JPH0344914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a means for supplying ink to a recording head in an electroosmosis printer that utilizes an electroosmosis phenomenon.

A thin two-dimensional porous membrane is placed on a dielectric support substrate having a first electrode forming a recording electrode and an auxiliary electrode for preventing ink from spilling out. A second electrode permeable to liquid ink is positioned on the side opposite to the auxiliary electrode for preventing extrusion, and the liquid ink is supplied to the porous membrane to impregnate it, and a signal is connected between the first electrode auxiliary electrode and the second electrode. A controlled liquid ink portion to be recorded on a recording medium in response to a signal voltage by applying a voltage to electro-osmote liquid ink through the porous membrane to one end side where the first electrode extends. An ink recording head and an ink recording apparatus using the same have already been proposed by one of the inventors of the present invention.

The first electrode forming the recording electrode is arranged such that a plurality of electrodes are separated from each other and adjacent to each other depending on the recording density, and the auxiliary electrode is arranged outside the recording electrode.

If the electroosmotic polarity of the liquid ink on the surface of the dielectric material forming the supporting base material surface is selected to be the same as that of the porous material, and the signal voltages are selected to have opposite polarities, the first The liquid ink converges on the tip side of the electrode,
Ink does not ooze out on the tip side of the auxiliary electrode.

In this way, a liquid ink portion is generated on the tip side of the first electrode in response to the on voltage, and the liquid ink portion disappears in response to the off voltage, and the amount of recording ink is directly modulated by the signal voltage. Combined with the ink convergence effect, high-resolution ink recording becomes possible.

The first electrode and the auxiliary electrode can be directly attached to the surface of the dielectric support base material, or alternatively, they can be placed inside a depression or recess formed on the surface of the support base material.

In this recording head, a recording medium such as paper is brought into direct contact with the end of the ink recording head and moved to transfer the ink, thereby enabling ink recording by a contact method with low voltage and high resolution.

Further, as a non-contact method, an ink image recording device for figures, symbols, etc. can be realized by flying the modulated liquid ink onto the recording paper using a column.

In order to increase the recording density, this type of ink recording head uses liquid ink in which dye is dissolved in a suitable solvent to the extent of saturation. For this reason, the liquid ink tends to become supersaturated due to evaporation of the solvent, causing precipitation of the dye, resulting in the problem of deterioration of recording quality due to clogging of the porous membrane.

In addition, in this type of recording head, it is important to control the amount of liquid ink contained in the porous film to a constant level, and if this is not possible, the figures etc. recorded on the recording medium will not be uniform. This results in unevenness in recording quality and a problem of deterioration in recording quality.

An object of the present invention is to provide an improved ink recording device in view of the above-mentioned problems.

The present invention is characterized in that, in an ink recording device that utilizes electroosmosis of the porous membrane, a means for electrically detecting the ink content of the porous membrane, and a means for electrically detecting the ink content of the porous membrane, and using the detected electric signal, A means is provided for controlling the amount of ink supplied to the porous membrane by utilizing electroosmosis of the second porous membrane.

In this way, the liquid ink contained in the porous film of this ink recording head has the precipitated dye removed by the second porous layer, and a constant amount of the liquid ink is controlled to be supplied by the detected electric signal. The above-mentioned problems are solved, and high-quality recording can be realized.

Examples of the present invention will be described in detail below. 1st
The figure shows an embodiment of an ink recording device using electroosmosis according to the present invention, and is a diagram showing a perspective partial structure and a power supply system.

In FIG. 1, 100 is an ink recording head;
Reference numeral 200 is liquid ink stored in the ink container 300, filtered by the second porous membrane 80, and supplied to and impregnated into the ink recording head 100 using the capillary action of the sponge body 700.

400 is a signal voltage source, 500 is a recording sheet such as paper, and 600 is a recording medium 500 connected to the edge 13 and side edge surface 1 of the ink recording head 100.
This is a pressure roller made of rubber or the like that is pressed against the roller 2 and feeds the paper in the direction of arrow 501 in the figure.

10 is a support substrate made of a plate-shaped dielectric base material such as borosilicate glass.

Depending on the desired recording resolution, for example 1
Recessed grooves 16 are formed by etching or machining techniques at a density of 3 to 8 grooves per mm, each having a width and depth, for example, in the range of about 20 to 70 .mu.m.

An auxiliary electrode 22 is attached to the surface of the support base 10 including at least the first electrode 20 made of a metal film on the bottom and sidewalls of the groove 16, and the edge 13 adjacent to the outside of the arrangement range of the electrode 20. be done.

The first electrode 20 and the auxiliary electrode 22 are formed by pre-evaporating chromium or the like to a thickness of about 0.1 to 0.3 μm in advance to improve adhesion strength, and then depositing gold, for example, to a thickness of about 1 μm from the viewpoint of electrochemical stability. Alternatively, gold plating or the like is performed on the chromium film to form a non-porous metal film.

Thus, on this support substrate surface 11, there is a porous membrane 40 having holes and gaps that substantially penetrate in the thickness direction, and through which the liquid ink 200 can permeate in the thickness direction.
A groove gap 3 is formed between the surface of the first electrode 20 and the surface of the first electrode 20.
0 is formed.

The porous membrane 40 and the second porous membrane 80 are, for example, so-called microporous membrane filters made of cellulose acetate with a thickness of 20 to 200 μm, an average pore diameter of 0.1 to 8 μm, and a porosity of about 60 to 80%. do.

As the porous membrane 40 and the second porous membrane 80, other plastic materials or
Glass, porcelain materials, etc. can also be used.

It is preferable that the edge 41 of the porous membrane 40 be located inside the edge 13 of the support substrate 10 by, for example, about 50 to 300 μm, so that an exposed edge surface 14 is formed on the surface 11 of the support substrate. The formation of the edge surface 14 utilizes the electrical convergence effect of the liquid ink utilizing the electroosmotic property of the liquid ink 200 on this surface 14, which is useful for high-resolution recording. The width of the porous membrane 40 determines the amount of ink supplied to the tip 21 of the first electrode 20, so it is selected as wide as necessary, for example, 20 mm or more.

The surface of the porous membrane 40 opposite to the support substrate 10 is provided with pores (not shown) that penetrate at a density of about 100 to 300 meshes per inch, and a liquid ink 200 with a thickness of about 50 to 300 μm permeates therethrough. A second electrode 50 made of stainless steel plate, metal mesh, etc.
is installed, and the porous membrane 40 is pressed and fixed.

Note that the second electrode 50 can also be configured to be permeable to the liquid ink 200 by applying a thin layer of conductive paint such as graphite to the surface of the porous membrane 40 .

The end of the porous membrane 40 opposite to the surface on which the recording medium 500 is installed is coated with a sealing agent 60 such as an adhesive.
The porous membrane 40 is sealed to the support surface 11 and the first electrode 20 surface to prevent backflow of liquid ink due to electroosmosis, which will be described later.

Reference numeral 401 is for electrically detecting the amount of ink contained in the porous membrane 40, and also serves as a power source for preventing the liquid ink from spilling out.

Reference numeral 402 denotes a power source that controls the filtering and supply of liquid ink 200 from the ink container 300 side to the porous membrane 40 side of the ink recording head 100 or in the opposite direction using electroosmosis based on the detected electric signal. .

Here, the third electrode 51 and the fourth electrode 52 have a density of 100 to 300 per inch, similar to the second electrode.
Pores penetrating with mesh-like density (not shown)
A liquid ink-permeable stainless steel plate or metal mesh having a thickness of about 50 to 300 μm and having a thickness of about 50 to 300 μm is used.

The liquid ink 200 is a liquid material made of, for example, γ-methacryloxypropyltrimethoxysilane, which provides good electroosmotic properties to the above-mentioned porous membrane 40, second porous membrane 80, and supporting substrate 10. Oil-soluble ink 200 is prepared by mixing, for example, an oil-soluble dye or the like in an amount of about 2 to 5% by weight along with necessary binders, charge control agents, surfactants, etc.
is configured.

This type of ink can be electroosmotic into the aforementioned porous membrane 40, second porous membrane 80, and support substrate 10 in the direction of the negative electrode.

The speed of this electroosmosis increases with the applied signal voltage, but its maximum amplitude is set so that the electric field strength does not exceed, for example, 2 V/μm, taking into account dielectric breakdown.

Each of the first electrodes 20 serving as recording electrodes is connected to a signal voltage source 400, and the auxiliary electrode 22 for preventing extrusion and detecting ink content is connected to a voltage source 401.

Signal voltages V _B , V _B ' are selectively applied between the second electrode 50 and the first electrode 20, and the auxiliary electrode 22
A suction voltage V _C is constantly applied to the ink via a resistor for detecting ink content.

Now, as a signal voltage as shown in the figure, the first electrode 2
Off-voltage at which the second electrode 50 becomes negative with respect to 0
V _B ′, on the other hand, when the on-voltage V _B , which makes the electrode 20 negative with respect to the electrode 50, is applied alternately, and the attraction voltage V _C , which makes the second electrode 50 negative, is constantly applied to the auxiliary electrode 22. The operation will be explained using an example. Here, if |V _C |=|V _B ′|, then in the part where V _B ′ and V _C are applied, the first electrode 2 forming the positive electrode
The liquid ink 200 electropenetrates from the 0 and auxiliary electrode 22 side to the second electrode 50 side forming the negative electrode through the porous membrane 40 as shown by arrows 210 and 213, and as a result, the electrode tip part Liquid ink 20 located on the 21 side and the edge portions 13, 13'
0 also connect to the second electrode 50 through the groove gap 30 and the surface of the electrode 22, as indicated by arrows 211 and 211' in the figure.
sucked up to the side.

Furthermore, the surface 11 of the support substrate 10 is also coated with the porous film 40.
Since it is configured to have the same electroosmotic polarity, V _B is applied from the electrode 20 side to which V _B ' is applied, forming a negative electrode, and liquid ink flows toward the adjacent electrode 20 side. 200 is the arrow 212
Electroosmosis is performed on the support surface 11, such as the electrode gap surface 15, including the exposed edge surface 14 within the array of the electrodes 2, as shown in FIG.

Therefore, the first electrode 20 to which V _B ' is applied
On the tip 21 side and the exposed edge surface 14 around it,
Also, no liquid ink 200 can exist on the edge 13' to which V _C is applied.

On the other hand, in the first electrode 20 portion to which V _B is applied,
The liquid ink 200 passes through the second electrode 50 and electroosmoses through the porous membrane 40 as shown by the arrow 220 and concentrates toward the surface of the first electrode 20 . Since the end opposite to the edge 13 is sealed with the sealant 60, the liquid ink 200 is transmitted through the surface of the first electrode 20, that is, the groove gap 30, due to its electroosmotic property. Then, as shown by an arrow 221 in the figure, a liquid ink portion 22 is pushed out toward the tip end 21 side, and corresponding to the electrode 20 on the exposed edge surface 14 side, the liquid ink portion 22 is controlled in position and ink amount with respect to the amplitude of _VB .
2 will be formed.

In addition, the liquid ink 200 electropenetrates from the side of the adjacent positive electrode 20 through the supporting substrate surface 11 and the exposed edge surface 14 as indicated by the above-mentioned arrow 212, and reaches the surface of the electrode 20 in the depressed groove 16. get together. Due to this extrusion effect and the convergence effect on the exposed edge surface 14, the liquid ink portion 222 can be effectively formed limited to the electrode surface of the electrode tip portion 21.

In order to effectively utilize the suction, extrusion, and convergence effects of the liquid ink 200 as in the present principle, the distance between the edges 41 and 13 must be kept constant, and the edge 1
It is desirable to keep the distance between 4 and 13 parallel to each other; if the distance between them is too narrow, the convergence effect of the liquid ink 200 on the surface 14 will be reduced and the recording resolution will be reduced; if it is too wide, the width of the exposed edge surface 14 will be
Ink 2 to be sucked on the tip 21 when V _B ' is applied
00 remains without being suctioned, reducing the quality of the recorded image. From the above, the width is usually 50 as mentioned above.
~300μm is selected.

A recording paper with a thickness of about 80 μm is used as the recording medium 500, and, for example, the attraction voltage V _C and the off voltage V _B ′ are set respectively.
Constant amplitude width of 150V, also as on-voltage V _B
When amplitude modulation and pulse width modulation are performed in this range according to the recording density with the polarity opposite to V _B ′ and V _C and the maximum amplitude is 150 V, the voltage at the tip of the electrode 21 applying V _B changes depending on the voltage value. A liquid ink portion 222 with a controlled amount of ink is generated, and the contact transfer causes the recording medium 50
Ink adhesion 240 occurs on the surface of 0, while V _B ′, V _C
Ink adhesion 240 does not occur because there is no liquid ink portion 222 or overflowing unnecessary ink on the application electrode tip 21 and the auxiliary electrode tip 13'.

For example, if a large amount of ink is supplied to the porous membrane 40 in a place where the ink is moving steadily as described above, the tip of the electrode where ink would normally not be present due to the application of V _B ′ and V _C The protruding ink stains the portion 21 and the auxiliary electrode tip 13', resulting in a decrease in recording quality.

Similarly, if ink is not supplied to the porous film 40, the recording density at the location where ink adhesion 240 should originally occur due to _VB application changes, resulting in a decrease in recording quality.

However, as shown in the figure, one method for detecting the amount of ink contained in the porous membrane 40 sandwiched between the auxiliary electrode 22 and the second electrode 50 is to use a bridge circuit, for example, to detect the amount of ink, and use the detected electrical signal. As a result, liquid ink 200 is filtered from the ink container 300 side to the porous membrane 40 side of the ink recording head 100 or in the opposite direction via the sponge body 700 using the electroosmosis phenomenon of the second porous membrane 80. By controlling the power supply 402, the amount of ink can be kept constant.

Here, the relationship between the amount of ink contained in the porous membrane 40 and its electrical resistance is as shown in FIG.

R _{1 , R 2 ,} R ₃ ,
By setting , even slight changes in the amount of ink can be detected and the amount of ink can be controlled to be constant.
Further, as another means of detecting the ink amount, an impedance bridge circuit may be used, and the suction voltage V _C
A similar effect can be obtained by superimposing an alternating current voltage on the porous membrane 40 and detecting the amount of ink contained in the porous membrane 40 from changes in capacitance and resistance.

Note that, assuming that the average pore diameter φ ₁ of the porous membrane 40 and the average pore diameter φ ₂ of the second porous membrane 80 are φ ₂ φ ₁ ,
Undissolved dyes of φ ₂ or more and dust are removed, allowing smoother electroosmosis of liquid ink through the porous membrane 40, resulting in more stable operation and higher performance.

As described above, the present invention provides an ink recording device using electroosmosis, which includes a means for electrically detecting the ink content of a porous membrane, and a means for electrically detecting the ink content of the porous membrane using the detected electric signal. By controlling the supply of the amount using electroosmosis of the second porous membrane, the problems of ink clogging and deterioration of recording quality due to changes in ink amount are improved, and the industrial effects are as follows. There is something big.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an ink recording apparatus according to an embodiment of the present invention and a diagram showing a power supply system, and FIG.
FIG. 3 is a diagram showing the relationship between the amount of ink and the electrical resistance value of the same device. 10... Support substrate made of dielectric base material, 16...
... Depression groove, 20 ... First electrode, 22 ... Auxiliary electrode, 30 ... Groove gap, 40 ... Porous body, 50 ...
...Second electrode, 100...Ink recording head, 2
00...liquid ink, 300...ink container, 4
00...Signal voltage source, 401...Power source for ink amount detection and overflow prevention, 402...Ink filtration supply power source, 500...Recording body, 600...Pressure roller, 700...Sponge body, V _B ...ON Voltage,
V _B ′...off voltage, V _C ...suction voltage.

Claims (1)

[Scope of Claims] 1. A first porous membrane is installed on the surface of a dielectric support base material having arrayed first electrodes, and a liquid ink is provided on the opposite side of the porous membrane to the first electrodes. A permeable second electrode is positioned to supply and impregnate the first porous membrane with liquid ink, and a signal voltage is applied between the first and second electrodes to transfer the liquid ink to the first porous membrane. An ink recording device configured to conduct electroosmosis through a porous membrane to form a controlled liquid ink portion on the tip side of the first electrode to be recorded on a recording medium in response to the signal voltage. A means for electrically detecting the ink content of the first porous membrane, and a means for electrically detecting the ink content of the first porous membrane by means of the detected electrical signal. An ink recording device characterized in that supply is electrically controlled by utilizing electroosmosis of a second porous membrane sandwiched therebetween. 2. As a means for electrically detecting the ink content of the first porous membrane, an auxiliary electrode is provided outside the arrayed first electrodes provided on the surface of the dielectric support base material,
The electrical resistance corresponding to the amount of ink in the first porous membrane sandwiched between the auxiliary electrode and the second electrode is detected as an electrical signal, and the detected electrical signal is used to connect the first porous membrane to the ink supply power source. 2. The ink recording device according to claim 1, wherein ink is controlled to be supplied to the first porous membrane by utilizing electroosmosis of the second porous membrane sandwiched between the third and fourth electrodes.