility and the stability of the gradation are excellent when the flow rate of the ions 8 is large and it enters the area gradation area,
The gradation reproducibility when the flow rate of the ions 8 is narrowed is inferior to that in the high concentration region. When the gradation of the electrostatic latent image is reproduced by changing the potential without changing the area of the electrostatic latent image, even if the electrostatic latent image is accurately formed with respect to the input signal, the toner adhesion amount in the developing process There are many factors that deteriorate the quality of the image, such as variations in the image quality, and as a result, the gradation reproducibility in the area gradation is inferior.

The fact that the size of the openings 3 and 13 cannot be reduced means that the resolution cannot be increased and that the openings 3 and 13 are
There is a problem in that there is a design limitation such as not being able to line up in a straight line.

Generally, even in an electrophotographic printer, a certain level of print quality can be obtained with respect to the reproducibility of a black and white binary image, but the reproducibility of an image including halftone is good. Absent. Therefore, in the current electrophotographic method, a method of pseudo-reproducing halftone by area gradation using dither is mainstream, and the printing resolution when using dither is electrostatic latent image formation. Significantly lower than the resolution in the instrument.

A typical dither matrix is formed of 4 × 4 pixels or 6 × 6 pixels. In that case, the gradation reproducibility becomes 16 steps and 36 steps, and the resolution of the formed image becomes 1/4 or 1/6. When importance is attached to gradation reproducibility, it is necessary to form an electrostatic latent image having a very high resolution in order to obtain a practical resolution.

Since the printing apparatus using the conventional ion writing head 1 has excellent halftone reproducibility, it is possible to reproduce density gradation without relying on dither. Therefore, it has been considered that the problem that the resolution cannot be increased due to the limitation of the size of the openings 3 and 13 can be compensated by the reproducibility of the density gradation. In other words, in applications where gradation reproducibility is prioritized, such as in photographs, reproducibility can be supplemented if the gradation reproducibility is excellent even if the resolution is low,
In applications that require high resolution such as character printing, gradation reproducibility can be used to make some improvements, but print quality is significantly inferior to electrophotographic methods with high resolution. There was a problem that I could not do it.

Further, in the conventional ion writing head 1, the plurality of openings 3 and 13 cannot be formed in a straight line in the print width direction, and the plurality of openings 3 and 13 are obliquely arranged.
A method of forming an electrostatic latent image of one line by time division is used, and the latent image carrier 7 has uneven speed,
If the writing timing is deviated, the position of the electrostatic latent image is deviated, and the printing quality is significantly deteriorated. Further, due to rearrangement of images, generation of timing, etc., the control circuit and drive circuit 15 not shown are likely to be complicated and expensive, and the ion writing head 1 itself becomes large, and the ion writing head 1 and latent image bearing are carried. There is a problem that it becomes difficult to keep a constant distance from the body 7.

The present invention has been made in view of these points, and overcomes the above-mentioned problems in the conventional ones.
It is an object to provide a small-sized ion writing head with high ion utilization efficiency.

[0019]

In order to achieve the above-mentioned object, the ion writing head of the present invention according to claim 1 is
An ion writing head for selectively depositing charged particles on a latent image carrier made of a dielectric to form an electrostatic latent image, the plurality of individual electrodes formed on a substrate, and the individual electrodes. An electron emission part that is formed on the electron emission part and can emit electrons to generate charged particles by heating, a heating part for heating the electron emission part, and the electron emission in cooperation with the individual electrode. And a gate electrode for accelerating the electrons emitted from the part.

An ion writing head according to a second aspect of the present invention is characterized in that, in the first aspect, the individual electrode also serves as the heating section.

Further, the ion writing head of the present invention according to claim 3 is characterized in that, in claim 1 or 2, the electron emitting portion is formed mainly of a ferroelectric substance.

Further, an ion writing head according to a fourth aspect of the present invention is the ion writing head according to any one of the first to third aspects, further comprising a drive circuit for causing the heating section to generate heat at a predetermined timing. I am trying.

[0023]

The ion writing head of the present invention having the above-mentioned structure generates ions by using the so-called thermoelectron emission principle, and by heating the heating portion formed on the substrate, the electron emission portion is removed. It is heated to emit thermoelectrons from it, and the electrons are accelerated by the electric field applied between the gate electrode and the individual electrode to generate ions, which are generated between the individual electrodes and the latent image carrier. An electrostatic latent image can be formed on the surface of the latent image carrier by moving it to the surface of the latent image carrier by the electric field applied to the latent image carrier.

[0024]

The present invention will be described below with reference to the embodiments shown in the drawings.

FIGS. 1 to 3 show a first embodiment of an ion writing head according to the present invention, FIG. 1 is a longitudinal sectional view showing the structure of the main part, and FIG. 2 shows the structure of the main part. FIG. 4 is a partially cut plan view showing FIG. 3, and FIG. 3 is a circuit diagram showing a drive circuit.

As shown in FIGS. 1 and 2, the ion writing head 16 of this embodiment has a thermal insulating layer 18 on a substrate 17.
Is provided, and a heater layer 19 is provided on the upper surface of the heat insulating layer 18. Then, on the upper surface of the heater layer 19, individual electrodes 21 having a base 77 having a diameter of, for example, about 30 μm, which are referred to as a plurality of cathode electrodes corresponding to the resolution (the number of pixels) via the intermediate insulating layer 20, are shown in the drawing. They are arranged in a line in the left-right direction (print width direction). Furthermore, on the upper surface of the base 77 of each individual electrode 21,
An electron emission unit 22 that can emit electrons to generate charged particles (ions) is provided. In addition, the heater layer 19
A conductive layer 23 for concentrating the heat generation of the heater layer 19 to each electron emitting portion 22 is provided on the upper surface of each electron emitting portion 22.
Is disposed except for a portion facing to. That is, in the present embodiment, a portion of the heater layer 19 corresponding to each electron emitting portion 22 and not covered with the conductive layer 23 is a heating portion 24 for heating each electron emitting portion 22. Furthermore, on the substrate 17, a gate electrode 26 having, for example, a circular opening 25 with a diameter of about 20 μm centering on each electron emitting portion 22 is provided via an insulating layer 27 having an appropriate thickness, Is formed in a substantially flat plate shape.

The substrate 17 may be made of any material as long as it has high heat resistance and has required mechanical strength and workability.
Insulators such as alumina ceramics and glass, and SiO
Various things such as a silicon substrate covered with an insulator such as ₂ can be selected.

As the material of the heat insulating layer 18, various materials such as high melting point glass, foam glass, zirconia ceramics, and silicon dioxide, which have small thermal conductivity, can be selected.

As the material of the heater layer 19, various materials such as tungsten, nichrome and tantalum nitride can be selected.

As the material of the intermediate insulating layer 20, use is made of an inorganic insulator such as SiO ₂ or A1 ₂ O ₃ which has high insulation performance and stability because it is exposed to ions generated by a large electric field. Is desirable.

In consideration of conductivity and workability, it is desirable to use a metal material such as platinum, tungsten, tantalum, molybdenum, etc. as the material of the individual electrode 21.

Examples of the material of the electron emitting portion 22 include a ferroelectric substance having a thermoelectron emitting action that emits electrons by heating, such as barium titanate, strontium titanate, barium zirconate, and strontium zirconate. These can be used alone or in combination as required.

The material of the conductive layer 23 is preferably platinum, tantalum, tungsten, molybdenum, etc., which has a smaller electric conductivity than the heater layer 19 and has high heat resistance.

As the material for the gate electrode 26, various materials such as molybdenum and tantalum can be selected.

As a material of the insulating layer 27, since it is exposed to ions generated by applying a large electric field and heat is added, heat loss is small and insulation performance and stability are high.
It is preferable to use a transparent or white inorganic insulator such as SiO ₂ or A1 ₂ O ₃ .

Further, as shown by an imaginary line in FIG. 1, a latent image carrier 28 on which an electrostatic latent image is formed is arranged so as to face the gate electrode 26 of the ion writing head 16. In this latent image carrier 28, an appropriate dielectric layer 30 is formed on the surface of a desired metal substrate 29, and at a constant distance G (gap) of about 100 μm from the gate electrode 26. Are arranged so as to be movable at a constant speed in the sub-scanning direction orthogonal to the main scanning direction in which each of the electron emitting portions 22 is arranged.

As shown in FIG. 3, in the drive circuit 31 of the ion writing head 16 of this embodiment, the metal base 29 provided on the opposite side of the latent image carrier 28 to the ion writing head 16 is attached to the back electrode 32. The reference potential is formed by grounding as. The drive circuit 31 is electrically connected to a latent image writing power supply VL that supplies a voltage of a negative polarity to the gate electrode 26, and the gate electrode 26 is a common electrode for each individual electrode 21. There is. Each individual electrode 21 is connected to an appropriate drive transistor 33, and each drive transistor 33 uses the gate electrode 26 as a reference potential and applies a negative polarity voltage to the gate electrode 26 for electron acceleration. It is connected to the power supply VE via the current setting resistor 34. The heater layer 19 is electrically connected to a heating power source VH via a temperature control unit (not shown) for controlling the heat generation temperature of the heating unit 24 at a constant temperature. Note that it is preferable to control the energization of the heating power source VH to the heater layer 19 by a pulse voltage synchronized with the formation of the electrostatic latent image of each pixel based on the control command.

Explaining the drive circuit 31 further, the drive circuit 31 of the present embodiment is constituted by a constant current circuit, and the current of this constant current circuit is set by the current setting connected to the emitter of each drive transistor 33. Resistor 34,
It is determined by the voltage applied to the base of each drive transistor 33. Then, the base voltage of each drive transistor 33 is applied by inputting a weighted digital signal through a D / A conversion circuit 35 in which resistors are combined in a ladder type. Further, the input signal to the ion writing head 16 is made into a serial signal 36 having a different weight, and is converted into a parallel signal by the shift register 37 corresponding to each serial signal 36.
Further, this parallel signal is once held in the latch 38, then output to the gate circuit 40 by the latch signal 39, ANDed with the strobe signal 41 by the gate circuit 40, and input to the D / A conversion circuit 35. . The strobe signal 41 is a signal that determines the operation time of the individual electrode 21 with respect to the gate electrode 26.

That is, each individual electrode 2 in this embodiment
1 is electrically insulated and electrically connected to a drive circuit having a constant current characteristic.
4 are connected in series.

The power can be reduced by dividing the heater layer 19 into a plurality of groups.

Next, the ion writing head 1 of the present embodiment.
The manufacturing process will be described with reference to FIGS.

First, a heat insulating layer 18 made of silicon dioxide, a heater layer 19 made of tantalum nitride, and a conductive layer 23 made of tantalum are formed on the upper surface of an appropriate substrate 17 made of an insulating material such as glass. Are sequentially formed using a known thin film forming method. Then, predetermined positions of the heater layer 19 and the conductive layer 23 are removed into the same shape by etching or the like, and the heater layer 19 and the conductive layer 23 are formed into the predetermined shapes as shown in FIGS. 4 (a) and 4 (b). To form. Then, a predetermined position of the conductive layer 23 is removed by etching or the like to expose a predetermined portion of the heater layer 19 as shown in FIGS. 4C and 4D, and a predetermined portion corresponding to the number of pixels. A number of heating units 24 are formed. Next, after the intermediate insulating layer 20 made of SiO ₂ is similarly formed by using a known thin film forming method, as shown in (e) and (f) of FIG. A predetermined number of electrodes 21 corresponding to the number of pixels are formed by using a known thin film forming method and etching. Next, the insulating layer 27 made of SiO ₂ and the gate electrode 26 made of metal such as tantalum.
And (3) are sequentially formed in the same manner, and then a predetermined position of the gate electrode 26 is removed by etching or the like to form an opening 25 having a desired size, as shown in (g) and (h) of FIG. To do. Then, a predetermined position of the insulating layer 27 is removed by etching or the like to expose the individual electrode 21 located below the opening 25, as shown in FIG. Next, an electrodeposition liquid containing a ferroelectric substance is electrophoretically electrodeposited on the individual electrodes 21 to form an electrodeposition film.
Are formed, and the manufacturing of the ion writing head is completed. When forming the electron emitting portion 22, the electron emitting portion 2
It is preferable that an appropriate release layer (not shown) is formed on the gate electrode 26 by a photoresist or the like in a step before forming 2, and the release layer is removed after the electron emission portion 26 is formed.

Next, the ion writing head 1 of the present embodiment.
The formation of the electron emission portion 22 of No. 6 will be described in more detail.

To form the electron emitting portion 22 of this embodiment, first, an electrodeposition liquid containing a ferroelectric substance as a main component is formed.
The electrodeposition liquid is obtained by crushing perovskite type ferroelectric powder such as barium titanate into particles having a particle size of about 1 μm or less by wet crushing and washing with pure water to remove impurities such as barium hydroxide. Next, 1% (wt%) of pure water as electrolyte and 0.0012% (wt%) of calcium chloride in methanol.
%) To form an electrolyte. Next, 0.15% of a powder of a ferroelectric compound is added to the electrolytic solution to form an electrodeposition solution. The pH of this electrodeposition solution is less than 7 and the conductivity is 3
It is about 0 μS / cm. At this time, the ferroelectric compound itself is chemically stable and has low solubility in water, but unreacted oxides such as barium and titanium react with water to become hydroxides and dissolve in water, It needs to be removed in advance in order to lower the resistivity of the electrodeposition liquid. Further, the calcium chloride in the electrolytic solution is ionized into calcium ions and chlorine ions in the electrodeposition solution, and is taken into the formed electrodeposition film as calcium hydroxide. Next, the electrodeposition solution is stirred and then left standing for several hours to precipitate and remove the ferroelectric compound having a large particle size, thus completing the production of the electrodeposition solution.

Next, the individual electrode 21 of the ion writing head 16 is used as a cathode, and platinum, which is difficult to be ionized, is used as an anode to apply a voltage of about 50 V to carry out electrophoretic deposition, thereby performing electrodeposition on each individual electrode 21. A film is deposited. The current density during electrophoretic deposition is preferably about 70 mA / cm ² , and the electrodeposition rate is preferably about 1 μm / min.

Next, in the atmosphere, 200 to 300 ° C.
The electron emitting portion 22 is formed on each individual electrode 21 by performing a heat treatment of heating for several hours to remove methanol and then heating at a temperature of about 600 ° C. in the atmosphere or in vacuum for several hours. The calcium hydroxide taken into the electrodeposited film partially reacts with carbon dioxide in the atmosphere by heat treatment to become calcium carbonate, and the rest becomes calcium oxide. It serves as a cement that solidifies the space between the powders of the dielectric compound), and strengthens the electrodeposition film that becomes the electron emission portion 22 formed on each individual electrode 21.

Next, the ion writing head 1 of the present embodiment.
6 was placed in a vacuum chamber and the electron emitting portion 22 was heated to evaluate the electron emission amount (emission). The heating temperature was gradually increased, and the process in which the emission increased from the minute current region was recorded. The emission for each temperature was at the same level as that of a general barium or calcium oxide-coated thermionic emission material, and it was confirmed that the work functions were almost equal. Also, when operating at that temperature for several hours,
It was confirmed that the characteristics were stable.

Then, the pressure in the vacuum chamber was gradually increased from the vacuum state to the atmospheric pressure state, and finally the characteristics in the atmospheric pressure were evaluated. The individual electrode 21 and the gate electrode 26 were evaluated.
By increasing the electric field between the
It was found that the electrons can be efficiently emitted from. Then, the current that can be taken out from the electron emitting portion 22 is
1 is proportional to the electric field between the gate electrode 26 and the gate electrode 26, and is inversely proportional to the distance therebetween, and the current that can be taken out in the atmosphere is 1/1 compared to the case in vacuum.
It was found that the value was around 00 to 1/1000.

Next, the ion writing head 16 described above is used.
The operation of will be described.

When the ion writing head 16 of this embodiment is driven and a current of the heating power source VH is applied to the heater layer 19, the heating portion 24 formed in the heater layer 19 generates heat, and the heating portion 24 generates heat. The individual electrode 21 and the electron emitting portion 22 are heated to a predetermined temperature. Then, the heated electron emitting portion 22 emits electrons (thermoelectrons) according to the principle of thermoelectron emission.
Are emitted to the space outside the electron emitting portion 22.

The electrons emitted to the space outside the electron emitting portion 22 are accelerated by an electric field formed by the voltage of the electron acceleration power source VE applied between the individual electrode 21 and the gate electrode 26. In the space between the gate electrode 26 and the latent image carrier 28, oxygen molecules are trapped and become oxygen ions, and negative polarity ions (not shown) as charged particles are generated. The ions move toward the surface of the latent image carrier 28 by the electric field formed by the voltage of the latent image writing power supply VL applied between the gate electrode 26 and the back electrode 32 of the latent image carrier 28. .

The ion writing head 16 of this embodiment is also used.
Is formed by forming each individual electrode 21 in a line using a conventional thin film forming method, etching, etc., and electrodepositing the electron emitting portion 22 above the individual electrode 21. Individual electrode 21 and electron emission portion 22
Can be easily formed and can be formed in a line shape, and the resolution of the ion writing head 16 can be easily improved.

Next, generation of ions and movement of ions will be described.

In this embodiment, the gap G between the gate electrode 26 and the latent image carrier 28 is 100 μm,
The potential of the gate electrode 26 is the back electrode 32 of the latent image carrier 28.
Is -500 to -600 V, and the electric field between the gate electrode 26 and the latent image carrier 28 is 5 to 6 KV / m.
It is set to m. The value of this electric field is about half the value of the spark discharge voltage in the atmosphere in the gap G between the gate electrode 26 and the latent image carrier 28.

When electrons are emitted into the atmosphere by heating the electron emitting portion 22, the mean free path of the electrons in the air at atmospheric pressure is about 400 nm, and the mean free path of oxygen molecules in the atmosphere. Is 64 nm and the emitted electrons drift 10 times during the gap G of 100 μm.
³ collide with gas molecules to 10 ⁴ times in the air, negative polarity ions as stochastically captured by the charged particles to a molecule of oxygen molecules and water vapor (O ₂ ^- ions) is generated. At this time, the probability that low-energy electrons are captured by oxygen molecules is about 2 × 10 ⁻⁴ , and the surface of the latent image carrier 28 has
When the ions and the electrons are mixed together, they arrive as an ion flow and reach the surface of the latent image carrier 28 to give a negative electric charge, and the surface of the latent image carrier 28 has a fine electrostatic charge of a negative polarity. A latent image is formed. That is, the surface potential of the latent image carrier 28 in the initial state (before the electrostatic latent image is written) is set to 0 V by static elimination, and electrons are emitted from the negative polarity ions reaching the surface of the latent image carrier 28. Upon reception, an electrostatic latent image having a potential proportional to the arrival amount of negative polarity ions is formed on the surface. At this time, the latent image carrier 28
Since the ions and electrons that reach the surface of the element move parallel to the lines of electric force, their spread can be ignored until the electrostatic latent image potential is saturated. The maximum value of the potential of the electrostatic latent image is saturated at a value close to the voltage of the latent image writing power source VL.

Therefore, the negative-polarity ions that have reached the surface of the latent image carrier 28 after the potential of the electrostatic latent image has been saturated move along the surface of the latent image carrier 28 toward the smaller latent image potential. Then, an electric charge is applied to the surface of that portion. That is, the electrostatic latent image on the latent image carrier 28 spreads concentrically. The spread of the electrostatic latent image decreases as the gap G between the gate electrode 26 and the latent image carrier 28 decreases.

The mass of the ion is 5.9 × 10 of the electron.
^{About 4} times, and the gate electrode 26 and the latent image carrier 28
The moving speed of the ions due to the electric field between the back electrode 32 and the back electrode 32 is about 100 m / S, and the gap G of 100 μm is
The ion transfer time between them is about 1 μS.

Here, the image forming resolution is set to 300 DP.
I, the moving speed (process speed) of the latent image carrier 28 is 10
Assuming 0 mm / S, the size of one pixel (dot) is about 84.67 μm square, the time required for writing one line is 847 μS, and the ion moving speed is sufficiently shorter than the writing time for one line. , It does not hinder the writing of the electrostatic latent image.

When the emission from the electron emitting portion 22 is small, the voltage of the gate electrode 26 becomes negative with respect to the potential of the electron emitting portion 22, and a portion near the opening 25 in the space around the electron emitting portion 22. Becomes negative, and the ion flow composed of ions and electrons converges at the center of the opening 25 of the gate electrode 26. The convergence rate of the ion flow with respect to the opening 25 of the gate electrode 26 is 3 at maximum.
About double.

That is, the size of the electrostatic latent image formed on the latent image carrier 28 is such that when the amount of ions of negative polarity reaching the surface of the latent image carrier 28 is small, the line of electric force is small. Concentrate on a small diameter that reaches, and the negative polarity potential of the electrostatic latent image rises as the amount of ions that reach increases, and the lines of electric force reaching the surface of the latent image carrier 28 spread. The negatively-polarized ions that reach it spread concentrically on the surface of the latent image carrier 28, and the area of the electrostatic latent image is enlarged.

Therefore, the linearity of the area of the electrostatic latent image with respect to the amount of generated ions can be made extremely high.

That is, when an electrostatic latent image is developed with toner to form a toner image, the linearity of the toner adhesion amount is as follows when the potential of the electrostatic latent image has a halftone and when the electrostatic latent image has a constant potential. When the area of the image changes, it is possible to form an electrostatic latent image with a fine area even in the print density region where the area gradation is lower, and it is possible to print with a wide range of area gradation. The ion writing head 16 of this embodiment can obtain high-quality printing quality with extremely excellent gradation reproducibility as compared with the conventional ion writing heads 1 and 1a.
This print quality is also superior to the print quality of the electrophotographic system having a high resolution used in applications where high resolution such as character printing is required.

The enlargement of the area of the electrostatic latent image does not occur indefinitely, and it depends on the amount of ions reached by the electric field applied between the gate electrode 26 and the back electrode 32 of the latent image carrier 28. Limited to a certain range. Further, the potential of the electrostatic latent image formed is also the same as that of the gate electrode 26 and the latent image carrier 2.
8 is limited to a substantially constant value close to the voltage applied to the back electrode 32.

The gap G between the gate electrode 26 and the latent image carrier 28 is a danger of a short circuit due to invasion of toner, and the gate electrode 2 when the latent image carrier 28 is run.
6 is limited by the accuracy of the gap G between the latent image carrier 28 and the latent image carrier 28, the gap G between the gate electrode 26 and the latent image carrier 28 is configured to always maintain a substantially constant distance G. Preferably.

The positive polarity ions existing in the atmosphere are formed on the surface of the ion writing head 16 due to the electric field between the gate electrode 26 and the latent image carrier 28, and the potential is the most negative. Since it collides with the surface of the gate electrode 26, the probability that the electron emitting portion 22 is sputtered and consumed is extremely small, and the electron emitting portion 22 can maintain a stable function for a long period of time.

Further, since the moving speed of the ions is proportional to the magnitude of the electric field, it is preferable that the electric field is high within the range where dielectric breakdown does not occur.

Next, the current required for forming the electrostatic latent image will be described.

The potential of the electrostatic latent image formed on the surface of the latent image carrier 28 depends on the electric charge of ions or electrons reaching the latent image carrier 28 and the electrostatic charge of the dielectric layer 30 of the latent image carrier 28. Determined by capacity ratio. Here, when the film thickness of the dielectric layer 30 of the latent image carrier 28 is 20 μm and its dielectric constant is 2.5,
The capacitance per 1 cm ² is 110.7 pF. The dielectric layer 30 of the latent image carrier 28 is changed from OV to -500V.
The charge required to charge up to 55.35 nC. When the image recording width of the latent image carrier 28 is 210 mm and the process speed is 100 mm / s, the current required for the entire ion writing head 16 is 11.62 μA. The number of pixels is 300D when the length of the printing part is 210mm.
2480 for PI and 3307 for 400 DPI,
3. The average current per individual electrode 21 is 300 DPI.
It becomes 3.51 nA at 69 nA and 400 DPI.

The size of the individual electrode 21 is 30 μm in diameter.
Then, the area is 7.07 × 10 ⁻⁶ cm ² , and the current density is 663 μA / cm ² , 400D at 300 DPI.
It becomes 497 μA / cm ^{2 in} PI. In terms of current density, it is 10 when the individual electrode 21 is operated in vacuum.
Although much smaller than 0 mA / cm ² , it is at a level equivalent to the fact that ions or electrons are scattered in the atmosphere and mobility is reduced. The size of the individual electrode 21 is limited by the current density and the dimensional accuracy of the processing technique.

Next, the gradation reproducibility using the liquid phenomenon will be described.

The gradation reproducibility when the liquid phenomenon is used is determined by the resolution of the ion writing head 16. The ion writing head 16 in the present embodiment is provided with the individual electrode 21.
Is 30 μm, the diameter of the gate electrode 26 is 20 μm, and the lower limit of the size of the electrostatic latent image is 7 μm.
The upper limit of the electrostatic latent image size is 84.67 at 300 DPI.
It becomes 63.5 μm square at 400 μm square and 400 DPI. When the diameter of the electrostatic latent image is 7 μm, the dot area is 3
The area of 1 pixel for each resolution is 8.5 μm ² .
7069 μm ² at 300 DPI, 403 at 400 DPI
2 μm ² and the area ratio is 183.6 at 300 DPI.
2 times, 104.7 times at 400 DPI, and about 128 gradations (7 bits) can be obtained without dither.
Further, it is possible to display 256 gradations (8 bits) of 1.67 million colors by dithering in units of 2 to 4 pixels.

Next, the gradation reproducibility in the case of using the dry development will be described.

The tone reproducibility when the dry phenomenon is used is determined by the toner particle size. The typical particle size of the high-image-quality toner obtained by the current pulverization method is about 7 μm, and the lower limit of the size of the electrostatic latent image is about 14 μm. In this case, the dot area is 153.9 μm ² , and the electrostatic latent image area ratio is 45.9 times at 300 DPI and 2 at 400 DPI.
Since the size is 6.2 times and the linearity of the size of the electrostatic latent image is high, when the print density of each pixel is larger than the minimum value determined by the above area ratio, dither processing is unnecessary. Further, when the print density is smaller than the minimum value of the above area ratio, in order to obtain 8-bit gradation reproduction of each color, the dither of the matrix of 3 × 3 9 dots or 4 × 4 16 dot units is used. Should be used.

Next, the resolution in ion writing will be described.

According to the printer using the ion writing head 16 of the present embodiment, a total of 1.67 million colors of 8 bits (256 gradations) for each of the three primary colors can be reproduced without using dither, and the image resolution is photographic or photographic. It can be a level close to a sublimation type.

In the case of a color bitmap image, most of the data pixels are smaller than the number of pixels of the image formed by the ion writing head 16 due to the limitation of the amount of information, and it is necessary to enlarge and print by software. become.
A typical number of pixels is 640 dots in the horizontal direction, 480 dots in the vertical direction, and the information amount of 24 bits (1,670,000 colors) is 900 kbytes when the data is not compressed. The image is horizontal 8c
When printing with a size of m and a length of 6 cm, the resolution is 8 dots / mm (about 200 DPI). If the resolution is 300 to 400 DPI, which is the same as that of a normal page printer, it is possible to obtain faithful reproducibility except when printing an image with a particularly high resolution.

The ion writing head 16 of this embodiment is also used.
According to the printing apparatus using, the reproducibility of the density gradation is overwhelmingly superior to the electrophotographic method, but in printing characters without gradation, the resolution of the print head is a factor that determines the image quality. Become. The resolution of the line head as a print head in the direction in which the pixels are arranged (main scanning direction) is determined by the resolution of the print head, but the number of individual electrodes 21 that is the number of pixels in the ion writing head 16 of this embodiment is It is easy to subdivide (increase) the direction in which the image carrier 28 or the print medium moves (sub-scanning direction),
In the case of printing characters, increasing the number of individual electrodes 21 in the ion writing head 16 to increase the resolution makes it possible to smooth the jagged edges of the printed characters.

Therefore, unlike the conventional ion writing heads 1 and 1a using corona discharge or high-frequency discharge using a high voltage, the ion writing head 16 of this embodiment produces only the amount of ions necessary for electrostatic latent image formation. It can be generated in real time, the drive circuit 31 can be easily integrated, the size and cost can be surely reduced, and the resolution can be surely improved.

FIGS. 5 to 8 show a second embodiment of the ion writing head according to the present invention, FIG. 5 is a longitudinal sectional view showing the structure of the main part, and FIG. 6 is a gate electrode and an insulating layer. 7 is a side view of FIG. 6, and FIG. 8 is a circuit diagram showing a drive circuit.

The ion writing head 16a of this embodiment is
The individual electrodes 21 of the first embodiment also have the function of the heater layer 19, and the individual electrodes 21 are grouped.

As shown in FIG. 5, in the ion writing head 16a of this embodiment, a thermal insulating layer 18 is provided on a substrate 17, and the thermal insulating layer 18 has an upper surface on which the above-mentioned first insulating layer 18 is formed.
A heating individual electrode layer 42 having a predetermined shape is provided so as to also serve as the heater layer 19 and the individual electrode 21 of the embodiment. The conductive layer 2 is formed on the upper surface of the heating individual electrode layer 42.
3 are provided. Further, the heating individual electrode layer 42 and the conductive layer 23 are etched into the same predetermined shape. Further, a predetermined position of the conductive layer 23 on the heating individual electrode layer 42 is removed by etching or the like, whereby the heating portion 24 which concentrates the heat generation of the heating individual electrode layer 42 on the electron emission portion 22, An individual electrode 21a called a cathode electrode corresponding to the resolution (number of pixels) is formed. This individual electrode 21a has, for example, a diameter of 30 μm.
The size is approximately the same, and as shown in FIGS. 5 and 6, they are arranged in a line in the left-right direction (print width direction). Then, on the upper surface of each individual electrode 21a, an electron emitting portion 22 capable of emitting electrons for generating charged particles (ions).
Is provided. Further, on the heat insulating layer 18, a gate electrode 26 having a circular opening 25 having a diameter of, for example, about 20 μm centering on each electron emitting portion 22 is provided via an insulating layer 27 having an appropriate thickness, It is formed in a substantially flat plate shape as a whole.

As the material of the heating individual electrode layer 42,
Platinum, tantalum, molybdenum, tungsten, etc. are suitable.

That is, in the ion writing head 16a of this embodiment, the portion of the heating individual electrode layer 42 which is not covered with the conductive layer 23 serves as the individual electrode 21a and heats each electron emitting portion 22. The heating unit 24a is used as the heating unit 24a, and the electron emission unit 22 is directly formed on the individual electrode 21a. In addition, as shown in FIG. 6, the heating individual electrode layer 42 in this embodiment includes four individual electrodes 21.
They are grouped so that a is one set. The number of the individual electrodes 21a in this one group may be determined according to the resolution of the ion writing head 16a, the design concept, etc., and is not particularly limited to the number of the individual electrodes 21a of this embodiment.

As shown in FIG. 8, the drive circuit 31a of the ion writing head 16a according to the present embodiment includes the individual electrodes 21a.
Is configured to be heated in a time-division manner, and the heating power source VH is provided via an insulating DC / DC converting circuit 43 and a heater switching circuit 44 as a connecting / disconnecting switch for each individual electrode 21a. It is connected to the individual electrode 21a. Then, a heater switching signal 46 for connecting and disconnecting the heater switching circuit 44 is input to the heater switching circuit 44 via the photocoupler 45 corresponding to each individual electrode 21a. Other configurations are the same as those of the drive circuit 31 of the first embodiment described above.

With this structure, this embodiment has the same effects as those of the first embodiment described above, and the electron heat dissipation portion 22 is directly formed on the individual electrode 21a which also serves as the heating portion 24. As a result, the manufacturing process can be simplified, the number of manufacturing processes can be reduced, the economic burden can be reliably reduced, the size can be reduced, and the heat capacity (heat storage amount) can be reduced. It is possible to improve the responsiveness to temperature changes and shorten the heating time for the electron emitting portion 22 to emit electrons. Also,
Since the intermediate insulating layer 20 in the first embodiment can be omitted, there is no temperature gradient and the heat utilization efficiency can be reliably improved.

9 to 13 show a third embodiment of the ion writing head according to the present invention, FIG. 9 is a longitudinal sectional view showing the structure of the main part, and FIG. 10 is a plan view of FIG. FIG. 11 is a plan view showing a configuration of a main part with a gate electrode and an insulating layer omitted, and FIG. 12 is a side sectional view of FIG.
FIG. 13 is a circuit diagram showing a drive circuit.

The ion writing head 16b of this embodiment is
The gate electrode 26 is divided so as to correspond to the individual electrodes 21a of the second embodiment.

As shown in FIGS. 9 to 12, in the ion writing head 16b of this embodiment, the insulating layer 2 is formed so as to correspond to each individual electrode 21a formed on the heating individual electrode layer 42.
The gate electrode 26a divided by 7 is arranged, and the heating individual electrode layer 42 is also formed so as to correspond to the gate electrode 26a. Other configurations are similar to those of the ion writing head 16a of the second embodiment described above.

As shown in FIG. 13, the drive circuit 31b of the ion writing head 16b of the present embodiment is provided with each gate electrode 2
6a is time-divided and heated, and each individual electrode 21a
Are heated for each group, and the latent image writing power source VL is connected to each date electrode 26a through a gate switching circuit 47 as a connection / disconnection switch for each gate electrode 26a. . This gate switching circuit 47
Are operated by the gate switching signal 48. Further, the heating power source VH is connected to the individual electrodes 21a grouped in units of four via an insulating DC / DC conversion circuit 43. Other configurations are the same as those of the drive circuit 31a of the second embodiment described above.

With this structure, this embodiment can achieve the same effects as the above-mentioned second embodiment.

Next, the ion writing heads 16A of the present embodiment (the reference numerals are the ion writing heads 16, 16a, 16).
b between the gate electrodes 26A (the reference numerals collectively refer to the gate electrodes 26 and 26a) and the latent image carrier 28.
14 to 18 will be used to explain the structure for holding constant.

FIG. 14 shows a first embodiment of a structure in which the distance between the gate electrode of the ion writing head and the latent image carrier is kept constant.

In this embodiment, as the latent image carrier 28, a dielectric drum 49 having a dielectric layer 30 on its surface is used.

In this embodiment, appropriate contact rollers 50, 50 are arranged at both ends in the longitudinal direction which is the print width direction of the ion writing head 16A, and the dielectric material is provided through the contact rollers 50, 50. The drum 49 is arranged. The contact rollers 50, 50 are rotatably arranged so as to avoid the print area on the surface of the dielectric drum 49, and are in contact with the surface of the dielectric drum 49. Further, the ion writing head 16A is supported so as to be movable in the direction of the normal line to the surface of the dielectric drum 49, and is brought into contact with a support frame (not shown) provided on the back surface of the ion writing head 16A as appropriate. A predetermined distance (interval) can be maintained with respect to the surface of the dielectric drum 49 by the pressing force of the pressurizing spring 51. The contact pressure of each contact roller 50 may be reduced so that the contact area is brought into contact with the print area of the dielectric drum 49.

FIG. 15 shows a second embodiment of the structure in which the distance between the gate electrode of the ion writing head and the latent image carrier is kept constant.

In this embodiment, as in the first embodiment shown in FIG. 14, the contact roller 5 is attached to the ion writing head 16A.
No. 0 is not provided, but instead, a desired blade 52 as a cleaning means for cleaning the dielectric drum 49 is provided below the ion writing head 16A. An appropriate waste toner receiver 53 is arranged below the blade 52. Also, the dielectric drum 49
In the transfer / fixing section 54 shown in the lower part of FIG.

With such a structure, the ion writing head 16 is also provided as in the first embodiment shown in FIG.
The distance between the A gate electrode 27A and the latent image carrier 28 can be kept constant.

16A and 16B show a third embodiment of a structure in which the distance between the gate electrode of the ion writing head and the latent image carrier is kept constant. FIG. 16A is a perspective view and FIG. 16B is a longitudinal sectional view. Is.

In this embodiment, a flexible endless belt-shaped dielectric belt 56 is used as the latent image carrier 28.

In this embodiment, the ion writing head 16A is provided with an appropriate belt holding member 57,
The dielectric belt 56 is positioned with respect to the ion writing head 16A, and the distance between the gate electrode 26A (not shown) of the ion writing head 16A and the surface of the dielectric belt 56 is kept constant. In this case, it is important to keep the thickness of the dielectric belt 56 constant.

According to such a configuration, as compared with the configuration using the dielectric drum 49 shown in FIGS. 14 and 15,
Since the position of the ion writing head 16A can be easily fixed, it is advantageous to keep the distance between the gate electrode 27A of the ion writing head 16A and the latent image carrier 28 constant.

FIG. 17 shows a fourth embodiment of the structure in which the distance between the gate electrode of the ion writing head and the latent image carrier is kept constant.

In this embodiment, as in the third embodiment shown in FIG. 16, a dielectric belt 56 is used as the latent image carrier 28.

In this embodiment, the surface of the dielectric belt 56 is pressed against the side of the belt holding member 57a arranged so as to cover the surface of the ion writing head 16A to keep the distance constant. The belt holding member 57a of the present embodiment has an insulating layer made of an appropriate insulator so that the downstream surface 58 of the ion writing head 16A does not disturb the electrostatic latent image formed on the surface of the dielectric belt 56. It is formed by 59. The ion writing head 16A
The downstream surface 58 of the dielectric belt 56 is prevented from coming into contact with the surface of the dielectric belt 56, and a conductive layer 61 made of a conductive material is formed on the upstream surface 60 of the ion writing head 16A to remove the charge from the dielectric belt 56. You may do it.

FIG. 18 shows a fifth embodiment of the structure in which the distance between the gate electrode of the ion writing head and the latent image carrier is kept constant.

In this embodiment, a fluid (air) is applied from the surface of the ion writing head 16A to the structure of the fourth embodiment shown in FIG.
Is jetted toward the dielectric belt 56, and the dielectric belt 56 is floated above the surface of the ion writing head 16A at a constant height.

In this embodiment, the head holding member 55
A plurality of injection holes 62 are provided on the surface of a, and an appropriate orifice 63 for maintaining the balance of the flow rate of the air flowing through each injection hole 62 is connected to each flow path 64.
It is provided in the above, and the pressurized air can be freely supplied to each flow path 64. The flying height of the dielectric belt 56 with respect to the ion writing head 16A is preferably about 50 μm.

According to this structure, the dielectric belt 5
Since 6 does not contact the ion writing head 16A, it is not affected by the presence or absence of conductivity on the surface of the ion writing head 16A. Further, since the toner (not shown) that adheres to the surface of the dielectric belt 56 can be removed to the outside by the pressure of air, it is possible to reliably prevent the inconvenience that the toner adheres to the electron emission portion.

Next, the ion writing head 1 of the present embodiment.
A printer using 6A will be described with reference to FIGS. 19 to 21.

FIG. 19 shows a first embodiment of the printing apparatus according to the present invention.

The printer 65 of this embodiment is the same as the latent image carrier 2
A dielectric drum 49 is used as 8.

As shown in FIG. 19, in the printing apparatus 65 of this embodiment, the dielectric drum 49 is arranged rotatably in the clockwise direction shown by the arrow in FIG. In FIG. 19, the ion writing head 16A as a latent image forming means for forming an electrostatic latent image corresponding to a desired image (not shown) on the dielectric drum 49 is shown in a clockwise direction from the top in FIG. 19, and the electrostatic latent image is shown. Appropriate developing device 66 as a developing unit that visualizes with toner, and pressure as a transfer fixing unit that transfers and fixes the electrostatic latent image visualized with toner onto a recording medium 55 such as paper. A roller 67, a cleaner 69 having an appropriate metal blade 68 as a cleaning means for cleaning the dielectric drum 49, and a charge removing means for removing the charged state of the dielectric drum 49. And appropriate AC discharger 70 of Te is formed are disposed in this order.

The developing device 66 uses the same positively charged toner (not shown) as in the normal development using a negatively charged photoconductor, and the sleeve 71 of the developing device 66 is provided with a bias voltage. Used at ground potential without addition.

Transfer and fixing are performed by the dielectric drum 4
The recording medium 55 is pressed against the dielectric drum 49 by bringing the pressure roller 67 into contact with the pressure roller 67 with a desired contact force, and the pressure of the pressure contact force is applied simultaneously. As a result, fixing can be performed without using a heat fixing device, power consumption can be reduced, and warm-up time can be eliminated.

The blade (not shown) of the cleaner used in the conventional electrophotography is made of rubber because the photosensitive member (not shown) is easily damaged. The blade 68 of the cleaner 69 can be made of metal because the dielectric drum 49 has a high strength, and the accuracy and durability of the blade 68 can be reliably improved. Then, for static elimination of the dielectric drum 49, A
The C static eliminator 70 can efficiently neutralize the charge on the surface of the dielectric drum 49 by using positive and negative polar ions.

According to the printing apparatus 65 of the present embodiment having such a configuration, combined with the effect of the ion writing head 16A described above, it is possible to obtain high-quality printing quality with extremely high gradation reproducibility. It can be used for various purposes.

FIG. 20 shows a second embodiment of the printing apparatus using the head according to the present invention.

The printer 65a of this embodiment uses the dielectric belt 56 as the latent image carrier 28.

As shown in FIG. 20, in the printing device 65a of the present embodiment, two rollers 72, 73 which are rotatably supported and vertically separated from each other are arranged. One of 73 is a drive roll,
The other is a driven roll. The dielectric belt 56 is wound so as to come into contact with the outer peripheral surfaces of the rollers 72 and 73. Furthermore, the dielectric belt 56
Is allowed to travel in the direction indicated by the arrow in FIG. 20 by the rollers 72 and 73.

On the lower left side of the dielectric belt 56, an ion writing head 16A as a latent image forming means for forming an electrostatic latent image corresponding to a desired image (not shown) is arranged. Further, on the lower right side of the dielectric belt 56, an appropriate developing device 66 as a developing means for visualizing the electrostatic latent image with toner (not shown) is arranged. Further, an appropriate cleaner 69 as a cleaning means for cleaning the dielectric belt 56 is arranged on the upper left side of the dielectric belt 56. Further, between the ion writing head 16A and the cleaner 69, an appropriate AC static eliminator 70 is arranged so as to face the dielectric belt 56 and removes the charged state of the surface of the dielectric belt 56. ing.

The upper part of the dielectric belt 56 is shown in FIG.
An ion generator 74 as an electrostatic transfer that transfers the electrostatic latent image visualized by the toner onto the recording medium via the recording medium 55 that can travel to the left in the horizontal direction indicated by the arrow in FIG. It is arranged. This ion generator 74 is
The structure has an electron emitting portion 22 similar to that of the ion writing head 16A.

Further, on the downstream side of the recording medium 55 in the traveling direction, a fixing roller 75 as fixing means for fixing the toner to the recording medium 55 by the action of heat and a pressure roller 76 having elasticity are provided. It is arranged so that it can be clamped.

According to the printer 65a of the present embodiment having such a configuration, the printer 65 of the first embodiment described above is used.
Has the same effect as. Since the structure of the ion generator 74 used for electrostatic transfer of the present embodiment does not require image formation and requires less uniformity of electric current, the number of electron emission portions 22 is reduced or the number of the ion generators 74 is reduced. Dielectric belt 56
The distance between and can be increased. Further, since the toner is fixed to the recording medium 55 by the fixing roller 75 and the pressure roller 76, the above-described first
When the pressure roller 67 of the printing apparatus 65 of the embodiment is used, the generation of gloss of the recording medium 55 and the toner due to the crushing of the recording medium 55 and the toner with a high pressure is reliably prevented, and higher quality printing is performed. You can get quality. Further, the ion generator 74 is the ion writing head 16
As with A, the ion generator 74 can be downsized and operated at low voltage and low power consumption.
In comparison with other ion generating means such as a corotron (not shown), the density of the generated ions is high, so that the transfer area is limited and the deterioration of the image due to the transfer can be reliably prevented. Further, since the ion generator 74 can be operated with the same polarity as the ion writing head 16A and with a small current, it is possible to share the power source of the drive circuit (not shown) of the ion writing head 16A. This makes it possible to surely reduce the size of the entire drive circuit and the device (not shown) of the printing device 65a, and to surely reduce the economical burden.

FIG. 21 shows another example of a printing apparatus using a dielectric belt as a latent image carrier.

In the printing device 65b of the present embodiment, as in the printing device 65a of the second embodiment described above, the electrostatic latent image visualized by toner is transferred onto the recording medium 55 as an electrostatic transfer. Ion generator 74 is not arranged,
Instead, a fixing roller 75 and a pressure roller 76 are arranged as transfer fixing means for transferring and fixing the toner onto the recording medium 55 so as to sandwich a dielectric belt 56a made of a heat resistant material such as polyimide. Below the fixing roller 75, the two rollers 72,
73 are arranged in parallel to the left and right, and the dielectric belt 56a
Is wound so as to contact the outer peripheral surfaces of the fixing roller 75 and the two rollers 72 and 73.

Below the dielectric belt 56a, an ion writing head 16A as a latent image forming means for forming an electrostatic latent image corresponding to a desired image (not shown) is arranged, and the lower part of the dielectric belt 56a. On the right side, an appropriate developing device 66 is arranged as a developing means for developing the electrostatic latent image with toner (not shown). Further, on the lower left side of the dielectric belt 56a, an appropriate cleaner 69 as a cleaning means for cleaning the dielectric belt 56a.
And an appropriate AC static eliminator 70 as a static eliminator that removes the charged state of the dielectric belt 56a so as to face the dielectric belt 56a.

According to the printer 65b of the present embodiment having such a configuration, the printer 65 of the second embodiment described above is used.
In addition to the same effect as a, the inferiority of the image at the time of transfer can be more surely prevented, higher quality printing quality can be obtained, and size reduction can be easily achieved. In addition,
Instead of the fixing roller 75, a one-dimensional heating element such as a thermal head or a two-dimensional heating element may be used.

Further, the present invention is not limited to the above-mentioned respective embodiments, but the respective ion write heads 16, 16 are mentioned.
The combination of a, 16b, the individual electrodes 21, 21a, and the drive circuits 31, 31a, 31b may be determined by a design concept, and various combinations can be selected.

Furthermore, the present invention is not limited to the above embodiments, but can be modified as necessary.

[0130]

As described above, according to the ion writing head of the present invention, ions are generated according to the principle of thermionic emission, so that ions can be generated with low energy.
Further, since corona discharge is not used for generating ions, ozone is not generated. In addition, the magnitude of the ion current that contributes to writing can be controlled only by controlling the electric field applied between the gate electrode and the individual electrode, and between the individual electrode and the latent image carrier. It is possible to easily perform multi-gradation printing by changing the number of steps into a multi-step manner.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a configuration of a main part of a first embodiment of an ion writing head according to the present invention.

FIG. 2 is a partially cutaway plan view of FIG.

FIG. 3 is a circuit diagram showing a drive circuit of a first embodiment of an ion writing head according to the present invention.

FIGS. 4A to 4J are explanatory views for explaining the manufacturing process of the first embodiment of the ion writing head according to the present invention.

FIG. 5 is a vertical cross-sectional view showing a configuration of a main part of a second embodiment of the ion writing head according to the present invention.

FIG. 6 is a plan view of the ion writing head according to the second embodiment of the present invention with the gate electrode and the insulating layer omitted.

7 is a side sectional view of FIG.

FIG. 8 is a circuit diagram showing a drive circuit of a second embodiment of the ion writing head according to the present invention.

FIG. 9 is a vertical cross-sectional view showing a configuration of a main part of a third embodiment of the ion writing head according to the present invention.

FIG. 10 is a plan view showing a configuration of a main part of a third embodiment of the ion writing head according to the present invention.

FIG. 11 is a plan view showing the configuration of a main part of the ion writing head according to the third embodiment of the present invention, in which a gate electrode and an insulating layer are omitted.

FIG. 12 is a side sectional view of FIG. 11.

FIG. 13 is a circuit diagram showing a drive circuit of a third embodiment of the ion writing head according to the present invention.

FIG. 14 is a perspective view of essential parts showing a first embodiment of a structure for keeping a constant distance between the gate electrode and the latent image carrier of the ion writing head according to the present invention.

FIG. 15 is a side view of the essential parts showing a second embodiment of the structure for keeping the distance between the gate electrode and the latent image carrier of the ion writing head according to the present invention constant.

16A and 16B show a third embodiment of the structure in which the distance between the gate electrode and the latent image carrier of the ion writing head according to the present invention is kept constant, wherein FIG. 16A is a perspective view and FIG. Plan

FIG. 17 is a longitudinal cross-sectional view of a main part showing a fourth embodiment of a structure for keeping a constant distance between the gate electrode and the latent image carrier of the ion writing head according to the present invention.

FIG. 18 is a vertical cross-sectional view of a main part showing a fifth embodiment of a structure for keeping a constant distance between the gate electrode and the latent image carrier of the ion writing head according to the present invention.

FIG. 19 is a structural diagram showing a configuration of a main part of a first embodiment of a printing apparatus using an ion writing head according to the present invention.

FIG. 20 is a structural diagram showing a configuration of a main part of a second embodiment of a printing apparatus using an ion writing head according to the present invention.

FIG. 21 is a structural diagram showing a configuration of a main part of a third embodiment of a printing apparatus using an ion writing head according to the present invention.

22A and 22B show an example of a conventional ion writing head, in which FIG. 22A is a perspective view showing the overall shape, FIG. 22B is a vertical cross-sectional view showing the configuration of the main part, and FIG. Explanatory drawing showing the arrangement state with finger electrodes

FIG. 23 is a schematic view showing another example of a conventional ion writing head.

[Explanation of symbols]

 16, 16a, 16b, 16A Ion writing head 17 Substrate 18 Thermal insulation layer 19 Heater layers 21, 21a, Individual electrode 22 Electron emission part 23 Conductive layer 24, 24a Heating part 25 Opening 26, 26a, 26A Gate electrode 27 Insulation layer 31 , 31a, 31b drive circuit 42, heating individual electrode layer

Claims (4)

[Claims] 1. An ion writing head for selectively depositing charged particles on a latent image carrier made of a dielectric to form an electrostatic latent image, the plurality of individual electrodes formed on a substrate. An electron emission part that is formed on the individual electrode and can emit electrons to generate charged particles by being heated; a heating part that heats the electron emission part; And a gate electrode for accelerating the electrons emitted from the electron emitting portion. 2. The ion writing head according to claim 1, wherein the individual electrode also serves as the heating unit. 3. The ion write head according to claim 1, wherein the electron emission portion is formed mainly of a ferroelectric material. 4. The ion writing head according to claim 1, further comprising a drive circuit that heats the heating section at a predetermined timing.