Embodiment
The capacitive touch screen of the embodiment of the present invention is described in detail below with reference to accompanying drawing.
Refer to Fig. 1 and Fig. 2, first embodiment of the invention provides a kind of capacitive touch screen 10, and this capacitive touch screen 10 comprises a cover plate 11 (Cover Glass), a transparency conducting layer, at least one first drive electrode 14a and at least one second drive electrode 14b.Described cover plate 11 has a first surface 111 and the second surface 112 relative with first surface 111.Described first surface 111 is touch-control surface.Described transparency conducting layer is a carbon nanotube layer 13.Described carbon nanotube layer 13 directly adheres to the second surface 112 of cover plate 11 by an adhesive layer 12.Described carbon nanotube layer 13 has conduction anisotropy to define a Low ESR direction D.Carbon nanotube layer 13 has relative first side 131 and second side 132, and described Low ESR direction D is for point to second side 132 by first side 131.Described at least one first drive electrode 14a is arranged at first side 131, and is electrically connected with carbon nanotube layer 13.Described at least one second drive electrode 14b is arranged at second side 132, and is electrically connected with carbon nanotube layer 13.
Described cover plate 11 is the transparency carrier of a curved face type or plane.This cover plate 11 is formed by the hard materials such as glass, quartz, adamas, polycarbonate, polyethylene terephthalate (PET) or plastics or flexible material.Described cover plate 11 mainly plays a part to support.In the present embodiment, cover plate 11 is rectangle glass.
Described carbon nanotube layer 13 comprises multiple being parallel to each other and the carbon nano-tube be axially arranged of preferred orient in the same direction.Described carbon nanotube layer 13 can be one deck carbon nano-tube film or multiple mutually stacked carbon nano-tube film.When described carbon nanotube layer 13 is multiple mutually stacked carbon nano-tube film, the carbon nanotube arrangement direction in adjacent two carbon nano-tube films is identical.Most of carbon nano-tube in carbon nano-tube film joins end to end along the direction that carbon nano-tube extends and axially substantially to extend along same direction preferred orientation.Further, this carbon nano-tube film comprises multiple carbon nano-tube bundle be arranged of preferred orient in the same direction, and this carbon nano-tube bundle has substantially equal length and is arranged in continuous print carbon nano-tube film end to end.
Because described carbon nano-tube has good electric conductivity along the axial direction being parallel to carbon nano-tube, therefore, the resistivity being parallel to the direction of the axis of wherein carbon nano-tube of carbon nanotube layer 13 is much smaller than other directions, and this direction is defined as Low ESR direction D.In the present embodiment, described first side 131 and second side 132 are perpendicular to Low ESR direction D.The resistivity in the direction of the axis perpendicular to carbon nano-tube of carbon nanotube layer 13 is much larger than other directions, and therefore this direction can be defined as a high impedance direction H further.In addition, substantially in the most of carbon nano-tube extended in the same direction in described carbon nano-tube film, each carbon nano-tube and carbon nano-tube adjacent are in the direction of extension joined end to end by Van der Waals force, and in described carbon nano-tube film, also there is the carbon nano-tube of minority random alignment, the carbon nano-tube of these random alignment can contact with each other with other adjacent carbon nano-tube, thus make this carbon nano-tube film still have electric conductivity at high impedance direction H, just comparatively large at the resistance of this high impedance direction H compared to this carbon nano-tube film of other directions, conductivity is lower.
In the present embodiment, the shape of carbon nanotube layer 13 is corresponding with the second surface 112 of described cover plate 11 with size.Described carbon nanotube layer 13 directly adheres to the second surface 112 of cover plate 11 by adhesive layer 12.
Be appreciated that the shape of described carbon nanotube layer 13 can be selected according to the shape of the touch area of capacitive touch screen 10.In the present embodiment, the touch area of capacitive touch screen 10 is rectangle, and the shape of described carbon nanotube layer 13 is also rectangle.
The preparation method of the carbon nano-tube film in the embodiment of the present invention in carbon nanotube layer 13, mainly comprises the following steps:
Step one: provide a carbon nano pipe array, preferably, this array is super in-line arrangement carbon nano pipe array.
In the present embodiment, the preparation method of super in-line arrangement carbon nano pipe array adopts chemical vapour deposition technique, its concrete steps comprise: (a) provides a smooth substrate, this substrate can select P type or N-type silicon base, or select the silicon base being formed with oxide layer, the present embodiment is preferably the silicon base of employing 4 inches; B () evenly forms a catalyst layer at substrate surface, this catalyst layer material can select one of alloy of iron (Fe), cobalt (Co), nickel (Ni) or its combination in any; C the above-mentioned substrate being formed with catalyst layer is annealed about 30 minutes to 90 minutes by () in the air of 700 DEG C to 900 DEG C; D the substrate processed is placed in reacting furnace by (); be heated to 500 DEG C to 740 DEG C under protective gas; then pass into carbon-source gas reaction about 5 minutes to 30 minutes, growth obtains super in-line arrangement carbon nano pipe array, and it is highly 200 microns to 400 microns.This super in-line arrangement carbon nano-pipe array is classified as multiple parallel to each other and pure nano-carbon tube array that is that formed perpendicular to the carbon nano-tube of substrate grown.By above-mentioned control growth conditions, substantially not containing impurity in this super in-line arrangement carbon nano pipe array, as agraphitic carbon or residual catalyst metal particles etc.Carbon nano-tube in this carbon nano pipe array forms array each other by Van der Waals force close contact.
The hydrocarbon that in the present embodiment, carbon source gas can select the chemical property such as acetylene more active, blanket gas can select nitrogen, ammonia or inert gas.
Step 2: adopt a stretching tool to pull from carbon nano pipe array and obtain a carbon nano-tube film.It specifically comprises the following steps: (a) selectes multiple carbon nano-tube segments of one fixed width from above-mentioned carbon nano pipe array, and the present embodiment is preferably and adopts the adhesive strips contact carbon nano pipe array with one fixed width with multiple carbon nano-tube segments of selected one fixed width; B () to stretch the plurality of carbon nano-tube segment, to form a continuous print carbon nano-tube film along being basically perpendicular to the carbon nano pipe array direction of growth with certain speed.
In above-mentioned drawing process, while the plurality of carbon nano-tube segment departs from substrate gradually along draw direction under a stretching force, due to van der Waals interaction, these selected multiple carbon nano-tube segments are drawn out end to end continuously with other carbon nano-tube segments respectively, thus form a carbon nano-tube film.
This carbon nano-tube film be the multiple carbon nano-tube bundles be arranged of preferred orient join end to end formed the carbon nano-tube film with one fixed width.In this carbon nano-tube film, the bearing of trend of carbon nano-tube is basically parallel to the draw direction of carbon nano-tube film.The method that this uniaxial direct tensile obtains carbon nano-tube film is simple and quick, is suitable for carrying out industrial applications.
In the present embodiment, the size of the substrate that width and the carbon nano pipe array of this carbon nano-tube film grow is relevant, and the length of this carbon nano-tube film is not limit, and can obtain according to the actual requirements.Adopt the substrate grown of 4 inches to surpass in-line arrangement carbon nano pipe array in the present embodiment, the width of this carbon nano-tube film can be 1 centimetre to 10 centimetres, and the thickness of this carbon nano-tube film is 0.01 micron to 100 microns.
Be appreciated that the carbon nano-tube surpassed in in-line arrangement carbon nano pipe array due to the present embodiment is very pure, and due to the specific surface area of carbon nano-tube itself very large, so this carbon nano-tube film itself has stronger viscosity.
In addition, above-mentioned carbon nano-tube film can with an organic solvent be processed.Particularly, by test tube, organic solvent is dropped in the whole carbon nano-tube film of carbon nano-tube film surface infiltration.This organic solvent is volatile organic solvent, as ethanol, methyl alcohol, acetone, ethylene dichloride or chloroform, adopts ethanol in the present embodiment.This carbon nano-tube film infiltrates after process through organic solvent, under the capillary effect of volatile organic solvent, parallel carbon nano-tube segment in carbon nano-tube film can become carbon nano-tube bundle by moiety aggregation, therefore, this carbon nano-tube film surface volume is than little, inviscid, and there is good physical strength and toughness.
In addition, when this carbon nanotube layer 13 is multilayer carbon nanotube film, the mode of the multiple carbon nano-tube films prepared along equidirectional can be adhered on the second surface 112 of cover plate 11 overlappingly according to said method.
Described adhesive layer 12 not only should have the performance respectively with carbon nanotube layer 13 and cover plate 11 strong bonded, also should have good transmittance and insulativity.The material of described adhesive layer 12 can be pressure sensitive adhesive, heat-sensitive glue or light-sensitive emulsion etc.Described adhesive layer 12 is formed by a pure adhesive cures.The thickness of this adhesive layer 12 should not be too thick, proper in the scope of 3 nanometer to 7 nanometers.If the thickness of adhesive layer 12 is too thick, the carbon nanotube layer 13 being then arranged at adhesive layer 12 surface easily sinks to the inside of adhesive layer 12 in preparation process, thus affects the electrical connection of carbon nanotube layer 13 and the first drive electrode 14a and the second drive electrode 14b.In the present embodiment, the material of this adhesive layer 12 is that ultraviolet light (UV) solidifies glue, and its coating thickness is 6 nanometers.Because UV solidifies glue, to have light transmission high and be easy to solidification, therefore, in the process preparing capacitive touch screen 10, had both been easy to avoid carbon nanotube layer 13 to sink to UV completely and solidified in glue, carbon nanotube layer 13 and UV can be made again to solidify cementing conjunction firm.In preparation process, will be layed in the surface of cover plate 11 by the carbon nano-tube film pulled out in carbon nano pipe array, the surface of cover plate 11 is provided with adhesive layer 12.Carbon nano-tube film directly adheres to the surface of cover plate 11 by this adhesive layer 12.Carbon nanotube layer 13 is formed by repeatedly laying carbon nano-tube film.Because carbon nanotube layer 13 directly adheres to the second surface 112 of described cover plate 11 by adhesive layer 12, this carbon nanotube layer 13 is reprinted without the need to other carriers, not only simplify the structure of capacitive touch screen 10, reduce cost and thickness, also improve the transmittance of capacitive touch screen 10 further.
Described at least one first drive electrode 14a and at least one second drive electrode 14b is formed by conductive material, may be selected to be metal, conducting polymer, conducting resinl, metallic carbon nanotubes, indium tin oxide etc.Shape and the structure of this first drive electrode 14a or the second drive electrode 14b are not limit, and may be selected to be stratiform, strip, bulk, bar-shaped or other shape.In the present embodiment, this first drive electrode 14a and the second drive electrode 14b is strip silver electrode.The number of described first drive electrode 14a can be one or more.The number of described second drive electrode 14b can be one or more.When described first drive electrode 14a and the second drive electrode 14b is multiple, described multiple first drive electrode 14a is arranged in first side along the direction being parallel to high impedance direction H, described multiple second drive electrode 14b is arranged in the spacing of these adjacent two the first drive electrode 14a or adjacent two the second drive electrode 14b of second side along the direction being parallel to high impedance direction H should be moderate, if too large, out of true when making the position of detected touch point, is preferably 1 millimeter to 5 millimeters.The length direction of this each first or second drive electrode 14a, 14b can be the high impedance direction H being parallel to described carbon nanotube layer 13, and this length can not be oversize, and oversize out of true when also easily making the position of detection described touch point, is preferably 1 millimeter to 5 millimeters.In the present embodiment, the quantity of this first drive electrode 14a and the second drive electrode 14b is 6, the length of each first drive electrode 14a or the second drive electrode 14b is 1 millimeter, and the spacing of these adjacent two the first drive electrode 14a or the second drive electrode 14b is 3 millimeters.The plurality of first drive electrode 14a and the plurality of second drive electrode 14b is oppositely arranged one by one, or interlaced setting, namely each first drive electrode 14a is parallel with the line of one of them the second drive electrode 14b and the Low ESR direction D of described carbon nanotube layer 13, or each first drive electrode 14a is all crossing and not parallel with the Low ESR direction D of described carbon nanotube layer 13 with the line of any second drive electrode 14b wherein.In the present embodiment, described multiple first drive electrode 14a and described multiple second drive electrode 14b is oppositely arranged one by one.Described each first drive electrode 14a and each second drive electrode 14b is all connected with one drive circuit 150 and a sensing circuit 160.
Described driving circuit 150 comprises a charging circuit 152 and in order to control the first switch 154 of charging circuit 152.Described charging circuit 152 is connected with described first drive electrode 14a or the second drive electrode 14b by described first switch 154.Described charging circuit 152 can be connected to a voltage source (not shown).Described sensing circuit 160 comprises memory circuit 162, reading circuit 164 and for the second switch 166 of control store circuit 162 with reading circuit 164.Described memory circuit 162 is in parallel with described reading circuit 164, and is connected with described first drive electrode 14a or the second drive electrode 14b by described second switch 166.Described driving circuit 150 and described sensing circuit 160 parallel with one another.Described memory circuit 162 can be connected a resistance (not shown) further, and this memory circuit 162 is by this resistance eutral grounding.
Selectively, in order to protect described carbon nanotube layer 13, a diaphragm 15 can be set in the surface away from cover plate 11 of described carbon nanotube layer 13.Described diaphragm 15 act as carbon nanotube layer 13 described in temporary protection, be destroyed to avoid carbon nanotube layer 13.When described capacitive touch screen 10 is applied to specific product, peelable described diaphragm 15.When described diaphragm 15 is peeled off from carbon nanotube layer 13, should ensure that carbon nanotube layer 13 is not destroyed.Described diaphragm 15 is an optional structure.The material of described diaphragm 15 can be formed by the hard materials such as glass, quartz, adamas or the flexible material such as plastics, resin.Particularly; when diaphragm 15 is formed by a flexible material; this material can be selected from the polyester materials such as polycarbonate (PC), polymethylmethacrylate (PMMA) or polyethylene terephthalate (PET), and the material such as polyethersulfone (PES), cellulose esters, benzocyclobutene (BCB), Polyvinylchloride (PVC) or acryl resin.In the present embodiment, the material of this diaphragm 15 is glass, and thickness is 2 millimeters.Diaphragm 15 is appreciated that the material forming described diaphragm 15 is not limited to the above-mentioned material enumerated, as long as can be made to play the effect of protection carbon nanotube layer 13, all in the scope of protection of the invention.
In the present embodiment, the principle of described capacitive touch screen 10 when applying is as follows.Touch-control conductor directly can touch and form touch point at the first surface 111 of cover plate 11.This touch point and carbon nanotube layer 13 form the coupling capacitance that a capacitance is C.The resistance value of the carbon nanotube layer 13 between this touch point and described each first drive electrode 14a is R
1n(n=1,2,3 ... y, x, z..., n represent multiple first drive electrode 14a), the resistance value of carbon nanotube layer 13 between this touch point and described each second drive electrode 14b is R
2n(n=1,2,3...y, x, z..., n represent multiple second drive electrode 14b).Input a pulse signal by described driving circuit to described each first drive electrode 14a, and read the resistance value R detected by each first drive electrode 14a respectively by described sensing circuit
1nwith the product of capacitance C, i.e. R
1nc value, thus simulate by the plurality of R
1nthe first curve that C value is formed.The coordinate of described touch point on the high impedance direction H of above-mentioned carbon nanotube layer 13 is judged by this first curve.Input a pulse signal by described driving circuit to described each second drive electrode 14b, and read the resistance value R detected by each second drive electrode 14b respectively by described sensing circuit
2nwith the product of capacitance C, i.e. R
2nc value, thus simulate by the plurality of R
2nthe second curve that C value is formed.Judge that the coordinate of described touch point on the high impedance direction of above-mentioned carbon nanotube layer 13 is further comprising the steps by this first curve: detect the maximal value R in this first curve
1kc, minimum value R
1xc, with minimum value R
1xthe sub-minimum R that C is adjacent
1yc and time sub-minimum R
1zc and this minimum value R
1xc, sub-minimum R
1yc and secondary sub-minimum R
1zcoordinate Xx, Xy and Xz at high impedance direction H corresponding to C, by the coordinate of touch point described in interpolation calculation in high impedance direction.Judge that the coordinate of above-mentioned touch point on the Low ESR direction of above-mentioned carbon nanotube layer 13 is further comprising the steps by this second curve and above-mentioned first curve: at least detect minimum R in this second curve
2xc value and the secondary little R be adjacent
2yc value, and to this R of major general
2xc value and R
2yc value sum and above-mentioned R
1xc value and R
1yc value sum is compared, and can calculate the coordinate of described touch point in Low ESR direction.
It also can be multiple touch point that above-mentioned touch point can be single touch point.When described touch point is multiple touch point, then when will judge multiple point touching, touch point is at the coordinate of the high impedance direction H of carbon nanotube layer 13, can comprise the following steps: S31, detect this first curve, the R namely detected by different first drive electrode 14a
1nc value change curve; S32, finds the multiple wave trough position in this first curve, at least detects the R of the plurality of wave trough position
1nc value (minimum R
1x1c, R
1x2c ... R
1xmc value) and with the plurality of minimum R
1x1c, R
1x2c ... R
1xmthe secondary little R that C value is adjacent
1y1c, R
1y2... R
1ymvalue, respectively by R
1xmc value and R
1ymtwo the first drive electrode 14a corresponding to C value are at the coordinate of high impedance direction H and this R
1xmc value and R
1ymc value obtains the coordinate of described multiple touch point at high impedance direction H by interpolation calculation.Judge that the coordinate in the Low ESR direction corresponding to described touch point can comprise following step: S41, detect described second curve, the R namely detected by different second drive electrode 108
2nc value change curve; S42, finds the wave trough position in this second curve, at least detects the R of this wave trough position
2nc value (minimum R
2xc value) and with this minimum R
2xthe secondary little R that C value is adjacent
2yc value, and to this minimum R of major general
2xc value and time little R
2yc value sum and above-mentioned minimum R
1xc value and time little R
1yc value sum is compared
the distance of this distance first side, touch point 131 and second side 132 can be judged by this ratio, thus the coordinate of described touch point at Low ESR direction D can be drawn.
Refer to Fig. 3, second embodiment of the invention provides a kind of touch control display apparatus 100 applying above-mentioned capacitive touch screen 10, and this touch control display apparatus 100 comprises a touch-screen and a display device 20.Described touch-screen is the capacitive touch screen 10 of the first embodiment.This display device 20 just to and the carbon nanotube layer 13 of capacitive touch screen 10 near the first embodiment arrange.Further, above-mentioned display device 20 and capacitive touch screen 10 interval one preset distance are arranged or integrated setting.Integrated when arranging, carbon nanotube layer 13 directly can be fitted by transparent insulating gel with the display surface of described display device 20 and be arranged, element that need not be extra.Described display device 20 can be the one in the display devices such as liquid crystal display, Field Emission Display, plasma display, electroluminescent display, vacuum fluorescent display and cathode-ray tube (CRT).The touch control display apparatus 100 that described touch-screen 10 and display device 20 forms also can comprise functional assembly further, as can comprise a decorative layer (Decoration Film) 30 be arranged on as described in the first surface of touch-screen 10 cover plate protect and deckboard.For another example can comprise a polaroid or screen layer to be arranged between touch-screen 10 and display device 20 etc.
Capacitive touch screen provided by the invention has the following advantages: one, only need arrange the surface that a transparency conducting layer is arranged at cover plate, the conduction anisotropy utilizing carbon nanotube layer special, this touch-screen can be made to realize single touch point touch-control or multiple touch points touch-control, multiple transparency conducting layer need not be set.And carbon nanotube layer can be set directly on cover plate, structure is simple, significantly can reduce the thickness of conventional touch screen, realize the application of ultra-thin touch screen.Its two, because carbon nanotube layer directly extracts from carbon nano pipe array and be laid immediately on cover plate, the simple environmental protection of method, be conducive to by this touch-screen import large-scale production.
In addition, those skilled in the art also can do other changes in spirit of the present invention, and certainly, these changes done according to the present invention's spirit, all should be included within the present invention's scope required for protection.