Patent Application
20100271328
The present application claims priority from Japanese applications JP2009-103495 filed on Apr. 22, 2009 and JP2009-267325 filed on Nov. 25, 2009, the contents of which are hereby incorporated by reference into these applications.
1. Field of the Invention
The present invention relates to an input device for inputting coordinates to a screen and a display device having the same, and more particularly, to a capacitive-coupling input device capable of inputting coordinates using a plastic pen or the like, which is an insulator, and a display device having the same.
2. Description of Related Art
A display device having an input device (hereinafter also referred to as a “touch sensor” or a “touch panel”) having an on-screen input function of inputting information to a display screen by a touch operation (a contact and press operation; hereinafter simply referred to as a “touch”) with a user's finger or the like is used for mobile electronic devices such as a PDA or a mobile terminal, various home appliances, stationary customer guiding terminals such as an automatic reception machine, and the like. As a method of realizing the input device using touch, there are some known methods including a resistance film method of detecting a change in resistance value of a touched portion, an electrostatic capacitive coupling method of detecting a change in capacitance of the touched portion, and an optical sensor method of detecting a change in light intensity at the portion shaded by the touch.
The electrostatic capacitive coupling method has the following advantages when compared with the resistance film method or the optical sensor method. For example, the resistance film method and the optical sensor method provide transmittance as low as about 80%. On the contrary, the electrostatic capacitive coupling method provides transmittance as high as about 90%, and the displayed image quality is not reduced. In the resistance film method, since the touched position is detected based on a mechanical contact with the resistance film, there is a possibility of deterioration or breakage (cracking) of the resistance film. On the contrary, in the electrostatic capacitive coupling method, the detection electrodes do not come into mechanical contact with other electrodes or the like. Thus, the electrostatic capacitive coupling method is advantageous in durability.
An exemplary electrostatic capacitive coupling method is disclosed in JP-T-2003-511799 (hereinafter referred to as Patent Document 1). According to the disclosed method, vertical detection electrodes (X electrodes) and horizontal detection electrodes (Y electrodes) are arranged in a vertical and horizontal two-dimensional matrix, and the capacitance of each electrode is detected by an input processing unit. When a conductor such as a finger or the like touches the surface of a touch panel, the capacitance of each electrode increases. Thus, the touch is detected by the input processing unit, and the input coordinates are calculated based on a signal indicative of a capacitance change detected by each electrode. Even when the detection electrodes are deteriorated and thus the resistance values which are physical characteristics are changed, they have little influence on the detected capacitance, and thus there is only a little influence on the input position detection accuracy of the touch panel. As a result, high input position detection accuracy can be realized.
Moreover, JP-A-2004-005672 discloses a touch panel in which a polymer layer containing conductive fine particles is formed on the surface of a transparent electrode, thus providing excellent anti-reflection effect and improved transparency.
However, since the electrostatic capacitive coupling-type touch panel detects the input coordinates based on the capacitance change in each detection electrode as discussed in Patent Document 1, it is required that the input means is made of a conductive material. The conductive material is represented by a human finger, and the electrostatic capacitive coupling-type touch panel is regarded as a finger-input touch panel. For this reason, when a plastic stylus which is a non-conductive insulator and used in the resistance film method or the like is brought into contact with the electrostatic capacitive coupling-type touch panel, almost no capacitance change occurs in the electrode, which disables detection of the input coordinates.
On the other hand, in case that an input operation is made on the electrostatic capacitive coupling-type touch panel using a stylus made of a conductive material such as metal, the number of electrodes need to increase. For example, a case will be considered in which an electrostatic capacitive coupling-type touch panel having a diagonal size of 4 inches and an aspect ratio of 3:4 is realized in a diamond-like electrode shape such as that described in Patent Document 1. Here, when the minimum contact surface of the finger is assumed to be 6 mm in diameter, and the detection electrodes are prepared using this size as the electrode interval, the total number of the electrodes will be 22. On the other hand, the contact surface of the stylus is assumed to be 1 mm in diameter, and when the detection electrodes are prepared using this size as the electrode interval, the total number of the electrodes will be 139, which indicates an increase of about six times. When the number of the electrodes increases, the surface area of a frame necessary for leading wirings out to the input processing unit increases, which also increases the number of signal connections with a control circuit, and consequently the reliability against impact and the like is lowered. Furthermore, since the circuit area also increases due to the increase in the number of terminals of the input processing unit, the costs may also increase. While, when a stylus whose tip is made of a conductive rubber is used, the stylus needs to have a shape that is 6 mm in diameter as its contact surface, assuming that the total number of the electrodes is the same. Thus, users may experience discomfort when inputting characters.
From the above, the electrostatic capacitive coupling-type touch panel disclosed in Patent Document 1 has a problem in dealing with input operations using an insulating material (stylus).
In order to solve the above-mentioned problems, according to a first aspect of the present invention, an electrostatic capacitive coupling-type touch panel is used which includes a plurality of transparent X electrodes, a plurality of transparent Y electrodes, and transparent Z electrodes. In the electrostatic capacitive coupling-type touch panel, the X electrodes and the Y electrodes intersect each other with a first insulating layer disposed therebetween and each have a configuration in which a pad part and a thin line part alternate in their extending direction. The pad parts of the X electrodes and the pad parts of the Y electrodes are arranged so as not to overlap each other in plan view. The Z electrodes are arranged over the X electrodes and the Y electrodes with spacers disposed therebetween for maintaining a constant distance and The Z electrodes are deformed along the shape of the spacers by compressive force resulting from touch pressing. In this way, the distance between the Z electrodes and the X electrodes and the distance between the Z electrodes and the Y electrodes are decreased, and accordingly, the electrostatic capacitance therebetween is increased. Therefore, it is possible to detect the coordinates of the touched position with non-conductive input means by detecting a capacitance change between the X and Y electrodes and the Z electrodes (portions where an inter-electrode distance is changed by the pressing).
Moreover, according to a second aspect of the present invention, the Z electrodes are arranged over the X electrodes and the Y electrodes with a plurality of dot-shaped elastic spacers disposed therebetween for maintaining a constant distance, and the elastic spacers are deformed by compressive force resulting from the touch pressing. The Z electrodes may be arranged with a spongy layer similar to the dot-shaped elastic spacers. However, the spongy layer may cause diffused reflection of light and lead to deterioration in image quality of the display device. Thus, the dot-shaped elastic spacers are preferable. By the elastic spacers, the distance between the Z electrodes and the X electrodes and the distance between the Z electrodes and the Y electrodes are decreased, and accordingly, the electrostatic capacitance therebetween is increased. Moreover, an insulating layer may be provided between the Z electrodes and the X and Y electrodes in order to detect the electrostatic capacitance that changes in response to the decrease in the distance between the Z electrodes and the X electrodes and the distance between the Z electrodes and the Y electrodes. Therefore, by providing an anti-reflection film at an interface between the space (air layer) formed by the elastic spacers and a stacked structure adjacent to the space, the transmittance can be improved and on-screen reflection can be reduced, thus suppressing deterioration in the image quality of the display device. Accordingly, it is possible to detect a capacitance change between the X and Y electrodes and the Z electrodes (portions where an inter-electrode distance is changed by the pressing) with non-conductive input means and thus to identify the coordinates of the touched position.
According to the aspects of the present invention, the electrostatic capacitive coupling-type touch panel allows input operations using not only a finger but also an insulator such as a plastic pen.
Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings.
The configuration of an input device (hereinafter referred to as a touch panel) and a display device having the same is shown in
In
The touch panel 101 is installed on a front face of a display portion 106 of the display device. It is therefore desirable for the touch panel 101 to have high transmittance since when a user views an image displayed on the display device, the displayed image must be transmitted through the touch panel 101. The X and Y electrodes of the touch panel 101 are connected to a capacitance detection portion 102 via detection wirings. The capacitance detection portion 102 is controlled based on a detection control signal output from an arithmetic and control unit 103 to detect capacitance of each electrode (each of the X and Y electrodes) included in the touch panel 101 and output a capacitance detection signal changing depending on the capacitance of each electrode to the arithmetic and control unit 103. The arithmetic and control unit 103 calculates a signal component of each electrode from the capacitance detection signal of each electrode and calculates input coordinates from the signal component of each electrode. Upon receiving the input coordinates from the touch panel 101 in response to a touch operation, a system 104 generates a display image corresponding to the touch operation and transfers the display image to a display control circuit 105 as a display control signal. The display control circuit 105 generates a display signal according to the display image transferred as the display control signal and displays an image on the display device.
The touch panel 101 of the present embodiment has a stacked structure in which a transparent conductive film XP, a first transparent insulating film 2, a transparent conductive film YP, a second transparent insulating film 3, non-conductive spacers 4 for maintaining a distance to a Z electrode, the Z electrode ZP which is a conductive layer, a transparent elastic layer 5, and a second transparent substrate 6 are successively stacked in that order on a first transparent substrate 1. The transparent elastic layer 5 is less rigid than the second transparent substrate 6.
In the following, when describing the shape of the pad part of the X electrode, it will be assumed that the position of a wiring (or the thin line part of the X electrode) for connecting the X electrode to the detection wiring is the horizontal center of the X electrode. The pad part of the X electrode has such a shape that its surface area decreases as it becomes closer to the center of the adjacent X electrode while increasing as it becomes closer to the center of the X electrode. Thus, regarding the surface area of the X electrode between the two adjacent X electrodes such as the electrodes XP1 and XP2, the surface area of the pad part of the electrode XP1 becomes the largest in the vicinity of the center of the electrode XP1, whereas the surface area of the pad part of the electrode XP2 becomes the smallest. On the other hand, in the vicinity of the center of the electrode XP2, the surface area of the pad part of the electrode XP1 becomes the smallest, whereas the surface area of the pad part of the electrode XP2 becomes the largest.
Next, the layer structure of the touch panel 101 will be described in the order of the layers stacked closer on the first transparent substrate 1. The material, thickness, and the like of the first transparent substrate 1 are not particularly limited and can be selected according to the purpose of use. Preferably, the material is selected from inorganic glasses such as barium borosilicate glass or soda glass, chemically reinforced glasses, and resin films such as polyethersulfone (PES), polysulfone (PSF), polycarbonate (PC), polyarylate (PAR), or polyethylene terephthalate (PET). Moreover, the X and Y electrodes XP and YP are formed by a transparent conductive film but are not particularly limited as long as they are thin films having conductive properties. The transparent conductive film can be made of existing materials such as indium tin oxide (ITO), antimony tin oxide (ATO), or indium zinc oxide (IZO). The transparent conductive film (thickness: 50 to 200 Å) is formed by a sputtering method so as to have surface resistance of 500 to 2000Ω, followed by deposition of resist materials and patterning with exposure and developing processes. In this case, the resist materials may be positive or negative types and can be easily formed if they are alkali developing types. Thereafter, the ITO pattern is formed by etching. In this case, as an etching solution, hydrobromic acid solution or the like can be used.
The X electrodes XP are formed at the proximity of the first transparent substrate 1, and then, the first insulating film 2 for insulating the X electrodes and the Y electrodes is formed. Then, the Y electrodes YP are formed. In this case, the order of the X electrodes XP and the Y electrodes YP may be reversed. Subsequently to the Y electrodes YP, the second insulating film 3 is formed. The thickness of the first and second insulating films 2 and 3 for ensuring insulation between the Y electrodes YP and the Z electrodes ZP provided later is appropriately selected considering the dielectric constant of the insulating film materials. The relative dielectric constant can be 2 to 4, and the thickness can be 1 to 20 μm. As the insulating film materials, UV (ultraviolet) curable resin materials, alkali-developable negative or positive insulating film materials, and heat-curable resin materials can be used, and the insulating film materials can be easily formed if they are alkali developing types.
The spacers 4 are formed by appropriately spraying uniformly sized polymer beads, glass beads, or the like. The bead particle size that defines the space between the second insulating film 3 formed on the first substrate and the Z electrodes is selected from 5 to 100 μm, and preferably from 20 to 50 μm. The density of the beads being sprayed, namely the distance between the adjacent beads, is preferably 20 μm or more and 10000 μm or less.
The transparent elastic layer 5 is a rubber-like layer having elasticity, and materials thereof are not particularly limited as long as they have elasticity. From the perspective of improving transmittance, materials that are transparent in the visible light region are preferred. For example, the following rubber materials can be used independently or in a mixture of two or more species: butyl rubber, fluoro rubber, ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber, ethylene-propylene rubber, silicon rubber, polyurethane rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber, hydrogenated NBR, polysulfide rubber, urethane rubber, and the like. These rubber or resin materials preferably have a refractive index of 1.4 to 1.8, and the film thickness is preferably 5 μm or more to be greater than the bead diameter of the spacers 4 (i.e., the thickness of the spacers 4) in order to allow sufficient deformation upon pressing.
The Z electrodes ZP are formed by a transparent conductive film but are not particularly limited as long as they are a thin film having conductive properties. The transparent conductive film can be made of existing materials such as indium tin oxide (ITO), antimony tin oxide (ATO), or indium zinc oxide (IZO). The transparent conductive film is formed by a sputtering method so as to have surface resistance of 500 to 2000Ω, followed by deposition of resist materials and patterning with exposure and developing processes so as to have a shape corresponding to the X and Y electrodes. In this case, the resist materials may be positive or negative types and can be easily formed if they are alkali developing types. Thereafter, the ITO pattern is formed by etching. In this case, as an etching solution, hydrobromic acid solution or the like can be used. Moreover, if the Z electrodes ZP are formed so as to have surface resistance of 10000 to 10000000Ω, the patterning is not necessary. In addition to a thin film in which fine particles of the existing materials such as indium tin oxide (ITO), antimony tin oxide (ATO), or indium zinc oxide (IZO) are dispersed in a transparent resin, other thin films maybe used in which conductive fine particles are dispersed in a resin. The conductive fine particles may be metallic fine particles of nickel, gold, silver, or copper, and insulating inorganic or resin-type fine particles which are plated with metals. Furthermore, there may be used fine particles composed of at least one metal oxide, or metal fluoride, selected from the group consisting of Al2O3, Bi2O3, CeO2, In2O3, (In2O3.SnO2)HfO2, La2O3, MgF2, Sb2O5, (Sb2O5.SnO2), SiO2, SnO2, TiO2, Y2O3, ZnO, and ZrO2. Furthermore, the following organic conductive materials may be used: polyaniline, polyacetylene, polyethylenedioxythiophene, polypyrrole, polyisothianaphthene, polyisonaphthiophene, and the like. Moreover, preferably, the Z electrodes are appropriately selected from materials that cause less absorption and scattering of light due to refraction or reflection of light.
The material of the second transparent substrate 6 is not particularly limited, but inorganic glasses such as barium borosilicate glass or soda glass, chemically reinforced glasses, and the like are not preferable since there is a need to transfer compressive force resulting from pressing to the transparent elastic layer 5. However, such materials can be used as long as they are 300 μm or less in thickness. Therefore, the materials of the second transparent substrate 6 are preferably selected from flexible resins such as polyethersulfone (PES), polysulfone (PSF), polycarbonate (PC), polyarylate (PAR), or polyethylene terephthalate (PET), or materials in which elastomeric components are added to such resin materials in order to improve flexibility. Moreover, to meet the flexibility requirements, the thickness of the second transparent substrate 6 is preferably 800 μm or less. Furthermore, when a substrate having a thickness of 100 μm or less is used as the second transparent substrate 6, the amount of deformation upon application of a great load is great, and the second transparent substrate 6 and the transparent elastic layer 5 can be easily delaminated at their interface. Therefore, the thickness of the second transparent substrate 6 is preferably 100 μm or more.
Next, a capacitance change when a touch operation is made on the touch panel 101 according to the first embodiment of the present invention will be described with reference to
The capacitance in the absence of the touch operation corresponds to the small inter-electrode capacitance between the X electrode XP1 and the Y electrode YP2 via the insulating film 2 disposed therebetween. It will be assumed that when the Z electrode ZP is pressed by the touch, the capacitance between the Z electrode ZP and the X electrode XP1 is Cxza, and the capacitance between the Z electrode ZP and the Y electrode YP2 is Cyza. When the capacitance detection portion 102 detects the electrode capacitance of the X electrode XP1, the Y electrode YP2 is reset to the GND potential. Thus, the combined capacitance when seen from the X electrode XP1 will be the sum of the series capacitances Cxza and Cyza since the Z electrode ZP is in the floating state. In this case, the combined capacitance Cxpa of the X electrode can be expressed by the following expression.
Cxpa=Cxza·Cyza/(Cxza+Cyza) (1)
The arithmetic and control unit 103 calculates the capacitance Cxpa of the electrode XP1 in the presence of the touch operation as a signal component of the electrode XP1. Since the capacitance detection portion 102 is able to detect the electrode capacitance in the presence/absence of the touch operation, the arithmetic and control unit 103 is able to calculate the signal component of the electrode XP1.
As will be understood from the above description, the non-conductive input means also enables the detection of the input coordinates based on the change in the electrostatic capacitance since the distance between the X electrode XP and the Z electrode ZP and the distance between the Y electrode YP and the Z electrode ZP are changed in response to the pressing.
While the first embodiment has been described in detail, the touch panel of the present embodiment is not limited to the example shown in
As described above, according to the present embodiment, since the touch of the non-conductive input means on the touch panel can cause a change in the distance between the capacitance detection X or Y electrode and the Z electrode disposed thereon, causing the capacitance change, it is possible to detect the input coordinates by the electrostatic capacitive coupling method.
The touch panel 101 of the present embodiment has a stacked structure in which a transparent conductive film XP, a first transparent insulating film 2, a transparent conductive film YP, a second transparent insulating film 3, a transparent elastic layer 5, a Z electrode ZP, spacers 4 for maintaining a distance to the Z electrode, and a second transparent substrate 6 are successively stacked in that order on a first transparent substrate 1.
Next, a capacitance change when a touch operation is made on the touch panel 101 according to the second embodiment of the present invention will be described with reference to
The capacitance in the absence of the touch operation corresponds to the small inter-electrode capacitance between the X electrode XP1 and the Y electrode YP2 via the insulating film 2 disposed therebetween. It will be assumed that when the Z electrode ZP is pressed by the touch, the capacitance between the Z electrode ZP and the X electrode XP1 is Cxza, and the capacitance between the Z electrode ZP and the Y electrode YP2 is Cyza. When the capacitance detection portion 102 detects the electrode capacitance of the X electrode XP1, the Y electrode YP2 is reset to the GND potential. Thus, the combined capacitance when seen from the X electrode XP1 will be the sum of the series capacitances Cxza and Cyza since the Z electrode ZP is in the floating state. In this case, the combined capacitance Cxpa of the X electrode can be expressed by the expression (1) similar to the first embodiment.
The arithmetic and control unit 103 calculates the capacitance Cxpa of the electrode XP1 in the presence of the touch operation as a signal component of the electrode XP1. Since the capacitance detection portion 102 is able to detect the electrode capacitance in the presence/absence of the touch operation, the arithmetic and control unit 103 is able to calculate the signal component of the electrode XP1.
As will be understood from the above description, the non-conductive input means also enables the detection of the input coordinates based on the change in the electrostatic capacitance since the distance between the X electrode XP and the Z electrode ZP and the distance between the Y electrode YP and the Z electrode ZP are changed in response to the pressing.
Other things are the same as those described in the first embodiment.
As described above, according to the present embodiment, since the touch of the non-conductive input means on the touch panel can cause a change in the distance between the capacitance detection X or Y electrode and the Z electrode disposed thereon, causing the capacitance change, it is possible to detect the input coordinates by the electrostatic capacitive coupling method.
The touch panel 101 of the present embodiment has a stacked structure in which a transparent conductive film XP, a first transparent insulating film 2, a transparent conductive film YP, a second transparent insulating film 3, spacers 4 for maintaining a distance to a Z electrode, the Z electrode ZP, a transparent elastic layer 5, and a second transparent substrate 6 are successively stacked in that order on a first transparent substrate 1.
The spacers 4 are made of a light-curable resin material and can be configured as dot-shaped pillar spacers. The spacers 4 are preferably formed at intervals of 20 μm or more and 10000 μm or less by a screen printing method or the like. The spacers 4 may have a circular or rectangular shape and have a diameter of 5 to 100 μm, and preferably 20 to 50 μm.
The materials and properties of the other layers are the same as those of the first embodiment, and description thereof will be omitted herein.
Next, a capacitance change when a touch operation is made on the touch panel 101 according to the third embodiment of the present invention will be described with reference to
The capacitance in the absence of the touch operation corresponds to the small inter-electrode capacitance between the X electrode XP1 and the Y electrode YP2 via the insulating film 2 disposed therebetween. It will be assumed that when the Z electrode ZP is pressed by the touch, the capacitance between the Z electrode ZP and the X electrode XP1 is Cxza, and the capacitance between the Z electrode ZP and the Y electrode YP2 is Cyza. When the capacitance detection portion 102 detects the electrode capacitance of the X electrode XP1, the Y electrode YP2 is reset to the GND potential. Thus, the combined capacitance when seen from the X electrode XP1 will be the sum of the series capacitances Cxza and Cyza, since the Z electrode ZP is in the floating state. In this case, the combined capacitance Cxpa of the X electrode can be expressed by the expression (1) similar to the first embodiment.
The arithmetic and control unit 103 calculates the capacitance Cxpa of the electrode XP1 in the presence of the touch operation as a signal component of the electrode XP1. Since the capacitance detection portion 102 is able to detect the electrode capacitance in the presence/absence of the touch operation, the arithmetic and control unit 103 is able to calculate the signal component of the electrode XP1.
As will be understood from the above description, the non-conductive input means also enables the detection of the input coordinates based on the change in the electrostatic capacitance since the distance between the X electrode XP and the Z electrode ZP and the distance between the Y electrode YP and the Z electrode ZP are changed in response to the pressing.
Other things are the same as those described in the first embodiment.
As described above, according to the present embodiment, since the touch of the non-conductive input means on the touch panel can cause a change in the distance between the capacitance detection X or Y electrode and the Z electrode disposed thereon, causing the capacitance change, it is possible to detect the input coordinates by the electrostatic capacitive coupling method.
The touch panel 101 of the present embodiment has a stacked structure in which a transparent conductive film XP, a first transparent insulating film 2, a transparent conductive film YP, a second transparent insulating film 3, a transparent elastic layer 5, a Z electrode ZP, spacers 4 for maintaining a distance to the Z electrode, and a second transparent substrate 6 are successively stacked in that order on a first transparent substrate 1.
The spacers 4 are made of a light-curable resin material and can be configured as dot-shaped pillar spacers. The spacers 4 are preferably formed at intervals of 20 μm or more and 10000 μm or less by a screen printing method or the like. The spacers have a circular or rectangular shape and have a diameter of 5 to 100 μm, and preferably 20 to 50 μm.
The materials and properties of the other layers are the same as those of the first embodiment, and description thereof will be omitted herein.
Next, a capacitance change when a touch operation is made on the touch panel 101 according to the fourth embodiment of the present invention will be described with reference to
The capacitance in the absence of the touch operation corresponds to the small inter-electrode capacitance between the X electrode XP1 and the Y electrode YP2 via the insulating film 2 disposed therebetween. It will be assumed that when the Z electrode ZP is pressed by the touch, the capacitance between the Z electrode ZP and the X electrode XP1 is Cxza, and the capacitance between the Z electrode ZP and the Y electrode YP2 is Cyza. When the capacitance detection portion 102 detects the electrode capacitance of the X electrode XP1, the Y electrode YP2 is reset to the GND potential. Thus, the combined capacitance when seen from the X electrode XP1 will be the sum of the series capacitances Cxza and Cyza since the Z electrode ZP is in the floating state. In this case, the combined capacitance Cxpa of the X electrode can be expressed by the expression (1) similar to the first embodiment.
The arithmetic and control unit 103 calculates the capacitance Cxpa of the electrode XP1 in the presence of the touch operation as a signal component of the electrode XP1. Since the capacitance detection portion 102 is able to detect the electrode capacitance in the presence/absence of the touch operation, the arithmetic and control unit 103 is able to calculate the signal component of the electrode XP1.
As will be understood from the above description, the non-conductive input means also enables the detection of the input coordinates based on the change in the electrostatic capacitance since the distance between the X electrode XP and the Z electrode ZP and the distance between the Y electrode YP and the Z electrode ZP are changed in response to the pressing.
Other things are the same as those described in the first embodiment.
As described above, according to the present embodiment, since the touch of the non-conductive input means on the touch panel can cause a change in the distance between the capacitance detection X or Y electrode and the Z electrode disposed thereon, causing the capacitance change, it is possible to detect the input coordinates by the electrostatic capacitive coupling method.
The touch panel of the present embodiment has a stacked structure in which a transparent conductive film XP, a first transparent insulating film 2, a transparent conductive film YP, a second transparent insulating film 3, elastic spacers 8 for maintaining a distance to a Z electrode, and the Z electrode ZP, and a second transparent substrate 6 are successively stacked in that order on a first transparent substrate 1.
In the figure, reference numerals 1 and 6 each denote a transparent substrate, 2 and 3 each denote an insulating film, 8 denotes elastic spacers, 9 denotes an air layer, and XP, YP, and ZP each denote a detection electrode.
The elastic spacers 8 are formed by appropriately spraying uniformly sized elastic polymer beads, elastic rubber beads, or the like. The bead particle size that defines the space between the second insulating film 3 formed on the first substrate and the Z electrodes can be 5 to 100 μm. If there is a small gap between the second insulating film 3 and the Z electrode, the Newton's ring may occur due to interference of external light, thus degrading the display performance. If there is a large gap between the second insulating film 3 and the Z electrode, the load necessary for detecting a touch increases. For this reason, the distance between the second insulating film 3 and the Z electrode is preferably 20 to 50 μm. The density of the beads being sprayed depends on the setting of the minimum load necessary for detecting a touch and the Young's modulus of the material of the elastic spacers, and is preferably one or more per 1 cm2 to be able to detect two points at the same time. In order to prevent deterioration in the display performance resulting from reflection and absorption of light by the elastic spacers, the density of the bead to be sprayed is preferably 400 or more per 1 cm2.
The elastic spacers 8 are of rubber-like materials having elasticity, and materials thereof are not particularly limited as long as they have elasticity. In order to decrease the minimum load necessary for detecting a touch, materials having a low Young's modulus are preferred, and materials having a Young's modulus of 100 MPa or less are particularly preferable. Moreover, materials having a Young's modulus of 1 MPa or less may also be used; however, in such a case, the material of the elastic spacers may undergo plastic deformation, and thus, the Young's modulus of the material of the elastic spacers is preferably 1 MPa or more. For example, the following rubber materials can be used independently or in a mixture of two or more species: butyl rubber, fluoro rubber, copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber, ethylene-propylene rubber, silicon rubber, polyurethane rubber, polynorbornene rubber, styrene-butadien-styrene rubber, epichlorohydrin rubber, hydrogenated NBR, polysulfide rubber, urethane rubber, and the like.
An anti-reflection film may be formed on the surface of the Z electrode ZP so as to suppress interfacial reflection and thus increase the transmittance of visible light of the touch panel.
The material of the second transparent substrate 6 is not particularly limited, but inorganic glasses such as barium borosilicate glass or soda glass, chemically reinforced glasses, and the like are not preferable since there is a need to transfer compressive force resulting from pressing to the elastic spacers 8. However, such materials can be used as long as they are 300 μm or less in thickness. Therefore, the materials of the second transparent substrate 6 are preferably selected from flexible resin materials such as polyethersulfone (PES), polysulfone (PSF), polycarbonate (PC), polyarylate (PAR), or polyethylene terephthalate (PET), or materials in which elastomeric components are added to such resin materials in order to improve flexibility.
Next, a capacitance change when a touch operation is made on the touch panel 101 according to the fifth embodiment of the present invention will be described with reference to
The capacitance between the adjacent X and Y electrodes corresponds to the combined capacitance of the capacitance (not shown) between the X and Y electrodes via the insulating film disposed therebetween and the parallel plate capacitances formed by the Z electrodes ZP and the X and Y electrodes. Here, it will be assumed that the capacitance between the X electrode (XP1) and the Z electrode in the absence of the touch operation is Czx (not shown), and the capacitance between the Y electrode (YP2) and the Z electrode is Czy (not shown). Here, when the Z electrode ZP is pressed by the pressing during the touch operation as shown in
Czxa>Czx (2)
Czya>Czy (3)
Since the Z electrode ZP is in the floating state, the combined capacitances in the presence/absence of the touch operation can be considered as the series capacitances as shown in
{Czxa·Czx·(Czya−Czy)+Czya·Czy·(Czxa−Czx)}/{(Czx+Czy)·(Czxa+Czya)} (4)
The capacitance detection portion 102 detects the capacitance of each electrode or the capacitance change resulting from the presence/absence of the touch operation as given by the expression (4). The arithmetic and control unit 103 calculates the coordinates of the touched position using the capacitance of each electrode or the capacitance change obtained by the capacitance detection portion 102 as a signal component.
As will be understood from the above description, the non-conductive input means also enables the detection of the input coordinates based on the change in the electrostatic capacitance since the distance between the X electrode XP and the Z electrode ZP and the distance between the Y electrode YP and the Z electrode ZP are changed in response to the pressing.
The deposition method used in this process is not particularly limited as long as the method is capable of uniformly depositing a coating solution. The following methods can be used: bar coating, blade coating, spin coating, die coating, slit reverse coating, 3-roll reverse coating, comma coating, roll coating, dip coating, and the like.
The thickness of the coating film is preferably 100 μm to 1500 μm, and more preferably 500 μm to 1000 μm.
Subsequently to the deposition process, in order to polymerize photopolymerizable monomers contained in the coating solution of the resin material deposited by the deposition process, the resin material is irradiated with ultraviolet rays for 10 to 180 seconds with illumination intensity of 1 mW/cm2 or more and 100 mW/cm2 or less.
As the adhesive sheet-like material having adhesive properties, acryl-based adhesive, vinyl acetate-based adhesive, urethane-based adhesive, epoxy resin, vinylidene chloride-based resin, polyimide-based resin, polyester-based resin, synthetic rubber-based adhesive, silicon-based resin, and the like can be mentioned. Among them, acryl-based adhesive and silicon-based resin having high transparency are preferred. In addition, silicon-based resin is more preferable from the perspective of shock-absorbing performance.
With this adhesive layer 7, it is possible to eliminate the interface between the first transparent substrate 1 and the air layer and the interface between the display portion 106 and the air layer.
Other things are the same as those described in the first embodiment.
As described above, according to the present embodiment, since the touch of the non-conductive input means on the touch panel can cause a change in the distance between the capacitance detection X or Y electrode and the Z electrode disposed thereon, causing the capacitance change, it is possible to detect the input coordinates by the electrostatic capacitive coupling method. Moreover, even when the touch panel 101 is mounted on the display portion 106, it is possible to display a high-luminance and high-contrast image and thus improve the image quality of the display device.
The display device of the present embodiment has a stacked structure in which a transparent conductive film XP, a first transparent insulating film 2, a transparent conductive film YP, a second transparent insulating film 3, elastic spacers 8 for maintaining a distance to a Z electrode, and the Z electrode ZP, and a second transparent substrate 6 are successively stacked in that order on a first transparent substrate 1.
The elastic spacers 8 are made of a light-curable elastic resin material and can be formed as dot-shaped pillar spacers which are formed on a side of the second insulating film 3 of the first transparent substrate close to the Z electrode or on a side of the Z electrode close to the first transparent electrode. The elastic spacers 8 are preferably formed at intervals of 500 μl or more and 10000 μm or less by a screen printing method or the like. The elastic spacers 8 have a circular or rectangular shape and have a diameter of 5 to 100 μm. If there is a small gap between the second insulating film 3 and the Z electrode, the Newton's ring may occur due to interference of external light, thus degrading the display performance. If there is a large gap between the second insulating film 3 and the Z electrode, the load necessary for detecting a touch increases. For this reason, the distance between the second insulating film 3 and the Z electrode is preferably 20 to 50 μm.
The elastic spacers 8 are of rubber-like materials having elasticity, and materials thereof are not particularly limited as long as they have elasticity. In order to decrease the minimum load necessary for detecting a touch, materials having a low Young's modulus are preferred, and materials having a Young's modulus of 100 MPa or less are particularly preferable. Moreover, materials having a Young's modulus of 1 MPa or less may also be used; however, in such a case, the material of the elastic spacers may undergo plastic deformation, and thus, the Young's modulus of the material of the elastic spacers is preferably 1 MPa or more. For example, the following elastomer materials can be used: styrene-based elastomer, olefin-based elastomer, polyester-based elastomer, polyamide-based elastomer, urethane-based elastomer, silicon-based elastomer, and the like. The elastomer materials are used as a mixture with acrylic resin, epoxy resin, polyolefin resin, or the like.
Furthermore, the following rubber materials can be used independently or in a mixture of two or more species: butyl rubber, fluoro rubber, ethylene-propylene-diene copolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber, ethylene-propylene rubber, silicon rubber, polyurethane rubber, polynorbornene rubber, styrene-butadiene-styrene rubber, epichlorohydrin rubber, hydrogenated NBR, polysulfide rubber, urethane rubber, and the like.
The materials and properties of the other layers are the same as those of the fifth embodiment, and description thereof will be omitted herein.
Next, a capacitance change when a touch operation is made on the touch panel 101 according to the sixth embodiment of the present invention will be described with reference to
In the touch panel 101 according to the present embodiment, the distance between the X and Y electrodes and the Z electrode decreases in the presence of the touch operation, similar to
The capacitance detection portion 102 detects the capacitance of each electrode or the capacitance change resulting from the presence/absence of the touch operation as given by the expression (4). The arithmetic and control unit 103 calculates the coordinates of the touched position using the capacitance of each electrode or the capacitance change obtained by the capacitance detection portion 102 as a signal component.
As will be understood from the above description, the non-conductive input means also enables the detection of the input coordinates based on the change in the electrostatic capacitance since the distance between the X electrode XP and the Z electrode ZP and the distance between the Y electrode YP and the Z electrode ZP are changed in response to the pressing.
Moreover, the stacking method of the display portion 106 and the touch panel 101 is the same as that of the fifth embodiment as shown in
Other things are the same as those described in the fifth embodiment.
As described above, according to the present embodiment, since the touch of the non-conductive input means on the touch panel can cause a change in the distance between the capacitance detection X or Y electrode and the Z electrode disposed thereon, causing the capacitance change, it is possible to detect the input coordinates by the electrostatic capacitive coupling method. Moreover, even when the touch panel 101 is mounted on the display portion 106, it is possible to display a high-luminance and high-contrast image and thus improve the image quality of the display device.
While there have been described what are at present considered to be certain embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claims cover all such modifications as fall within the true spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-103495 | Apr 2009 | JP | national |
| 2009-267352 | Nov 2009 | JP | national |
