JPH0452177A - Image formation device - Google Patents

Abstract

PURPOSE:To prevent current leakage from occurring by providing detecting means for detecting the current leakage at a voltage apply circuit for forming image by applying a voltage between a roll having image pattern and a roll for supplying ink. CONSTITUTION:An electric conductor is used for an ink carry roll 1 which is connected to an end of a DC power 103. A form plate 4 wound on a plate roll 3 contacts to an ink 2 on the surface of the roll 1. The form plate 4 is equipped with a desired pattern 4b consisting of insulating material on a base material 4a consisting of conductive material. Thus, the DC power 103 applies a voltage between the form plate 4 and the roll 1, so that the adhesive property of the ink 2 contacting with a conductive part of the form plate 4 changes and an ink image is formed by the difference of the adhesive property. A detector 17 binding the roll 1 to the plate roll 3 detects a current exceeding a normal current generated due to a leakage. The signal is sent to a controller 16 and the DC power 103 is shifted from an ON state to an OFF state, so that a problem caused by the current leakage can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus for printing using ink whose adhesion changes with the application of voltage.

[Prior Art] Conventional printing methods using ink include lithographic printing, letterpress printing, and gravure printing.

These methods involve complex steps to create the plates, which make them too expensive, and require dampening water to pacify the ink between the image and non-image areas on the plate. There were also problems that needed improvement, such as the need for complicated operations to control the ink adhesion of the resin on the plate surface.

Therefore, an ink whose adhesion properties change depending on the applied voltage was proposed (see Japanese Patent Laid-Open Publication No. 71359/1983).
. An image forming method in which a voltage is applied to such ink in a desired pattern and adhesion and transfer is performed according to the pattern is relatively easy to make a plate, and the printing process is also relatively simple. Furthermore, since the amount of ink transferred can be controlled by the amount of electrical charge, there is no need to adjust the amount of ink using a large number of rollers as in conventional printing machines.

[Problems to be Solved by the Invention] However, while the above-mentioned ink has such a revolutionary advantage, if a pair of conductive members for applying voltage come into direct contact with each other, current may leak. However, excessive current flows through this portion, causing problems such as deterioration and damage of the conductive member, generation of smoke and explosion, and deterioration of image quality.

The present invention has been made in view of the problems of the prior art described above, and it is an object of the present invention to provide an image forming apparatus that can prevent current leakage and stably obtain high-quality images.

[Means for Solving the Problems] The present invention provides a pair of electrodes, one of which is provided with an image pattern, and means for supplying ink whose adhesion changes depending on the applied voltage between the electrodes (ink supply means). and a voltage applying means (ink adhering means) for applying a voltage between the electrodes to make ink adhere to the electrodes on which the image pattern is provided (ink adhering means), and forming an ink image. The image forming apparatus further comprises a detection means for detecting current leakage caused by the pair of electrodes coming into contact with each other.

According to the present invention, it is possible to prevent deterioration and breakage of electrodes (conductive members) and generation of fire and smoke caused by current leakage between a pair of electrodes, and at the same time prevent deterioration of image quality. .

That is, the present inventors have discovered that in an image forming apparatus using ink whose adhesion changes depending on voltage application, current leakage caused by partial contact between a pair of four-electroconductive members It was discovered that this causes the risk of component deterioration, damage, and even the generation of fire and smoke, as well as deterioration of image quality, leading to the present invention. Incidentally, the flow of a large amount of current due to this current leak sometimes reaches more than IOA.

Next, the mechanism of image formation according to the image forming apparatus of the present invention will be explained.

As shown in the schematic diagram of FIG. 1, the image forming apparatus of the present invention includes an electrode 4 (plate), which is a pair of conductive members having a desired pattern, and a counter electrode 1 (ink carrying roll). This method utilizes the characteristic of the specific ink 2 supplied between the two electrodes, that is, the characteristic that its adhesion changes depending on the pattern of the electrode 4 when a DC voltage is applied between the pair of electrodes by the power supply 103. The ink 2 is transferred from the counter electrode 1 onto the electrode 4, and finally onto the recording medium 7 to form an image.

The ink that can be applied to the apparatus of the present invention will be described later and has the following properties. That is, the ink is sticky when no voltage is applied, and the stickiness disappears when a voltage is applied. By using this ink, the ink adheres to the insulating portion of the plate, forming a desired recorded image.

The mechanism of the ink exhibiting such properties can be considered as described below. That is, the ink electrolyzes and generates gas when it is energized by applying a voltage, thereby changing its adhesiveness. That is, the ink is adjusted so that it is inherently sticky, and when a voltage is applied, the ink generates gas near the electrode on one side, and this gas prevents the ink from adhering to the electrode. In order for the ink to electrolyze and generate gas, water, alcohol,
It may contain a solvent such as glycol or a solvent in which an electrolyte such as sodium chloride or potassium chloride is dissolved.

The lower the electrical resistance of the ink, the better, and the volume resistivity should be 10'
It is preferable to set it to Ω·crn or less. Volume resistance is 10
If it exceeds 2 Ω·cm, the amount of current flowing decreases, or a high voltage is required to prevent the amount of current flowing from decreasing. In addition, in the transfer of ink from the plate, when the ink changes from adhering to non-adhering by applying a voltage, almost the entire part of the ink layer to which voltage is applied moves in the thickness direction (referred to as bulk movement). Also, for the parts to which no voltage was applied,
It is considered that part or all of the surface layer of the ink is transferred due to the relationship between the adhesive force at each interface of each electrode and the cohesive force of the ink.

Next, an image forming apparatus according to the present invention will be explained.

An example of the image forming apparatus of the present invention is shown in the schematic configuration diagram of FIG. That is, the apparatus shown in this figure includes a coating roll 9, an ink supply means consisting of an ink carrying roll 1, a pair of electrodes consisting of the ink carrying roll 1 and a plate 4 provided with an image pattern, and a plate to which the plate 4 is mounted. It is provided with an ink adhesion means consisting of a roll 3 and a DC power source 103, a current leak detection means consisting of a detection section 17, and a leak prevention means consisting of a control section 16 and a DC power source 103. Here, the current leak prevention means is not essential, and may be taken manually upon receiving the current leak detection signal.

In FIG. 1, an ink carrying roll 1 is a member that has a cylindrical shape and rotates in the direction of arrow A. In FIG. The roll 1 is made of a conductive material such as aluminum, copper, or stainless steel. Ink 2, which is a recording material, is formed on the surface of the ink carrying roll 1 to have a uniform thickness by a coating roll 9 rotating in the direction of arrow E. The ink carrying roll 1 is a DC type a1
It is connected to one end of 03.

A plate 4 wound around a plate roll 3 is in contact with ink 2 on the surface of the ink carrying roll 1. The plate roll 3 is rotating in the direction of arrow B in the opposite direction to the roll 1. For example, as shown in FIG. 2, the plate 4 has a desired pattern 4b made of an insulating material on a base material 4a made of a conductive material such as metal.

As the material of the base material 4a, aluminum, copper, stainless steel, platinum, gold, chromium, nickel, steel copper, carbon, etc., or conductive polymers or various polymers in which metal fillers are dispersed are used. Materials for pattern 4b include thermal transfer recording materials (mainly wax and resin),
Electrophotographic toners, vinyl polymers, and natural or synthetic polymers are used.

In this way, by applying a voltage between the plate 4 and the ink carrying roll 1 from the power source 103, the adhesion of the ink 2 that comes into contact with the conductive portion of the plate 4 changes, and the ink 2 is deposited on the plate due to the difference in adhesion. It is deposited in a pattern to form an ink image.

Practically speaking, the voltage of the power supply 103 is preferably a DC voltage of 3 to 100 V, more preferably a DC voltage of 5 to 80 V, and a high frequency (10 Hz
~100 KHz) AC bias voltage (10■~10
By further applying 0 V), the image quality can be partially sharpened.

In Figure 1, the plate 4 side is the cathode, and the ink carrying roll 1 side is the anode, but depending on the properties of the ink used, the plate 4 side
The side may be used as an anode and the roll 1 side may be used as a cathode.

Specifically, the voltage from the power source 103 is preferably applied between the respective rotation axes of the printing roll 3 and the ink carrying roll 1.

Furthermore, a plate having an insulating film formed with an image-like conductive pattern by discharge breakdown on a base material made of a conductive material can also be used as a plate. Furthermore, on the base material made of conductive material,
Plates with photographic images formed with conductive patterns of silver images by deposition of silver particles can also be used.

In addition, the shape of the plate is not limited to a flat surface, but can be rolled, curved, etc.
A polygonal shape is also acceptable.

Next, a detection means for detecting current leakage due to local contact between a pair of electrodes will be explained based on the apparatus shown in FIG.

In FIG. 1, as a current leak detection means, a detection unit 17 for detecting current is connected in addition to a DC power supply 103 between the ink carrying roll 1 and the printing roll 3.
Further, as a current leak prevention means, it is configured to be able to control ON/OFF of voltage application based on the current value detected by the detection section 17. This configuration can be easily constructed electrically. If this device does not have the above-mentioned configuration, if the ink carrying roll 1 and the plate 4 wound around the plate roll 3 partially come into direct contact without intervening ink, an excessive amount of current will flow in that part. If image formation is performed in this state, almost no current will be supplied to the ink 2, making it impossible to control the adhesion.Furthermore, the material of the ink carrying roll 1 may locally change or deteriorate, and the gap between the ink 2 and the plate 4 may deteriorate. This can cause serious problems such as creating smoke and causing an explosion. To prevent this kind of thing, it is first necessary to provide a means for detecting complete recovery.

To detect a current leak, first, the detection unit 17 connecting the ink carrying roll 1 and the plate roll 3 detects a current that is larger than normal due to the leak. This signal is sent to the control unit 16 to switch the DC power supply 17 from ON to OFF, thereby preventing the above-mentioned problems caused by current leakage. With this configuration, the voltage application means, current leak detection means, and current leak prevention means can be integrated, so new detection terminals, settings, etc. are unnecessary, and effective current leak prevention can be achieved without complicating the device. It will come true. Specifically, current leak detection means include an ammeter (15A degrees), a method of reading voltage using a resistor and outputting a signal, and a relay as a control unit.
A comparator circuit or the like may be used.

Further, it is also possible for the control section 16, which receives a signal from the detection section 17 to indicate the occurrence of leakage current, to take measures other than turning off the power.

For example, the current can also be cut off by separating the ink carrying roll 1 and the plate 4. Furthermore, when the current is cut off, it is also possible to cancel the drive of the rollers or sound an alarm to notify of the occurrence of a leak. These functions can be constructed by electrically connecting the current leak detection signal and necessary means using known techniques. Further, the current leak detection means may be provided separately without being integrated with the voltage application means. It is also possible to apply a differentiating circuit to the current to detect the protruding current due to leakage.

Next, an explanation will be given of an ink whose adhesion changes depending on an applied voltage that can be suitably applied to the apparatus of the present invention.

When the ink contains a large amount of liquid such as water or alcohol, the cohesive force is weak and suitable tackiness cannot be obtained. For example, when applying ink to a thickness of 2 mm on a platinum-plated stainless steel plate held vertically,
It is preferable that the ink be substantially retained on the platinum-plated stainless steel plate. In addition, ink was sandwiched between two platinum-plated stainless steel plates to make the ink thickness 2 mm, and when the two platinum-plated stainless steel plates were separated from each other with no voltage applied, there was no ink on either plate. It is preferable that they adhere to the same degree. This ink is basically an amorphous solid composed of inorganic or organic fine particles and a liquid dispersion medium, and is a non-Newtonian fluid in terms of fluidity.

In a preferred embodiment, in order to control the viscosity of the ink, 1 to 90 parts by weight, more preferably 1 to 5 parts by weight of a polymer soluble in the above-mentioned liquid dispersion medium is added to 100 parts by weight of the ink material in the ink.
It can be contained in a proportion of 0 parts by weight, particularly 1 to 20 parts by weight.

Changes in ink viscosity are caused by the generation of gas due to electrolysis, so solvents such as water, methanol, ethanol, chryseson, ethylene glycol, and propylene glycol, or electrolytes such as sodium chloride and potassium chloride are used as liquid dispersion media. A dissolved solvent is preferably used. The contents of the liquid dispersion medium and fine particles are the same as those described above. In particular, it is preferable to use water or a liquid containing water as the liquid dispersion medium because hydrogen gas is likely to be generated on the negative electrode side. When mixing water with another liquid dispersion medium, the water content is 1 part by weight - F for 100 parts by weight of ink.
, more preferably 5 parts by weight or more.

Silica, fluorocarbon, titanium oxide, carbon black, etc. can be used as the fine particles contained in the ink that generates gas by electrolysis.

As a preferred example of the ink, considering the viscoelastic properties of the ink, the fine particles are preferably swellable fine particles that can retain the above-mentioned liquid dispersion medium in the particles. Examples of such swellable fine particles include Na-montmorillonite, Ca
-Montmorillonite, 3-octahedral synthetic smectite, N
Examples include fluorinated mica, synthetic mica, and silica, such as a-hectolite, Li-hectolite, Na-teniolite, Na-tetotasilisic mica, and Ll-duolite.

Furthermore, the ink may contain a colorant such as a pigment generally used in the fields of printing and recording, such as carphone black, if necessary. When the ink contains a coloring material, the content of the coloring material is 100 times as much as the ink! 0.
1 to 40 parts by weight, more preferably 1 to 20 parts by weight. Further, instead of or together with the coloring material, a coloring compound that develops color upon application of voltage may be contained.

In addition, electrolytes that give conductivity to ink, thickeners,
It may contain a thinning agent, a surfactant, etc. or,
It is also possible for the above-mentioned fine particles themselves to also function as a coloring material.

As mentioned above, an image forming method using ink whose adhesion changes when energized, especially ink that partially transfers to the plate,
Since the amount of ink transferred can be controlled by the amount of electrical charge, there is no need to use multiple rollers to adjust the amount of ink as in conventional printing machines.

[Example code] Hereinafter, the present invention will be explained by examples.

Example 1 Image formation was performed using the following ink.

200g of chrycerin and lithium teniolite (LjMg
2Li (514010)F2, average particle size 2.57. z
m) 140 g and 20 g of carbon black were kneaded in a homosinizer for 30 minutes at a rotational speed of 1.0 (llorpm), then 200 g of water was added and mixed in a roll mill to obtain a black amorphous identifier colloidal sol ink. was prepared.

After applying the above ink to a thickness of approximately 2 mm on a platinum-plated stainless steel plate of 1 cm x t cm, the platinum-plated stainless steel plate of the same size was placed on top of the ink, and then the two sheets were coated under no voltage. When the two platinum-plated stainless steel plates were separated by gradually widening the interval between the platinum-plated stainless steel plates, ink was found to have adhered to almost the entire area on both platinum-plated stainless steel plates.

Next, a voltage of +30v was applied to both platinum-plated stainless steel plates with a 2m+n thick ink layer sandwiched between one side as a negative 8i (earth) and the other as an anode, and while applying this voltage, the two plates were Two platinum-plated stainless steel plates were separated by gradually widening the interval between the platinum-plated stainless steel plates.

All of the ink adhered to the anode side electrode, and no ink adhered to the cathode side.

Next, image formation was performed using the printing machine shown in FIG.

As the ink carrying roll 1, a platinum-plated stainless steel cylindrical roll (surface roughness Is) with a diameter of 30 mm was used, and as the printing roll 3, a 30 mm diameter iron cylindrical roll with a heart chrome plating on the surface was used. On this plate roll 3, a plate 4 made of an aluminum plate patterned with vinyl resin is wound. Further, the detection section 17 reads the voltage through a resistor and outputs a signal, and the control section 16 has a voltage application automatic cutoff function that turns off the current 103 upon receiving the signal from the detection section. It is something.

Between the ink carrying roll 1 and the coach ink roll 9,
The ink mentioned above was added. Ink carrying roll 1 to 5
The coating roll 9 is rotated at a circumferential speed of ++ on/sec in the six directions of the arrows, and the cap with the coach-in roll 9, which is a cylindrical roll made of surface Teflon rubber that rotates in the direction of the arrow E, is controlled, and the coating roll 9 is rotated at a speed of 5+ nm/sec. By this, the ink layer thickness on the ink carrying roll 1 is reduced to 0.2 m.
It was controlled to 1I11. Plate roll 3 moves 5 + in the direction of arrow B.
It was rotated at a circumferential speed of n+n/sec.

When this recording device was printed with no voltage applied from the DC power supply 103, no image-like printed matter was obtained, but when printed with a DC voltage of 30 V applied from the DC power supply 103, I was able to obtain prints with sharp image quality.

In addition, when the above image formation was repeated, a slight amount of smoke was generated, which was thought to be due to leakage current, and at the same time the power supply was turned off.
3 was turned OFF and the voltage application was stopped, so no deterioration or damage occurred to the ink support roll 1 or the plate 4.

Thereafter, the operation was started by increasing the ink supply amount, and the ink 2 on the ink carrying roll 1 was again coach inked, thereby restoring the image formation as described above.

Example 2 In Example 1, instead of using the automatic cutoff of voltage application by the control unit 16, an alarm means for notifying a current leak from the detection unit 17 was provided, and when the same application was applied to multiple plates, the alarm was activated. Therefore, since the DC chamber @103 was immediately turned off manually, no deterioration or damage to the ink carrying roll 1 or the plate 4 occurred.

Thereafter, the operation was started by increasing the ink supply amount, and the ink 2 on the ink-bearing roll 1 was again coach-inked, thereby making it possible to restore the above-described image formation again.

Comparative Example In Example 1, when the same image formation was performed continuously without using the detection means by the detection unit 17, there was smoke that was thought to be caused by leakage current, and furthermore, the surface of the ink carrying roll 1 was deteriorated. However, the image quality has deteriorated.

[Effects of the Invention] As explained above, in an image forming apparatus using ink whose adhesion changes depending on the polarity of voltage application, it is possible to prevent current leakage due to mutual contact between a pair of conductive members, which are voltage application means. By providing a prevention means for detecting and preventing current leakage, it is possible to prevent deterioration, damage, etc. of the conductive member and generation of fire and smoke, and to form an image while maintaining high image quality.

Therefore, the apparatus of the present invention is suitably used as a recording peripheral device for computers and the like, and is extremely useful as it enables stable image formation with high quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing an example of an image forming apparatus of the present invention, and FIG. 2 is a schematic perspective view showing an example of a plate used in the apparatus of the present invention. 1... Ink carrying roll, 2... Ink, 3...
Plate roll, 4... version (electronic Fi>, 5... plan cylinder,
6... Impression cylinder, 7... Recorded object, 8... Ink image, 9... Coach ink roll, 10... Ink reservoir,
16...control unit, 17...detection unit, 103...,
DC power supply. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] 1. A pair of electrodes, one of which is provided with an image pattern;
means for supplying ink whose adhesion changes depending on the voltage applied between the electrodes, and applying a voltage between the electrodes to cause the ink to adhere to the electrodes on which the image pattern is provided to form an ink image. An image forming apparatus comprising at least a voltage applying means, further comprising a detecting means for detecting current leakage caused by the pair of electrodes coming into contact with each other. 2. The image forming apparatus according to claim 1, wherein the detection means is electrically connected to the application means. 3. The image forming apparatus according to claim 1, further comprising means for receiving a current leak signal from the detecting means and preventing current leak. 4. The image forming apparatus according to claim 3, wherein the means for preventing current leakage cuts off voltage application by the voltage applying means.