JP5321990B2 - Electric characteristic inspection device for capacitive touch screen panel using resonant frequency shift - Google Patents

Description

  The present invention relates to an apparatus for inspecting the electrical characteristics of a capacitive touch screen panel (hereinafter referred to as “CTSP”), and more particularly, an LC parallel resonant circuit is coupled to CTSP for resonance. The present invention relates to an inspection apparatus capable of discriminating electrical characteristics of CTSP by using frequency shift.

  In general, touch screen panels that are mounted on a display screen such as a mobile phone or a kiosk and are used for inputting various buttons or information by hand touch are classified into a resistive film type and a capacitive type. Among these, the capacitive touch screen panel “CTSP” generally has a lower grounding film at the lowermost end, and a sensor electrode film on which a transparent ITO electrode pattern serving as a touch sensor is formed. And a dielectric film bonded to the ITO electrode with an adhesive, and an uppermost protective film. The pattern of the ITO electrode pattern as a touch sensor electrode for each manufacturing company varies depending on its performance and the driving method of the dedicated controller chip, but the overall basic structure is as described above, and in particular, the electrostatic capacitance between ITO sensor electrodes The method of maintaining capacity is a common issue for each company.

Generally, a capacitive touch screen panel (CTSP) is used by laminating a horizontal electrode made of a transparent ITO pattern and a vertical electrode with a dielectric sandwiched between them. From the viewpoint of the circuit, the overresistance (R _{p in} FIG. 2) of the capacitance (C _{p in} FIG. 2) of the ITO electrode is seen in a form connected in series.

If the ITO sheet resistance is very low and the ITO electrode length resistance is less than 1 KΩ, the resistance R _p is ignored in the electrical characteristics of the CTSP and only the capacitance value C _p is the CTSP electrical resistance. In general, the surface resistance of an ITO electrode of CTSP used in a smartphone or the like is about 200 to 500 Ω / sq, and the resistance in the length direction is several tens of kΩ. Therefore, since the electrical characteristics of CTSP are affected by the series connection of R _p and C _p , it is very important to measure these two electrical characteristic values in the CTSP characteristic inspection and functional inspection. However, since the ITO electrode in the actual situation are hidden is arranged at the lower end of the protective film, it is very difficult to separately measure the resistance R _p and the capacitance value C _p of the ITO electrode.

The present invention has been made in view of the above problems, its object is operable to measure the ITO resistance R _p and the capacitance C _p of the CTSP due to a change in the resonant frequency at the same time, the resonance frequency shift It is an object of the present invention to provide a device for inspecting electrical characteristics of a capacitive touch screen panel using the above.

To achieve the above object, the present invention provides a testing device of a capacitive touch screen panel using a resonance circuit, and a power supply unit for supplying a voltage or current in the circuit, the resistance R _p and the ITO electrodes of the CTSP a CTSP portion disposed capacitance C _p between the electrodes in series, is connected to the power supply unit, and a resonance part including an LC resonance circuit to cause electrical resonance, is connected to the resonating part, resonance of the resonant portion A resonance frequency changing unit that changes a frequency; and an operation unit that operates between the CTSP unit and the resonance frequency changing unit and connects the CTSP unit and the resonance frequency changing unit. while connecting the resonance part and the CTSP unit by operation, characterized by simultaneously measuring the resistance R _p and the capacitance C _p of the CTSP part by a change in the resonant frequency, the resonant circumferential An apparatus for inspecting electrical characteristics of a capacitive touch screen panel using wave number shift is provided.

Here, change in the resonant frequency, it is preferable to produce in response to a change in r by connecting the modifiable resistors r in series with arbitrarily resistance R _p of the CTSP portion.

Further, the resonance frequency changing unit, the switch is further connected in parallel a separate capacitor to the resonating unit operates as turn, measure the capacitance C _p of the CTSP portion by changing the resonant frequency It is preferable to do.

Here, to secure the resistance _{R p} of the CTSP portion, it is preferable to measure the capacitance _{C p} of the CTSP portion due to a change in the resonant frequency.

According to the inspection apparatus of the present invention, it is possible to easily detect electrical characteristics R _p and C _p of CTSP by using a resonance frequency characteristic by connecting a simple LC resonance circuit in series to an existing CTSP. There is an effect. Moreover, since the actual capacitance value between the ITO electrodes of the CTSP can be obtained from the relational expression between the constant of the LC resonance circuit and the resonance frequency, it can be easily used for failure analysis.

It is a circuit block diagram concerning one example of the present invention. It is a circuit diagram of the form which connected LC resonance circuit concerning one example of the present invention to CTSP. 3 is a graph for calculating a change in resonance frequency due to a change in resistance r in the circuit diagram of FIG. 2.

  The above objects, features and other advantages of the present invention will become more apparent by describing in detail preferred embodiments of the present invention with reference to the accompanying drawings. Hereinafter, a device for inspecting electrical characteristics of a capacitive touch screen panel using a resonant frequency shift according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. For the purposes of this specification, the same reference numbers in the figures refer to the same components unless otherwise indicated.

FIG. 1 is a circuit block diagram according to an embodiment of the present invention. FIG. 2 is a circuit diagram of an embodiment in which an LC resonance circuit according to an embodiment of the present invention is connected to CTSP. As shown in FIG. 1, the present invention includes a power supply unit 100 supplies the generated power power, the CTSP portion 500 connected to the capacitance _{C p} between the resistance _{R p} and the electrode of the ITO electrode of the CTSP in series A resonance unit 200 including an LC resonance circuit connected to the power source unit 100 and causing electrical resonance; a resonance frequency changing unit 300 connected to the resonance unit 200 to change the resonance frequency of the resonance unit 200; and a CTSP unit 500. An operation unit 400 that operates between the resonance frequency changing unit 300 and connects the CTSP unit 500 and the resonance frequency changing unit 300 is included.

Inspection apparatus according to the present invention, while connecting the CTSP portion 500 and the resonance part 200 by the operation of the SW1 of the operation section 400, the resistance _{R p} and the capacitance _{C p} of the CTSP portion 500 by the change in the resonance frequency at the same time Works to measure. Here, it is possible to produce in response to changes in r and the change in the resonance frequency is connected optionally changeable resistance r in the resistance R _p of the ITO electrodes in series.

Further, the resonance frequency changing unit 300 further connected in parallel separate capacitor _{C 1} to the resonance unit 200 turns on a separate switch SW2, to measure the capacitance _{C p} of the CTSP portion 500 by changing the resonant frequency be able to. In this case, it is possible to secure the resistance _{R p} of the CTSP unit 500, measuring the capacitance _{C p} of the CTSP portion 500 by the change in the resonance frequency.

  The power supply unit 100 means a general independent power supply. In this way, the independent power supply in a general sense is boosted or stepped down to a voltage required on the load side using a transformer or the like and transmitted to the load. The independent power source as the power source unit 100 may be an AC power source or a DC power source. The AC power source includes both an AC voltage power source and an AC current power source, and the DC power source includes both a DC voltage power source and a DC current power source. When the independent power source is a DC power source, it can be converted into AC via an inverter.

In the present invention, the “modified LC parallel resonance circuit” configured by coupling between the operating unit 400 having the switch SW1 shown in FIG. 2, the general LC parallel resonance circuit (same as the resonance unit) 200, and the CTSP unit 500 is expressed mathematically. Thus, a method of simultaneously measuring the capacitance value C _p and the resistance value R _p of the ITO electrode constituting the electrical characteristics of the CTSP unit 500 was devised.

The principle of the present invention is as follows. The resonance frequency f ₀ of a general LC parallel circuit is determined by the frequency at which the impedance Z becomes infinite (∞), and is derived as follows. For reference, the resonance frequency f ₀ means the frequency until the current or voltage reaches the maximum when the natural frequency of the circuit and the frequency of the power supply coincide with each other in the circuit combined with L and C to cause a resonance phenomenon. . The resonance frequency f _o of the RLC circuit is derived from the following equation 1.

Formula 1

ここで、数式１のように基本ＬＣ_{r e f}並列回路としてのＬＣ並列共振回路２００にＣＴＳＰ部５００のＩＴＯ電極の抵抗Ｒ_ｐおよび静電容量Ｃ_ｐが接続されるように作動部４００のＳＷ１を閉じると、ＬＣ並列共振回路２００は、ＬＣ_ｒｅｆ並列回路と、ＩＴＯ電極の抵抗Ｒ_ｐ、静電容量Ｃ_ｐの直列回路との間での並列回路である、変形ＬＣ共振回路と見なされる。この際、それぞれのインピーダンスＺ_１とＺ_２は下記数式２で与えられる。

Here, closing SW1 of the operation unit 400 so that the resistance _{R p} and the capacitance _{C p} of the ITO electrodes of the basic LC _ref CTSP unit 500 to the LC parallel resonance circuit 200 as a parallel circuit is connected as Equation 1 The LC parallel resonance circuit 200 is regarded as a modified LC resonance circuit that is a parallel circuit between the LC _ref parallel circuit and the series circuit of the ITO electrode resistance R _p and the capacitance C _p . At this time, the respective impedances Z ₁ and Z ₂ are given by the following Equation 2.

Formula 2

この回路の総インピーダンスＺは下記数式３で求めることができる。

The total impedance Z of this circuit can be obtained by the following Equation 3.

Formula 3

前記総インピーダンスＺにおいて、共振周波数はインピーダンスＺの虚数部が０となる条件で決定される。よって、下記数式４を満足する周波数が共振周波数である。

In the total impedance Z, the resonance frequency is determined under the condition that the imaginary part of the impedance Z is zero. Therefore, the frequency satisfying the following formula 4 is the resonance frequency.

Formula 4

ここで、Ｃ_ｒｅｆＣ_ｐＬＲ_ｐ≠０の場合、正の実根を求めると、下記数式５のとおりである。

Here, in the case of C _ref C _p LR _p ≠ 0, a positive real root is obtained as shown in Equation 5 below.

Formula 5

ここで、抵抗Ｒ_ｐ＝０の場合には基本共振となり、抵抗Ｒ_ｐ→∞の場合には

に収束することが分かる。

Here, when the resistance R _p = 0, the basic resonance occurs, and when the resistance R _p → ∞,

It turns out to converge to.

Only with the solution, the resistance R _p and the capacitance C _p in the given CTSP unit 500 cannot be obtained simultaneously. However, if a resistor r having a known resistance value is connected in series to the resistor R _p and the change data of the resonance frequency due to the change of the resistor r is measured, and this is applied to the following equation (fitting), resistance R _p and the capacitance C _p can be obtained simultaneously.

Formula 6

図３は抵抗ｒの変化による共振周波数の変化計算グラフを示す。図３のグラフは、Ｌ＝Ｒ_ｒｅｆ＝Ｒ_ｐ＝Ｃ_ｐ＝１のとき、０．００１＜ｒ＜１０の範囲で共振周波数の変化計算グラフを示すものである。特定ｒの範囲ではｒが増加するときに共振周波数が線形的に増加することが分かる（０．０１＜ｒ＜５）。

FIG. 3 shows a graph for calculating the change in resonance frequency due to the change in resistance r. The graph of FIG. 3 shows a change calculation graph of the resonance frequency in the range of 0.001 <r <10 when L = R _ref = R _p = C _p = 1. It can be seen that the resonance frequency increases linearly when r increases in the range of specific r (0.01 <r <5).

In FIG. 1, if the time constant of a series RC circuit composed of a resistor R _p and a capacitance C _p is τ _p, and the resonance frequency of a parallel resonance circuit composed only of L and the capacitance C _p is ω _p , A relationship such as Equation 7 is formed.

Formula 7

元々の共振条件方程式は数式８のとおりであり、その解は下記数式９のとおりである。

The original resonance condition equation is as shown in Equation 8, and the solution is as shown in Equation 9 below.

Formula 8

Formula 9

一方、共振条件方程式をω_ｐに対して解くと、下記数式１０のとおりである。

On the other hand, when the resonance condition equation is solved with respect to ω _p , the following Equation 10 is obtained.

Formula 10

前記数式１０でω_ｐとτ_pを求めるためにω_０を変化させ、これにより変化するωを測定する。このために、前記共振周波数変更部３００のスイッチＳＷ２をターンオンして共振部２００に別途のキャパシタＣ_１をさらに並列接続することにより共振周波数を変更させることができる。すなわち、図２のＳＷ２を閉じてＣ_１を共振回路に並列接続してω_０を変化させる。この際、測定によってω_０、ω値を２つ以上求めると、未知数が２つ、方程式が２つなので、ω_ｐとτ_pを求めることができ、最終的には下記数式１１でＲ_ｐと静電容量Ｃ_pを求めることができる。

In order to obtain ω _p and τ _p in Equation (10), ω ₀ is changed, and ω thus changed is measured. For this, it is possible to change the resonant frequency by further parallel-connected separate capacitor C ₁ to the resonance part 200 turns on the switch SW2 of the resonance frequency changing unit 300. In other words, changing the omega ₀ connected in parallel to the resonant circuit C ₁ closes the SW2 of FIG. At this time, if two or more values of ω ₀ and ω are obtained by measurement, since there are two unknowns and two equations, ω _p and τ _p can be obtained. Finally, R _p and it can be determined capacitance C _p.

Formula 11

前記数式１１において、抵抗Ｒ_ｐはＣＴＳＰ部５００上の一つの静電容量(Electrostatic Capacity)に対して変わらない値なので、この値を固定し、タッチ環境（手指の位置などの変更）が変化するにつれて変化するωによって各瞬間の静電容量Ｃ_ｐを正確に測定することができる。このような方法でＣＴＳＰ部５００の単純な不良有無を超えて製作されたＣＴＳＰ部５００の全体的な性質を特性化する装備を構築することができる。

In Equation 11, since the resistance R _p is a value that does not change with respect to one electrostatic capacity on the CTSP unit 500, this value is fixed, and the touch environment (change of finger position and the like) changes. The capacitance C _p at each instant can be accurately measured by ω that changes with time. In this way, it is possible to construct equipment that characterizes the overall properties of the CTSP unit 500 manufactured beyond the presence or absence of simple defects in the CTSP unit 500.

According to the inspection apparatus of the present invention, the electrical characteristics of the ITO electrode of the CTSP (resistance R _p , capacitance) can be easily obtained by connecting a simple LC resonance circuit in series with the existing CTSP and using the resonance frequency characteristics. C _p ) can be detected. Moreover, since the actual capacitance value between the ITO electrodes of the CTSP can be obtained from the relational expression between the constant of the LC resonance circuit and the resonance frequency, it can be easily used for failure analysis.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above. That is, a person having ordinary knowledge in the technical field to which the present invention belongs can make many changes and modifications to the present invention without departing from the spirit and scope of the claims. Appropriate changes and modifications equivalents are to be considered within the scope of the invention.

DESCRIPTION OF SYMBOLS 100 Power supply part 200 Resonance part 300 Resonance frequency change part 400 Actuation part 500 CTSP part

Claims (4)

In an inspection device for a capacitive touch screen panel using a resonance circuit,
A power supply for supplying voltage or current to the circuit;
A CTSP unit in which the resistance Rp of the ITO electrode and the capacitance Cp between the electrodes of the capacitive touch screen panel are connected in series;
A resonance unit including an LC resonance circuit connected to the power supply unit and causing electrical resonance;
A resonance frequency changing unit connected to the resonance unit and changing a resonance frequency of the resonance unit;
An operation unit that operates between the CTSP unit and the resonance frequency changing unit, and that connects the CTSP unit and the resonance frequency changing unit;
The resonance frequency shift is characterized by simultaneously measuring the resistance Rp and the capacitance Cp of the CTSP unit by changing the resonance frequency in a state where the CTSP unit and the resonance unit are connected by the operation of the operation unit. Electricity inspection device for the capacitive touch screen panel used.
Change in the resonant frequency, and wherein the generated according to a change in r by connecting the modifiable resistors r in series with arbitrarily resistance R _p of the CTSP portion, the resonance frequency shift according to claim 1 A device for inspecting the electrical characteristics of a capacitive touch screen panel using a touch panel. The resonance frequency change unit, the switch is further connected in parallel a separate capacitor to the resonating unit operates as turned on to measure the capacitance C _p of the CTSP portion by changing the resonant frequency The apparatus for inspecting electrical characteristics of a capacitive touch screen panel using a resonance frequency shift according to claim 1. The capacitance type touch using the resonance frequency shift according to claim 3 , wherein the resistance Rp of the CTSP unit is fixed, and the capacitance Cp of the CTSP unit is measured by a change in resonance frequency. Screen panel electrical characteristics inspection device.

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