JPS62242555A - Print recording method - Google Patents

Abstract

PURPOSE:To improve the energy efficiency and to increase the printing speed by employing an ink medium composed of an ink supporter layer, a resistor layer for producing heat upon power supply, a return path electrode contacting electrically the supporter layer and an ink layer to be fused by the heat produced from the resistor layer. CONSTITUTION:In an ink medium 13, a heat producing resistor layer 15 is formed on one face of an ink supporter 14 then a return path electrode 16 and a thermally fusable ink layer 17 are formed sequentially in layers thereon. When recording is performed, a signal applying electrode 24 is pressure contacted against the supporter 14 but the ink medium has anisotropic conductivity where the conductivity in the direction of the thickness is more than ten times more higher than that in the surface direction. When the return path electrode 16 is grounded with the signal applying electrode 24 sliding against one face of the ink supporter 14, transfer of heat to a recording paper 21 is performed by transferring the ink fused in the thermally fusable ink layer to the recording paper 21. Since a current flows unilaterally through the heat producing resistor layer, high speed printing can be achieved with high efficiency.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a print recording method capable of performing non-impact type recording. The present invention relates to a printing and recording method for forming an image by transferring molten ink onto recording paper.

"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, (11) 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 (ii) 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 (i
ii) In the thermal transfer printing method, a heat generating 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 long distances, and the printing speed is slow, with the printing time required per pixel (dot) being 1 m5 (mi'J seconds) or more, for example.

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 limited. 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.

Next, (ii) the current transfer method has the disadvantage that color recording is difficult because imparting conductivity to the ink layer makes color tone control difficult. Furthermore, the conductive loss in the support portion is large, and the mechanical properties of this portion are also poor. Furthermore, 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, (iir) in the thermal transfer printing method, the ink support lacks conductive anisotropy, resulting in dot spreading. Also, there is a large leakage current that does not contribute to heat generation.
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 print ribbon.

FIG. 20 is for explaining the principle of this print recording method. In this method, a print ribbon 1 is constituted by an upper layer 2, a lower layer M, a conductor layer 4 and an ink layer 5. 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 and the upper layer 2 again.
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. As a result, ink is transferred to the recording paper.

``Problem to be solved by the invention'' However, in this proposed print recording method, the current
As shown by broken lines in Figure 0, the lower layer 3 is crossed at two locations. Therefore, not only is the efficiency of using thermal energy low, but the printed electrode 6 and the ground electrode 7 are used for printing and
It will come into sliding contact with the ribbon. As a result, there is a problem in that contact resistance increases and energy is wasted accordingly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a print recording method that is energy efficient and can increase printing speed.

``Means for Solving the Problems'' Therefore, in the present invention, a layered ink support having higher conductivity in the thickness direction than in the surface direction, and a layered ink support that is superimposed on the other surface of the ink support and generates heat by a7J1. a heating resistor layer which is formed on the opposite side of the return electrode and is melted by the heat generated by the heating resistor layer; An ink medium comprising at least an ink layer is used. Then, a voltage is applied to the surface of the ink medium on the support side according to the image signal, and the return electrode is kept at a predetermined potential for at least the voltage application time, and the heating resistor layer is selectively heated by controlling the current flow.

The melted ink is thereby transferred to the recording paper superimposed on the ink medium to form an image.

In this print recording method, it is also effective to provide an ink release layer between the return electrode and the ink layer to ensure perfect release. Further, the return electrode may be grounded or biased to a predetermined voltage. When applying a predetermined voltage to the return electrode, it may be a constant voltage that does not vary over time, or it may be a voltage that is periodically applied in synchronization with the application of an image signal. But that's fine.

The ink layer of the ink medium may be preheated prior to printing to increase its responsiveness to thermal energy and to compensate for variations in ambient temperature.

The voltage applying means for applying a voltage to the surface of the ink medium on the support side according to the image signal may be an electrode array in which a plurality of needle electrodes are arranged in parallel. In this case, a voltage is selectively applied to these needle electrodes according to the image signal, and a current flows between them and the return electrode. If the shape of each end face of the needle electrode is long and narrow in the length direction of the electrode array, the amount of ink transfer in the direction perpendicular to the length direction of the electrode array can be controlled by changing the time of voltage application to this electrode. For example, gradation expression using the area gradation method becomes possible.

The voltage applied to the ink medium by the voltage application means is
It may be a pulse voltage, and in this case, if the voltage waveform has peaks both near the rising edge and near the falling edge, the image will be sharper.

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

"First Embodiment" FIG. 1 shows an apparatus to which the print recording method of the first embodiment of the present invention is applied. This apparatus includes an ink medium roll 11 wound with a long ink medium, and a transfer material roll 12 wound with a long recording paper.

FIG. 2 shows the structure of the ink medium. The ink medium 13 constituting the ink medium roll has a heating resistance layer 15 formed on one surface of an ink support 14, and a return electrode 16 and a heat-melting ink layer 17 formed in this order in a layered manner. The ink support 14 is an anisotropic support having conductivity in the vertical direction in the figure, that is, in the direction perpendicular to the surface of the ink medium 13.

The ink medium 13 having such a structure is the ink medium roll 1.
After being fed out from the transfer material roll 12, the recording paper 21 passes through a pair of transport rolls 22 together with the recording paper 21 fed out from the transfer material roll 12, and these are overlapped. The overlaid ink medium 13 and recording paper 21 pass between the signal application electrode 24 and the back pressure contact drive roll 25. The signal applying electrode 24 is a recording head in which needle-like electrodes are arranged in a line in a direction perpendicular to the direction in which the ink medium 13 and the like are transported (the sub-scanning direction) 26 (the main scanning direction). The voltage applied to these needle-like electrodes is controlled according to the image signal, and recording is performed.

FIG. 3 shows this recording principle.

The signal applying electrode 24 is brought into pressure contact with the support 14 of the ink medium. The ink support 14 has anisotropic conductivity, and the conductivity in the thickness direction is 1 greater than the conductivity in the surface direction.
It's more than 0 times better.

When the return electrode 16 is grounded with the signal applying electrode 24 in sliding contact with one surface of the ink support 14,
The following current flow occurs.

Signal application electrode 24←Ink support 14-Heating resistance layer 15
+Return electrode 1, heat generated by energization of heat generating resistor layer 150 is transferred as follows.

Heat generating resistance layer 15-return electrode 16←thermofusible ink layer 17
+Recording paper 21 Here, heat is transferred to the recording paper 21 by transferring the melted ink 17A in the heat-melting ink layer to the recording paper 21.

An example of a method for manufacturing the ink medium 13 used in the above print recording method will be described next.

FIGS. 4 and 5 show an example of an ink support constituting such an ink medium. Of these, FIG. 4 is a plan view, and FIG. 5 is a sectional view. The ink support 14 consists of a 50 μm thick nickel wire 28 with a diameter of 35 μm.
They are arranged vertically at a density of one in an area of
, 5mm. As a result, the resistance value in the thickness direction of the support body 14 is 5 X I O-''Ωcm
Therefore, the surface resistance is 10 ohms per square cm.

The fact that the ink support 14 has such conductivity in the thickness direction and is at least one-fourth or less, preferably one-tenth or less of the resistance value in the plane direction is selective from the signal application electrode 24. This is necessary in order to efficiently flow the current supplied to the return electrode 16 without spreading it toward the return electrode 16.

After the ink support 14 is formed, it is thoroughly washed with an organic solvent. After this, the ink support 14 is dried,
Installed in a vacuum system. The vacuum system is 2 x 10-'tor
After being brought to a high vacuum state of r, argon gas is introduced,
This is set to 3 X l O-3.

Then, a thin film of SiC is formed on one side of the support 14 to a thickness of 500 mm using a high frequency sputtering method, and this is used as the heating resistor layer 15. The resistive material layer constituting the heat-generating resistive layer 15 generally needs to be made of a material having a specific resistance between 10-2 Ω·cm and 104 Ω·cm, and also generates heat by itself, so it cannot be heated at temperatures above 200°C. endured.

It is also necessary to

On the heating resistance layer 15 made of a SiC film, an Au film is deposited at 4 X l O-'' torr by vacuum evaporation, and its thickness is adjusted by about 1500. In this way, The formed Au film constitutes the return electrode 16. On the return electrode 16, an ink layer 17 of 7 μm is arranged, which is made by mixing and dispersing 5 wt % of carbon black in polyethylene wax having a melting point of 606C. This completes the ink medium. Note that the return electrode 16 preferably has a volume resistivity value of 0.5 times or less than that of the heat generating resistor layer material, and since it is adjacent to the heat generating resistor layer 15, it is generally
The material must be able to withstand temperatures of 00''C or higher.

Returning to FIG. 1, the explanation will continue. The recording paper 21 that has passed between the signal application electrode 24 and the back pressure contact drive roll 25 is
The signal applying electrode 24 allows the ink medium 1 to be
3, the ink is selectively transferred. Conveyance roll 31,
After passing through the recording paper 32, the recording paper 21 is separated from the ink medium 13 and collected in the discharge tray 33. On the other hand, the ink medium 13 has a pulse application amount W roll 34 and a pinch roll 3.
5 and is sequentially wound around a paper tube to form a used media roll 36. Pulsing electrode roll 34 is adapted to maintain electrical contact with ink media return electrode 16. For this reason, the heat-melting ink layer 17 is not formed in the ink medium 130 portion (both sides of the ink medium 13) that contacts the pulse application electrode roll 34, and the return electrode 16 is exposed in this portion. .

By the way, the pulse application electrode roll 34 is a pulse oscillator 37.
It is connected to the. The pulse oscillator 37 periodically generates a pulse voltage having a polarity opposite to that of the voltage applied to the signal application electrode 24 at the timing when the voltage is applied to the signal application electrode 24 . Of course, instead of applying a pulse voltage, it is also possible to simply ground the pulse application electrode roll 34 or set it to a predetermined bias potential.

When a pulsed voltage is applied from the signal application electrode 24 to a pixel portion where printing is performed, a current flows through the support 14 in the thickness direction, causing that portion of the heating resistor layer 15 to generate heat by being energized. This results in selective transfer of ink.

Experimental Example 1 In Experimental Example 1, the ink support described in this first example was used. Needle electrodes with a diameter of 90 μm were used as the signal applying electrodes 24, and the needle electrodes were arranged at a density of 8 needles/mm. -30V from the pulse oscillator 37 to the return electrode 16
When a pulse voltage of 100% was applied periodically and 3 types of voltages (+50V, +110V, +240V) were applied from the signal application electrode 24, the dots transferred to the recording paper 21 were as shown in Table 1 below. became.

Table 1 Comparative Example 1-1 For comparison, the ink support was changed from one with a diameter of 35 μm to a nickel wire with a diameter of 180 μm.

Further, the arrangement density was changed from one per 50 μm x 507 m to one per 240 μm x 240 μm. The ink support in Comparative Example 1-1 has a resistance value of 10-6 Ω·cm in the thickness direction and a surface resistance of 10'
4 Ω/cm". This was used for printing in the same manner as in Experimental Example 1. The evaluation is as shown in Table 2 below.

Table 2 In order to further evaluate the characteristics of the ink support, the following ink supports were prepared. That is, a thermosetting silicone resin in which 3 Q wt% of conductive carbon black is dispersed is made into a resin with a thickness of 40 μm and a resistance value of 4XlOΩ.
・It was made into a film with a surface resistance of 7 x 10 Ω/cm". Then, a heating resistance layer, a return electrode (conductive layer), and a heat-melting ink layer were formed on it in the same manner as in the previous experimental example.
This was used as an ink medium for comparison. The evaluation based on this is shown in Table 3 below.

On the right side of Table 3, in this comparative example 1-2, the signal application electrode 24 has 24
When a voltage of 0 V was applied, the ink support generated considerable heat, and a large deformation occurred in the part of the support to which the voltage was applied.

Experimental Example 2 In this second experimental example, an ink support was manufactured as follows. First, carbon fibers having a wire diameter of about 0.1 μm were fixed with a urethane elastomer in a state in which they were arranged perpendicularly to each other. After this, both sides were sufficiently polished to obtain a sheet with a thickness of about 5 mm, and the surface was roughened to several hundred degrees. This ink support has a resistance value of 5 in the thickness direction.
:Xl 0-'Ω・cm, and the surface resistance value is 5X1
It was 0"Ω/cm".

The ink support was then thoroughly washed and dried, and then placed in a vacuum system to create a high vacuum of I.times.10-'torr. Argon gas was introduced into the vacuum system as a carrier gas to 6 X 10-' torr, followed by oxygen gas to 2 X I Q-' torr. In this state, the AI cover is sputtered with high frequency, and Af is 0.
A mixed crystal of 3 and Af was formed to a thickness of 1500 mm.

The heating resistance layer thus formed had a resistance value of 1020 in the thickness direction.

On this heating resistor layer, an Au film with a thickness of 1500 mm and a heat-melting ink layer with a thickness of 7 μm were further formed in this order to form an ink medium.

In addition, the measurement of the resistance value at the time of manufacturing this ink medium is as follows.
This was carried out using the principle shown in Figure 6. That is, two types of measurement electrodes 4, first and second, are placed on one surface of the measurement sample 41.
2.43 were arranged at predetermined intervals, and a third measurement electrode 44 was arranged on the other side at a position opposite to the first measurement electrode 42. The first and third measurement electrodes 42.44 were used to measure the thickness, and the first and second measurement electrodes 42.43 were used to measure the surface resistance.

Figure 7 shows measurement sample 41 during these measurements.
This shows the arrangement of ammeter 45 and voltmeter 46.

The evaluation of printing in this second experimental example is shown in Table 4 below.

(Margin below) Table 4 As described above, in this second experimental example, by changing the applied voltage, the dot diameter can be changed in a plurality of stages, making it possible to express gradations in units of dots.

In the first embodiment described above, since the heat-melting ink layer is directly formed on the return path electrode of the ink medium, the structure is simpler and the thermal efficiency is better than that of other embodiments described later. There is.

"Second Embodiment" In order to explain the print recording method in the second embodiment, FIG. 8 shows an outline of an apparatus to which this method is applied. In this embodiment, unlike the previous embodiment, an ink medium 51 having an ink release layer is used. Components that are the same as those in FIG. 1 are designated by the same reference numerals, and their description will be omitted as appropriate.

In the apparatus shown in this figure, an ink medium 51 is sequentially fed out from an ink medium roll 52 and wound onto a transfer material roll 53.

FIG. 9 shows the cross-sectional structure of the ink medium used in this example. The ink medium 51 has a heating resistance layer 15 formed on one side of an ink support 14, and a return electrode 16, an ink peeling layer 55, and a heat-melting ink layer 17 stacked on top of this in order. The ink support 14 is an anisotropic support having conductivity in the vertical direction in the figure, that is, in the direction perpendicular to the surface of the ink medium 13.

FIG. 1O is for explaining the energization control of the heating resistor layer in this second embodiment.

The corresponding needle electrode of the signal application electrode 24 (FIG. 8) is
As shown in the upper part of Figure 1O, a pulse voltage of +100 cm is applied to the line where printing is performed (solid line part 57 in the figure). Line where no printing is performed (dashed line 58 in the figure)
No voltage is applied to.

On the other hand, the pulse oscillator 37 is activated at the printing timing of each line, as shown by the solid line 59 in the lower part of FIG.
Generates a voltage of V. Pulsing electrode roll 34 will apply this negative voltage to ink media return electrode 16. The current flow in this ink medium 51 is as shown below.

Signal application electrode 24 - ink support 14 - heating resistance layer 15
-Return electrode 16 In other words, in the part where printing is performed, a voltage of nearly 150 V is applied to both sides of the heating resistor layer 15, and this part is energized. In this print recording method, a voltage of nearly 50 V is applied at the print timing even in areas where printing is not performed. However, the current caused by this is minute compared to the previous current.

The heat generated in the heat generating resistor layer 15 is transferred as follows.

Heat-generating resistor layer 15 → return electrode 16 - ink peeling layer 55 → heat-melting ink layer 17 ← Recording paper 21 In the area where printing is performed, a large amount of current flows through the heat-generating resistor layer 15, so this area generates strong heat. The heat reaches the heat-melting ink layer 17 through the ink peeling layer 55, and the ink is selectively melted.

Since only a small current flows through the heating resistance layer 15 in the area where printing is not performed, even though this area may be preheated, the ink in the corresponding area of the heat-melting ink layer 17 will not melt.

Now, in this second embodiment, an ink release layer is provided between the return electrode and the heat-fusible ink layer. This improves the transfer efficiency of the ink to the recording paper when it is heated, and the ink is completely removed. It will be transferred to recording paper.

That is, since the stability of ink transfer is ensured, it is possible to stably change the dot diameter in multiple stages by changing the applied energy.

Also, since the ink release layer is provided, the selection of ink is the first step.
This is easier than that of the embodiment. The only necessary and sufficient conditions required for the ink are that it has thermoplasticity or heat-melting properties that reduce its viscosity and facilitate transfer when heated, and there are no restrictions on the coloring material or the like. For this reason,
Providing an ink release layer allows for a wider selection of coloring materials, making it possible to reproduce high color tones.

Experimental example 2 An ink support was prepared as follows.

Copper wires with a diameter of 15 μm were arranged in parallel in an area of 100 μmm x 100 u, with a probability of 9 or more, and these were fixed with room temperature curing silicone elastomer. Next, this sheet-like member is precisely polished in the surface direction (direction perpendicular to the length direction of the copper wire).
Their surfaces were made uneven with a size of 400 Å or less. The thickness of the produced ink support was adjusted to 1.5 mm. The resistance value of this ink support in the thickness direction was 0.1Ω, and that in the planar direction was 1013Ω.

The ink support was then thoroughly washed, dried and placed in a vacuum system. The vacuum system was set at 2 x 10-'torr and brought to 3 x 10-'torr by introducing argon gas. In this state, a thin heat generating resistor layer was formed using a ZnO target doped with Cu. This heating resistance layer had a volume resistance value of 102 Ω·cm.

Next, the vacuum system was set to a degree of vacuum of 4 and OX 10-'torr, and Cr was first formed to a thickness of 5000 mm using a vacuum evaporation method. Furthermore, a Cu film was deposited thereon to a thickness of 2000 nm using electron beam vacuum evaporation to form a return electrode. A 1 μm thick film of polyester resin was formed on the return electrode to serve as an ink release layer. This ink release layer had a critical surface tension of 36 dyne (dyne) of 7 cm.

An ink layer was formed on this ink release layer to complete an ink medium. This ink medium has a glass transition temperature of 55
℃, containing 5 wt% of colorant, and deposited to a thickness of 3 mm. The ink medium is completed through the above process.

In this experimental example, copper needle electrodes with a diameter of 70 μm are used as the signal applying electrodes 24, and the arrangement of these needle electrodes is 8 wood/mm.
density. The signal applying electrode (line head) 24 is
The ink medium was pressed against the surface of the ink support at 1.0 kg/m'. The tip of each needle-like electrode constituting the signal applying electrode 2 II may be ground into a wedge shape, and the needle-like electrode is pressed against the surface of the ink support at an oblique angle so as to oppose the movement of the ink medium 51. may be done. Due to such pressure and contact state, the needle electrode can be stably contacted even if some waviness occurs on the surface of the ink medium. Since the ink support has considerable rigidity, it is stable against mechanical strain caused by contact with the needle electrode.

Three types of voltages, +1QV, +50V, and +100V, were applied to the needle-shaped electrode corresponding to the printed dots of the signal application electrode 24 as rectangular pulses of 180 μs. At this time, a negative voltage pulse was applied to the ink medium return electrode 16 by the pulse application electrode roll 34 in contact with the exposed side portion thereof. This negative voltage pulse had a pulse width of 300 μs, and its application was started 20 μs earlier than the respective timings at which the image signals were input. However, the time width of the voltage pulse applied from the pulse application electrode roll 34 side is usually equal to or, for example, 1.1 times or more longer than the time width of the voltage pulse applied from the signal application electrode 24 side. However, it is not limited to this experimental example.

In this experimental example, a rubber roll with a rubber hardness of 45 is used as the back pressure contact drive roll 25, and plain paper for copying machines (L paper sold by Fuji Xerox Co., Ltd.) is placed between the ink medium 51 and this back pressure contact drive roll 25. ) to print. The following Table 5 shows the evaluation based on this.

Table 5 Comparative Example 2 Using the same ink medium and printing device as in Experimental Example 2, printing was performed with the return electrode 16 grounded. The evaluation of the printed dots in this case is shown in Table 6 below.

Table 6 As explained above, in this second example, an ink release layer was provided on the ink support, and a voltage of opposite polarity to the signal application electrode side was applied to the return electrode side, so that it could not correspond to the image signal. It becomes possible to perform stable printing simply by generating a relatively low voltage. Furthermore, by obliquely polishing the tips of the needle electrodes constituting the signal application electrodes as in this embodiment, it is also possible to eliminate uneven printing.

"Third Embodiment" FIG. 11 is for explaining a third embodiment of the present invention. This print recording method uses the same ink medium 51 as already described in the second embodiment. That is, the ink medium 51 has a heating resistance layer 15 formed on one side of the ink support 14, and a return electrode 16, an ink peeling layer 55, and a heat-fusible ink layer 17 stacked on top of this in order.

The ink support 14 is arranged in the vertical direction in the figure, that is, the ink medium 1
It is an anisotropic support that has conductivity in the direction perpendicular to the plane of 3. The ink peeling layer 55 is attached to the recording paper 2 as a transfer material.
Critical surface tension on the surface of 1? It is desirable that the material is made of a material with a surface property of a value lower than "c" and that its thickness is as thin as possible in order to prevent loss due to thermal energy diffusion. Preferably, the thickness is 1 μm or less, and the critical surface tension rc is A substance of 38 dyne/cm or less is used as the ink peeling JI 55. By providing the ink peeling layer 55 in this way, the ink layer peels off from the interface of the ink peeling layer when heated above the glass transition point, and the ink layer is always kept constant. The thick ink will be transferred to the recording paper 21.

By the way, in this third embodiment, the signal applying electrode 61 is brought into pressure contact with the surface of the ink support 14.

The signal applying electrode 61 is made up of a large number of needle-like electrodes 62 fixed with an epoxy resin (not shown). Needle electrode 6
2 are respectively connected to corresponding output terminals of a driver mounted on the head body, also not shown. The needle-like electrode 62 is made of six Ni-covered wires each having a diameter of 150 μm.
They are arranged in a straight line with a density of mm.

As can be seen from FIG. 12, the tips of these needle-shaped electrodes 62 are polished into a shape cut at an angle of 45 degrees with two surfaces 62A and 62B perpendicular to the conveying direction of the ink medium 51. An end surface 62C, which is elongated in the arrangement direction (main scanning direction) of the needle electrodes 51, comes into contact with the ink medium 51.

The printing device used in this third embodiment is substantially the same as the device shown in FIG. 1 or FIG. The printing operation will then be performed.

The printing operation will be explained with reference to FIG. The end surface 62C of the needle electrode is in contact with the ink support 14 constituting the ink medium under a pressure of about 40 gr/cm. This pressure is
For example, it is provided by the back pressure contact drive roll 25 shown in FIG. The recording paper 21 and the ink medium 51 move in the transport direction (sub-scanning direction) 26 at a speed of 200 mm/s. As shown in FIG. 1, the rectangular end surface 62C of each needle electrode 62 has a length I21 in the longitudinal direction equal to a length Il in the direction perpendicular to this.
It is set to 8 times z. Therefore, as shown in principle in FIGS. 13a to 13d, the longer the time width of the voltage pulses applied to these needle electrodes 62 (as the time width advances from a to d in the figure), the more the voltage pulse in the sub-scanning direction increases. This increases the length of the printed dots.

For example, in Figure A, the shaded area shows the case where a pulse is applied in a very short time on the assumption that no heat diffusion occurs, and the printed dot ideally has an area of 1.xl. The figure shows a state in which the pulse application time becomes longer and printing is performed twice as long in the sub-scanning direction. The same applies below.

By changing the pulse width applied to the needle electrode 62 in this way, the area of the printed dots can be changed, making it easy to express gradations.

The solid arrows in FIG. 12 represent the flow of current through the needle electrode 62, and the anisotropy of the ink support 14 causes the current to flow in the thickness direction of the ink medium 51, resulting in such gradation expression. It turns out that is possible. The arrows indicated by broken lines in FIG. 12 represent the transmission paths of heat generated by the heat generating resistor layer 15. Thermal energy is transmitted through the relatively thin return electrode 16 and the ink release layer 55.
It can be seen that the ink reaches the heat-melting ink layer 17 without much diffusion and melts the ink.

Experimental Example 3 With the transport speed of the recording paper 21 set to the conditions described above, the return electrode 16 was grounded, and a DC voltage of 40 V was applied to the corresponding needle electrode 62 of the signal application electrode 61. In this case, the applied pulse width is 200μS, 400μS, 600μS,
When I changed it to 4 stages of μs and 800 μs,
The lengths of the dots printed on the recording paper 21 in the sub-scanning direction 26 were 40 μm, 180 μm, 120 μm right, and 160 μm, respectively. Both of these dots are number 13.
As illustrated in the figure, the shape is close to a rectangle.

Next, increase the applied voltage to 65V and similarly increase the pulse width to 200V.
The time was changed in four steps: μS, 400μS, 600μs, and 800μs. In this case, the print dots in the sub-scanning direction 2
The length of 6 is 60 μm, 100 μm, and 130 μm, respectively.
and 180 μm. In this case as well, these dots were nearly rectangular in shape. Furthermore, in the above two experiments, the density of the printed dots and the shape and size of the dots at each applied pulse were sufficiently stable.

In the third embodiment described above, the shape of the tip of the needle electrode is processed. Therefore, for example, in order to process the heating element (heat generating element) of a thermal head in the same way, the rectangle's length-to-width ratio is limited to about twice, but unlike this, a rectangular contact part (current-carrying part) with a larger ratio is the limit. can be created, and gradation can be expressed finely and stably.

"Fourth Embodiment" FIG. 14 is for explaining the fourth embodiment of the present invention. In the print recording method of the fourth embodiment, a method is realized in which printing operations can be performed at high speed and, moreover, good printing can be performed stably over a long period of time.

As shown in FIG. 14, the mechanical parts of the apparatus for realizing this print recording method are the same as those in the previous embodiment. That is, in this method, the ink medium 51 shown in FIG. 9 is used as the ink medium.

A signal applying electrode 71 is brought into pressure contact with the surface of the ink medium 51 on the ink support 14 side.

The signal applying electrode 71 is formed by fixing a large number of needle-like electrodes 72 with an epoxy resin (not shown).

Each of the needle electrodes 72 is connected to a corresponding output terminal of a driver mounted on the head body, also not shown. The recording paper 21 is placed on the other side of the ink medium 51 (thermofusible ink layer 17) by the back pressure drive roll 2.
5. When the back pressure contact driving roll 25 rotates in the direction of the arrow 73, the ink medium 51 and the recording paper 21 are transported in the sub-scanning direction 26.

Now, when a voltage is applied to the needle electrode 72, the current flows from the ink support 14 to the return electrode 16 in the thickness direction of the ink medium 5.1, causing the energized portion of the heating resistor layer 15 to generate heat. . The thermal energy generated by this heat generating portion is approximately equal to the integral value of the flowing current. That is, printing is performed on the recording paper 21 according to the temperature distribution generated by this thermal energy.

Conventionally, a pulse signal having a voltage or current waveform as shown in FIG. 15A has been applied to the signal application electrode 71. The recording paper 21 and the ink medium 51 are sub-scanned at a predetermined speed while this pulse signal is applied. Therefore, the temperature change of the heat-fusible ink layer 17 in the direction of their movement took on a mountain-shaped waveform with a flat top as shown in the same figure.

By the way, FIG. 16 shows the relationship between the temperature rise of the ink constituting the heat-melting ink layer 17 due to energization and the transfer to the recording paper 21.

It can be seen that when the temperature of the ink rises to a certain temperature (glass transition point), the ink undergoes a rapid transition.

This is largely due to the effect of the ink release layer 55.

In this way, images are recorded using binary values of "O" and "1", so if the timing at which the glass transition point is reached differs depending on the printing dots, the dot diameter will vary and the printing density will not be uniform. As shown in FIG. 15B, the temperature of the ink does not necessarily rise rapidly, so the timing at which it reaches the glass transition point varies, which can prevent slight fluctuations in print density. Of course, if the overall voltage of the applied pulses were increased to allow a large current to flow in a short period of time, the temperature rise would be improved, but this would result in a larger power supply and an increase in the price of the printing device. In addition, when a high voltage pulse is used, there is a problem in that the ink medium 51 is seriously damaged, and in printing devices that can be reused by reapplying ink, the reuse life is shortened. .

Therefore, in this fourth embodiment, variations in the dispersion of ink in the heat-melting ink layer 17, local variations in surface (interface) physical properties, or surface properties of the recording paper 21,
1 and other conditions such as variations in the pressing force of the hot-melt ink layer 17, this eliminates variations in the diameter of printed dots due to variations in the glass transition point.

This will be explained based on FIG. 17. In this embodiment, as shown in FIG. 1A, a pulse voltage having a peak at both the rise and fall of the voltage is applied to the signal application electrode 71, and the current conduction characteristics are also set almost in the same way.

As a result, the temperature characteristics of the heat-melting ink layer 17 are as shown in FIG.
The temperature rises rapidly. As a result, the timing of ink transfer is aligned, and the diameter of the printed dot is also stabilized.

In this embodiment, the voltage is set higher than usual at both the rising and falling parts of the applied pulse, and set lower than usual at the central part, but other modifications are possible. For example, as shown in FIG. 18, the voltage may be set high only for the rising portion. Furthermore, by stopping the conveyance of the recording paper 21, etc. during the time period during which the printing operation is performed, or at least during the first half of the printing operation, the timing of printing can be similarly aligned, and the print density can be made uniform. can.

In this example, the voltages at both peaks of the applied pulse were set to 40V, and the voltage at the center was set to 20V.

Here, the total pulse width of the applied pulse was 400 μs, and the time width of each peak portion was 100 μs.

When the average diameter of the printed dots was 100 .mu.m, the average value of the variation width of the diameter in this case was 7 .mu.m.

Comparing this with a case where the pulse voltage is uniformly 30V and the time width of the applied pulse is 400μm, in this conventional type, when the average diameter of the printed dots is 100μm, the average value of the fluctuation width of the diameter is 15μm. , it can be seen that the present example achieves much more stable printing density.

As explained above, according to the fourth embodiment, the temperature of the heat-melting ink layer increases more rapidly, so that sharp printing can be performed. Furthermore, since the temperature rises rapidly, the recording is stable even when the environmental temperature fluctuates.

"Fifth Embodiment" FIG. 19 is for explaining the fifth embodiment of the present invention.

In this fifth embodiment, the ink medium is preheated in order to achieve higher speed recording. That is, by providing a heating means 81 for preheating the heat-fusible ink layer 17 constituting the ink medium 51, the energy applied during printing is relatively reduced, and the time width of the applied pulse is shortened, thereby increasing the speed. Realize. Therefore, the heating means 81 is heated (preheated) to such an extent that the hot-melt ink layer 17 is not touched.
need to be done.

Incidentally, in a thermal transfer recording type device that uses a thermal head as a print head, it is necessary to make an extremely thin ink donor film as a thermal recording medium. Also,
In an electrical thermal transfer recording type device, the ink itself has a heat generating function, and the control electrode is separated from the ink medium, so the ink donor film is also very thin.

In this way, in the conventional thermal transfer recording method, even if an attempt is made to achieve high-speed printing by preheating before the printing operation and reducing the applied energy during printing, the ink donor film is thin and its mechanical strength is weak. Also, due to the small heat capacity, there was a risk of deformation or breakage. Further, the heat resistance of the ink donor film itself may not be sufficient in some cases, and in this case, deterioration, thermal expansion, or thermal contraction may occur, which may adversely affect image reproduction.

In the print recording method of the present invention, the ink support 14 is strong, has excellent heat resistance, and has a large heat capacity, so that it does not deform or
Inconveniences such as deterioration and breakage can be eliminated.

The characteristics of the ink medium 51 used in this embodiment will be briefly described below. The ink support 14 is a 2° ink support 14 that is an anisotropic conductor having an electrical conductivity of 10:1 or more in the thickness direction and the surface direction, preferably 1000:1 or more.
The resistance value in the thickness direction is 1000 or less, preferably 10Ω
It is as follows. The thickness of the ink support 14 is 1 μm or more.

The heating resistance layer 15 has a specific volume resistivity of 10-1Ω'
cm or more and 104 Ω-cm or less, preferably 10 Ω-cm
It is a substance with a resistance of at least 103 Ω・cm and a thickness of 100 Ω・cm or less.
OA or more and 20μm or less, preferably 400OA or more and 1μm
It is desirable that it be less than m.

The volume resistance value of the heat generating resistive layer 150 is 10 as a stable resistive film condition with high reliability.
A film thickness of 00 Å or more, preferably 4000 Å or more is required. Since heat generation and thermal conductivity are good when the film thickness is 1 μm or less, in order to apply a pulse and perform a printing operation at that film thickness, the volume resistivity must be within the appropriate range, that is, 10
A value of Ω·cm or more and 10 3 Ω·cm or less is desired.

The return electrode 16 has a volume resistivity of 1 higher than that of the heating resistance layer 15.
Comprised of substances with a value of 1/0 or less, 200°C
It must have a heat resistance of the above.

The ink peeling layer 55 has a surface characteristic having a value lower than the critical surface tension rc of the surface of the recording paper 21 as a transfer body, and is preferably as thin as possible.

The thickness is preferably 10 μm or less, and 1 μm or less is sufficient. Critical surface tension γ. The value is 38dyne/c
m or less is better. The heat-melting ink layer 17 is preferably made of a thermoplastic material, with a melting point of 2006C or less and a glass transition point of 120°.
It is better to use a polymer substance of C or lower as the basic material and to mix or dissolve a coloring material therein.

Experimental Example 4 In this experimental example, the ink support 14 was created as follows. That is, Nl wires coated with gold vapor deposition with a diameter of 15 μm are arranged vertically so that one or more wires are present in an area of 40 μm x 40 μm, fixed with a room temperature curing silicone elastomer, and both sides are precisely finished with a surface accuracy of 300 Å or more. Polished. The resistance value of the ink support 14 in the thickness direction was 0.7Ω, and the resistance value in the planar direction was 1014Ω or more.

Next, this ink support 14 is thoroughly washed and dried,
The degree of vacuum was set at 2 x 10-'torr in a vacuum chamber. Next, after introducing argon gas, a TaN target containing 20 wt% of SiO2 was sputtered by high-frequency sputtering under a pressure of 3.times.10@-3 torr, and a heat generating resistive layer 15 of 6500 A with a resistance value of 80 Ω/10 mm was provided. On this heat generating resistor layer 15, 500 Cr and -
2,000 layers of Cu were deposited by electron beam evaporation to form the return electrode 16.

Next, a film with a thickness of 3 μm was made of Teflon resin, and an ink peeling ti55 with a critical surface tension of 2 Qdyne/cm was provided on the return electrode 16.

The signal applying electrode 24 for signal control has a diameter of 90 mm.
Micrometer needle electrodes were arranged in a line at a density of 8 electrodes/mm.

In this experimental example, a heat roll fuser for heat fixing, which is commonly used in electronic copying machines, was used as the heating means 81. And the surface of the heat roll passenger is 406C or more 1
The ink medium 51 was preheated from the heat-melting ink layer 17 side to 106C or less. Preheated thermofusible ink layer 1
7, when a voltage was applied for a time width of 100 .mu.s at an applied voltage of 10.mu., good printed dots with a diameter of 100 .mu.m were obtained.

For comparison, printing was performed under the same conditions without using a heat roller printer.

As a result, it was found that in order to obtain printed dots with a diameter of 100 μm, it was necessary to apply a voltage of 40 V to the signal application electrode 24 for 100 μs. If the applied voltages are made equal, in this embodiment, the time width of the applied pulse can be shortened by that amount, and the printing speed can be increased.

In the experimental examples described above, a heat roll fan was used as the heating means, but the heating means is not limited to this. For example, the ink medium 51 may be preheated using an infrared lamp, or uniform heating using a laser beam is also effective.

In this way, in this fifth embodiment, since the ink medium preheating means is provided, the drive circuit for driving the signal application electrode 24 can be downsized.

Furthermore, even in cold regions or during winter, it is possible to always ensure good printing operation regardless of the environment.

[Effects of the Invention] As explained above, according to the present invention, the following advantages are achieved because the signal applying electrode and the return electrode are arranged so as to sandwich the ink medium therebetween.

■Enables printing with low energy.

Efficiency is high because current flows in only one direction through the heating resistance layer. Therefore, in this respect as well, it is possible to increase the speed of printing.

■Good color reproducibility.

The heat-melting ink layer does not need to function as a current path, and the range of ink selection is widened, making it easy to control the color tone of the ink and stabilizing the color characteristics.

■The ink medium is mechanically strong.

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.

[Brief Description of the Drawings] Figures 1 to 7 are for explaining the first embodiment of the present invention. Of these, Figure 1 shows a printing device to which the print recording method of this embodiment is applied. Schematic configuration diagram, Figure 2 is a sectional view showing the structure of the ink medium, Figure 3 is a principle diagram showing the principle of print recording, Figure 4 is a plan view of the ink support, and Figure 5 is a cross section of the ink support. Fig. 6 is a principle diagram showing the principle of measuring resistance value, Fig. 7 is a measurement circuit diagram showing the configuration of a measuring circuit for this purpose, and Figs. 8 to 10 show a second embodiment of the present invention. Figure 8 is a schematic configuration diagram of a printing device to which the print recording method of this embodiment is applied, Figure 9 is a sectional view showing the configuration of the ink medium, and Figure 10 is a heat generating resistor layer. Various waveform diagrams showing applied pulses for energization control, 1st
Figures 1 to 13 are for explaining the third embodiment of the present invention, of which Figure 11 is an explanatory diagram showing the main parts of a printing device to which the print recording method of this embodiment is applied; Figure 12 is an explanatory diagram for explaining current control and thermal energy transfer status, Figure 13 is a principle diagram showing the principle of gradation expression, and Figures 14-
FIG. 18 is for explaining the fourth embodiment of the present invention, of which FIG. 14 is an explanatory diagram showing the main parts of a printing device to which the print recording method of this embodiment is applied, and FIG. 15A 17 is a waveform diagram of a conventional applied pulse, B is a characteristic diagram showing changes in ink temperature, FIG. 16 is a characteristic diagram showing ink temperature and its transition state, and FIG. 17A is an applied pulse in this embodiment. Figure B is a characteristic diagram showing the temperature change of the ink.
Fig. 8 is a waveform diagram showing another example of applied pulses, Fig. 19 is a principle diagram of a printing device to which the print recording method according to the fifth embodiment of the present invention is applied, and Fig. 20 is a principle of a conventional print recording method. It is a diagram. 13.51...Ink medium, 14...Ink support, 15...Heating resistance layer, 16...Return electrode, 17...・
Heat-melting ink layer, 21...Recording paper, 24.61.71...Signal application electrode, 37...
...Pulse oscillator, 55 ... Ink release layer, 62.72 ... Needle electrode, 81 ... Heating means.

Claims (1)

[Scope of Claims] 1. A layered ink support having higher conductivity in the thickness direction than in the planar direction, a heat generating resistor layer superimposed on the other surface of the ink support and generating heat when energized; a return electrode that is in electrical contact with the surface of the heat-generating resistor layer that is not overlapped with the ink support; and an ink that is formed on the opposite surface of the return electrode and is melted by the heat generated by the heat-generating resistor layer. A voltage is applied to the surface of the ink medium on the support side in accordance with an image signal, and the return electrode is kept at a predetermined potential for at least the voltage application time, 1. A printing and recording method comprising forming an image according to image information by transferring a portion of ink melted by selective heating of the heat generating resistive layer to a recording sheet overlaid on an ink layer. 2. The print recording method according to claim 1, wherein an ink release layer is formed between the return electrode and the ink layer to separate the ink layer. 3. The print recording method according to claim 1, wherein the return electrode is grounded. 4. The print recording method according to claim 1, wherein a predetermined voltage is applied to the return electrode in synchronization with the application of the image signal to the ink support. 5. The print recording method according to claim 1, wherein the ink layer is heated to a temperature that does not melt the ink layer prior to application of the image signal. 6. The voltage applying means for applying a voltage to the surface of the ink medium on the support side in accordance with an image signal is an electrode array in which a plurality of needle-like electrodes are arranged in parallel, and voltage is applied to these needle-like electrodes in accordance with the image signal. 2. The print recording method according to claim 1, wherein: is selectively applied. 7. The print recording method according to claim 1, wherein the voltage applied to the support side surface of the ink medium in accordance with the image signal is a pulsed voltage. 8. The printing and recording method according to claim 6, wherein the shape of each end face of the needle-shaped electrode that comes into sliding contact with the support layer of the ink medium is elongated in the length direction of the electrode array. 9. The print recording method according to claim 7, wherein the pulsed voltage has a voltage waveform having peaks both near its rise and near its fall.