JP2002067332A - Image forming device and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which can form an image without using complicated electrode structure in a recording head 1 and prevent from pulling out of a colored liquid 6 in the neighborhood caused by the colored liquid 6 lifting from a tip of a discharge electrode 2 without providing a partition wall between the tip of each discharge electrode. SOLUTION: A toner, which has so high density that it can be discharged from the tip of a discharge electrode 2 by the voltage difference between a counter electrode and the discharge electrode 2 in a state the toner is dispersed into a liquid carrier as a colored liquid 6 to be housed in a recording head 1, is used. Then a fluoroplastic film 5 is applied between each discharge electrode on an insulating substrate, and a fluoroplastic film 3 is applied on an insulating top plate part 13 facing the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recording by discharging colored particles in a colored liquid held on a substrate having a plurality of parallel electrodes arranged in parallel at a predetermined pitch from the tips of the parallel electrodes. The present invention relates to an image forming apparatus and an image forming method for forming an image by adhering to a member.

[0002]

2. Description of the Related Art Conventionally, as this type of image forming apparatus,
Japanese Patent Application Laid-Open No. Hei 8-90825 is known. FIGS. 13A, 13B, and 13C are a longitudinal sectional view, a plan view, and a front view, respectively, showing a main configuration of the image forming apparatus. In these drawings, a recording head 1 has an insulating substrate 4 on which a plurality of ejection electrodes 2 as parallel electrodes are formed.
And an insulating top plate 13 which is a facing plate in which a common electrode 14 facing each ejection electrode 2 with a predetermined gap therebetween is formed.

The tip of each discharge electrode 2 is tapered, and only the tapered portion of the insulating substrate is covered with the common electrode 14.
Are arranged so as to protrude to the left side in the figure from the insulating top plate 13 so as not to face the same. The discharge electrodes 2 are electrically independent from each other, and a common voltage is applied to them by the power supply 8a. In addition, a recording voltage is applied by a recording signal power supply 7 to the arbitrary discharge electrode 2 so as to fly toner aggregates described later from this tip, in addition to the common voltage.

[0004] A bias voltage is applied to the common electrode facing each ejection electrode 2 by a power supply 8b.

[0005] Between the insulating substrate 4 and the insulating top plate 13, a colored liquid 6 comprising positively charged toner as colored particles and a liquid carrier is contained.

When no voltage is applied to each of the ejection electrodes 2 and the common electrode 14, the toner T is uniformly dispersed in the colored liquid as shown in FIG. From the dispersed state, when a positive voltage is applied from the power source 8a to each of the ejection electrodes 2 and a lower positive voltage is applied to the common electrode 14 from the power source 8b, The toner T electrophoreses toward the common electrode 14 having a lower potential. When the colored liquid is pressed by pressing means (not shown) in this state, as shown in FIG. 14B, the toner T is applied to the inclined liquid surface formed between the tip of the common electrode 14 and the tip of the discharge electrode 2. Flows eccentrically along
It gathers at the tip of the discharge electrode 2. Then, it is electrostatically attracted to the grounded counter electrode 9 and further gathers at a portion slightly protruding from the front end to form toner aggregates. When the recording voltage is applied to an arbitrary discharge electrode 2 in a state where the toner aggregate is formed as described above, the toner aggregate flies from the tip of the discharge electrode 2, and the recording head 1 is connected to the recording head 1. One dot is formed by adhering to a recording paper (not shown) disposed between the counter electrode 9 and the counter electrode 9.

[0007]

In the conventional image forming apparatus shown in FIG. 13, the common electrode 14 faces each ejection electrode 2 in order to generate the above-mentioned toner aggregate. In addition, a complicated electrode configuration is adopted in which the tip of each discharge electrode 2 is tapered and protruded toward the counter electrode 9 side from the common electrode 14. Then, there is a problem that the cost of the recording head 1 is increased by such a complicated electrode configuration.

On the other hand, the present inventors prototyped a discharge test apparatus as shown in FIG. In the figure, the discharge test apparatus 100 includes transparent glass plates 101 and 102. On the glass plate 101, a counter electrode 9 of 1000 [μm] width (W1) made of transparent ITO (indium tin oxide) is laminated. In addition, on the glass plate 102, ejection electrodes 2a, 2b, and 2c of 100 [μm] width (W2) made of ITO are stacked in parallel with a gap of 100 [μm]. The glass plate 102 is arranged beside the glass plate 101 such that the tips of the discharge electrodes 2a, 2b, 2c face the counter electrode 9 via a gap G1 of 120 [μm].

Although there is no description in JP-A-8-90825 about the toner concentration of the colored liquid, the apparatus shown in FIG. 13 has the same toner concentration and viscosity (toner concentration: 1 wt. %, Viscosity 1.5mPa ・
s) may be used. Therefore, a conventional general liquid developer discharge test was performed using the discharge test apparatus 100 as follows.

[Ejection Test 1] A conventional general liquid developer, which is a colored liquid, is dropped on a glass plate 102 shown in FIG. 1, and the liquid droplet is leveled with a wire bar to obtain a liquid having a thickness of 20 μm. A film was formed. Then, with the counter electrode 9 grounded and applying a positive discharge voltage to the discharge electrodes 2a, 2c at both ends, the state of the colored liquid near the tip of each of the discharge electrodes 2a, 2b, 2c is observed with a microscope. Observation was performed while photographing with a high-speed camera attached to the camera. Then, no matter how much the discharge voltage was increased, the toner did not fly from the tips of the discharge electrodes 2a and 2c. In the discharge test apparatus 100 shown in FIG. 1, the configuration is not such that a toner aggregate is generated in advance, and the electric field is concentrated at a position where the toner aggregate is generated by sharpening the tip of the discharge electrode 2. Since this is not done, it can be said that this is a natural result when a liquid developer having a low toner concentration is used.

Next, the present inventors conducted a similar ejection test by replacing a conventional general liquid developer with a colored liquid having a higher toner concentration and a higher viscosity. [Ejection Test 2] A colored liquid having a viscosity of 500 [mPa · s] in which a positive toner having a concentration of 15 [wt%] was contained in a polysiloxane oil as a liquid carrier was used. Then, the discharge voltage is increased to +0.8 [kV].
Although no change was observed in the colored liquid even when the pressure was increased to above, the colored liquid started to move little by little as the pressure was further increased, and when the pressure was increased to +1.0 [kV], as shown in FIG. The colored liquid 6 protruded about 10 [μm] from the tips of the ejection electrodes 2a and 2c. However, the raised portion maintained its shape while slightly vibrating without extending to the counter electrode 9. A force to return to the original shape due to the surface tension of the raised portion, the ejection electrode 2 to the counter electrode 9
It is considered that the electrostatic force caused by the electric field formed by the electric potential difference of the above was applied with almost the same strength, and the raised portion vibrated slightly while maintaining its shape.

When the value of the discharge voltage is further increased to 1.2 [kV] in the state where the raised portion is slightly vibrating, the raised portion further extends as shown in FIG. To reach the counter electrode 9, and the space between the counter electrode 9 and the discharge electrode 2 b was bridged. Then, as shown in FIG. 2C, the protruding portions that were cut off halfway immediately and remained on the ejection electrode 2a, 2c side were pulled back toward the ejection electrodes 2a, 2c, respectively. Therefore, depending on the toner concentration of the colored liquid 6, FIG.
It has been found that even with a simple electrode configuration like the discharge test apparatus 100 described above, the colored liquid 6 can be raised from the tip of the discharge electrode 2 and adhere to the recording member.

[Ejection Test 3] Next, the present inventors reduced the gap between each of the ejection electrodes 2 from 100 [μm] to 50 [μm], which is half, assuming higher resolution image formation. A glass plate 102 was prepared, and the same test as the discharge test 2 was performed. Then, an unexpected problem occurred. +1.2
The colored liquid 6 protrudes from the tip of the discharge electrode 2b to which the discharge voltage of [kV] is not applied, and the discharge electrodes 2 on both sides are raised.
The colored liquid 6 protruded from the tips of a and 2c was attached to the counter electrode 9 integrally. Then, it was cut off immediately on the way and remained on the side surface of the glass plate 101. This means that dots have been formed on the side surfaces of the glass plate 101 where they should originally be non-pixel portions. The reason why the colored liquid 6 is raised from the tip of the discharge electrode 2b is that the high-viscosity (500 mPa · s) colored liquid 6 raised from the tip of the discharge electrodes 2a and 2c on both sides.
However, the colored liquid 6 near the tip of the discharge electrode 2b was dragged out by the surface tension. In general, since the viscosity of the colored liquid 6 such as a liquid developer increases as the toner concentration increases, when the colored liquid 6 having a relatively high toner concentration is used to simplify the electrode configuration of the recording head,
The possibility of causing such dragging is very high.

As a method of suppressing the dragging of the colored liquid 6, a partition wall may be provided between the discharge electrodes 2. However, the colored liquid 6 has a high concentration (1
(5% by weight), and if such a partition wall is provided, the discharge electrode 2
The toner is likely to be clogged between the substrate on which is formed and the facing plate facing the substrate. In addition, despite the simplification of the electrode configuration, the provision of the partition wall may make it impossible to reduce the cost of the recording head.

The present invention has been made in view of the above background, and an object of the present invention is to form an image without employing a complicated electrode configuration as described above.
Further, it is an object of the present invention to provide an image forming apparatus and an image forming method capable of suppressing a colored liquid protruding from a tip of a parallel electrode from drawing out a nearby colored liquid without providing a partition wall between the parallel electrodes.

[0016]

In order to achieve the above object, the present invention is directed to a substrate for holding a colored liquid containing charged colored particles and a liquid carrier, and a liquid holding surface of the substrate. A plurality of parallel electrodes arranged in parallel at a predetermined pitch, a facing plate facing the liquid holding surface, and a counter electrode facing a tip of each parallel electrode via a predetermined gap,
An aggregate of colored particles in the colored liquid on the parallel electrode is discharged from the tip toward the counter electrode side by a potential difference between the parallel electrode and the counter electrode, and the discharged aggregate is recorded on a recording member. An image forming apparatus for forming an image by adhering, wherein as the colored liquid, colored particles are dispersed from a liquid carrier and discharged from the tip of the parallel electrode by the potential difference so as to adhere to the recording member. It is characterized in that a cavity having a high concentration of colored particles is used, and a cavity forming means for forming a cavity free of a colored liquid is provided in a region between the parallel electrodes between the substrate and the facing plate. Things.

"Colored liquid" in this image forming apparatus
Indicates a colored liquid of a type designated by a manufacturer or a distributor of the device. This designation is performed by, for example, describing the product name or standard of the usable colored liquid in an instruction manual or a sticker of the apparatus, or packing the colored liquid with the apparatus. In this image forming apparatus, by using a colored liquid having a high colored particle concentration as the colored liquid, the colored liquid is ejected from the distal end of the parallel electrode to the recording member without generating an aggregate of colored particles at the distal end of the parallel electrode. Can be attached. Therefore, unlike the conventional image forming apparatus, the common electrode faces each parallel electrode, the tip of each parallel electrode is formed to be tapered, and the tapered portion is protruded to the counter electrode side from the common electrode. An image can be formed without employing an electrode configuration. Further, by forming a cavity where no colored liquid is present in a region corresponding to between the parallel electrodes between the substrate and the facing plate by the cavity forming means, the surface tension of the colored liquid raised from the tip of the parallel electrode is reduced. It is difficult to transfer to the colored liquid located near the tip on another parallel electrode. In such a configuration, it is possible to prevent the colored liquid protruding from the tip of the parallel electrode from drawing out the nearby colored liquid without providing a partition wall between the parallel electrodes.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, a liquid-repellent coating is provided between the parallel electrodes on the substrate as the cavity forming means.

In this image forming apparatus, the colored liquid existing between the parallel electrodes is repelled by the lyophobic coating on the substrate, so that a cavity is formed in the region between the parallel electrodes between the substrate and the facing plate. Can be formed.

According to a third aspect of the present invention, in the image forming apparatus of the first aspect, a liquid-repellent coating is provided on the facing plate portion facing between the parallel electrodes as the cavity forming means. is there.

In this image forming apparatus, the liquid repellent film provided on the facing plate portion facing between the parallel electrodes repels the colored liquid in a region corresponding to between the parallel electrodes between the substrate and the facing plate. Thereby, a cavity can be formed in the region.

According to a fourth aspect of the present invention, in the image forming apparatus of the second or third aspect, the moving means is provided between the parallel electrodes on the substrate and the facing plate portion facing between the parallel electrodes. , Each of which is provided with a liquid repellent coating.

In this image forming apparatus, by providing the lyophobic coating on both the substrate and the facing plate, the area between the parallel electrodes between the substrate and the facing plate can be more reliably determined. The colored liquid can be more reliably flipped to form a larger cavity in the area.

According to a fifth aspect of the present invention, in the image forming apparatus of the second, third or fourth aspect, a fluororesin coating is provided as the liquid-repellent coating.

In this image forming apparatus, the fluororesin whose good liquid repellency to a colored liquid containing a toner as a colored particle and a polysiloxane oil as a liquid carrier has been confirmed by the present inventors has been confirmed. By the coating, the colored liquid existing between the parallel electrodes can be favorably moved to the adjacent parallel electrodes.

According to a sixth aspect of the present invention, in the image forming apparatus of the second, third, fourth, or fifth aspect, the lyophobic coating is provided within a predetermined distance range from a front end to a rear end of the substrate facing the counter electrode. It is characterized by having been provided.

In this image forming apparatus, the amount of the colored liquid existing between the parallel electrodes is reduced by a predetermined distance range from the front end to the rear end of the substrate. Is larger in the amount of the colored liquid held on the substrate than in the area within the distance range. From the region where the amount of the colored liquid has increased, the colored liquid is smoothly supplied to the parallel electrodes that have consumed the colored liquid by image formation. Therefore, it is possible to suppress the supply shortage of the colored liquid on each parallel electrode.

According to a seventh aspect of the present invention, in the image forming apparatus of the sixth aspect, the distance range is 0.2 mm or more,
It is characterized by being set to 0.9 [mm] or less.

In this image forming apparatus, the length of the liquid-repellent coating is set to be long while the length of the liquid-repellent coating from the front end of the substrate is set to be too short for the reason described below. Insufficient supply of the colored liquid onto each parallel electrode due to over-treatment can be suppressed. That is, the present inventors set the ejection test apparatus 1 described above.
A recording head to which No. 00 was applied was prototyped. Then, dots were continuously formed using this recording head in which the appropriate length of the liquid-repellent coating (fluorine resin coating in the prototype) from the head tip was set to various values. Then, when the length of the liquid-repellent coating from the tip of the head falls below 0.2 [mm], the surface tension of the colored liquid raised from the tip of the parallel electrode is reduced by the colored liquid located near the tip on another parallel electrode. The effect of making the color liquid difficult to be transmitted was not sufficiently obtained, and the drag of the latter colored liquid by the former colored liquid was recognized. When the length of the liquid-repellent coating from the head tip exceeds 0.9 [mm], the color on the parallel electrode from the area on the substrate where the liquid-repellent coating is not provided to the area where the liquid-repellent coating is provided It was confirmed that the supply of the liquid was not smoothly supplied, and the colored liquid on the parallel electrode was cut off halfway. Therefore, "0.2
By setting “mm ≦ distance range ≦ 0.9 mm”, it is possible to suppress the dragging of the colored liquid and the insufficient supply of the colored liquid as described above.

The invention according to claim 8 is based on claims 1, 2, 3,
The image forming apparatus according to any one of 4, 5, 6 and 7, further comprising a recording member moving means for moving the recording member in a direction orthogonal to a direction in which the parallel electrodes are arranged at a position facing the tip of each parallel electrode. It is assumed that.

In this image forming apparatus, dots are sequentially formed on the moving recording member by the respective parallel electrodes on the substrate. In such a configuration, it is possible to form not only a one-dimensional line image in which a plurality of dots are arranged in a straight line, but also a two-dimensional image such as a character image or a video image.

As described above, the toner in the conventional liquid developer did not fly from the tip of the discharge electrode 2b in the discharge test 1 as described above. Of the toner and moved to and gathered on the middle ejection electrode 2b. This is because the positive polarity toner positioned on the discharge electrodes 2a and 2c receiving the supply of the positive discharge voltage electrostatically migrates toward the lower potential discharge electrode 2b. On the other hand, in the ejection tests 2 and 3, the concentration of the toner on the ejection electrode 2b was not so conspicuous. However, the toner electrophoresis similar to that in the ejection test 1 may be slightly caused.

If a preliminary voltage is previously supplied to all the discharge electrodes 2 and a predetermined voltage is added to only the discharge electrodes 2b from which the colored liquid (liquid developer) is to be discharged from the tip, the preliminary voltage is supplied. It should be possible to suppress the electrophoresis of the toner by reducing the potential difference between the ejection electrodes 2. Therefore,
The present inventors conducted the following ejection test.

[Ejection Test 4] As the ejection test apparatus 100, the same apparatus as that used in the ejection test 2 (the distance between the ejection electrodes 2 was not reduced) was used. Colored liquid 6 (toner concentration: 15 wt.
%, Viscosity: 500 mPa · s).
2, the glass plate 1 in the glass plate 101
Plain paper (70 μm thick) as a recording member
m) was fixed. Then, a preliminary voltage of +1.0 [kV] was applied to each of the ejection electrodes 2a, 2b, and 2c to cause the colored liquid 6 to protrude from the tip of each electrode. In this state,
Each raised portion does not reach the plain paper. Next, a voltage of +0.2 [kV] was applied to only the discharge electrode 2b among the discharge electrodes 2 for only 5 [msec], and a discharge voltage of +1.2 [kV] was supplied. Then, among the raised portions, the ejection electrodes 2a, 2c
Only the tip of the paper reaches plain paper and has a diameter of about 10
A dot having a high image density of 0 [μm] and a sharp shape was formed. When the state of the toner on the ejection electrodes 2a, 2b, and 2c at this time is photographed by a high-speed camera and the photographed image is reproduced slowly, not only is the electrophoresis of the toner between the ejection electrodes 2 suppressed, but also No toner electrophoresed.

[Ejection Test 5] An ejection test similar to the ejection test 4 was carried out by replacing the colored liquid 6 with a conventional liquid developer (toner concentration: 1 wt%, viscosity: 1.5 wt%). Then, the discharge voltage of +1.2 [kV] (1.0 + 0.2 kV)
+1.0 from the top of the ejection electrodes 2a and 2c to which V) is supplied.
It was confirmed that the toner was electrophoresed on the ejection electrode 2b to which only the preliminary voltage of [kV] was supplied and gathered in the same manner as in the ejection test 1. Further, the additional supply of the voltage of +0.2 [kV] to the ejection electrodes 2a and 2b is completed,
Even if the potential differences between the ejection electrodes 2a and 2b and between the ejection electrodes 2b and 2c disappear, the collected toner remains
a, 2c. When the toner is collected in this way, the ejection electrodes 2a, 2
The liquid developer on c has a lower toner concentration than usual,
In addition, since the liquid developer on the ejection electrode 2b has a higher toner density than usual, the density and size of the formed dots differ for each ejection electrode, and a stable quality image cannot be obtained. In the image forming apparatus disclosed in JP-A-8-90825, which uses a conventional liquid developer, if a potential difference is generated between the discharge electrodes 2, the toner that has been electrophoresed from the discharge electrode 2 to the common electrode is used. However, there is a possibility that the electrophoresis is performed toward the discharge electrode 2 having a lower potential.

[Ejection Test 6] Walls for preventing toner electrophoresis were formed between the ejection electrodes 2a and 2b and between the ejection electrodes 2b and 2c. Then, a test similar to the ejection test 5 was performed. Then, as expected, the ejection electrode 2
The toner electrophoresed from the side a to the side of the discharge electrode 2b collides with the wall formed between the two electrodes and gathers on the wall. Further, the toner electrophoresed from the ejection electrode 2c side to the ejection electrode 2b side also collided with the wall formed between the two electrodes and collected on the wall surface. However, the ejection electrodes 2a, 2c
Even if the supply of an additional voltage of +0.2 [kV] is completed and the potential difference between the discharge electrodes 2 disappears (+1.0 kV, respectively), the toner collected on each wall remains
a, 2c were maintained almost without returning. Therefore, even if a wall is provided between each of the discharge electrodes 2, it is not possible to avoid instability of the image quality due to electrophoresis of the toner.

On the other hand, the present inventors prototyped an electrophoresis test apparatus as shown in FIG. 3 in order to observe the state of electrophoresis of toner in a liquid. In FIG. 3, the electrophoresis test apparatus 105 includes a transparent glass plate 106, a T-shaped transparent first electrode 107, 100 [μm] laminated on the surface thereof.
And a T-shaped transparent second electrode 108 laminated on the glass plate 106 so as to take a position symmetrical with the first electrode 107 via the migration gap G2. These first
The electrode 107 and the second electrode 108 are each made of ITO. A conductive tape 109 is conductively connected to an end of the second electrode 108 having a thickness of 0.15 [μm], and the conductive tape 109 is further connected to a power supply 110.
It is connected to the. In addition, the first layer having the same thickness
A grounded conductive tape 111 is connected to an end of the electrode 107.

In the electrophoresis test apparatus 105 having such a configuration, the second electrode 108 corresponds to the ejection electrode 2 and the first electrode 107 corresponds to the counter electrode 9. We have:
Using the electrophoresis test apparatus 105, the following electrophoresis test was performed.

[Electrophoresis Test 1] The state of toner electrophoresis in the electrophoresis test apparatus 105 for a colored liquid having a lower viscosity than the colored liquid used in the ejection test 4 and a higher viscosity than the conventional liquid developer. Was observed. Specifically, in FIG. 4, toner concentration: 15 [wt%], viscosity: 10
A colored liquid 6 of 0 [mPa · s] is dropped into the migration gap G2 of 100 [μm] and squeezed so as to have a thickness of about 20 [μm], and then a high-speed video with a 50 × objective lens mounted thereon. An electrophoresis test apparatus 105 was provided between a camera 112 and a cold light 113 as a non-heat-generating light source. Then, a positive DC voltage is output from the power supply 111, and the state of the toner electrophoresed from the second electrode 108 to the first electrode 107 is displayed on the high-speed video camera 112.
(Kodak high speed filming camera Model 4540) was used to shoot one frame at a time every 1/500 to 1/5000 seconds.

When the photographed image was reproduced at a slow speed, "1.0" between the first electrode 107 and the second electrode 108 was obtained.
× 10 ⁶ V / m ”even when an electric field having an intensity of 6
The inside toner does not undergo electrophoresis and is “2.0 × 10 ⁶ V / m”
When an electric field having an intensity of .times.1 was applied, it gradually started to move after a time lag of 100 [msec] or more had elapsed. Therefore,
In the colored liquid 6 used in the electrophoresis test, the minimum electric field strength at which the toner inside the liquid 6 can be electrophoresed is “2.0 ×
10 ⁶ V / m ”and the electric field of this electric field strength is 100
When the action is performed for [msec] or more, the toner starts electrophoresis (hereinafter, this electric field intensity is referred to as an electrophoresis start electric field intensity). The electrophoretic velocity of the toner that has started to move is such that the electric field strength is “3.0 × 10 ⁶ V / m” or “5.0 × 10 ⁶ V / m”.
m ”and“ 7.0 × 10 ⁶ V / m ”, the speed gradually increases, and when it reaches“ 1.0 × 10 ⁷ V / m ”, 1 to 10
It was found that it reached up to [mm / sec].

[Electrophoresis Test 2] A conventional liquid developer (1 wt.
%, 1.5 mPa · s), and a migration test similar to the migration test 1 was performed. Then, the toner in the liquid developer becomes
It was found that electrophoresis immediately started at a speed of 1 to 10 [mm / sec] only by the application of an electric field of “1.0 × 10 ⁶ V / m”. Therefore, in the conventional liquid developer, and weakened much than electrophoretic start electric field strength of the inside of the toner "1.0 × 10 6 ^{V /} m", and "1.0 × 10 ⁶ When an electric field having an intensity of “V / m” or more acts, the toner starts electrophoresis immediately without a time lag. In the discharge tests 5 and 6 using such a liquid developer, “2.0 × 10 ⁶ V / V” is applied between the discharge electrode 2b and the discharge electrode 2a or between the discharge electrode 2b and the discharge electrode 2c. An electric field of intensity "m" is formed. Since the electric field having such an intensity acts on the toner in the liquid developer, the toner immediately starts high-speed migration, and 1 [msec
c] on the discharge electrode 2a or the discharge electrode 2
That is, it gathered on the ejection electrode 2b from above c.

The reason why the electrophoretic start electric field intensity of the toner in the electrophoretic test 2 becomes significantly weaker than the electrophoretic start electric field intensity of the toner in the electrophoretic test 1 is considered as follows.
That is, the toner in the low-viscosity (1.5 mPa · s) liquid developer can be pushed away from the surrounding liquid carrier and electrophoresed, while the high-viscosity (100 mPa · s)
-The toner in the colored liquid 6 of s) must be electrophoresed following the surrounding liquid carrier. Therefore, it is considered that a stronger electrostatic force needs to be applied for electrophoresis. In addition, since the toner dispersed in the liquid developer having a low toner concentration (1 wt%) maintains a certain distance from other toners, electrophoresis is hardly affected by charges of other toners. Can be.
On the other hand, the colored liquid 6 having a high toner concentration (15 wt%)
The toner dispersed inside is close to each other, and is subjected to electrostatic repulsion by the charge of the surrounding toner, so it is considered that a stronger electrostatic force must be applied for electrophoresis. Can be

Since the colored liquid (viscosity: 500 mPa · s) used in the above-mentioned ejection test 4 has a higher viscosity than the colored liquid (viscosity: 100 mPa · s) used in the migration test 1, the toner It is considered that the electrophoresis start electric field intensity was also increased. That is, it is considered that the intensity is higher than “2.0 × 10 ⁶ V / m”. In the ejection test 4, between the ejection electrode 2b and the ejection electrode 2a,
b and the discharge electrode 2c, “2.0 × 10 ⁶ V /
An electric field having an intensity of 50 m "is formed.
It is considered that the toner on the ejection electrodes 2a and 2c could not be electrophoresed toward the ejection electrode 2b because the electrophoresis start electric field strength of the colored liquid of 0 [mPa · s] was weaker. Incidentally, if the electrophoresis start electric field intensity of the toner in a colored liquid having a viscosity of 500 [mPa · s] is 100
[2.0] same as that of the colored liquid of [mPa · s].
Even if it is × 10 ⁶ V / m ”, the toner will not electrophorese unless the electric field of such intensity acts for 100 [msec] or more. In the above-described ejection test 4, the electric field between the ejection electrodes 2 acts on the toner for only 1 [msec]. Therefore, even if the electrophoresis start electric field intensity of the toner and the electric field intensity between the ejection electrodes 2 are the same. The toner did not undergo electrophoresis.

On the other hand, in the above-mentioned ejection test 4, the counter electrode 9 grounded and the ejection voltage of +1.2 [kV] (1.0
+0.2 kV) between the discharge electrodes 2a and 2c (gap G1 = 120 μm).
× 10 ⁷ V / m ”is formed. Such an intensity is stronger than the electrophoresis start electric field intensity of the toner in the colored liquid used in the ejection test 4, and countless toners present near the tip of the ejection electrode 2b are attracted by the high viscosity liquid carrier under the influence of the electric field. Since the electrophoresis is performed with a strong force toward the electrode 9, it is considered that the colored liquid protrudes from the tips of the ejection electrodes 2a and 2c.

In view of the above discharge test and migration test, a ninth aspect of the present invention is the image forming apparatus according to the eighth aspect, wherein the parallel electrode from which the colored liquid is to be discharged from the front end and the parallel electrode adjacent to the parallel electrode. The combination of the intensity of the electric field between the parallel electrodes formed by the potential difference from the parallel electrodes that are arranged and the colored liquid should not be ejected, and the duration of the electric field between the parallel electrodes, In which the colored fine particles present in the liquid carrier are not electrophoresed in the liquid carrier.

Even if an electric field between the parallel electrodes less than the electrophoresis start electric field strength of the colored particles or an electric field between the parallel electrodes that is higher than the electrophoresis start electric field strength is formed, the electric field between the parallel electrodes before the electrophoresis of the colored particles starts. The electrophoresis of the colored particles between the parallel electrodes is avoided by reducing the intensity of the electrophoresis to a value lower than the intensity of the electrophoresis start electric field. In such a configuration, the toner concentration of the colored liquid on each parallel electrode can be maintained uniform, and the density and size of the dots formed on the recording member can be maintained uniform. However, in this image forming apparatus, if an attempt is made to employ a combination of the intensity of the electric field between the parallel electrodes and the duration of the electric field that can avoid the electrophoresis of the colored particles between the parallel electrodes, There remains a possibility that the electric field strength between the counter electrode and the counter electrode cannot be increased to such a level that the colored particles are largely discharged from the tips of the parallel electrodes and adhere to the recording member.

According to a tenth aspect of the present invention, there is provided the image forming apparatus according to the ninth aspect, wherein the colored liquid is discharged with a strength necessary to discharge the colored liquid at a discharge distance capable of reaching the recording member. An electric field is formed between the parallel electrode and the counter electrode, and the colored particles have a high concentration of colored particles and a high enough concentration that the electric field between the parallel electrodes can be formed such that the colored particles are not electrophoresed during the duration. It is characterized in that a high viscosity material is used.

In this image forming apparatus, by using a high-concentration and high-viscosity liquid such as the colored liquid 6 used in the above test, the electrophoresis of the colored particles between the parallel electrodes is ensured. While avoiding this, it is possible to reliably form an ejection electric field having an intensity required for attaching the colored particles to the recording member (hereinafter, referred to as an attachment strength) between the parallel electrode and the counter electrode. However, since the electric field strength depends not only on the potential difference between the electrodes but also on the distance, if the distance between the parallel electrodes is hardly provided in order to achieve high resolution, no matter how high the concentration and viscosity of the colored liquid are, Even so, there is a possibility that the electric field strength between the parallel electrodes may be higher than the electrophoresis start electric field strength.

Therefore, the invention of claim 11 is based on claim 10
Wherein the plurality of substrates are arranged in the moving direction of the recording member.

In this image forming apparatus, the gap between dots formed on the recording member by the substrate disposed on the upstream side in the moving direction of the recording member is formed by the substrate disposed on the downstream side in the moving direction. Can be filled with dots. Therefore, even when a relatively high-resolution image such as 600 [dpi] is formed, the distance between the parallel electrodes is secured to some extent, and the electric field strength between the parallel electrodes is more reliably reduced to less than the electrophoresis start electric field strength. can do.

According to a twelfth aspect of the present invention, in the image forming apparatus of the tenth aspect, there is provided a substrate moving means for moving the substrate in the direction in which the parallel electrodes are arranged, and repeatedly passes the position facing the tip of each parallel electrode. The recording member moving means is configured to move the recording member along such a moving path.

In this image forming apparatus, a plurality of substrates are used through the following process.
Unlike the image forming apparatus described above, it is possible to use one substrate to fill gaps between dots. That is, first,
A plurality of dots are formed on a recording member passing through a position facing the tip of each parallel electrode with a gap therebetween. Next, after the substrate is slightly moved by the substrate moving means in the direction in which the parallel electrodes are arranged (hereinafter, referred to as the main scanning direction), the recording member moving means moves the substrate to the facing position again in the gap portion. To form dots. If these series of processes are performed a number of times corresponding to the size of the gap, the gap between the dots can be filled using one substrate. Therefore, even when a relatively high-resolution image is formed, a certain distance between the parallel electrodes can be secured, and the electric field strength between the parallel electrodes can be more reliably made smaller than the electrophoresis start electric field strength. Further, the number of parallel electrodes and expensive HVIC can be significantly reduced as compared with the image forming apparatus of the eleventh aspect using a plurality of substrates.

According to a thirteenth aspect of the present invention, in the image forming apparatus of the tenth aspect, the recording member moving means is configured to move the recording member also in the direction in which the parallel electrodes are arranged. It is.

In this image forming apparatus, a twelfth aspect is provided.
By moving the recording member in the main scanning direction instead of moving the substrate in the main scanning direction as in the image forming apparatus of
Using one substrate, it is possible to fill the gap between each dot. Therefore, even when a relatively high-resolution image is formed, a certain distance between the parallel electrodes can be secured, and the electric field strength between the parallel electrodes can be more reliably made smaller than the electrophoresis start electric field strength. Further, compared to the image forming apparatus according to claim 11 using a plurality of substrates, parallel electrodes and expensive HVI
The number of C can be greatly reduced. However, if an image is formed by the following process in this image forming apparatus, the image forming speed is reduced by reciprocating the recording member many times in the main scanning direction. That is, first, the movement of the recording member in the sub-scanning direction (the direction of passage of the recording member at the above-described facing position) is temporarily stopped to form each dot, and then the recording member is slightly moved in the main scanning direction. , Dots are formed so as to fill the interval between the dots. Then, a dot is formed by slightly moving the recording member in the sub-scanning direction so that a new region of the recording member is opposed to each parallel electrode. Dots are formed so as to fill in the dots. In such a series of processes, an image is formed while the recording member is repeatedly reciprocated in the main scanning direction. The number of reciprocating movements varies depending on the length of the recording member in the main scanning direction, the resolution of the formed image, and the like, but is at least several tens of units for an A4 size recording member. Is twice as large as one hundred to several hundred times. In this process in which the movement of the recording member in the sub-scanning direction needs to be stopped many times as described above, the image forming speed is naturally reduced by repeatedly stopping the recording member.

Therefore, the invention of claim 14 is based on claim 13
In the above image forming apparatus, the recording member moving means is configured to move the recording member along a moving path that repeatedly passes through the facing position.

In this image forming apparatus, an image can be formed by the following process. That is, first, the dots are sequentially formed while moving the recording member in the sub-scanning direction without stopping, and the recording member that has passed the position facing the tip of each parallel electrode is slightly moved in the sub-scanning direction. It is moved to the opposite position again, and dots are sequentially formed so as to fill the above-mentioned space. In such a process, an image can be formed without stopping the movement of the recording member in the sub-scanning direction or repeatedly reciprocating in the main scanning direction. Therefore, the recording member is repeatedly reciprocated in the main scanning direction. Therefore, it is possible to avoid a reduction in the image forming speed due to this.

According to a fifteenth aspect of the present invention,
4. The image forming apparatus according to 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, wherein an intermediate recording member is used as the recording member to which a colored liquid from the tip of the parallel electrode adheres. And a transfer unit for transferring an image formed on the intermediate recording member to another recording member.

In this image forming apparatus, a specific type of intermediate recording member is conveyed to a recording position between a counter electrode and each parallel electrode and an image is recorded on the intermediate recording member.
The image is transferred onto various types of recording members such as OHP sheets. For this reason, unlike the case where images are recorded on various types of recording members at the recording position, the liquid movement distance from the front end of the substrate to the intermediate recording member at the recording position, the liquid adhesion to the intermediate recording member, the intermediate recording The liquid resilience on the member is kept constant. Therefore, it is possible to form an image of stable quality irrespective of the type of recording member used, without changing the image quality due to the change of the liquid moving distance, the liquid adhesion, the liquid repulsion, and the like. Can be.

According to a sixteenth aspect of the present invention,
In the image forming apparatus of any one of 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14, a conveying unit that conveys the recording member to a recording position between the counter electrode and each of the parallel electrodes. Discharging means for discharging the recording member on which an image has been recorded at the recording position to the apparatus main body.

In this image forming apparatus, unlike an image forming apparatus according to claim 15, an image is temporarily recorded on an intermediate recording member and then transferred to another recording member. Since the image is directly recorded on the final recording member, no intermediate recording member or transfer means is required. Therefore, it is possible to eliminate an increase in size and cost of the apparatus due to the provision of the intermediate recording member and the transfer unit.

According to a seventeenth aspect of the present invention, the charged colored particles and the liquid carrier are provided between a substrate having a plurality of parallel electrodes arranged in parallel at a predetermined pitch and a facing plate facing the electrode surface. Holding a colored liquid containing: a step of causing a potential difference between the counter electrode and the parallel electrode facing each other through a predetermined gap at the tip of each parallel electrode of the substrate; and In the image forming method of forming an image by performing a step of discharging particles from the tip toward the counter electrode side by the potential difference and a step of attaching the discharged colored particles to a recording member, In the state where the colored particles are dispersed in a liquid carrier, a material having a high colored particle concentration is used so that the colored particles are discharged from the tip of the parallel electrode and adhere to the recording member by the potential difference, and at least the colored liquid is used. At the time of ejecting from the tip, it is characterized in that the moved to said parallel electrodes provided adjacent the colored liquid present between the parallel electrodes on the substrate.

In this image forming method, the common electrode faces each parallel electrode and the tip of each parallel electrode is tapered in the apparatus used for image formation by the same operation as the image forming apparatus of the first aspect. In addition, an image can be formed without employing a complicated electrode configuration in which the tapered portion protrudes toward the counter electrode from the common electrode. Further, without providing a partition wall between the parallel electrodes of the apparatus used for image formation, it is possible to suppress the colored liquid protruding from the tips of the parallel electrodes from drawing out the nearby colored liquid.

[0063]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an image forming apparatus according to an embodiment, a test performed to complete the present invention will be described in more detail. [Ejection Test 7] In Ejection Test 4, the ejection electrodes 2a, 2
A common voltage of +1.0 [kV] is applied to each of the electrodes b and 2c, and a voltage of +0.2 [kV] is added only to the ejection electrode 2b, thereby reducing the potential difference between the ejection electrodes 2. I was The discharge voltage required for discharging the colored liquid 6 from the tip of the discharge electrode 2 is +1.2 [kV], but the common voltage is set higher than +1.0 [kV] and added by that amount. By adjusting the discharge voltage to +1.2 [kV] by lowering the discharge voltage, the potential difference between the discharge electrodes 2 can be further reduced.

Therefore, the present inventors set the common voltage to +1.
While gradually increasing the voltage from 0 [kV], the additional test voltage is lowered from +0.2 [kV] by the increased amount, and the discharge test 4 is performed.
The same test was performed. Then, the colored liquid 6 raised from the tip of the discharge electrode 2b cannot be reliably attached to plain paper, or the colored liquid 6 raised from the discharge electrodes 2a, 2b by applying a common voltage is applied to plain paper. But it should have been attached when it shouldn't. This is because the adhesion between the counter electrode 9 and the plain paper changes every test, the distance between each discharge electrode 2 and the plain paper changes, and the viscosity of the colored liquid 6 changes every day.

When the same ejection test was repeatedly performed, even if such a change in the distance or the change in the viscosity occurred, the colored liquid 6 to be adhered to the plain paper was surely adhered and the colored liquid 6 to be adhered was not. It has been found that in order to prevent the liquid 6 from adhering reliably, it is necessary to secure a potential difference of 0.2 [kV] or more between the common voltage and the additional voltage.

[Piezo inkjet test] Conventional liquid developer (toner concentration: 1 wt%, viscosity: 1.5 wt%)
Was accommodated in a laminated piezo inkjet device prototyped by the present inventors, and thereby printed on plain paper. Then
The diameter is very large, about 180 [μm], and the image density is 0.1 μm.
As a result, a thin dot of 89 [ID] and a blurred periphery were formed. It is considered that such poor quality dots were formed because the liquid developer scattered when landing on plain paper, flowed along paper fibers, or entered paper fibers. Therefore, the ejection test apparatus 100 shown in FIG.
Even if the conventional liquid developer can be ejected from the tip of the ejection electrode 2, it is considered that only poor quality dots can be formed as in this test.
On the other hand, in the above-described ejection test 4, the colored liquid 6 (15
%, 100 mPa · s) on plain paper,
No flow along the paper fiber and no penetration into the paper fiber occurred, small diameter (100 μm), high image density (1.41)
[ID]) and dots with sharp edges were formed.

[Ejection Test 8] The present inventors made the following simple recording bed by applying the ejection test apparatus 100 shown in FIG. That is, 100 [μm] in FIG.
Each of the discharge electrodes 2a, 2b, 2c having a width (W2) is 5
After laminating in parallel on the glass plate 102 with a gap of 0 [μm], using a mask material provided with an opening corresponding to the non-electrode portion of the glass plate 102, spraying a primer on the non-electrode portion Applied. Next, the primer was dried in an environment of 80 [° C.] for 30 minutes, and the glass plate 10 was dried.
A primer layer having a thickness of 0.1 [μm] was formed on the non-electrode portion of No. 2. Further, a fluorine-containing resin solution (manufactured by Asahi Glass Co., Ltd .: Cytop) is spray-coated on the primer layer using the above mask material, and heat-treated at 120 [° C.] for 2 hours to obtain a thickness. A fluororesin film of 0.4 [μm] was formed. A simple recording head was prepared by facing the facing glass plate via a gap of 30 [μm] to the electrode forming surface of the glass plate 102 on which the fluororesin coating was formed in this manner. The formed fluororesin film was firmly fixed to the glass plate 102 via the primer layer.

In the gap of 30 [μm] between the glass plate 102 of the simple recording head and the facing glass plate, the colored liquid 6 having a toner concentration of 15 [wt%] and a viscosity of 500 [mPa · s] was placed on the plate. The injection was performed from the rear end toward the front end. Then, in the non-electrode portion of the glass plate 102, the colored liquid 6 was repelled by the excellent liquid repellency of the fluororesin coating, and a cavity was formed. In the colored liquid 6 having a high viscosity and a high surface tension, the cavities are larger than a liquid having a relatively low surface tension such as water. With respect to the injected colored liquid 6, pressure was applied to such an extent that it did not spill from the tip of the simple recording head. The counter electrode 9 is placed at the tip of the simple recording head into which the colored liquid 6 is injected in this manner, with a gap of 120 [μm] therebetween.
Were grounded facing each other. Then, the ejection electrodes 2a, 2b,
After applying a voltage of +1.0 [kV] to each of the discharge electrodes 2c, +0.2 [k] is applied only to the discharge electrodes 2a and 2c at both ends.
V] and a pulse voltage having a width of 5 [msec] was applied and an attempt was made to form dots. Then, the colored liquid 6 in the simple recording head did not protrude from the tip of the ejection electrode 2b to which the pulse voltage was not applied, but protruded from the tip of the ejection electrodes 2a and 2b to which the pulse voltage was applied. And
Attached to the side surface of the glass plate 101 holding the counter electrode 9,
Two dots arranged side by side with a gap were formed.

In the prototype simple recording head, since the cavity was formed between the discharge electrodes by the above-mentioned fluororesin coating, the surface tension of the colored liquid 6 protruding from the tips of the discharge electrodes 2a and 2c was reduced by the discharge electrode 2b. It is difficult to be transmitted to the upper colored liquid 6. As a result, dragging of the colored liquid 6 on the discharge electrode 2b by the raised colored liquid 6 was suppressed, and the two dots were formed neatly without the colored liquid 6 rising from the tip of the discharge electrode 2b.

However, when such formation of two dots is repeated, the colored liquid 6 rarely rises from the tip of the discharge electrode 2b and adheres to the side surface of the glass plate 101 on which the opposing electrode 9 is formed. In some cases, dots were connected and formed. The state at this time was photographed with a high-speed camera, and the photographed image was played back slowly and observed. In practice, the colored liquid 6 was raised not from the tip of the discharge electrode 2b but from the facing glass plate portion facing the tip. I knew I was doing it. When the simple recording head is closely observed from the side, as shown in the vertical cross section of FIG. 5A and the front of FIG. Is formed on the facing glass plate 11
4 and the colored liquid 6 above the cavity 11
Layer was formed.

In the discharge test 8, the intensity of the electric field formed between the discharge electrodes 2 was “(0.2 × 10 ³ ) /
(50 × 10 ⁻⁶ ) = 4.0 × 10 ⁶ V / m ”, and the electric field of this intensity is applied to the toner on the glass plate 102 by 5%.
[Msec], the toner was not electrophoresed between the discharge electrodes 2.

[Ejection Test 9] On the facing glass plate 114, a fluororesin film similar to that of the glass plate 102 was formed on the portion facing the ejection electrode 2 to recreate a simple recording head, and then the colored liquid 6 was injected. Thereafter, the simplified recording head was well observed from the side. Then, the vertical cross section of FIG.
As shown in the front of FIG. 6B, the colored liquid 6 was repelled by the fluororesin coating 3 also on the facing glass plate 114 side, and the cavity 11 was connected between the glass plate 102 and the facing glass 114 plate. Therefore, the colored liquid 6 did not completely exist on the non-electrode portion between the two plates.

In this state, 2
When the dots were repeatedly formed, no matter how many times the dots were formed, the colored liquid 6 did not protrude from the tip of the discharge electrode 2b, and two dots lined up with a gap were clearly formed.

However, during the formation of two dots continuously, there were cases where dots were not formed because the colored liquid 6 was rarely ejected from the tips of the ejection electrodes 2a and 2c. When the state before and after this time was observed by slow reproduction of the photographed image, the following phenomenon was observed. That is, pressure is applied to the colored liquid 6 in the simple recording head from the rear end of the head as needed so as not to spill the colored liquid 6 from the head end. Therefore, basically, even if the colored liquid 6 is consumed in the vicinity of the head end due to the formation of dots, the colored liquid 6 moves from the rear end of the head and is supplied to the head end. However, if continuous recording is performed, this supply may not be able to keep up,
In the length direction on the ejection electrodes 2a and 2c, a portion where the colored liquid 6 is interrupted occurs. When this part was moved to the head end with the continuous printing, the colored liquid 6 did not discharge from the front ends of these discharge electrodes.

[Ejection Test 10] The inventors of the present invention have made various attempts to improve the replenishability of the colored liquid 6 to the head end, and found that the above-described test was performed only in a limited area from the head end to the rear end. It has been found that when the fluororesin coatings 3 and 5 are formed, good replenishment can be obtained. In such a configuration, the amount of the colored liquid 6 per unit area is larger in the region where the fluororesin coatings 3 and 5 are formed than in the region where the fluororesin films 3 and 5 are formed from the head end to the rear end. As described above, the colored liquid 6 is smoothly supplied from the region where the amount of the colored liquid 6 is large toward the head end where the amount of the colored liquid 6 is small. However, it is necessary to appropriately set the length from the head end of the area where the fluororesin coatings 3 and 5 are formed. When the length from the tip of the head is less than 0.2 [mm], the effect of making it difficult to transmit the surface tension of the colored liquid 6 raised from the tips of the ejection electrodes 2a and 2c to the colored liquid 6 on the ejection electrode 2b is sufficient. And the former colored liquid 6 was dragged out by the former colored liquid 6. If the length from the head tip exceeds 0.9 [mm], the supply of the colored liquid 6 from the rear end of the head to the tip of the head is not smoothly supplied, and the colored liquid on the ejection electrodes 2a and 2c is not supplied. It was confirmed that 6 was cut off halfway. Therefore, it is desirable that the length of the area where the fluororesin coatings 3 and 5 are formed from the tip of the head be set to 0.2 [mm] or more and 0.9 [mm] or less.

Next, an embodiment in which the present invention is applied to a printer as an image forming apparatus will be described. FIG. 7 is a cross-sectional view illustrating a main part of the recording head of the printer according to the present embodiment. In FIG. 7, a recording head 1 includes an insulating substrate 4 on which a plurality of ejection electrodes 2 as parallel electrodes are formed,
An insulating top plate 13 is provided as a facing plate facing the electrode forming surface with a gap of 30 [μm] therebetween. This gap serves as a liquid chamber of the recording head 1 and has a viscosity of 500 [mPa] in which polysiloxane oil as a liquid carrier contains toner, which is colored particles charged to a positive polarity, at a concentration of 15 [wt%]. [S] is stored. The colored liquid 6 is appropriately replenished to the liquid chamber by a replenishing means (not shown).

The toner in the colored liquid 6 is obtained by dispersing a pigment composed of carbon black in a matrix composed of an epoxy resin, and has an average particle diameter of 2.0 [μm] and a specific gravity of 1.
0, and the average charge amount is adjusted to 60 [μC / g].
In the above-mentioned ejection test 4, the value of the ejection voltage for forming the ejection electric field having the adhesion strength is +1.2 [kV].
However, this value differs depending on the configuration of the device. In addition, even if the colored liquids have the same toner concentration and viscosity, if the average particle diameter, specific gravity, average charge amount, and the like of the toner are different, the required discharge voltage and the electrophoresis start electric field strength of the toner are also different.

Each ejection electrode 2 is formed so as to be electrically independent from each other. When the recording head 1 is driven, a voltage of +1.0 [kV] is commonly applied to each ejection electrode 2 from the power supply 8a. Of the ejection electrodes 2, the one for forming dots has a voltage of +0.2 [kV] of 5 under the control of the voltage ON / OFF driver 10 connected to the power supply 8 c.
It is applied while being added only for [msec]. By this additional application, + is applied to the discharge electrode 2 where a dot is to be formed.
A discharge voltage of 1.2 [kV] is applied for 5 [msec].

The insulating top plate 13 and the insulating substrate 14 are partially coated with fluororesin films 3 and 5, respectively.

FIG. 8 is a perspective view showing the insulating substrate 4. In the figure, 2480 discharge electrodes 2 having a width W3 of 34.7 [μm] are arranged in parallel with a gap (pitch = 84.7 μm) of 50 [μm]. These discharge electrodes 2 make it possible to form an image in an area corresponding to the width of A4 (210 mm). Note that a dot pitch of 84.7 [μm] corresponds to a resolution of 300 [dpi]. Further, each discharge electrode 2 having a width W3 of 34.7 [μm]
Has been confirmed by the present inventors to form dots having a diameter of about 60 [μm].

The above-mentioned fluororesin film 5 is coated only between the discharge electrodes 2 in the region of the length L1 from the front end to the rear end of the insulating substrate 4. In the printer according to the present embodiment, the length L1 is set to 0.5 [mm]. The fluororesin coating 3 of the insulating top plate 13 is formed only on the portion facing the fluororesin coating 5. At the portion where the fluororesin film 5 and the fluororesin film 5 face each other, as shown in FIG. 7, the colored liquid 6 is repelled by both films to form a cavity 11 in which the colored liquid 6 does not exist.

FIG. 9 is a schematic configuration diagram of the printer according to the present embodiment. In FIG. 9, the printer includes two recording heads 1, an intermediate recording drum 20, a paper feed cassette 21,
A registration roller pair 22, a transfer roller 23, a power supply 8d, a fixing device 24, a drum cleaning device 26, and the like are provided.

The intermediate recording drum 20 is such that a high resistance rubber layer 20b as an intermediate recording member is coated with a thickness of 0.03 [mm] on a peripheral surface of a grounded aluminum drum 20a as an opposite electrode. In addition, it is rotated in a direction indicated by an arrow in the figure at a peripheral speed of 40 [mm / sec] by a driving unit (not shown).

On the right side of the intermediate recording drum 20 in the figure, the two recording heads 1 are each 120 [μm].
So as to face the intermediate recording drum 20 with a gap of
Two layers are stacked. In each of the recording heads 1, the one located on the lower side in the figure is 42.3 [μ] than the one located on the upper side.
m], and is shifted to the far side in the figure. That is,
The two recording heads 1 are arranged so as to be shifted in the main scanning direction by 42.3 [μm] corresponding to a dot pitch of 600 [dpi].

The transfer roller 23 is provided on the intermediate recording drum 2
The transfer nip is formed in contact with the lower peripheral surface in FIG. A transfer electric field is formed in the transfer nip by a potential difference between the grounded aluminum drum 20a of the intermediate recording drum 20 and the transfer roller 23 to which a negative transfer bias is applied by the power supply 8d.

The paper feed cassette 21 accommodates therein transfer paper 25 as a recording member, and is provided with a paper feed roller 21a.
Is rotated, the uppermost one of the contained transfer paper 25 bundles is sent out toward the registration roller pair 22.

In the printer according to the present embodiment, for example, when a one-line image extending in the main scanning direction is formed on the transfer paper 25, the following process is performed. That is, first, of the two recording heads 1, the one located on the upper side in the figure is placed on the high resistance rubber layer 20 b of the rotating intermediate recording drum 20 by about 60 as shown in FIG.
2,480 dots Dt having a diameter of [μm] are formed at a pitch of 84.7 [μm]. Next, the print head 1 located on the lower side in the figure is four times smaller in the main scanning direction than the print head 1 on the upper side.
At a position shifted by 2.3 [μm], dots Dt having a diameter of about 60 [μm] are similarly formed at a pitch of 84.7 [μm].
Eighty pieces are formed (FIG. 10B). At this time, in the gap between the dots Dt formed by the upper recording head 1, each dot D formed by the lower recording head 1 is set.
At the position t, this gap is filled, and a one-line image is formed.

The image formed on the high-resistance rubber layer 20b of the intermediate recording drum 20 by the two recording heads 1 enters the transfer nip as the drum rotates.

On the other hand, prior to the entry, the paper feed cassette 21 sends out the transfer paper 25 toward the registration roller pair 22. The registration roller pair 22 receives the transferred transfer 2
5 is sandwiched between the two rollers, and sent out toward the transfer nip at a timing when the transfer roller 5 can be superimposed on the image on the high-resistance rubber layer 20b by the transfer nip.

The image on the high-resistance rubber layer 20b superimposed on the transfer paper 25 at the transfer nip is transferred onto the transfer paper 25 by the action of the transfer electric field and the nip pressure. Roller 24a and pressure roller 24
b and the toner is melted while being pressed. The transfer paper 25
The image is fixed on top. The transfer paper 25 after fixing is transferred to the fixing device 2
4 to the outside of the machine.

The residual colored liquid adhering to the high resistance rubber layer 20b after passing through the transfer nip is scraped off by the cleaning blade 26a of the drum cleaning device 26.

In the printer having the above-described configuration, even if the aggregate of the colored particles 6 is not generated at the tip of the discharge electrode 2,
The colored liquid 6 is discharged from the tip to form the high-resistance rubber layer 20.
b, the aggregate of toner can be attached to the high-resistance rubber layer 20b to form an image. Therefore, unlike the image forming apparatus disclosed in JP-A-8-90825, there is no need to generate toner aggregates at the tip of the discharge electrode 2. For this reason, a complicated electrode configuration in which the common electrode 14 faces each of the ejection electrodes 2, the tip of each of the ejection electrodes 2 is formed to be tapered, and the tapered portion is projected to the counter electrode 9 side of the common electrode 14. An image can be formed without adopting it.

Further, 0.5 [mm] (L1) from the tip of the recording head 1 between the respective ejection electrodes 2 on the insulating substrate 4.
And the fluororesin coating 5 formed on the insulating top plate 13 so as to face the colored liquid near the tip of the head between the discharge electrodes 2. 6 is flipped toward each of the ejection electrodes 2 to form a cavity between the ejection electrodes 2 near the head end. Since this cavity is formed so as to extend from the surface of the insulating substrate 4 to the surface of the insulating top plate 13, each of the discharge electrodes 2 near the tip of the head is formed.
If the colored liquid 6 does not completely exist between them, a state occurs. For this reason, the surface tension of the colored liquid 6 raised from the tip of the discharge electrode 2 is not transmitted to the colored liquid 6 on the adjacent discharge electrode 2, and even if continuous recording is performed, the former colored liquid 6 , The dragging of the latter colored liquid can be reliably suppressed.

Further, by setting the length of the fluororesin coatings 3 and 5 to 0.5 [mm] (L1) from the tip of the recording head 1, the colored liquid 6 caused by being set too short can be dragged out. While suppressing, it is possible to suppress the shortage of the supply of the colored liquid 6 onto each of the ejection electrodes 2 due to the setting being too long.

Further, the toner is not electrophoresed between the discharge electrodes 2 while the recording head 1 is being driven, so that the toner concentration of the colored liquid 6 on each discharge electrode 2 is maintained uniform. For this reason, each ejection electrode 2 allows the high-resistance rubber layer 20
The density and size of the dots formed on b can be kept uniform.

Further, by using the colored liquid 6 having a high concentration and a high viscosity, such as a toner concentration of 15 [wt%] and a viscosity of 500 [mPa · s], the electrophoresis start electric field strength of the toner is raised to avoid the migration. While discharging, an electric field higher than the adhesive strength required for discharging the toner is applied to each of the discharge electrodes 2 and the aluminum drum 2.
0b.

Since the gap between the dots Dt formed by the recording head 1 on the upstream side in the drum rotation direction can be filled with the dots Dt formed by the recording head 1 on the downstream side, the dot diameter is 60 [μm]. Despite forming an image of 600 [dpi] with a dot pitch of 42.3 [μm], the distance between each ejection electrode 2 was set to 50 [μm].
In addition, the electric field strength between the ejection electrodes 2 can be more reliably set to be lower than the electrophoresis start electric field strength.

Note that Japanese Patent No. 2,920,960 describes an image forming apparatus in which a recording head is provided with a liquid-repellent film. A liquid-repellent coating is provided only on the electrodes, not between the electrodes, in order to enhance the ejection property.

Next, a description will be given of a printer according to each embodiment in which a more characteristic configuration is added to the printer according to the present embodiment. [Embodiment 1] FIG. 11 is a schematic configuration diagram showing an intermediate recording drum 20 of a printer according to Embodiment 1 together with peripheral devices. As shown in the figure, this printer has only one recording head 1. That is, the number of recording heads 1 is half that of the printer of the embodiment. The recording head 1 is provided with a head moving means (not shown) as a substrate moving means for moving the recording head 1 in the main scanning direction (the depth direction in the figure). A marker detection sensor 27 that detects a marker image formed on the high-resistance rubber layer 20b of the intermediate recording drum 20 is provided upstream of the recording head 1 in the drum rotation direction. Further, the drum cleaning device 26 is provided with a cleaning contacting / separating means (not shown) for bringing the drum cleaning device 26 into or out of contact with the intermediate recording drum 10. Further, the transfer roller 23 is also provided with a roller contacting / separating means (not shown) for bringing the intermediate roller 10 into and out of contact with the transfer roller 23.

Voltage ON / OFF driver 1 shown in FIG.
0, the voltage applied to 2480 ejection electrodes 2
Expensive HV for individually switching N / OFF
2,480 ICs are provided. Therefore, the first embodiment
, The number of recording heads 1 is １ ／.
Not only is the number of expensive HVICs
Reduced to two.

In the present printer, an image is formed by the following process. That is, first, when the image forming operation of the printer body is started, the transfer roller 23 and the drum cleaning device 26 are moved so as to be separated from the drum surface by the roller contacting / separating means and the cleaning contacting / separating means, respectively. Next, the control unit (not shown) converts the image information sent from the personal computer or the like to 60
Is converted into output image information for 0 [dpi].
The image data is divided into primary output image information and secondary output image information for 300 [dpi] with a 4.7 [μm] pitch. And
A control signal based on the image information is sent to the recording head 1.

When the recording head 1 receives the control signal based on the primary output image information, first, it receives a high-resistance rubber layer 20 on the intermediate recording drum 20 rotating in the direction of the arrow in FIG.
b, after forming the marker image in the non-image area, the primary image based on the primary output image information is converted to the high-resistance rubber layer 20b.
Is formed in the image area of. Thereby, the high resistance rubber layer 20
On b, a marker image and a primary image are formed. After this primary image has been formed, it is
While the recording head 1 returns to the recording position, which is the position where the drum and the recording head 1 face each other with the rotation of the recording head 1, the recording head 1 is moved by 42.3 [μm from the near side to the far side in the drawing by the head moving means. ].

When the marker image passes immediately below the intermediate recording drum 20 with rotation of the intermediate recording drum 20, the marker detection sensor 27 detects the marker image and sends a detection signal to the control unit. The control unit sends a control signal based on the secondary output image information to the recording head 1 at an appropriate timing based on the detection signal.

Upon receiving this control signal, the recording head 1 forms a secondary image based on the secondary output image information so as to overlap the primary image. This superimposition fills the gap between the dots of the primary image,
An image of 600 [dpi] is formed on the high resistance rubber layer 20b.

Prior to the image entering the transfer nip, the transfer roller 23 and the drum cleaning device 26 are moved to contact the intermediate recording drum 20.

After the image formed on the surface of the high-resistance rubber layer 20b is transferred onto the transfer paper 25 by the transfer nip, the remaining colored liquid remaining on the surface is scraped off by the cleaning device 26. Is done.

In this printer having the above configuration, although the image forming speed is reduced to half or less of the printer of the embodiment, the number of the recording heads 1 and expensive HVICs is reduced to half to reduce the cost. be able to.

[Embodiment 2] The main configuration of a printer of Embodiment 2 is almost the same as that of Embodiment 1 shown in FIG. However, in this printer, a drum moving means (not shown) for moving the intermediate recording drum 20 in the main scanning direction is provided instead of providing the head moving means in the recording head 1. The image forming process in this printer is the same as that of the first embodiment except that the intermediate recording drum 20 is moved in the main scanning direction instead of moving the recording head 1 in the main scanning direction.

Here, in the present printer, an image can be formed by the following process.
That is, first, the high-resistance rubber layer 20b of the intermediate recording drum 20
Immediately after the image area has entered the recording position with the rotation of the drum, the rotation of the drum is temporarily stopped.
To form each dot. Then, the intermediate recording drum 10 is moved by the drum moving means in the main scanning direction.
After moving by 3 [μm], each dot is formed by the recording head 1. Next, the intermediate recording drum 10 is
After each dot is formed by the recording head 1 by rotating by 2.3 [μm], the recording head is moved in the main scanning direction opposite to the above and the formation of each dot. By repeating the above series of processes until the intermediate recording drum 20 is rotated by the length of the transfer paper 25, an image of 600 [dpi] can be formed on the high-resistance rubber layer 20b.

However, in such a process,
By reciprocating the intermediate recording drum 20 in the sub-scanning direction while stopping the rotation of the intermediate recording drum 20 for a large number of times, the image forming speed is significantly reduced. On the other hand, in this printer, an image can be formed without reducing the image forming speed in this way.

Also in the present printer having the above configuration, the number of recording heads 1 and expensive HVICs can be reduced to half, and the cost can be reduced.

[Embodiment 3] FIG. 12 is a schematic structural view of a printer according to Embodiment 3 of the present invention. In the figure, grounded counter electrodes 9 are provided at the tips of three recording heads 1 at 120 μm.
m]. When the transfer paper 25 sent from the paper feed cassette 21 enters a recording position where the three recording heads 1 and the opposing electrode 9 face each other, an image is recorded on the front surface thereof while the back surface thereof is in close contact with the opposing electrode 9. You.

In the printer having such a configuration, since the intermediate recording drum 20 and the transfer roller 23 are not provided, the apparatus main body can be made compact as shown in the figure.

[0114]

According to the present invention, claims 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, or 16
According to the invention, a complicated electrode configuration is adopted in which the common electrode faces each parallel electrode, the tip of each parallel electrode is tapered, and the tapered portion is protruded toward the counter electrode side from the common electrode. Even without this, there is an excellent effect that an image can be formed. In addition, there is an excellent effect that the colored liquid protruding from the tip of the parallel electrode can be prevented from being dragged out of the nearby colored liquid without providing a partition wall between the parallel electrodes.

In particular, according to the second aspect of the present invention, the colored liquid existing between the respective parallel electrodes is repelled by the liquid-repellent coating on the substrate, so that the distance between the respective parallel electrodes between the substrate and the facing plate is reduced. There is an excellent effect that a cavity can be formed in the region where the heat treatment is performed.

According to the third aspect of the present invention, the liquid-repellent coating provided on the facing plate portion facing between the parallel electrodes allows the region corresponding to between the parallel electrodes between the substrate and the facing plate. By repelling the colored liquid, there is an excellent effect that a cavity can be formed in the region.

According to the fourth aspect of the present invention, since a larger cavity is formed in a region between the parallel electrodes between the substrate and the facing plate, the colored liquid protruding from the tips of the parallel electrodes is formed. There is an excellent effect that the dragging of the colored liquid in the vicinity due to the above can be suppressed more reliably.

Further, according to the fifth aspect of the present invention, the fluorine resin coating has an excellent effect that the colored liquid existing between the parallel electrodes can be favorably moved to the adjacent parallel electrodes. is there.

Further, in particular, according to the invention of claim 6 or 7, there is an excellent effect that the shortage of the supply of the colored liquid onto each parallel electrode can be suppressed.

According to the seventh aspect of the present invention, the length of the liquid-repellent coating is set to be too long while the dragging of the colored liquid caused by setting the length of the liquid-repellent coating from the front end of the substrate to be too short is suppressed. Thus, there is an excellent effect that the shortage of the supply of the colored liquid onto each parallel electrode due to the above can be suppressed.

In particular, claims 8, 9, 10, 11, 1
According to the invention of 2, 13 or 14, it is possible to form not only a one-dimensional line image in which a plurality of dots are arranged in a straight line, but also a two-dimensional image such as a character image or a video image. Has an effect.

In particular, claims 9, 10, 11, 12,
According to the invention of the thirteenth or fourteenth aspect, since the density and the size of the dots formed on the recording member are maintained uniformly by each parallel electrode, there is an excellent effect that a stable quality image can be formed.

In particular, claims 10, 11, 12, and 13
According to the invention of the fourteenth aspect, it is possible to reliably form an electric field having a strength equal to or higher than the above-described adhesion strength between the parallel electrode and the counter electrode while reliably avoiding electrophoresis of the colored particles between the parallel electrodes. There is an excellent effect.

[0124] In particular, the present invention relates to claim 11, 12, 13 or 1.
According to the invention of the fourth aspect, even when a relatively high-resolution image is formed, a certain distance between the parallel electrodes is ensured, and the electric field strength between the parallel electrodes is more reliably reduced to less than the electrophoresis start electric field strength. There is an excellent effect that can be.

In particular, according to the invention of claim 12, 13 or 14, the number of parallel electrodes and expensive HVIC can be significantly reduced as compared with the invention of claim 11 using a plurality of substrates.

In particular, according to the fourteenth aspect of the present invention, there is an excellent effect that it is possible to avoid a reduction in image forming speed caused by reciprocatingly moving the recording member in the main scanning direction.

According to the invention of the fifteenth aspect, there is an excellent effect that an image of stable quality can be formed regardless of the type of the recording member used.

In particular, according to the sixteenth aspect of the invention, there is an excellent effect that it is possible to eliminate the increase in size and cost of the apparatus due to the provision of the intermediate recording member and the transfer means.

According to the seventeenth aspect of the present invention, in the apparatus used for image formation, the common electrode faces each parallel electrode, the tip of each parallel electrode is tapered, and the tapered portion faces the common electrode. There is an excellent effect that an image can be formed without employing a complicated electrode configuration such as protruding toward the electrode. Further, there is an excellent effect that the colored liquid protruding from the tip of the parallel electrode can be prevented from being drawn out of the nearby colored liquid without providing a partition wall between the parallel electrodes of the apparatus used for image formation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an ejection test apparatus prototyped by the present inventors.

FIGS. 2A to 2C are schematic diagrams each showing a toner discharge state in the same discharge test apparatus.

FIG. 3 is a perspective view showing an electrophoresis test device prototyped by the present inventors.

FIG. 4 is a schematic diagram for explaining a test using the electrophoresis test apparatus.

FIG. 5A is a longitudinal sectional view showing a state of a colored liquid repelled by a fluororesin coating between discharge electrodes in a simplified recording head prototyped by the present inventors. (B) is a front view showing the same state.

FIG. 6A is a longitudinal sectional view showing a state of a colored liquid that is repelled by the fluororesin coating and the fluororesin on the facing glass plate in the simple recording head. (B) is a front view showing the same state.

FIG. 7 is an exemplary sectional view showing a main part of a recording head of the printer according to the embodiment;

FIG. 8 is a perspective view showing an insulating substrate of the recording head.

FIG. 9 is a schematic configuration diagram of the printer.

FIGS. 10A to 10C are schematic diagrams each showing a dot formed by a recording head.

FIG. 11 is a schematic configuration diagram illustrating an intermediate recording drum of the printer according to the first embodiment together with devices around the intermediate recording drum.

FIG. 12 is a schematic configuration diagram of a printer according to a third embodiment.

FIG. 13A is a vertical cross-sectional view illustrating a configuration of a main part of a conventional image forming apparatus. (B) is a top view which shows the principal part structure. (C)
2 is a front view showing the configuration of the main part.

FIGS. 14A and 14B are schematic diagrams illustrating states of toner in a recording head of the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2 Discharge electrode (parallel electrode) 3 Fluororesin coating 4 Insulating substrate (substrate) 5 Fluororesin coating 6 Colored liquid 7 Power supply for recording signal 8 Power supply 9 Counter electrode 10 Voltage ON / OFF driver 13 Insulating top plate 20 Intermediate recording drum 20a Aluminum drum (counter electrode) 20b High resistance rubber layer (intermediate recording member) 21 Paper feed cassette 22 Registration roller pair 23 Transfer roller 24 Fixing device 25 Transfer paper (recording member) 26 Drum cleaning device 27 Marker detection sensor 100 Discharge test device 101, 102 Glass plate 105 Migration test device 106 Glass plate 107 First electrode 108 Second electrode 109, 111 Conductive tape 110 Power supply 112 High-speed camera 113 Cold light 114 Face-to-face glass plate T Toner (colored fine particles) Dt dot

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koichi Kato 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Company (reference) 2C057 AH07 BD05 2C162 AE12 AE25 AE31 AE47 AE68 AE76 AE84

Claims (17)

[Claims] 1. A substrate for holding a colored liquid containing charged colored particles and a liquid carrier, a plurality of parallel electrodes arranged in parallel at a predetermined pitch on a liquid holding surface of the substrate, and the liquid holding A facing plate facing the surface, and a counter electrode facing a tip of each parallel electrode with a predetermined gap therebetween, and an aggregate of colored particles in the colored liquid on the parallel electrode is placed on the parallel electrode and the counter electrode. An image forming apparatus that discharges from the tip toward the counter electrode side by a potential difference from an electrode and forms an image by attaching the discharged aggregate to a recording member, wherein, as the colored liquid, colored particles are used. In the state of being dispersed in the liquid carrier, the particles having a high concentration of colored particles are used so as to be discharged from the tips of the parallel electrodes and adhere to the recording member by the potential difference, and each of the particles between the substrate and the facing plate Area corresponding to between parallel electrodes An image forming apparatus characterized by comprising a cavity forming means for forming a non-existent cavity of colored liquid. 2. The image forming apparatus according to claim 1, wherein a liquid-repellent coating is provided between the parallel electrodes on the substrate as the cavity forming means. 3. An image forming apparatus according to claim 1, wherein a liquid-repellent coating is provided on said facing plate portion facing between said parallel electrodes as said cavity forming means. 4. The image forming apparatus according to claim 2, wherein
An image forming apparatus as the moving means, wherein a liquid-repellent coating is provided between each of the parallel electrodes on the substrate and on the facing plate portion facing between the respective parallel electrodes. 5. An image forming apparatus according to claim 2, wherein a fluororesin coating is provided as said liquid-repellent coating. 6. The image forming apparatus according to claim 2, wherein said liquid-repellent coating is provided within a predetermined distance range from a front end of the substrate facing said counter electrode to a rear end thereof. Image forming apparatus. 7. An image forming apparatus according to claim 6, wherein said distance range is set to be 0.2 mm or more and 0.9 mm or less. 8. The image forming apparatus according to claim 1, wherein the recording member is positioned at a position opposed to a tip of each parallel electrode in a direction orthogonal to a direction in which the parallel electrodes are arranged. An image forming apparatus provided with a recording member moving means for moving the image forming apparatus to the image forming apparatus. 9. The image forming apparatus according to claim 8, wherein the parallel electrodes from which the colored liquid is to be ejected from the tip end;
The combination of the strength of the electric field between the parallel electrodes formed by the potential difference from the parallel electrode that is disposed next to the parallel electrode and from which the colored liquid should not be ejected, and the duration of the electric field between the parallel electrodes, An image forming apparatus, wherein the combination is such that colored fine particles present in an electric field between electrodes are not electrophoresed in a liquid carrier. 10. An image forming apparatus according to claim 9, wherein said colored liquid is supplied to said parallel electrode and said parallel electrode by a discharge electric field having an intensity necessary to discharge said colored liquid at a discharge distance capable of reaching said recording member. Formed between the counter electrode and
An image forming apparatus characterized in that a colored particle having a high concentration and a high viscosity is used to such an extent that the electric field between the parallel electrodes can be formed so as not to cause electrophoresis of the colored particles during the duration. . 11. An image forming apparatus according to claim 10, wherein a plurality of said substrates are arranged side by side in a moving direction of said recording member. 12. The image forming apparatus according to claim 10, further comprising a substrate moving means for moving the substrate in the direction in which the parallel electrodes are arranged, and by a moving path which repeatedly passes the position facing the tip of each parallel electrode. An image forming apparatus, wherein the recording member moving means is configured to move the recording member. 13. The image forming apparatus according to claim 10, wherein said recording member moving means is configured to move said recording member also in a direction in which said parallel electrodes are arranged. 14. An image forming apparatus according to claim 13, wherein said recording member moving means is configured to move said recording member along a moving path that repeatedly passes said opposed position. apparatus. 15. The method of claim 1, 2, 3, 4, 5, 6, 7,
8. The image forming apparatus according to 8, 9, 10, 11, 12, 13 or 14, wherein an intermediate recording member is used as the recording member for adhering a colored liquid from the tip of the parallel electrode, and formed on the intermediate recording member. An image forming apparatus comprising: a transfer unit that transfers a transferred image to another recording member. 16. The method of claim 1, 2, 3, 4, 5, 6, 7,
In the image forming apparatus of any one of 8, 9, 10, 11, 12, 13 and 14, a conveying means for conveying the recording member to a recording position between the counter electrode and each parallel electrode, and an image is recorded at the recording position. And an ejecting means for ejecting the formed recording member to the apparatus main body. 17. A colored liquid containing charged colored particles and a liquid carrier between a substrate having a plurality of parallel electrodes arranged in parallel at a predetermined pitch and a facing plate facing the electrode surface. A step of retaining a liquid, a step of causing a potential difference between the counter electrode and the parallel electrode that face each other through a predetermined gap to the tip of each parallel electrode of the substrate, and In an image forming method for forming an image by performing a step of discharging from the tip toward the counter electrode side and a step of attaching the discharged colored particles to a recording member, the colored particles may be liquid. In a state of being dispersed in a carrier, a liquid having a high concentration of colored particles is discharged from the tip of the parallel electrode by the potential difference so as to adhere to the recording member, and at least the colored liquid is discharged from the tip. The image forming method characterized by moving the said parallel electrodes provided adjacent the colored liquid present between the parallel electrodes on the substrate when.