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(11) | EP 0 129 379 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Media and method for printing |
| (57) Media and method for printing which is so constructed that on one main surface of
a heat-conductive layer of electric-insulating property are successively laminated
a first conductive layer, a resistive layer, and a second conductive layer, media
for printing having an ink layer laminated on the other main surface of the heat-conductive
layer is superposed at the ink layer side on an object to be printed, and an electrode
is brought into press-contact with the surface of the second conductive layer, so
that electric signals are applied between the electrode and the first conductive layer,
thereby enabling the printing of images corresponding to the electric signals. |
[0001] This invention relates to a printing method for printing on an object to be printed patterns or picture images converted into electric signals.
[0002] Conventionally, many methods have been well known which print onto an object to be printed the patterns or picture images converted into electric signals. For example, there has been a method called xerography which converts electric signals to optical signals before printing on paper the patterns or picture images.
[0003] A method called the wire-dot matrix impact printer has also hitherto been used which impacts an ink ribbon by a thin wire to print out paper. Further, a method called the ink-jet which jets drops of liquid ink from a nozzle so as to print the patterns or picture images, that of printing the same on a heat-sensitive paper by use of a thermal head, and that of flowing a current from an electrode pin onto an electro- sensitive paper to break a metallic film and print onto paper the patterns or picture images, have hitherto been used.
[0004] These methods, however, are defective respectively. For example, the xerography method is complicated in imaging to enlarge an apparatus and also need good maintenance. The wire-dot method improves no resolution because of mechanically making one dot so that the printed characters or patterns are not of so good quality and the printing speed is slow. The method of ink-jet causes clogging at a thin nozzle bore and is slow in speed, The method using the heat-sensitive paper is slow in speed. A thermal transfer method for printing on ordinal paper has been proposed which superposes on ordinal paper a sheet coated with heat- melting ink and then heats them by the thermal head for printing, but is defective in the resolution and speed.
[0005] Also, the electro-carbon-transfer method has hitherto been well known (the Journal of the Institute of Image Electronics Engineers of Japan, Vol. 11, No. 1 Pages 3 - 9, 1982), which uses a printing medium comprising a second conductive layer of resin containing copper powder, a resistive layer of resin containing carbon powder, and a first conductive layer of vapor deposition film of aluminum or the like, successively in layers. This printing method is that an electrode is brought into contact with the upper surface of the second conductive layer and voltage is applied between the electrode and the first conductive layer, at which time the applied voltage heats and breaks down the resistive layer and first conductive layer so that a part of carbon powder contained in the resistive layer is adhered to an object to be printed when existing at the first conductive layer side. Such phenomenon occurs in a short time to result in that relatively high speed printing is possible. In other words, the printing was possible at the speed of 100 µs/dot more than ten times the printing speed by use of thermal head, such as heat-sensitive method or thermal transfer method. Also, there has been a method of reducing an amount of carbon on the resistive layer, using not-black conductors, and coating color ink on the first conductive layer, so that,when voltage is applied, both the resistive layer and conductive layer are broken to scatter the color ink to thereby also enable the color image printing. However, in order to obtain the conductivity enough to carry out heat-breakdown, carbon need be mixed to a certain extent and therefore the color ink is mixed with the carbon when broken and scattered, to be a cloudy color.
[0006] An object of the invention is to provide a medium and a method for printing, which eliminate the above conventional defects and enable high speed printing and also color printing.
[0007] A medium for printing according to the invention comprises: a heat-conductive layer having an electrical insulating property; a resistive layer formed on one surface of said heat-conductive layer; a conductive layer formed on said resistive layer; and an ink layer formed on the other surface of said heat-conductive layer.
[0008] By using this printing medium, a method of printing according to the invention comprises the steps of: providing the printing medium; putting said printing medium on an object to be printed so that a surface of said ink layer contacts a surface of said object to be printed; contacting an electrode on a surface of said conductive layer; and applying a voltage between said electrode and said resistive layer so that a current flows through said electrode, said conductive layer and said resistive layer to heat said resistive layer at a position below said electrode to molten said ink layer at a position below said electrode, whereby the molten ink is printed on said object to be printed at a position below said electrode.
[0009] Further, more preferably, a medium for printing according to the invention comprises: a heat-conductive layer having an electrical insulating property; a first conductive layer formed on one surface of said heat-conductive layer; a resistive layer formed on said first conductive layer; a second conductive layer formed on said resistive layer; and an ink layer formed on the other surface of said heat-conductive layer.
[0010] By using this printing medium, a method of printing according to the invention comprises the steps of : providing the printing medium; putting said printing medium on an object to be printed so that a surface of said ink layer contacts a surface of said object to be printed; contacting an electrode on a surface of said second conductive layer; and applying a voltage between said electrode and said first conductive layer so that a current flows through said electrode, said second conductive layer and said first conductive layer to heat said resistive layer at a position below said electrode to molten said ink layer at a position below said electrode, whereby the molten ink is printed on said object to be printed at a position below said electrode.
[0011] A further method of printing according to the invention comprises the steps of: providing a first printing medium having a resistive layer; providing a second printing medium comprising a heat-conductive layer and an ink layer; putting said first printing medium on said second printing medium so that one surface of said first printing medium contacts a surface of said heat-conductive layer;
[0012] putting said second printing medium on an object to be printed so that a surface of said ink layer contacts a surface of said object to be printed; contacting an electrode on the other surface of said first printing medium; and applying a voltage between said electrode and the surface of said first printing medium contacting said heat resistive layer so that a current flows through said electrode and said resistive layer to heat said resistive layer at a position below said electrode to molten said ink layer at a position below said electrode, whereby the molten ink is printed on said object to be printed at a position below said electrode.
[0013] The above and other objects and novel features of the invention will more fully appear from the following detailed description in accordance with the accompanying drawings.
Fig. 1 is an enlarged sectional view of an embodiment of a medium for printing of the invention,
Fig. 2 is a schematic view explanatory of the printing method using the medium for printing in Fig. 1,
Fig. 3 is an enlarged sectional view of a modified embodiment of a medium for printing of the invention,
Fig. 4 is an enlarged sectional view of another modified embodiment of a medium for printing of the invention,
Fig. 5 is a schematic view explanatory of a printing method using the medium for printing in Fig. 4,
Fig. 6 is an enlarged sectional view of a modification of the medium for printing in Fig. 4, and
Fig. 7 is an enlarged sectional view of another modification of the medium for printing in Fig. 4, different from that in Fig. 6.
[0014] Referring to Fig. 1, reference numeral 101 designates a heat-conductive layer having anelectrical insulating property, which is a thin plastic sheet of about 5 to 50 µm in thickness, for example, polyester terephthalate or polyvinyl chloride; 102 designates a first conductive layer, which is preferably a metallic vapor-coating film of 500 to 1000 1, such as Al; 103 designates a resistive layer of resin of 1 to 50 µm in thickness and containing conductive powder, the conductive powder being preferably metallic powder or carbon; and 104 designates a second conductive layer which comprises resin of 1 to 50 µm in thickness and contains conductive powder. The resistive layer 103 is adjusted to be larger in a thickness resistance value than the second conductive layer 104. The second conductive layer 104 and resistive layer 103 are adjusted to be larger in length resistance than the first conductive layer 102. The relation between the resistance values is the same as in the electro-carbon-transfer printing media detailed in the aforesaid Journal of the Institute of Image Electronics Engineers of Japan, Vol. 11, No. 1 Pages 3 to 9 (1982) in which the construction and material for the second conductive layer and resistive layer are also detailed. Also, 105 designates an ink layer made of low-melting-point resin mixed with color or black pigment or dye (for example, wax or not- hardening epoxy resin) or of resin mixed with thermal-sublimating dye.
[0015] Next, a printing method using the medium for printing in Fig. 1 will be described in accordance with Fig. 2. The medium for printing, as shown in Fig. 2, is superposed on an object 206 (such as paper) to be printed, an electrode 207 is press-contacted with a second conductive layer 204, and voltage from a power source 208 is applied between the electrode 207 and a first conductive layer 202. Hence, a current flows in the second conductive layer 204 as shown by 209 in Fig. 2 to heat the resistive layer 203 in part (a portion 210), whereby an ink layer 211 just below the portion 210 is molten by heating through the heat-conductive layer, or the sublimating dye sublimates, to thereby adhere to the object 206 to be printed. The adhering amount relates to an amount of flowing current or the flowing time thereof. Thereafter, when the medium for printing are removed from the object to be printed, the printing is completed. In this case, the heat-conductive layer 201 prevents the debris of resistive layer caused by energization from adhering to the object to be printed, thereby obtaining distinct dot pattern and color .
[0016] In addition, the object to be printed is not defined to the paper as in the above-mentioned embodiment. For example, plastic or metal may apparently be applicable.
Example 1
[0017] A polyethylene terephthalate sheet of 10 µm in thickness was used as the heat-conductive layer, on one main surface of which was formed an aluminum 0 vapor coating film of 600 A as the first conductive layer. The surface resistance of the aluminum vapor coating film was 7 to 10 Ω/sq.
[0018] The composition of:
was formed as the resistive layer of 10 pm in thickness on the first conductive layer. The surface resistance of this resistive layer was 2 x 104 Ω/sq.
[0019] Next, the composition of:
was formed as the second conductive layer of 15 µm in thickness on the low resistive layer. The surface resistance of this resistive layer was 2 x 1012 Ω /sq.
[0020] Next, the composition of:
Polyvinyl chloride acetate copolymer:
was formed as the low-melting-point resin ink layer of 5 pm in thickness on the other main surface of heat-conductive layer. Thus a medium for
printing which is a laminated object in five layers of 45 µm in thickness as a whole
was obtained.
[0021] The thus obtained medium for printing was superposed on a sheet of ordinary paper and set up as shown in Fig. 2 and was applied with a voltage of 100 V for 0.1 msec.
Example 2
[0024] A medium for printing using another ink layer was obtained in the same way as that of Example 1. Cyanic color sublimating dye ink of the composition of:
was coated as the ink layer and dried to form a film of 1 um in thickness.
[0025] The thus obtained medium for printing was set up on a sheet of ordinary paper as shown in Fig. 2 and was applied with a voltage of 100 V for 0.1 msec. As the result a dot of clean cyanic color was printed on the paper.
[0026] In the above examples, butyral resin was used as the binder of the second conductive layer or resistive layer, but the binder is not limited to butyral resin. For example, polyvinyl chloride, polyethylene, polyurethane, ethylene-vinyl acetate copolymer, polystyrene, polypropylene, or polyvinyl acetal, may be usable as the binder. Also, as the conductive powder added to the second conductive layer and resistive layer, powder of zinc oxide tin oxide, aluminum, tin, gold or silver may be used. Also, the following sublimating dyes may be used, for example, so as to obtain the three primary colors. Yellow
[0028] In addition, in the above example examples, the object to be printed was paper or the like, but other materials may be used. For example, when the distinct printing is intended to be obtained by use of sublimating dye, the object to be printed is preferably not-ordinary paper but paper or plastic sheet coated on the surface with a developer. These include a plastic sheet coated on the surface of which is coated, for example, Japanese acid clay, fine grain powder of silica, or fine grain powder of 2-acrylamide-2-methylpropane sulfonic acid or the like, through polyvinyl alcohol, casein, polyester, styrenebutadiene copolymer, and the like or the same coated or laminated only with a resin layer of polyester or poly-2-acrylamide-2-methyl propane sulfonic acid or the like.
[0029] Referring to Fig. 3, reference numeral 301 designates a heat-conductive layer having an electrical insulating property, which is a thin plastic sheet of about 5 to 50 µmin thickness. For example, polyester terephthalate or vinyl chloride is usable as the heat-conductive layer. Reference numeral 302 designates a resistive layer of resin of about 1 to 50 µm in thickness, containing conductive powder which is preferably metallic powder or carbon. Reference numeral 303 designates a conductive layer of resin of 1 to 50 µm in thickness, containing conductive powder in the same way as the resistive layer 103 in Fig. 1. The resistive layer 302 is adjusted to be larger in a thicknesswise resistance value than the conductive layer 303. This construction is equivalent to that obtained by omitting the first conductive layer from the medium for printing comprising five layers as shown in Fig. 1, the resistive layer 302 being used also as the first conductive layer in Fig. 1. Reference numeral 304 designates an ink layer the same as in the medium for printing in Fig. 1.
[0030] Since the printing method using the medium in Fig. 3 is quite the same as that using the medium in Fig. 1, its explanation is omitted here.
Example 3
[0031] On one main surface of a sheet of polyethylene terephthalate of 9 µm thick used as the heat-conductive layer, the composition of:
was coated and dried to be 5 µm in film thickness after dried, to form a resistive layer.
[0032] Next, on the above resistive layer, the composition of:
was coated and dried to be 20 µm in film thickness, to form a conductive layer.
[0034] Polyvinyl chloride acetate copolymer:
was coated to be of 5 µm in film thickness, to obtain a medium for printing.
[0035] The thus obtained medium for printing was set up on a sheet of ordinary paper as shown in Fig. 2, and applied with a voltage of 200 V for 100 p sec. As the result, a distinct black dot was printed or the paper.
[0036] Next, explanation will be given on another modified embodiment of a medium for printing and printing method of the invention. Referring to Fig. 4, this medium for printing comprises two separate sheets which are equivalent to those obtained by dividing the media for printing in Fig. 1 into the heat-conductive layer 101 and first conductive layer 102 at the boundary
[0037] therebetween. Such a construction is easy to be applied with a voltage because the first conductive layer is exposed to the exterior. A first printing medium 406 comprises a first conductive layer 401, a resistive layer 402, and a second cnductive layer 403, the respective layers being the same as the first conductive layer 102, resistive layer 103 and second conductive layer 104 in Fig. 1, where, in this case, these three layers form one sheet. A second printing medium 407 ; comprises a heat-conductive layer 404 serving also as a support, and an ink layer 405, the heat-conductive layer 404 being preferably a thin plastic sheet of about 5 to 50 µm thick, for example, polyethylene terephthalate or polyvinyl chloride. The ink layer 405 coated on the layer 404 is made of low-melting-point resin (e.g. wax or not- hardening epoxy resin) mixed with color or black pigment or dye or resin mixed with sublimating dye.
[0038] Now, explanation will be given on the printing method using the medium for printing of Fig. 4 with reference to Fig. 5. In Fig. 5, the surface of the second conductive layer 501 of the first printing medium 506 is superposed on the surface of the heat-conductive layer 504 of the second printing medium 507,and further the surface of the ink layer 505 of the second printing medium 507 is superposed on an object 508 te.g. paper or the like) to be printed. In other words, the first printing medium 506 is superposed on the second printing medium 507, and the second printing medium is superposed on the object 508 to be printed. An electrode 509 is brought into contact with the second conductive layer 503 of the first printing medium, and a grounding roller 510 is brought into contact with the first conductive layer 501 of the first printing medium 506. A voltage from a power source 511 is applied between the electrode 509 and the grounding roller 510 so that a current flows therebetween. The current heats or sometimes breaks a part 512 of the resistive layer 502 just below the electrode 509'
[0039] The heat generated at this time passes through the heat-conductive layer 504 of the second printing medium 507 and raises the tenperature of a part 513 of the ink layer 505. In a case where the ink layer 505 is formed of heat-molten ink, the ink is molten by the temperature rise and adheres to the surface of the object to be printed. Thereafter, the object 508 and the second printing medium 507 together with the first conductive layer 506 are peeled off and a part 508 of the thermally transfered ink remains on the surface of the object to be printed, thereby completing the printing. In this case, debris of the resistive layer caused by energization is prevented from adhering to the object to be printed, so that a distinct dot formation and color can be obtained. Since the first conductive layer 501 of the first medium for printing is exposed, the electrical connection of low contact resistance can be obtained ty a simple grounding roller or the like. This eliminates the problem of heating at the portion of the grounding roller in comparation with the conventional grounding method of using a grounding roller having a contact area larger than that of an electrode at the same side as the electrode 509 (on the surface of the second conductive layer with the surface of second conductive layer).
[0040] Incidentally, in the aforesaid description, the first medium for printing is of three layers, but other constructions are possible. Fig. 6 shows a modified construction of the first medium for printing in Fig. 4. Reference numeral 601 designates a resistive layer, and 602 designates a conductive layer. Inother words, the first conductive layer is omitted from the first medium for printing in Fig. 4. The printing method using the medium for printing of Fig. 6 is the same as shown in Fig. 5.
[0041] Fig. 7 shows another modified construction of the first medium for printing. Reference numeral 701 designates a first conductive layer, 702 designates a resistive layer, 703 designates a second conductive layer, and 704 designates a protective layer. In other words, the protective layer 704 is provided on the surface of the first conductive layer of the first medium for printing in Fig. 4. The protective layer 704 is preferably a resin film to thereby prevent the first conductive layer from corroding due to humidity or the like.
Example 4
[0042] On a glass substrate, the composition of:
was coated and dried to form a second conductive layer of 25 µm in film thickness. On this conductive layer, the composition of:
was coated and dried to be of 15 µm in film thickness, to obtain a resistive layer. Fur-0 ther, aluminum was vacuum-deposited in 400 A thickness to form a conductive layer and then a film in three layers was peeled off from the glass substrate, thereby obtaining a first medium for printing.
[0043] Next, on a polyethylene terephthalate sheet of 9 µm thick, the conposition of:
Polyvinyl chloride acetate copolymer:
were coated to be of 5 µm in film thickness, to obtain a second medium for printing.
[0044] The first and second media for printing and a sheet of ordinary paper were set up as shown in Fig. 5 and a voltage of 100 V was applied to the first medium for 200 p sec. As the result, a distinct black dot was printed on the paper.
Example 5
[0045] Onto a polyethylene terephthalate sheet of 9 µm thick, the composition of:
Sublimating dye (magenta)
was coated and dried to be of 1 µm in film thickness to obtain a second medium for
printing.
[0046] This second medium for printing and the first medium for printing obtained in the Example 4 were set up as shown in Fig. 2 and a voltage of 70 V was applied to the first medium for 1 msec. As the result, a clean magenta dot was printed on the paper.
Example 6
[0047] Onto a glass substrate, the composition of:
was coated and dried to be of 20 µm in film thickness to form a conductive layer. On this layer, the composition cf:
was coated and dried to be of 5 µm in film thickness , to form a resistive layer. Then, the film in two layers was peeled off from the glass substrate to thereby obtain a first medium for printing.
[0048] The thus obtained first medium for printing and the second medium for printing obtained in the example 4 were set up cn a sheet of ordinary paper as shown in Fig. 5 and a voltage of 200 V was applied to the first medium for 100 p sec. As the result, a distinct dot was printed on the ordinary paper.
[0049] Although several embodiments have been described, they are merely exemplary of the invention and not limit the scope of the invention. It should be understood that various changes and modifications are made without departing from the scope of the invention which is defined solely by the appended claims.
1. A medium for printing comprising:
a heat-conductive layer having an electrical insulating property;
a resistive layer formed on one surface of said heat-conductive layer;
a conductive layer formed on said resistive layer; ana an ink layer formed on the other surface of said heat-conductive layer.
2. The medium according to claim 1, wherein said ink layer comprises a low melting
point resin containing dye cr pigment.
3. The medium according to claim 1, wherein said ink layer comprises a resin containing
sublimating dye.
4. The medium according to claim 1, wherein the thickness of said heat-conductive
layer in 5-50 µm .
5. A medium for printing comprising:
a heat-conductive layer having an electrical insulating property;
a first conductive layer formed on one surface of said heat-conductive layer;
a resistive layer formed on said first conductive layer;
a second conductive layer formed on said resistive layer; and
an ink layer formed on the other surface of said heat-conductive layer.
6. The medium according to claim 5, wherein said ink layer comprises a low melting
point resin containing dye or pigment.
7. The medium according to claim 5, wherein said ink layer comprises a resin containing
sublimating dye.
8. The medium according to claim 5, wherein the thickness of said heat-conductive
layer is 5-50µm .
9. A method of printing comprising the steps of:
providing a printing medium comprising a heat-conductive layer having an electrical insulating property, a resistive layer formed on one surface of said heat-conductive layer, a conductive layer formed on said resistive layer, and an ink layer formed on the other surface of said heat-conductive layer;
putting said printing medium on an object to be printed so that a surface of said ink layer contacts a surface of said object to be printed;
contacting an electrode on a surface of said conductive layer; and
applying a voltage between said electrode and said resistive layer so that a current flows through said electrode, said conductive layer and said resistive layer to heat said resistive layer at a position below said electrode to molten said ink layer at a position below said electrode, whereby the molten ink is printed on said object to be printed at a position below said electrode.
10. The medium according to claim 9, wherein said ink layer comprises a low melting
point resin containing dye or prigment.
11. The medium according to claim 9, wherein said ink layer comprises a resin containg
sublimating dye.
12. The medium according to claim 9, wherein the thickness of said heat-conductive
layer is 5-50 µm.
13. A method of printing comprising the steps of:
providing a printing medium comprising a heat-conductive layer having an electrical insulating property, a first conductive layer formed on one surface of_said heat-conductive layer, a resistive layer formed on said first conductive layer, a second conductive layer formed on said resistive layer, and an ink layer formed on the other surface of said heat-conductive layer;
putting said printing medium on an object to be printed so that a surface of said ink layer contacts a surface of said object to be printed;
contacting an electrode on a surface of said second conductive layer; and
applying a voltage between said electrode and said first conductive layer so that a current flows through said electrode, said second conductive layer and said first conductive layer to heat said resistive layer at
a position below said electrode to molten said ink layer at a position below said electrode, whereby the molten ink is printed on said object to be printed at a position below said electrode.
14. The medium according to the claim 13, wherein said ink layer comprises a low melting
point resin containing dye or pigment.
15. The medium according to claim 13, wherein said ink layer comprises a resin containing
sublimating dye.
16. The medium according to claim 13, wherein the thickness cf said heat-conductive
layer is 5-50 pm .
17. A method of printing comprising the steps of:
providing a first printing medium having a resistive layer;
providing a second printing medium comprising a heat-conductive layer and an ink layer;
putting said first printing medium on said second printing medium so that one surface of said first printing medium contacts a surface of said heat-conductive layer;
putting said second printing medium on an object to be printed so that a surface of said ink layer contacts a surface of said object to be printed;
contacting an electrode on the other surface of said first printing medium; and
applying a voltage between said electrode and the surface of said fist printing medium contacting said heat resistive layer so that a current flows through said electrode and said resistive layer to heat said resistive layer at a position below said electrode to molten said ink layer at a position below said electrode, whereby the molten ink is printed on said object to be printed at a position below said electrode.
18. The method according to claim 17, wherein said first printing medium comprises
said resistive layer and a conductive layer formed on one surface of said resistive
layer, the other surface of said resistive layer, the other surface of said resistive
layer being the surface for contacting the surface of said heat-conductive layer.
19. The method according to claim 17, wherein said first printing medium comprises
said resistive layer, a first conductive layer formed on one surface of said resistive
layer, and a second conductive layer formed on the other surface of said resistive
layer, a surface of said first conductive layer being the surface for contacting the
surface of said heat-conductive layer.
20. The method according to claim 17, wherein said first printing medium comprises
said resistive layer, a first conductive layer formed on one surface of said resistive
layer, a second conductive layer formed on the other surface of said resistive layer,
and a protective layer formed on a surface of said first conductive layer, a surface
of said protective layer being the furface for contacting the surface of said heat-conductive
layer.