JPS62242569A - Ink medium for electro-thermorecording - Google Patents

Abstract

PURPOSE:To enhance energy efficiency and printing speed, by providing a heat generating resistor layer, an electrode layer and a heat-fusible ink layer in that order on a laminar ink support. CONSTITUTION:A heat generating resistor layer 15 for generating heat when being supplied with electric currents, an electrode layer making electrical contact with the resistor layer 15, and a heat-fusible ink layer 18 to be melted by the heat generated by the resistor layer 15 are provided in that order on a laminar ink support 14 the conductivity of which is higher in the thickness direction than in plane directions, thereby obtaining an ink medium for electro- thermorecording. It is effective to provide an ink-releasing layer for ensuring easy release of the ink melted by heating from the electrode layer, between the electrode layer and the ink layer. It is effective that the heat generating resistor layer is a layer of a substance having a negative temperature coefficient. It is preferable that the resistor layer has a volume resistivity of 10<-1>-10<4>OMEGAcm, and the resistance of the electrode layer is not more than 1/10 times that of the resistor layer.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an ink medium for electrically conductive thermal recording used for non-impact type recording.

"Prior Art" Various printing and recording methods for recording image information on plain paper by converting electrical signals into thermal energy have been proposed and put into practical use. Typical of these print recording methods are (i) thermal head transfer method, (ii) current transfer method, and (iii) thermal transfer printing method.

Among these, (i) the thermal head transfer method uses a thermal head as a print head and slides this head into contact with the base side of a thermal recording medium (ink donor film) coated with low melting point ink. Then, a heat pulse is applied to the ink donor film according to the image information, and the ink in the corresponding area is melted by thermal conduction. Plain paper (hereinafter referred to as recording paper) is superimposed on the ink layer side of the ink donor film, and the molten ink is transferred to this recording paper.

On the other hand, in the (11) current transfer method, electricity is applied to the ink layer using a needle electrode, and the heat generated at this time is used to melt the ink and transfer it to the recording paper. Also (ii
i) In the thermal transfer printing method, a heating resistive layer and a return electrode are provided on a medium-resistance ink support. Then, a needle electrode is brought into contact with the ink support and a current path is provided in the ink medium to selectively melt the ink and transfer it to the recording paper.

In the (i) thermal head transfer method, thermal pulses are transmitted to the ink layer through a base paper such as capacitor paper that constitutes the ink donor film. Therefore, it is necessary to rely on heat conduction over a long distance, and the printing speed is slow, for example, with the printing time required per pixel (dot) being 1 mS (mi!J seconds) or more.

Also, because thermal energy is lost in this base paper portion, less energy is transferred to the ink layer. For this reason, only wax-based ink materials can be used, and the latitude for selection is small. Therefore, it is difficult to control the transfer of ink to the recording paper, and for example, it is actually difficult to control the size of dots in multiple stages to express gradation.

(11) In the current transfer method, imparting conductivity to the ink layer makes color tone control difficult. This has the disadvantage that color recording is difficult. Furthermore, the conductive loss in the support portion is large, and the mechanical properties of this portion are also poor. Further, there are also disadvantages in that the printed dots are not stable and the electrical anisotropy of the support portion is insufficient, resulting in large energy loss in this portion.

Finally, (iii) in the thermal transfer printing method, the ink support does not have conductive anisotropy, so dots spread. In addition, leakage current that does not contribute to heat generation is large, resulting in poor energy efficiency. Furthermore, since this method requires a certain amount of resistance layer on the ink support, there is also the problem that the contact resistance between the electrode and the ink support increases.

Therefore, Japanese Patent Laid-Open Publication No. 56-93585 and the like disclose a print recording method using a non-impact type electrically conductive heat-sensitive recording ink medium (print ribbon).

FIG. 11 is for explaining the principle of this print recording method. In this method, an ink medium for electrically conductive thermal recording is used.
is composed of an upper layer 2, a lower layer 3, a conductor layer 4, and an ink Fm5. Then, a printed electrode 6 and a ground electrode 7 are brought into contact with the low-resistance upper layer 2. The upper layer 2 and the printed electrode 6 are kept in a non-contact state with each other. When a voltage is applied to the printed electrode 6 according to the image signal, a current flows through the upper layer 2, the lower layer 3, the conductor layer 4, and the lower layer 3 again.
flows through the upper layer 2 and reaches the ground electrode 7.

At this time, although little heat is generated in the upper layer 2, most of the heat is generated in the current path portion of the lower layer 3. Thermal energy from the heat generating portion reaches the ink layer 5 via the conductor layer 4, causing the ink to melt.

"Problems to be Solved by the Invention" FIG. 12 shows the main parts of a recording apparatus using this conventional ink medium for electrically conductive thermal recording.

Recording paper (plain paper) 8 is superimposed on the ink layer 5 side of the ink medium 1 for electrically conductive thermal recording. The press roll 9 presses the ink medium 1 for energized heat-sensitive recording against the printed electrode 6, and also moves the ink medium 1 for energized heat-sensitive recording and the recording paper 8 superimposed thereon in a predetermined direction (perpendicular to the longitudinal direction of the print electrode). Plays the role of transport.

When a voltage is applied between the printed electrode 6 and the ground electrode 7 in this recording device, a current crosses the lower layer 3 at two locations as shown in the same figure and FIG. 11. Therefore, heat energy is generated in two places for one pixel, and only the ink in the part corresponding to the print electrode 6 is generated on the recording paper 8.
transcribed into.

That is, the heating of the ink in the portion corresponding to the return path electrode 7 is completely wasted, and energy usage efficiency is poor.

Further, in this current-carrying heat-sensitive recording ink medium l, electrical contact occurs at two locations, the print electrode 6 and the ground electrode 7. As a result, contact resistance increases, and energy is wasted accordingly.

In addition, the conventional ink medium 1 for electrically conductive thermal recording explained above
Although an upper layer 2 and a lower layer 3 were formed in the previous example, there is also a structure in which these layers have a 1 layer structure.

However, the same problem as already pointed out exists in this case as well.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink medium for energized thermal recording that has good energy efficiency and can increase printing speed.

"Means for Solving the Problems" In the present invention, on a layered ink support having higher conductivity in the thickness direction than in the planar direction, there is provided a heat generating resistor layer that generates heat when energized; An electrically contacting electrode layer and a heat-melting ink layer that melts due to the heat generated by the heat-generating resistor layer are laminated in this order to form an ink medium for electrically conducting heat-sensitive recording.

It is effective to dispose an ink peeling layer between the electrode layer and the heat-melting ink layer so that the ink melted by heating can be easily peeled off from the electrode layer. Further, it is effective that the heating resistance layer is a material layer having a negative temperature coefficient. For example, the heating resistance layer is preferably made of zirconium oxide.

The heating resistive layer preferably has a volume resistivity of 10<-1> to 10<4 >[Omega].cm, and the electrical resistance of the electrode layer is preferably one-tenth or less of the electrical resistance. The heating resistance layer may contain, for example, a ruthenium compound.

The critical surface tension of the ink release layer is 33 dyn.
It is preferable that it is not more than e/cm. In addition, since the ink support conducts electricity mainly in the thickness direction, it is preferable that the conductivity in the thickness direction is 10 times or more as compared to the conductivity in the surface direction.

As for the electrode layer, it is preferable that its end portion be exposed to the outside in order to ground it or apply a predetermined voltage to it.

According to the present invention, since the return electrode is disposed in the ink medium for electrically conductive thermal recording, 1. There is no need to arrange two electrodes on the ink support side. That is, the current flows, for example, from the relevant portion of the ink support through a path in the opposite return electrode portion I, resulting in efficient utilization of energy.

"Example" The present invention will be described in detail with reference to Examples below.

"First Embodiment" FIG. 1 shows the structure of an ink medium for electrical thermal recording in a first embodiment of the present invention.

The ink medium 13 for electrically conductive thermal recording has a heat generating resistive layer 15 formed on one side of an ink support 14, and a return electrode 1 on this.
6, an ink release layer 17, and a heat-melting ink layer 18 are formed in this order in a layered manner.

The ink support 14 is a sheet-like anisotropic support,
The electrical conductivity in the thickness direction is 10 times or more, preferably 1000 times or more, that in the planar direction. The resistance value in the thickness direction is 1000 or less, preferably 100 or less,
The ink support 14 has a thickness of 1 mm or more.

The heating resistance layer 15 has a resistance of 10-' Ω·cm to 104 Ω·cm.
cm, preferably from 10 Ω·cm to 10 3 Ω·cm. Its thickness is 100
08 to 20 μm 1 preferably 4000 to 1 μm.

This heating resistor layer 15 has a thickness of 1000 Å or more in order to form a highly reliable and stable resistive film on the ink support 14.
Preferably, a film thickness of 4,000 mm or more is required. Also,
From the standpoint of heat generation and heat conduction efficiency, the thickness needs to be 1 μm or less. Therefore, in order to drive the heating resistance layer 15 to generate heat with a pulse current, the above-mentioned 10
A volume resistivity value of Ω·cm to 10′ Ω·cm is preferred. The durability of the heating resistance layer 15 is greatly improved by containing the ruthenium compound. As ruthenium compounds, Ruoa, B lz Run
Ot etc. are preferred.

The return electrode 16 is made of a material having a volume resistivity that is one-tenth or less than that of the heat generating resistor layer 15.

This material needs to have heat resistance of 200 degrees Celsius or higher.

In principle, it is also possible to omit the ink release layer 17 as in the case of an ink medium 19 for electrically conductive heat-sensitive recording shown as a modified example in FIG. The ink peeling layer 17 is a layer for easily and stably transferring ink to a transfer material such as recording paper. When this ink peeling layer 17 is used, variations in the ink transfer rate are eliminated, so it becomes possible to control the recording density by modulating the amount of ink transfer, which changes the amount of ink transfer by controlling the applied energy.

The ink peeling layer 17 shown in FIG. 1 has a surface characteristic having a value lower than the critical surface tension Tc of the surface of a transfer material such as a recording paper, and is preferably as thin as possible.

The thickness is preferably 10 μm or less, preferably 1 μm or less. The critical surface tension rc is preferably 38 dyne/am.

The ink material constituting the heat-melting ink layer 18 is preferably a thermoplastic substance, and the base ink material is a polymeric substance with a melting point of 200 degrees C or less and a glass transition point of 120 degrees C or less, and a coloring material is mixed or Dissolved and colored ones are more preferable.

An ink medium 13 for electrical thermal recording was prepared as follows.

First, a nickel wire with a diameter of 15 μm was attached in a 40 μm×40
Created in such a way that there is a probability of two or more in μm,
Precision polishing (irregularities of 2 μm or less) was performed in the surface direction to smooth the surface. The resistance value in the thickness direction is 0.03Ω/cm”
The resistance value in the planar direction was 10 days Ω/cm" or more. This sheet was thoroughly washed, dried, and placed in a vacuum system to a vacuum level of 1. After this, argon gas was introduced and 3
The temperature was set to O-'torr, and the substrate temperature was set to 120 degrees Celsius.

Then, by using a high-frequency sputtering film deposition method, Ru0-
2,000 people deposited ZrO-based heat-generating resistive films. The volume resistance value of the heat generating resistor layer 15 created is 2×10”
It was Ωcm.

Next, on this heating resistor layer 15, a film of Al with a purity of 99.99 wt% was deposited by electron beam vacuum evaporation at an ultimate vacuum of 2, OX 10-'torr, and a substrate temperature of 150 degrees Celsius.
A return electrode 16 with a film thickness of 000A was created.

Next, a thermosetting silicone resin was applied onto the return electrode 16 and cured to obtain an ink release layer 17 consisting of a cured film having a thickness of 0.8 μm. The critical surface tension rc of the surface of this ink release layer 17 was 29 dyne/cm.

On the ink release layer 17, an ink material prepared by mixing and dispersing 3 wt % red azo pigment in a polyacid resin having a softening point of 60 degrees C was applied to a thickness of 4 μm to form a heat-soluble ink layer 18.

As a result, the ink medium 13 for electrically conductive thermal recording was completed.

FIG. 3 schematically shows a recording apparatus using the ink medium for electric thermal recording of this experimental example.

This apparatus is equipped with an ink medium roll 21 wound with a long electrically conductive heat-sensitive recording ink medium 13, and a transfer material roll 22 wound with a similarly long recording paper.

The ink medium 13 for energized thermal recording is connected to the ink medium port 21.
After being fed out from the transfer material roll 22, it passes through a pair of conveyance rolls 24 together with the recording paper 23 fed out from the transfer material roll 22,
These are superimposed.

The overlaid ink medium 13 and recording paper 23 pass between the printing electrode line head 26 and the back pressure contact drive roll 27. The printing electrode line head 26 includes 12 square copper squares of 75 μm square in the direction (main scanning direction) perpendicular to the conveyance direction (sub scanning direction) 28 of the ink medium 13 for electrically conductive thermal recording.
The recording heads are arranged in a row at a pitch of 5 μm. The voltage applied to these square copper electrodes is controlled according to the image signal, and recording is performed. The pressing force on the ink support 14 by the back pressure contact driving roll 27 is 900 g.
/cm.

After the recording is completed, the ink medium 13 and the recording paper 23 are separated after passing through a pair of transport rolls 31 and 32, and the recording paper 23 is separated.
The other one is accommodated in the discharge tray 33.

The ink medium 13 for energized thermal recording passes between the pulse application electrode roll 34 and the pinch roll 35, and becomes a used medium roll 36. The pulse application electrode roll 34 maintains electrical contact with the return path electrode 16 of the current-carrying thermosensitive recording ink medium 13. For this reason, the ink medium 13 for energized thermal recording comes into contact with the pulse application electrode roll 34.
The heat-melting ink layer 17 is not formed in the portion (both sides thereof), and the return electrode 16 is exposed in this portion. The pulse application N pole roll 34 is connected to the pulse oscillator 37
It is connected to the.

A printing electrode line head 2 is placed on one side of the ink support 14.
When the return electrode 16 is grounded while the electrodes 6 are in sliding contact, the following current flow occurs.

When the printing electrode line head 26←ink support 14-heating resistance layer 15-return electrode 1, heat generated by energization of the heating resistance layer 15 is transferred as follows.

Heat generating resistance layer 15→return electrode 16←thermofusible ink layer 17
- Recording paper 23 Here, heat is transferred to the recording paper 23 by transferring the melted ink in the heat-melting ink layer 17 to the recording paper 23.

With a pulse width of 250 μs to the printing electrode line head 26,
Pulses of 5V, 20V, and 50V were respectively applied to transfer the image onto plain paper as recording paper. At this time,
A voltage of opposite polarity is applied to the pulse application electrode roll 34 from the pulse oscillator 37 in synchronization with the application of the image signal.
A rectangular pulse of 00 μs was applied.

The image transfer status at this time is as shown in Table 1 below.

Table 1, FIG. 4 shows an outline of a recording apparatus capable of regenerating a heat-fusible ink layer.

Components that are the same as those in FIG. 3 are designated by the same reference numerals, and their description will be omitted as appropriate.

Now, in this recording device, there are three rotating rolls 41 to 43.
are arranged parallel to each other at positions forming the respective apex angles of the triangle, and an endless electrically conductive heat-sensitive recording ink medium 13 is spanned over these. A printing electrode line head 26 and an elastic back pressure contact member 44 are arranged between the first rotating roll 41 and the third rotating roll 43, and the ink medium 13 for thermal recording and the recording paper 23 are electrically connected between them. is allowed to pass. The elastic back pressure contact member 44 is connected to the back pressure contact drive roll 27 in FIG.
It has the role of pressing the electrically conductive heat-sensitive recording ink medium 13 and the recording paper 23 against the printing electrode line head 26.

An ink regenerating device 45' is disposed between the second rotating roll 42 and the third rotating roll 43.

The ink regenerating device 45 is an ink medium 13 for electric thermal recording.
This is a device that reapplies ink to the surface of the hot-melt ink layer side. Such a device can be constructed, for example, by an ink tank that is heated to a molten state and a coating roll immersed in the ink tank. Third rotating roll 43
A surface-leveling roll 47 heated to a predetermined temperature is placed opposite to this to smooth the surface of the applied ink.

The thermofusible ink layer was regenerated using this ink layer regeneration type recording device, and repeated use equivalent to 1000 cycles was performed. Table 2 below shows the stamp results in this case. It can be seen that a sufficient printed image can be obtained even after repeated use 1000 times.

Table 2 Comparative Example 1 A recording device similar to Experimental Example 1-2 was used. The current-carrying heat-sensitive recording medium has 52wt% of Z in its heat-generating resistance layer.
A resistive material consisting of r Oa and 33 wt% Cu was used instead. When the hot-melt ink layer was used repeatedly for 1000 cycles, the results shown in Table 3 below were obtained.

Table 3 By comparing Table 3 with Table 2, the effect of using the ruthenium compound can be recognized.

"Second Embodiment" FIG. 5 is for explaining a second embodiment of the present invention. In this embodiment, the ink medium 13 for electrical thermal recording is
Zirconium oxide was used as the heating resistance layer 15A of A. Zirconium oxide has a negative temperature coefficient as shown in FIG. 6, and its resistance value decreases with heat generation. Therefore, the applied current is concentrated in the area where heat is being generated, and the spread of printed dots can be considerably suppressed. As a result, there is no need to perform excessively detailed temperature control during heat generation, and a control circuit for this purpose can be easily manufactured. Furthermore, the contact resistance between the ink support 14 and each needle electrode of the printing electrode line head can also be reduced.

Furthermore, a heating resistance layer 15A made of zirconium oxide
This creates a large margin in heat resistance.

Since zirconium oxide is resistant to thermal shock, large amounts of energy can be applied over a relatively short period of time.

This creates a margin for control during printing, making it possible to employ various control means.

The heat generating resistance layer 15A made of zirconium oxide preferably has a thickness of 100 to 3 μm;
A range of 2,000 to 2,000 people is optimal. Even with this current-carrying thermal recording ink medium 13A, a pulse signal synchronized with the image signal can be applied to the return path electrode 16, thereby reducing the overall driving voltage and contact resistance value. , efficient use of energy can be achieved. It is also possible to improve the reliability of the recording process, which has a very large effect.

Experimental Example 2-1 An ink medium 13A for electrical thermal recording was prepared as follows.

Carbon fibers having a diameter of 30 μm were vertically arranged at a density of 50 μm×5Q μm, fixed with a silicone elastomer, and polished in the surface direction. 7. The unevenness on the surface shall have a flatness accuracy of 0.1 μm or less. The thickness was set to 2.5 mm. The resistance value of this ink support 14 in the thickness direction is 5 X l O-'Ω
・cm, and the surface resistance was 1013Ω/cm”.

Next, this ink support 14 was thoroughly washed with an organic solvent, dried, and placed in a vacuum system.

After creating a high vacuum of 1 x 10-' torr, argon gas was introduced to make the vacuum 3 x 10-' torr. A 1,500-layer heat-generating resistive layer 15A of ZrO was placed on one side of the ink support 14 by high-frequency sputtering. was formed.

On this ZrO2 film, I X 1
A Cu film was deposited at 0-'torr to form a return electrode 16 made of a 3,000-layer Cu film. A 1 μm thick film of Teflon material was formed on the return electrode 16 by emulsion coating. On this ink release layer, a 109 m long heat-melting ink layer 18 made of polyethylene wax having a melting point of 80° C. mixed with 5 wt % of carbon black and dispersed therein was provided to form an ink medium 13A for electrically conductive heat-sensitive recording.

Ink medium 1 for electrical thermal recording created as above
A printing electrode line head (see FIG. 3) was brought into sliding contact with the ink support side surface of 3A. The printing electrode line head 26 has needle electrodes arranged in a line at a density of 8 needles/mm. The voltage applied to the printing electrode line head 26 using a recording device similar to that shown in FIG.
The printing operation was performed by switching to three types of QV and using an applied pulse of 80 μs width. Further, a pulse of elOV was applied to the return electrode 16 in synchronization with this pulse.

The following Table 4 shows a table of printed dots in this case.

Table 4 Comparative Example 2 The same ink support as in Experimental Example 2-1 was used. However, the heating resistance layer was made of SiO□, and an ink medium having a thickness of 90 mm was used as the heat-melting ink layer. As a result of printing in the same manner as in Experimental Example 2-1, the results shown in Table 5 below were obtained.

(Hereinafter, blank spaces) Table 5 An ink medium 13A for electrical thermal recording was prepared as follows.

Ni balls with an average particle size of 8 μm are placed in silicone resin for 3Qw.
After dispersing by t% and forming into a sheet, 2K from the top surface when unfixed.
A pressure of g/cm2 was applied to thermally cure the material to obtain a sheet-like member. The surface direction of this sheet-like member is 0.1μ
The ink support 14 was obtained by smoothing the ink support to the extent of unevenness of m or less.

Next, the support was placed in a high vacuum of 1 (1'torr) and argon gas was introduced to 3 x 10-3torr.
ZrO2 was deposited by high frequency sputtering at a deposition rate of 500 people/hour by 2,000 people to form a heat generating resistor layer 15A. Next, under the same conditions, Cr was sputtered onto 506 ZrO2, and Cu was further deposited thereon to a thickness of 3000 by vapor deposition to form the return electrode 16. On top of this, an ink release layer 17 of silicone resin was provided with a thickness of 1 μm. A heat-melting ink prepared by mixing and dispersing 5 wt % carbon black in polyethylene wax having a melting point of 80 degrees Celsius was applied thereon to a thickness of 10 μm to complete an ink medium 13A for electrically conductive thermal recording.

Experimental example 2 regarding this ink medium 13A for electrically conductive thermal recording
The same printing test as in -1 was conducted, and the printing evaluations shown in Table 6 below were obtained.

Table 6 "Third Embodiment" FIG. 7 is for explaining the third embodiment of the present invention. In this embodiment, the ink medium 1 for electrical thermal recording is
The heating resistance layer 15B of 3B is 10-' to 104 Ω・cm
A material with a volume resistivity of .

If the heat generating resistor layer 15B has a volume resistivity of 10' Ω·cm or more, the thickness of the heat generating resistor layer 15B will be very thin, 1000 Å or less, and it will be difficult to control the film thickness during production. Furthermore, the surface irregularities of the heating resistor coating base require considerable precision, and many problems such as variations in resistance value and poor insulation of the resistor occur.

Furthermore, if the heat generating resistor layer 15B is made of a material having a resistivity value of 10-10 cm or less, not only will the leakage current in the heat generating resistor layer 15B increase, but also the layer will become thicker, causing the ink to heat up. efficiency will decrease.

On the other hand, if the heating resistor layer 15B is made of a material having a volume resistivity of 10<-1> to 10<4> Ω·cm, the thickness of this layer can be set to 100 OA to several tens of μm. At this thickness, it is easy to create a physical thin film by sputtering or vacuum deposition.

Furthermore, variations in film thickness during film formation can also be reduced.

In this third embodiment as well, the ink medium 13B for electrically conductive thermal recording
Since the ink support 14 is made of an anisotropic material, it is possible to save energy during printing. for example,
Printing is possible using a printing energy of 500 erg/dot or less, and high-speed printing of 500 μS/dot or less is possible.

Furthermore, the only requirement for the ink material of the heat-fusible ink layer 18 is coloring thermoplasticity (heat-fusibility), and there is sufficient leeway in selecting printing materials.

Experimental Example 3 An ink medium 13B for electrical thermal recording was prepared as follows.

A 2mm thick sheet of one room temperature curing silicone elastomer is coated with 100μm x tooμ copper wire of 15μm in the thickness direction.
A sheet-like member was created by arranging them so that 9 or more pieces existed in m. Then, precision polishing was performed in the direction of the surface by puff polishing to create surface irregularities of 400 Å or less. This ink support 14 has a resistance value of 0.1Ω or less in the thickness direction,
The resistance value in the plane direction was 1O13Ω or more.

The ink support 14 prepared in this manner is thoroughly washed, and 3×10-”to
It was made rr. In this state, sputtering was performed by high frequency sputtering using a target containing 1 wt% of Cu mixed with ZrO2. In this way, the resistance value 1
Heat generating resistor layer 15B using a volume resistance value of 02 Ω・Cm
was formed with a thickness of 3,000 people.

Next, the heating resistor layer 15B is coated with Cr500A at an ultimate vacuum of 1, OX 1 (1'torr) by vacuum evaporation.

Affi was deposited using a 2,000-person vacuum evaporation method, and the return electrode 1 was
It was set at 6. Furthermore, a Teflon resin 2 is placed on this return electrode 16.
A film with a thickness of μm was formed to serve as the ink release layer 17. A heat-melting ink layer 18 was provided on the ink release layer 17. This ink material is a mixture of polyester resin with a glass potential point of 55 degrees C and 3 wt% phthalocyan dye.
A film was deposited to a thickness of 3 μm. In this way, the ink medium 13B for electrically conductive thermal recording was completed.

Ink medium 1 for electrical thermal recording created as above
A printing electrode line head (see FIG. 3) was brought into sliding contact with the surface of the ink support member 3. The printing electrode line head 26 has needle electrodes arranged in a line at a density of 8 needles/mm.
These are 1.0 kg for the ink medium 13B for electric thermal recording.
/cm” of pressure.

Using a recording apparatus similar to that shown in FIG. 3, the voltage applied to the printing electrode line head was switched to three types: 5 V, 20 V, and 40 V, and printing was performed using an applied pulse of 100 μs width. Further, in synchronization with this pulse, a pulse voltage of 10 V of opposite polarity was applied to the return electrode 16. The back pressure contact driving roll (see Figure 3) is a rubber roll with a rubber hardness of 42 degrees, and the recording paper is copy paper (usually used in copying machines).
L paper for copying sold by Fuji Xerox Co., Ltd. was used.

Table 7 below shows the evaluation of the printing test in this case.

Table 7 Comparative Example 3 A recording device similar to that of the experimental example was used, and a Ta-3iOz mixture was used as the return electrode 15B of the ink medium 13B for electrically conductive thermal recording. The volume resistivity of this mixture is 10
The thickness of the return electrode 15B was adjusted to 0.4 μm.

The printing results in this case are shown in Table 8 below.

(Margin below) Table 8 "Fourth Example" FIG. 8 shows the structure of the ink medium for electrically conductive thermal recording in the fourth example. This ink medium 13C for current-carrying heat-sensitive recording has a heating resistance layer 15C formed on one surface of the ink support 14, as well as the ink medium for current-carrying heat-sensitive recording shown in FIG. The layer 17 and the heat-melting ink layer 18 are formed in this order in a layered manner.

Among these, the ink support 14 is an anisotropic conductor, and it is preferable that the electrical conductivity in the thickness direction is 10 times or more, preferably 1000 times or more, that in the planar direction. The resistance value of the ink support 14 in the thickness direction is 100Ω or less, preferably 100 or less, and the thickness thereof is required to be 1 μm or more.

The heat generating resistor layer 15C has a specific volume resistivity of 10-1Ω・
cm or more and 10' Ω·cm or less, and has a thickness of 1000 Å or more and 20 μm or less, preferably 4000 Å or more and 1 μm or less. The volume resistivity value of the heating resistor layer 15c is desirably 10 Ω·cm or more and 10 3 Ω·cm or less.

The return electrode 16 has a volume resistivity of 1 than that of the heating resistance layer 15C.
Composed of substances with a value of 1/0 or less, 200 degrees C
It is necessary that the material has the above heat resistance.

The ink peeling layer 17 has a critical surface tension γ of the surface of a transfer medium such as recording paper. The film should be as thin as possible, with surface properties having a value lower than . The thickness is preferably 10 μm or less, and 1
A thickness of μm or less is sufficient. Critical surface tension γ. For closing, 38 dyne/cm is preferable.

The heat-melting ink layer 18 is preferably made of thermoplastic material.

It is preferable that the base material is a polymer substance whose melting point is 200 degrees C or less and whose glass transition point is 120 degrees C or less, and a coloring material is mixed or dissolved and colored.

By the way, in the ink medium 13C for electrically conductive thermal recording of this embodiment, the return electrode 16 is exposed at both ends thereof with a width of about 1 cm. That is, the ink peeling layer 17 and the heat-melting ink layer 18 are not provided at both ends.

Therefore, the width (length in the main scanning direction) of the electrically conductive heat-sensitive recording ink medium 13C is increased by the exposed return electrode 16. In conventional thermal transfer recording devices that use an ink donor film as a thermal recording medium, the ink donor film is made very thin and does not have sufficient mechanical strength. Therefore, in the case of an ink donor film, if this width is made too wide, there are problems such as wrinkles occurring or the film itself meandering.

However, in the ink medium 13C for electrically conductive thermal recording of this embodiment, an anisotropic and strong sheet member is used as the ink support 14. Therefore, it can be made thicker to some extent and has considerable mechanical strength. Therefore, even if the width of the ink medium 13C for energized thermal recording becomes wider, there is no risk that it will twist or meander during recording, and uneven density or ink blurring due to this will occur during printing. There isn't.

FIG. 9 shows the main parts of a recording apparatus using this ink medium 13C for electrically conductive thermal recording.

In this recording apparatus, the printing electrode line head 26 comes into contact with the surface of the ink support 14 of the ink medium 13c for electrically conductive thermal recording with a predetermined pressure. The recording paper 23 passes between the back pressure contact drive roll 27 and the print electrode line head 26 in a state where it is overlapped with the electrically conductive thermal recording ink medium 13C. At both ends of the electrically conductive heat-sensitive recording ink medium 13C, conductive rolls 5L51 are arranged in rolling contact with the surface of the return electrode 16, as shown in FIG. be done. Of course, it is also possible to apply a constant bias voltage to the conductive rolls 51, 51, or to apply a predetermined voltage pulse in synchronization with the application of an image signal. It is also possible to use metal springs instead of the conductive rolls 51, 51.

"Effects of the Invention" As explained above, according to the present invention, there is provided a layered ink support having higher conductivity in the thickness direction than in the planar direction. An electrode layer that is in electrical contact with the layer and a heat-melting ink layer that melts due to the heat generated by the heat-generating resistor layer are laminated in this order to obtain an ink medium for electrically conducting thermosensitive recording.

Printing using such an ink medium for electrically conductive thermal recording has the following effects.

■Enables printing with low energy.

The efficiency is high because the current flows in only one direction through the heat generating resistance layer of the ink medium for current-carrying thermal recording. For example, when recording at a density of 8 degrees/mm, 300 to 1 OQ per degree
It is possible to perform printing using the energy of erg.

Since printing can be performed with low energy, it is possible to increase the printing speed. Since heat is generated directly by electric current without the transmission of heat pulses, printing speed can be increased in this sense as well.

The amount of time delay required for printing per pixel (dot) is 100 μs or less.

■Good color reproducibility.

The heat-melting ink layer does not need to function as a current path, which widens the range of ink choices.

Furthermore, a transparent polymer material can be easily selected.

Therefore, the color tone of the ink can be easily controlled and the color characteristics are also stabilized.

In the ink medium for electrically conductive thermal recording of the present invention, since the coloring material is contained in the plastic material, it is not directly irradiated with strong light and is less susceptible to decomposition due to oxidation or reduction due to oxygen or the like. In other words, it is possible to obtain an image in which the fastness of the coloring material is extremely high. This robustness is at the same level as images in the printing technology field and electrophotography field, which have similar ink structures.

The ink medium for electrically conductive thermal recording of the present invention has a larger margin for coloring material than those in the field of printing technology.
From this point of view, the color tone of the image is equivalent to or better than that of printing.

■Good gradation expression.

Since the ink medium for electrical thermal recording of the present invention has good responsiveness to human input signals, it is possible to adjust the amount of ink transferred to recording paper or the like by modulating the input signal. Therefore, multi-level gradation expression can be achieved by directly changing the diameter of the print dots without using pseudo-halftone expression such as a dither matrix. Therefore, images can be reproduced with high-resolution pixels, and full-color reproduction can be performed with halftone expression equivalent to that of printing.

With a resolution (print density) of 8 to 16 dots/mm, it is possible to reproduce 4 to 16 intermediate tones per dot.

(2) The ink medium itself is mechanically strong, improving the reliability of the recording device.

No damage to the ink medium occurs, and therefore it can be used repeatedly, such as by reapplying the hot-melt ink. Furthermore, since the signal applying electrodes can be brought into contact with considerable pressure, unevenness in recording does not occur. Furthermore, by using a material such as ruthenium oxide for the heating resistance layer, not only the durability against pulse voltage can be increased, but also the weather resistance can be improved. For example, the ink medium for electrically conductive thermal recording of the present invention has a temperature of 10% R at an environmental temperature of 0 degrees Celsius to 40 degrees Celsius.
It has weather resistance of h to 90% Rh, and can perform highly reliable printing operations.

[Brief explanation of drawings]

Figures 1 to 4 are for explaining the first embodiment of the present invention, of which Figure 1 is a sectional view of an ink medium for electrically conductive thermal recording, and Figure 2 is a cross-sectional view of an ink medium for electrically conductive thermal recording, and Figure 2 does not include an ink release layer. A cross-sectional view of the ink medium for current-flow heat-sensitive recording, and FIG. 3 is a schematic configuration diagram of a recording apparatus using the current-flow heat-sensitive recording ink medium of this embodiment.
FIG. 4 is a schematic diagram of a recording apparatus capable of regenerating a heat-fusible ink layer, and FIGS. 5 and 6 are for explaining a second embodiment of the present invention. FIG. 5 is a cross-sectional view of an ink medium for current-flow heat-sensitive recording, FIG. 6 is a characteristic diagram showing the temperature characteristics of zirconium oxide, and FIG. 7 is a cross-sectional view of an ink medium for current-flow heat-sensitive recording in the third embodiment of the present invention. 8 to 10 are for explaining the fourth embodiment of the present invention, of which FIG. 8 is a cross-sectional view in the width direction of an ink medium for current-conducting heat-sensitive recording, and FIG. A principle diagram showing the principle of recording using a recording ink medium, FIG. 10 is a perspective view showing the main parts of the recording section, and FIGS. 11 and 12 show a conventional electrically conductive thermal recording ink medium and recording using it. 11 is a cross-sectional view showing the arrangement of an ink medium for electrically conducting heat-sensitive recording and electrodes in contact therewith, and FIG. 12 is a principle diagram showing the recording principle. 14...Ink support, 15...Heating resistance layer, 16...Return electrode, 17...
Ink release layer, 18...Thermofusible ink layer. Applicant: Fuji Xerox Co., Ltd. Representative
Person Patent Attorney Ume Yu Yamauchi Figure 1 Figure 2 Figure 4 Figure 5 Figure 60 1st Degree Figure 7 Figure 80 Figure 90

Claims (1)

[Scope of Claims] 1. On a layered ink support having higher conductivity in the thickness direction than in the planar direction, a heating resistor layer that generates heat when energized, and an electrode in electrical contact with the heating resistor layer. layer and
An ink medium for electrically conductive heat-sensitive recording, characterized in that a heat-melting ink layer that melts due to heat generated by the heat-generating resistor layer is laminated in this order. 2. An ink peeling layer is disposed between the electrode layer and the heat-melting ink layer for easily peeling off the melted ink from the electrode layer. Ink medium for electrically conductive thermal recording. 3. The ink medium for current-carrying thermal recording according to claim 1, wherein the heating resistance layer has a volume resistivity of 10^-^1 to 10^4 Ωcm. 4. The electrical resistance of the electrode layer is 10 compared to the electrical resistance of the heating resistance layer.
2. The ink medium for electrically conductive thermal recording according to claim 1, wherein the ink medium has a value of less than 1/1. 5. The ink medium for electric heat-sensitive recording according to claim 3, wherein the heating resistance layer contains a ruthenium IV compound. 6. The ink medium for electrically conductive heat-sensitive recording according to claim 1, wherein the heating resistance layer is a layer of material having a negative temperature coefficient. 7. The ink medium for electrically conductive heat-sensitive recording according to claim 6, wherein the heat generating resistance layer is made of zirconium oxide. 8. The ink medium for electrothermal recording according to claim 2, wherein the ink release layer has a critical surface tension of 38 dyne/cm or less. 9. The ink medium for current-flow heat-sensitive recording according to claim 1, wherein the ink support has a thickness direction conductivity that is 10 times or more greater than its planar direction conductivity. 10. The ink medium for electrical heat-sensitive recording according to claim 1, characterized in that the ends of the electrode layer are exposed.