JPS6045430B2 - Image forming method - Google Patents

Description

[Detailed Description of the Invention] The present invention provides facsimile information, output information from a computer, etc.
Alternatively, the present invention relates to an image forming method in which an image is formed using liquid ink according to optical information or the like.

It is widely used in the data processing field to enable vibration-free and noise-free printing devices.

As a typical example, ink droplets are continuously ejected toward the recording material, and ink droplets that do not want to adhere to the recording material are suppressed from flying toward the recording material during the flight process. There is a method of forming an image on a recording material according to an information signal. However, with this configuration, ink droplets that fly only at minute intervals must be suppressed during the flight process for a minute amount of time, making accurate control according to information signals difficult, and there is a limit to image accuracy. Furthermore, a circulation mechanism is required to collect and reuse the ink droplets that have been prevented from flying toward the recording material, which also has the drawback of increasing the size of the apparatus. In addition, as another image forming method, multiple ink supply holes (nozzles) are arranged facing the recording material, and pin electrodes corresponding to each nozzle are independently provided on the back side of the recording material, and in response to information signals. There is a method of selectively applying a high voltage pulse between each nozzle and an electrode to cause ink to fly and form an image.

With this configuration, since information signals can be accurately applied to each nozzle, image accuracy is improved. Furthermore, since the ink droplets whose flying should be suppressed are not caused to fly from the beginning, there is no need to circulate the ink droplets, and there is an advantage that the apparatus can be made smaller. However, in order to improve image accuracy, it is necessary to accurately match the corresponding positions of the nozzle and pin electrode, but since both the nozzle jet port and the pin electrode are minute, it is difficult to match the corresponding positions of the two. is extremely troublesome in terms of device configuration. Furthermore, even if the installation positions of both are slightly shifted, the image accuracy will decrease. In addition, high voltage pulses must be applied to the pin electrodes, and if nozzles are arranged in a high density, interactions between adjacent electrodes will occur, making it impossible to arrange the nozzles in a high density. There is a drawback that image formation cannot be expected. Therefore, the present invention makes it possible to obtain high-resolution images by enabling low-voltage control of image formation, and at the same time, the troublesome operation of precisely aligning the corresponding positions of the ejection opening of a minute nozzle and the pin electrode is required. The present invention provides an image forming method that does not require.

That is, the present invention that achieves the above-mentioned object is one in which a control electrode is disposed in contact with a screen-like member and near the through-hole thereof.

Then, an image is formed by applying a voltage to the control electrode according to the information signal and selectively introducing conductive ink into the through hole. With this configuration, the troublesome operation of precisely aligning the corresponding positions of the minute nozzle ejection port and the pin electrode is no longer necessary. Further, the present invention is characterized in that, in addition to the above structure, a counter electrode is provided on the opposite side of the screen-like member to the surface that contacts the conductive ink liquid.

By adopting this configuration, the above-mentioned effects can be achieved. In addition, it is possible to control the control electrode at a low voltage, and the through-holes can be provided more densely, making it possible to obtain high-resolution images. Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows one of the screen-like members used in the present invention. FIG. 3 is a plan view showing an example. FIG. 2 is a cross-sectional view of the screen-like member shown in FIG. 1 taken along the product line.
1 is a screen-like member having a large number of capillary through holes 2, and its surface is covered with an ink repellent layer 3 made of a water-repellent and insulating material such as tetrafluoroethylene. 4 is a screen-like base material made of an insulating material such as polyimide or polyester. 5 is a conductive liquid ink, which is in contact with the screen-like member.

Reference numeral 6 denotes a control electrode, which is arranged around the periphery of the through hole 2.

The entire surface of the screen-like member shown in Figure 1 is coated with a water-repellent and insulating material, but it is not necessary to cover the entire surface with a water-repellent and insulating material. Instead, the surface that comes into contact with the ink may be coated with at least a water-repellent and insulating material. Here, the present invention applies a pulse voltage only to the selected control electrode using an electric signal according to image information.

As a result, each through hole selected according to the image information is filled with ink, and an image according to the image information is drawn on the screen-like member. That is, the ink is filled into the through hole by the electrostatic attraction of the electric field generated by applying a pulse voltage to the control electrode. In the figure, arrows indicate the directions of electric lines of force generated by applying a pulse voltage only to the selected control electrode 61. Note that since the surface of the through wall is covered with the ink repellent layer 3, the ink is repelled by the ink repellent layer 3 and does not enter the through hole where no pulse voltage is applied to the control electrode. .
In this embodiment, the control electrode is provided on the top surface of the through hole or in the vicinity of the top surface inside the through hole in contact with the screen-like member, so that the troublesome positioning of the nozzle outlet and the pin electrode as in the conventional method is eliminated. Not necessary.

Furthermore, since ink can be supplied to each through hole from the same ink liquid layer, there is an effect that the apparatus can be simplified. Furthermore, in this configuration, the surface of the control electrode is coated with a water-repellent substance, which prevents the control electrode from being corroded by ink, and also prevents deterioration of electrode function due to ink adhesion. Additionally, the durability of the control electrode can also be increased. The pulse voltage is applied to the control electrode using a bias power source 6.

At the same time, an information signal is sent from a signal source 63 according to the image and converted into a pulse by a pulse converter 64, and control is performed according to the image. Here, the third
Other embodiments of the present invention will be further described with reference to the drawings.

In the present invention, the screen-like member 1 is brought into contact with the conductive ink 5, and a counter electrode 8 is arranged above and parallel to the screen-like member 1. Then, the conductive ink 5 is grounded, and a voltage is continuously applied between the conductive ink 5 and the counter electrode 8 from the power supply device 9. However, this applied voltage is kept at a level that does not cause the ink 5 to rise into the through hole, and the selected control electrode (in the figure, the control electrode A pulse voltage is applied to the electrode 61). As a result, the selected through hole is filled with ink. The ink filling the through-hole forms a meniscus and remains in a state slightly protruding from the through-hole. As a result, an image corresponding to the image information is formed on the screen-like member. Note that since the control electrode is provided on the periphery of the through hole in contact with the through hole, ink will not overflow from the through hole. That is, in this embodiment, the ink 5 and the counter electrode 8
By lowering the voltage applied between the counter electrode and the control electrode to an extent that the ink 5 does not rise into the aperture, and applying a pulse voltage to the control electrode according to the image information, the electrostatic charge between the counter electrode and the control electrode is reduced. The ink is filled into the through hole by the cooperation of attractive force. Note that since the surface of the through-hole wall is covered with the ink repellent layer 3, as described above, ink is repelled by the ink repellent layer 3 and does not flow into the through-hole where no voltage pulse is applied to the control electrode. There will be no intrusion. This state is shown in FIG. In FIG. 4, as shown in FIG. 3, the voltage pulse was applied only to the control electrode 61 disposed around the periphery of the through hole 21, so that only the selected through hole 21 was filled with ink. . Note that in FIG. 3, arrow 7 indicates the direction of the lines of electric force from the control electrode and the counter electrode.

Furthermore, the electric field E generated inside the through hole is E≧2(α/EO
It is necessary to satisfy the conditions of ESR) 112. Here, α is the surface tension coefficient of the ink, εo is the dielectric constant in vacuum, εs is the relative dielectric constant of the medium, and R is the radius of the through hole.
As described above, in the present invention, the ink is raised into the through hole through cooperation between the counter electrode and the control electrode, so a low pulse voltage is required to be applied to the control electrode.

That is, low voltage control of the control electrode becomes possible. Therefore,
Since the pulse responsiveness, which is determined by the product of capacitance and resistance, can be controlled by low-voltage pulses, high-speed pulses can be obtained, and the responsiveness of image formation is significantly enhanced. Furthermore, in the case of high voltage, the electrical distortion caused by the interaction between adjacent electrodes is large, which may impair image quality, and it is not possible to arrange the electrodes in high density. However, since it can be controlled using low-voltage pulses, electrodes can be arranged in high density, and high-resolution images can be obtained. Furthermore, since a low voltage pulse is sufficient, small transistors, ICs, etc. can be used, and the device can be made more compact. Note that once the ink enters the through-hole, even if the electrostatic attraction stops working,
It has been experimentally confirmed that it does not fall.

Therefore, the following transfer process becomes possible.
Note that the method of applying the pulse voltage is the same as that of the embodiment shown in FIG. 2, so it is not particularly illustrated. Further, FIG. 5 shows the step of forming an image on a screen-like member and transferring the image to a print medium for transfer.

The imaged screen-like member is endless and suspended between two drive rollers. In FIG. 5, only the drive roller 10 is shown. The screen-like member is moved by these two drive rollers. At this time, the portion of the screen-like member that is in contact with the ink layer 5 gradually separates from the ink layer 5, but at this time, the doctor wall 12 forming the end of the ink container 11 allows the portion of the screen-like member that is in contact with the ink layer 5 to move away from the ink layer 5. Excess ink is removed only from the surface of the screen-like member without discharging the filled ink. As mentioned above, it has been experimentally confirmed that even after the ink is removed from the surface of the screen-like member, the ink once filled into the through-hole is retained in the through-hole even if the screen-like member moves. There is. Therefore, the ink droplets selectively filled into the through-holes and forming the image j on the screen-like member are carried to the transfer position by the movement of the screen-like member based on the electrical signals corresponding to the image information. Note that the roller 13 rotates in synchronization with the screen-like member, and presses the screen-like member against the doctor wall 12. Next, FIG. 6 shows the transfer process. A screen-like member with an image formed on its surface is
The image is transferred onto the printing medium 16 by being carried to the transfer position and sequentially coming into contact with a printing medium such as paper provided on the roller 15 . In the present invention, the size of the ink droplet can be easily changed by changing the diameter of the through hole, so complex images can be printed while ensuring a high degree of sharpness and resolution. Note that if a counter electrode is further provided on the non-transfer side of the print medium 16 on which the transfer is performed, and the ink droplets held and carried into the through holes are electrostatically attracted, the transfer can be performed more reliably. , and more quickly. Further, the transfer is possible even if either the front or back surface of the screen member is brought into contact with the printing medium 16. In addition, if the configuration is such that the transfer is performed below the roller 10, the transfer of the ink droplets to the print medium 16 is also assisted by the gravity of the ink droplets, so that the transfer is performed even more quickly. Further, other embodiments are shown in FIGS. 7 and 8.
This will be explained using figures. FIG. 7 is a sectional view showing another embodiment of the screen-like member. A photoconductive layer 19 made of selenium (Se), cadmium sulfide (CdS), or the like is laminated on the insulating film 18, and a conductive transparent film such as a NESA film 20 is further laminated thereon. Further, it has a capillary through hole 21 similar to the previous embodiment. These entire surfaces are coated with a water-repellent and insulating substance such as tetrafluoroethylene. The liquid ink capillary layer 22 is brought into contact with the insulating film 18 side of the screen-like member of this configuration. In this state, a predetermined voltage is applied to the Nesa film 20, and light is selectively irradiated using an electric signal according to image information. (In the figure, light irradiation is indicated by an arrow). Photoconductive layer 1 at the location irradiated with this light
9 becomes conductive when irradiated with light. Therefore, by applying a predetermined voltage to the NESA membrane 20, the lines of electric field of the electric field generated within the through-hole, and the photoconductive layer 19 becoming conductive, cause the photoconductive layer 19 to be removed from the through-hole. In addition to the lines of electric force generated within the through-hole, the electric field strength is strengthened, so that ink can be filled into the through-hole with stronger electrostatic attraction. That is, in this embodiment, the NESA film and the photoconductive layer serve as the control electrode shown in the previous embodiment. For that purpose, simply irradiate the light with 0N,
By setting it to 0FF, it is possible to control the operation of raising the ink into the through hole. That is, unlike the embodiments described above, complicated wiring for controlling the control electrodes is not required. Note that in this example as well, the surface of the screen-like member is covered with an ink repellent layer, as in the previous example.
Ink enters only those through-holes that are selectively irradiated with light according to electrical signals corresponding to image information. In addition, a predetermined voltage is uniformly applied to all the Nesa membranes, but the voltage strength is set to such a level that the ink cannot rise into the through hole 21 only by the electrostatic attraction generated thereby. . For this purpose, as described above, the photoconductive layer 19 selectively irradiated with light becomes conductive by an electric signal corresponding to the image information, and the electrostatic attraction generated by the electrostatic attraction is applied, and the ink is drawn through the hole. It is something that can be raised inward. Furthermore, in this example as well, by providing a high voltage counter electrode on the back surface of the screen-like member as in the previous example, low voltage control of the NESA film and the photoconductive layer becomes possible. In this case as well, the disadvantages caused by high voltage control are eliminated, and the same remarkable effects as in the previous embodiment can be obtained. Furthermore, FIG. 8 shows a schematic diagram of an apparatus using this screen-like member.

Reference numeral 23 denotes an endless screen-like member, which has the same structure as that shown in FIG.

This screen-like member 23 is connected to a drive roller (not shown)
It receives the drive and rotates. A voltage is applied to the screen-like member as in FIG. 10. As shown in the figure, a capillary layer container 24'' is brought into contact with the insulating film side of the screen-like member.Ink is supplied to the container 24 from an ink tank 25 through a capillary tube 26, and the ink forms a thin layer. Above the screen-like member in contact with the thin ink layer, light is emitted from a light source 27 that selectively irradiates the photoconductive layer with light according to an electric signal according to image information. is irradiated by the reflecting mirror 28. By being selectively irradiated with light, the photoconductive layer becomes conductive, and along with the electrostatic attraction generated from the Nesa film, it is irradiated with light according to the image information. The through holes are filled with ink.The ink droplets filled into the through holes are carried to the transfer roller 29 as the screen-like member moves while being held in the through holes. ,
The printing medium is transferred to the screen-like member 2 by a known conveying means.
It is transported in synchronization with 3. The printed media that has been transported is
Due to the cooperation of the transfer roller 29 and the belt 30, one end is held between the transfer roller 29 and comes into contact with the screen-like member. Therefore, the ink droplets that have been held in a protruding state by forming a meniscus in the through-hole of the screen-like member are sequentially transferred to the printing medium, and the image is transferred. After the transfer, both sides of the screen-like member are cleaned by rollers 31. Note that 32 is a cleaning liquid for cleaning the roller 31. Also, 33 is a doctor wall,
This is to remove excess ink from the surface of the screen-like member. Further, the roller 34 is connected to the screen-like member 23
is held between the top and bottom and positioned so as to properly contact the thin layer of ink inside the container 34. Note that, similarly to the above embodiment, it is also possible to provide a counter electrode on the back surface of the print medium at the transfer position to increase the reliability of transfer by electrostatic attraction. In this device, by selectively irradiating the photoconductive layer with light using an electric signal according to image information, it is possible to selectively inject ink into the through holes. No need for complicated electrical wiring for control.

Therefore, the device becomes smaller and failures are significantly reduced. The ink used in the image formation of the present invention described above must be electrically conductive, but its electrical conductivity is not particularly limited and can be applied to a wide range of applications in the present invention.

Further, the shape of the control electrode is not limited to one provided surrounding the periphery of the through hole, and a plurality of control electrodes may be provided near the through hole at intervals.

Furthermore, it is limited to being placed in contact with the top surface of the through hole, but may be placed near the top surface within the through hole. In addition, the surface of the control electrode can be coated with a water-repellent and insulating material, which significantly reduces corrosion of the control electrode by ink or deterioration of electrode function due to ink adhesion. be able to. Therefore, the durability of the control electrode can be significantly increased. Further, the precision of images can be improved without requiring troublesome alignment between the nozzle and the pin electrode. Further, in the present invention, since conductive ink can be used, the resistance value in the circuit can be lowered, and the responsiveness of pulses can be improved. Therefore, the image quality is improved and the image forming speed is improved, making it possible to form images at a higher speed.
Furthermore, since an image is drawn by providing a control electrode for each through-hole and controlling the low bias voltage applied to the control electrode according to image information, pulse conversion is easy. The device can be manufactured easily, inexpensively, and compactly. In addition, since low voltage control is possible, there is less interference between control electrodes, and through holes can be provided densely. Therefore, by providing through holes densely, it is possible to easily improve the image quality. It is.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the screen-like member, FIG. 2 is a sectional view thereof, FIG. 3 is a sectional view for explaining the present invention, and FIG.
The figure is a sectional view showing a state in which a screen-like member is filled with ink according to image information, FIGS. 5 and 6 are schematic diagrams of an apparatus to which the present invention is applied, and FIG. 7 is a diagram illustrating the present invention. FIG. 8, a sectional view showing another embodiment of the invention, is a schematic diagram of the device.

Claims (1)

[Scope of Claims] 1. A screen-like member having a plurality of through-holes each provided with its own control electrode is disposed against the surface of the conductive ink, and the screen-like member has a plurality of through-holes each provided with a unique control electrode, and a An image forming method characterized in that an image is formed by selectively applying a voltage according to an information signal between the two and selectively introducing the conductive ink liquid into the corresponding through hole. 2. The image forming method according to claim 1, wherein the screen-like member has at least an ink repelling layer formed on a surface that can come into contact with the conductive ink liquid. 3. The image forming method according to claim 1, characterized in that a counter electrode is provided on a side of the screen-like member opposite to a surface that can come into contact with the conductive ink liquid. 4. An image forming method according to claim 1, characterized in that the image is transferred to a transfer material.