JP2012243001A - Liquid crystal display device having touch panel sensor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode material for a capacity detection electrode, the electrode material exhibiting predetermined resistance characteristics and optical characteristics without exposing a liquid crystal display device part to a temperature equal to or higher than 200°C because the capacity detection electrode material needs to be annealed.SOLUTION: A liquid crystal display device having a touch panel uses a glass substrate on the side with a color filter of a pair of glass substrates as a support substrate of a touch panel sensor. The liquid crystal display device is characterized in that a touch panel sensor of a capacitance type is formed in a direct and integrated manner on the opposite side of a common glass substrate from a color filter side. In addition, a capacity detection electrode of the touch panel sensor is characterized by being IZO metal oxide that has a mixture ratio of InOto ZnO falling into a range from 90:10 to 80:20 by w%.

Description

  The present invention relates to a color liquid crystal display device including a touch panel, and particularly to a material used for a capacitance detection electrode of a touch panel sensor and a composition thereof.

  2. Description of the Related Art In recent years, touch panel type input devices (hereinafter simply referred to as touch panels) have been adopted for operation units of various electronic devices such as mobile phones, portable information terminals, and car navigation systems. The touch panel is used as an input device for detecting a contact position of a fingertip or a pen tip on a display surface of a display panel such as a liquid crystal display device. There are various types of touch panel sensors such as a resistance film type and a capacitance type depending on the structure and detection method.

  As shown in FIG. 1, a capacitive touch panel sensor is formed by forming a matrix-like translucent electrode pattern on a single glass substrate, and is induced by contact of a finger or the like between the electrodes. The touched position on the touch panel is specified by detecting the change in capacitance as a weak current change, and it has the advantage of higher transmittance than the resistance film type input device used conventionally. There is.

  In a liquid crystal display device including a touch panel, the touch panel is mounted and fixed on a polarizing plate of a display panel of the liquid crystal display device after alignment (see, for example, Patent Document 1 and Patent Document 2). That is, the touch panel is manufactured independently of the liquid crystal display device and then integrated. As a method of fixing the touch panel to the liquid crystal display device, a method of fixing the touch panel by laying a cushion rubber with an adhesive having a thickness of about 0.5 mm or more on the outer periphery of the display panel, or a transparent adhesive between the display panel and the touch panel. The method of pasting all over is adopted.

  By the way, the liquid crystal display device with a touch panel in which two completed sets of panels are stacked has the following problems. First, there is a problem that it becomes thicker and heavier by the amount of overlap. Next, since a glass substrate is used for both the liquid crystal display device and the touch panel, there is a problem that optical loss due to scattering and reflection of light between the glass substrates is large and display characteristics are deteriorated.

  Therefore, a technique is disclosed in which one glass substrate of two glass substrates constituting the liquid crystal panel, generally the glass substrate on the side where the color filter is formed, is shared as a support substrate for the touch panel (see Patent Document 3). . In this case, although described as a touch panel sensor, Patent Document 3 does not particularly describe the material of the capacitive detection transparent electrode on the touch panel sensor side, but when ITO that is commonly used as a liquid crystal driving transparent electrode material is used, In order to obtain the desired characteristics of high transmittance and low resistance, it is necessary to anneal the ITO electrode at a high temperature of 200 ° C. or higher.

  As shown in FIG. 4, members constituting the color liquid crystal display device include a glass substrate 1 having a color filter 5, a TFT substrate 2, a seal material 6 for bonding these opposing substrates, and a liquid crystal 4. The liquid crystal 4 can be sealed after the liquid crystal panel is manufactured, that is, after the ITO is annealed, but even in that case, the sealing material 6 is inevitably damaged.

  It is also possible to form a color filter 5 and a touch panel sensor 10 on the front and back of a single glass substrate 1 and then attach them to the TFT substrate 2 to form a panel. However, in order to reduce the thickness of the panel, it is preferable to etch the glass substrate with hydrofluoric acid. However, if this procedure is employed, etching cannot be performed on either the front or back side of the glass substrate 1, and the entire panel cannot be thinned. There is a problem. This is because the functional film formed in advance is damaged by hydrofluoric acid.

  Although it is conceivable to introduce a thin glass substrate from the beginning, it is difficult to circulate the process by itself. Therefore, generally, after the liquid crystal panel is completed, it is necessary to perform a process of etching the outside of the pair of glass substrate 1 and glass substrate 2, and then perform touch panel sensor processing.

  In that case, if an electrode material such as ITO is used for the touch panel sensor, the liquid crystal panel itself must be exposed to a high temperature, and a sealing material or a sandwich holding a pair of glass substrates constituting the liquid crystal panel is required. There is a problem that the liquid crystal material is deteriorated.

JP 2007-178758 A JP-A-2-135317 Japanese Patent Laid-Open No. 5-19233

  Therefore, the present invention is a liquid crystal display device with a touch panel sensor using a glass substrate on the side provided with a color filter as a support substrate for a touch panel sensor, out of a pair of glass substrates holding a liquid crystal, and the liquid crystal display device portion Since it is necessary to anneal the capacitance detection electrode material, it is directly necessary to find an electrode material that can obtain predetermined resistance characteristics and optical characteristics for the capacitance detection electrode without being exposed to a high temperature of 200 ° C. or higher. The object was to provide a very thin liquid crystal display device with a touch panel sensor using the electrode material.

  In order to achieve the above object, the invention according to claim 1 is a liquid crystal with a touch panel sensor of a type in which a glass substrate on the side provided with a color filter is also used as a support substrate for a touch panel sensor among a pair of glass substrates holding a liquid crystal. In the display device, a liquid crystal display device with a touch panel sensor is characterized in that a capacitive touch panel sensor is directly and integrally formed on a back surface side when viewed from a color filter of a shared glass substrate.

  The invention according to claim 2 is the liquid crystal display device with a touch panel sensor according to claim 1, wherein the capacitance detection electrode of the touch panel sensor is made of a metal oxide formed at a low temperature of 120 ° C. or less. It is what.

The invention according to claim 3 is characterized in that the metal oxide is an IZO metal oxide having a mixing ratio of In ₂ O ₃ and ZnO in the range of 90:10 to 80:20 by weight%. The liquid crystal display device with a touch panel sensor described in 2 is used.

  The invention according to claim 4 is characterized in that the sheet resistance of the IZO metal oxide is 300 Ω / □ or less and the transmittance is 80% or more, with the touch panel sensor according to claim 2 or 3. This is a liquid crystal display device.

The invention according to claim 5 includes at least a step of manufacturing a color liquid crystal display device, a step of thinning two glass substrates constituting the liquid crystal surface device by wet etching, and a glass substrate provided with a color filter on the back surface. Forming a capacitive touch panel sensor on the surface of the liquid crystal display device with the touch panel sensor in this order, wherein the touch panel sensor is formed by sputtering using In ₂ O ₃ and ZnO. A step of sputtering a sputtering target with a mixing ratio of 90:10 to 80:20 by weight% to form an IZO metal oxide, and a step of annealing the IZO metal oxide at a temperature of 120 ° C. or lower. A liquid crystal display device with a touch panel sensor, comprising: a step of patterning an IZO metal oxide It is those of the manufacturing method.

The liquid crystal display device with a touch panel sensor according to the present invention has the characteristics that the visual characteristics are good, thin and light, as a result of reducing the number of glass substrates and reducing optical loss.
In particular, since wet etching can be performed with hydrofluoric acid from the front and back of the liquid crystal panel, a thin liquid crystal display device with a touch panel sensor can be provided.
In addition, the sputter deposition of IZO (indium zinc oxide), which is a capacitance detection electrode material, can be deposited at a temperature lower than 120 ° C. compared to ITO (indium tin oxide), so that the liquid crystal display device itself is damaged. In particular, the adhesive strength of the sealing material is not deteriorated. In addition, IZO has the effect that the production cost of the touch panel sensor part can be reduced as a result of less nodule generation in the sputtering apparatus and maintenance-free implementation.

It is a figure of the top view explaining an example of electrode arrangement | positioning of a touchscreen sensor. It is a figure of the expanded sectional view of the II-II line shown in FIG. It is the figure of the upper surface view to which the through hole was expanded. It is a figure of the cross sectional view which shows the outline of a structure of a liquid crystal display device with a touch panel sensor. The surface resistivity and transmittance is plotted as a function of In ₂ O ₃ and the mixing ratio of ZnO.

  Hereinafter, the present invention will be described in accordance with the manufacturing process of the liquid crystal display device with a touch panel sensor.

  The color filter substrate on which the touch panel sensor 10 is formed on the back surface of the substrate was manufactured by applying a regular photolithography method using a glass substrate 1 of 40 cm × 50 cm and a thickness of 0.5 mm (see FIG. 4). This is a method in which a colored photosensitive resin is slit coated on the glass substrate 1 and then a process of forming a colored pattern by repeating predetermined procedures such as exposure and development.

  After the TFT substrate 2 is aligned with the glass substrate 1 on which the color filter 5 is formed, an epoxy adhesive is bonded as a sealing material 6 to form a liquid crystal panel, and then the nematic liquid crystal 4 is sealed under reduced pressure. A color liquid crystal display device 7 shown below was obtained. Since the epoxy sealant 6 melts and deteriorates when the temperature is raised to 120 ° C. or higher, the adhesive force is reduced or deformed, and therefore it is preferable to expose the liquid crystal display device 7 to a high temperature in the subsequent touch panel sensor process. Absent. The temperature at which the temperature can be raised needs to be determined depending on the allowable upper limit temperature of the sealing material 6.

  Next, the frame-shaped decoration part (not shown) was printed on the back side surface of the glass substrate 1 in which the color filter 5 was formed using black ink by screen printing. The size of the frame-shaped decoration portion is about the periphery of the display portion of the mobile phone. Employment ink GLS-912 was used as the printing ink, and a 230 mesh plate was used so that the thickness after drying was about 2 μm. After printing, oven drying was performed at 120 ° C. for 30 minutes.

Next, an acrylic UV curable overcoat resin (NN901 manufactured by JSR Co., Ltd.) is applied to the same back surface with a thickness of 4 μm using a slit coat method to form an overcoat layer (not shown). UV cured. The purpose of the overcoat is to reduce and flatten the convex shape of the frame-shaped decorative part, and to uniformly cover the decorative part and prevent outgas from the decorative part. As the overcoat material, an epoxy thermosetting resin or a novolac positive material having high transmittance in the visible light region can be used. However, the overcoat layer is not necessarily essential and is therefore omitted from the drawing.

  Next, a touch panel sensor is formed on the overcoat layer. FIG. 1 is a top view showing a schematic configuration of electrodes of a capacitive touch panel alone, and FIG. It is an expanded sectional view of the II-II line shown. FIG. 3 is an enlarged view of the vicinity of the through hole 17 shown in FIG. The decoration is omitted because it is at the end.

  The capacitive touch panel sensor 10 includes a plurality of jumper wires 18, an insulating film 16, a plurality of first transparent electrodes 13, and a plurality of second electrodes on the overcoat layer or the glass substrate 1 described above. The transparent electrode 14 is provided. Jumper wire 18, insulating film 16, and transparent electrode (first transparent electrode 13 is formed in isolation, and second transparent electrode 14 is connected in the Y direction through constricted connection 15) Are formed in this order on the overcoat layer 5 or the glass substrate 1.

  The jumper wires 18 are formed of a conductive material and are arranged in a matrix on the surface of the overcoat layer 5. Each of the jumper wires 18 is for connecting the isolated first transparent electrodes 13 in the X-axis direction, and each of the pair of first transparent electrodes 13 whose both ends are adjacent in the X-axis direction. It is formed in the position and dimension which overlap. The jumper wire 18 can be formed by selecting from, for example, a transparent electrode material, a Mo / Al / Mo laminate, Ag, an Ag alloy, a conductive polymer, and the like. In this embodiment, IZO described later is used.

  The insulating film 16 is formed by laminating a transparent insulating material (product name: NN901 manufactured by JSR) so as to cover the entire surface of the jumper wire 18 and the overcoat layer 5, and the first transparent electrode 13 and the jumper wire. A through hole 17 reaching the surface of the jumper wire 18 is provided in a portion overlapping with 8 by using a regular photolithographic method. As the insulating material, an acrylic material having a high permittivity with a dielectric constant of 2 to 4 is preferable.

  The first transparent electrode 13 and the second transparent electrode 14 are arranged in a matrix as shown in FIG. 1 in the X-axis direction and the Y-axis direction perpendicular thereto in the same layer on the insulating film. In this embodiment, the transparent electrode 13 and the second transparent electrode 14 are formed into a film with a thickness of 2 μm by a sputtering method using a light-transmitting IZO conductive material, and then a photolithographic method, which is a fixed method, is applied in the same process. It was formed by patterning. The IZO film was used as it was without annealing at high temperature. Oxalic acid was used as the etchant.

  As shown in FIG. 1, each of the first IZO transparent electrodes (hereinafter simply referred to as IZO electrodes) 13 is connected to both the X-axis direction and the Y-axis direction on the insulating film 16. Although not shown, it is connected to the jumper wire 18 on the overcoat layer through the through hole 17. As a result, the first transparent electrodes 13 aligned in the X-axis direction are electrically connected to each other.

  On the other hand, each of the second IZO electrodes 14 is disposed between the rows and the columns of the first IZO electrodes 13, and has a constricted connection portion 15 patterned simultaneously with the second IZO electrodes 14 on the insulating film 6. Are connected to each other in the Y-axis direction.

When the first IZO electrode 13 connected in the X-axis direction and the second IZO electrode 14 connected in the Y-axis direction are arranged in the same layer, a crossing portion is generated. In order to do so, a wiring portion such as a jumper wire 18 is required. In the capacitive touch panel according to the present embodiment, the jumper wire 18 is formed on the surface of the overcoat layer 5, and the insulating film 16, the first and second IZO electrodes 13, and the IZO transparent 14 are formed thereon. Therefore, the jumper wire 8 can be made inconspicuous when viewed from the front side.

  In the present embodiment, since the entire opening of the through hole 17 is covered with the first IZO electrode 13, for example, even if an overhang of the insulating film occurs in the range of the arrow shown in FIG. The first IZO electrode 13 can reach the surface of the jumper wire 18 along the inner wall of the through hole 17 that is not present. Therefore, disconnection of the jumper wire 18 can be prevented regardless of the cross-sectional shape of the inner wall of the through hole 17.

  If the jumper wire 18 can be formed of a metal-based light-shielding material, the alignment mark for positioning and the terminal on the substrate using the same material as the jumper wire 18 in the same process as the patterning of the jumper wire 18 An electrode can be formed. As a result, the alignment mark formation process can be omitted, and positioning at the time of exposure can be performed using a standard reading mechanism without any special modification to the exposure machine used to form the second and subsequent layers. It becomes possible to do.

  In addition, when the alignment is performed by visually confirming with a microscope or the like when forming the second and subsequent layers, the visibility is improved because the first-layer jumper wire 18 is formed of a light-shielding material. It is possible to easily perform alignment.

  The conductive polymer material has a trade-off relationship between translucency and conductivity. However, the light-transmitting property of the entire input device is improved even if it has a light shielding property within a limited range where the jumper wire 18 is formed. The effect is small. In addition, regarding the conductivity, any material having a resistance value comparable to that of IZO or ITO may be used, and thus the use of a conductive polymer has an advantage that the production efficiency is increased.

  Next, after covering the touch panel sensor with the above-mentioned transparent insulating material as a protective layer, the multi-sided liquid crystal display device group is cut into individual devices, and a polarizing film, a retardation film, etc. are attached to the touch panel Completed as a liquid crystal display with sensor.

Finally, measurement results of the surface resistance value and light transmittance (λ = 550 nm) of an IZO metal oxide formed by sputtering using an IZO target with a mixed ratio of In ₂ O ₃ and ZnO will be described. As a comparison, measurement was also performed on an ITO film having a standard composition In ₂ O ₃ : SnO ₂ = 90: 10. A list of compositions and results is shown in Table 1, and a graph showing the surface resistance and transmittance is shown in FIG.

First, as is apparent from FIG. 5, the composition dependence of the surface resistance of IZO shows that the In ₂ O ₃ component takes a minimum value of about 250 Ω / □ in the range of 90 wt% to 80 wt%, and the ZnO component increases. It turns out that it increases rapidly. This value is a value at room temperature (about 25 ° C.) after film formation without high temperature annealing of IZO.
Note that IZO had little change in surface resistance and transmittance with respect to the annealing temperature, and had a surface resistance of 210Ω / □ at 100 ° C. and a transmittance of about 87% (λ = 550 nm).

On the other hand, the surface resistance of ITO is 150Ω / □, which is lower than that of IZO, when the annealing temperature is 230 ° C., but it is 1050Ω / □, which is about four times that of IZO, and is high resistance. In addition, a phenomenon that the sealing material was dissolved by 230 ° C. annealing was observed.
In addition, ITO had a surface resistance of 400Ω / □ at an annealing temperature of 100 ° C. and a transmittance of about 89% (λ = 550 nm).
Therefore, IZO has a surface resistance of about 250 Ω / □ and is sufficiently practical as a capacitance detection electrode without performing an annealing treatment.

As for the transmittance, IZO has a higher transmittance as the In ₂ O ₃ component is larger, and is about the lower limit of ITO or a value close thereto.
Judging comprehensively from the above, the merit that IZO does not require high-temperature annealing like ITO was superior to the demerit that the surface resistance and transmittance are slightly lower than those of ITO.

1. Glass substrate 2, TFT side substrate 3, TFT (Thin film Transistor)
4, liquid crystal 5, color filter 6, sealing material 7, color liquid crystal display device 10, touch panel sensor 12, substrate 13, first transparent electrode 14, second transparent electrode 15, connection portion 16, (transparent) insulating film 17 , Through hole 18, jumper wire

Claims (5)

  In a liquid crystal display device with a touch panel sensor that uses the glass substrate on the side equipped with the color filter as a support substrate for the touch panel sensor among the pair of glass substrates holding the liquid crystal, the back surface as viewed from the color filter of the glass substrate to be shared A liquid crystal display device with a touch panel sensor, wherein a capacitive touch panel sensor is directly and integrally formed on the side.   2. The liquid crystal display device with a touch panel sensor according to claim 1, wherein the capacitance detection electrode of the touch panel sensor is made of a metal oxide formed at a low temperature of 120 ° C. or lower. _{3. The} liquid crystal display with a touch panel sensor according to claim 2, wherein the metal oxide is an IZO metal oxide having a mixing ratio of In ₂ O ₃ and ZnO in a range of 90:10 to 80:20 by weight%. apparatus.   4. The liquid crystal display device with a touch panel sensor according to claim 2, wherein the sheet resistance of the IZO metal oxide is 300Ω / □ or less and the transmittance is 80% or more. 5. At least a step of manufacturing a color liquid crystal display device, a step of thinning two glass substrates constituting the liquid crystal display device by wet etching, and a capacitive touch panel sensor on the surface of the glass substrate having a color filter on the back surface The process for forming a liquid crystal display device with a touch panel sensor having the steps of forming the touch panel sensor in this order, wherein the touch panel sensor forming step is a sputtering method in which the mixing ratio of In ₂ O ₃ and ZnO is 90% by weight. Sputtering a sputtering target in the range of 10 to 80:20 to form an IZO metal oxide film, annealing the IZO metal oxide at a temperature of 120 ° C. or less, and patterning the IZO metal oxide And a process for producing a liquid crystal display device with a touch panel sensor.