CN102539950A - The apparatus for inspection of electrical characteristics of the capacitive touch screen panel using resonance frequency shift - Google Patents

Abstract

The invention discloses an apparatus for inspection of electrical characteristics of the capacitive touch screen panel (CTSP) using resonance frequency shift. The apparatus comprises a power supply unit constructed to provided voltage or current to a circuit, a CTSP unit constructed to connect a resistor Rp of ITO electrode of CTSP to a resistor Cp of ITO electrode of CTSP in series, a resonance unit constructed to have an LC resonance circuit connected to the power supply unit and generate electrical resonance, a resonance frequency change unit which is connected to the resonance unit and is constructed to change the resonance frequency of the resonance unit, and an operation unit which is disposed between the CTSP unit and the resonance frequency change unit to connect the CTSP unit and the resonance frequency change unit. Under the situation that the CTSP unit is connected to the resonance unit, the resistance and capacitance of a changed CTSP unit responding to the resonance frequency can be measured at the same time through operating the operation unit.

Description

Utilize the device of the electrical specification of resonance frequency displacement inspection capacitance touch screen panel

Technical field

The present invention relates to check the device of the electrical specification of capacitance touch screen panel (calling " CTSP " in the following text), relate in particular to the LC parallel resonant circuit is connected to CTSP and utilizes the resonance frequency displacement to check the device of the electrical specification of CTSP.

Background technology

Usually, the display screen that is attached to mobile phone or all-in-one is classified as electric resistance touch screen panel and capacitance touch screen panel, the touch of response finger and can carry out the selection of various buttons or the input of information.In the middle of these touch panels, capacitance touch screen panel (CTSP) comprising: the following counterdie that is arranged in the panel bottom; The sensor electrode film, it is arranged in down on the counterdie, and is constructed to make formation above that as the transparent ITO electrode pattern of touch sensor; Dielectric film, it is arranged on the sensor electrode film and uses adhesive attachment to the ITO electrode; And the diaphragm that is arranged in the top of panel.Although the structure of the pattern of ITO electrode, promptly the touch sensor electrode can be made or performance or the mode that drives the nonshared control unit chip change according to it, and its basic one-piece construction is same as described above.Especially, keeping the method for the electric capacity between the ITO sensor electrode is common for all manufacturers.

Usually, capacitance touch screen panel (CTSP) is constructed to have horizontal electrode and the vertical electrode of transparent ITO pattern and between horizontal electrode and vertical electrode, is furnished with dielectric film, and said modules overlaps each other to form thin shape.That is,, think that capacitance touch screen panel (CTSP) is constructed to make the capacitor (C of Fig. 2 of ITO electrode from the viewpoint of circuit _p) and the resistor (R of Fig. 2 _p) connection is one another in series.

If the longitudinal electrical resistance of ITO electrode is owing to its low-down surface resistance is lower than 1K Ω, then the electrical specification of CTSP will only receive the influence of the electric capacity of ITO electrode, and not receive the influence of the resistance of ITO electrode.Yet generally speaking, the surface resistance of ITO electrode that is used for the CTSP of smart mobile phone etc. is about 200～500 Ω/sq, and longitudinal electrical resistance is tens of k Ω.Therefore, the electrical specification of CTSP receives resistor R _pWith capacitor C _pBetween the influence that is connected in series, therefore and when the characteristic of checking CTSP and function, it is highly important that, measure these electrical specification values.But, in fact,, hidden at the ITO electrode because of being arranged under the diaphragm, therefore, be difficult to separate and measure the resistance and the electric capacity of ITO electrode.

Summary of the invention

Therefore; The present invention is designed to address the above problem; And the object of the present invention is to provide a kind of device that uses the electrical specification of resonance frequency displacement inspection CTSP, wherein side by side measure resistance and electric capacity according to the ITO electrode of the CTSP of the variation of resonant frequency.

In order to achieve the above object, aspect of the present invention provides a kind of device that uses the electrical specification of resonance frequency displacement inspection capacitance touch screen panel, comprising: power supply unit, to circuit supply voltage or electric current; The CTSP unit is the resistor R of the ITO electrode of CTSP _pWith the interelectrode capacitor C of the ITO of CTSP _pConnection is one another in series; The resonance unit is constructed to comprise the LC resonant circuit that is connected with power supply unit and produces electric resonance; Resonant frequency changes the unit, is connected to the resonance unit and is constructed to change the resonant frequency of resonance unit; Operating unit; Being arranged in CTSP unit and resonant frequency changes between the unit to connect CTSP unit and resonant frequency change unit; Wherein be connected under the situation of resonance unit, measure resistance and electric capacity simultaneously in response to the CTSP unit of the change of resonant frequency through operating said operating unit in the CTSP unit.

Here, through the resistor R of change with CTSP _pThe resistance of the resistor r that can change arbitrarily that is connected in series can cause the change of resonant frequency.

In addition, can connect resonant frequency and change the switch of unit and therefore extra capacitor is connected to the resonance unit concurrently, thereby change resonant frequency, measure the electric capacity of CTSP unit thus.

Here, can under the fixing situation of the resistance of CTSP unit, measure electric capacity in response to the CTSP unit of the change of resonant frequency.

Description of drawings

In conjunction with accompanying drawing, according to following detailed description, of the present invention above with other purposes, feature and advantage will be clearer, wherein:

Fig. 1 is a circuit block diagram according to an embodiment of the invention;

Fig. 2 is that the LC resonant circuit is connected to the circuit diagram of CTSP according to an embodiment of the invention; And

Fig. 3 is the figure that illustrates in the circuit diagram of Fig. 2 in response to the variation of the resonant frequency of the changes in resistance of resistor r.

Embodiment

, of the present inventionly above will be more prone to understand according to following detailed description in conjunction with accompanying drawing with other purposes, characteristic and advantage.Below, the device of checking the electrical characteristic of CTSP based on the use resonance frequency displacement of embodiments of the invention will be described with reference to the drawings in detail.In this manual, except that indicating especially, the identical Reference numeral in the accompanying drawing is represented components identical.

Fig. 1 is a circuit block diagram according to an embodiment of the invention, and Fig. 2 is that the LC resonant circuit is connected to the circuit diagram of CTSP according to an embodiment of the invention.As shown in Figure 1, comprising according to the device of inspection capacitance touch screen panel of the present invention (CTSP): power supply unit 100, be constructed to voltage or electric current are provided to circuit CTSP unit 500, be constructed to make the resistor R of the ITO electrode of CTSP _pAnd the capacitor C between the ITO electrode of CTSP _pConnection is one another in series; Resonance unit 200 is constructed to comprise the LC resonant circuit that is connected with power supply unit 100 and produces electric resonance; Resonant frequency changes unit 300, and it is connected with resonance unit 200 and is constructed to change the resonant frequency of unit 200 of resonating; And operating unit 400, be arranged in CTSP unit 500 and resonant frequency and change between the unit 300 to connect CTSP unit 500 and resonant frequency change unit 300.

The device that is used to check capacitance touch screen panel (CTSP) is used to use the operation of the switch (SW1) of operating unit 400; Be connected in CTSP unit 500 under the situation of resonance unit 200, measure resistance and electric capacity simultaneously in response to the CTSP unit 500 of the variation of resonant frequency.At this, the variation of resonant frequency can by with the resistor R of CTSP _pThe change of the resistance of the resistor r that can change arbitrarily that is connected in series causes.

In addition, change the switch SW 2 of unit 300 and be connected extra capacitor C concurrently through connecting resonant frequency with resonance unit 200 ₁Thereby, change the electric capacity that resonant frequency is measured CTSP unit 500.In this case, can be in the resistance R of fixation of C TSP unit 500 _pSituation under measure capacitor C in response to the CTSP unit 500 of the variation of resonant frequency _p

Power supply unit 100 is general independent current sources.In general independent current source, through transformer the voltage rising perhaps is reduced to the voltage of expectation, and then it is transferred to load.Independent current source as power supply unit can be corresponding to AC power supplies and DC power supply.AC power supplies comprises AC voltage source and AC current source.The DC power supply comprises dc voltage source and DC current source.When independent current source is the DC power supply, can be converted into AC power supplies through inverter.

According to the present invention; The electric capacity of the ITO electrode through " the LC tank circuit of modification (a modified LC parallel resonance circuit) " doing mathematics analysis being designed the electrical specification that measure to constitute CTSP unit 500 and the method for resistance; In above-mentioned " the LC tank circuit of modification "; Have the operating unit 400 of switch (SW1), general LC tank circuit (identical) and CTSP unit 500 and be combined in together, as shown in Figure 2 with resonance unit 200.

Principle of the present invention is following: the resonant frequency f of general LC parallel circuit ₀Be defined as the frequency when the impedance Z of circuit is infinitely great (∞), it is derived as follows.Can be for reference be, the resonant frequency in the lc circuit refers to the frequency when the natural frequency of circuit coupling power supply, thus the frequency when causing resonance effect and making electric current or the voltage maximization of circuit.Resonant frequency f in the rlc circuit ₀Represent by following equality 1:

${\mathrm{\ω}}_0=2\mathrm{\π}{f}_0=\frac{1}{\sqrt{\mathrm{LC}}}---\left(1\right)$

At this, when the switch (SW1) of making operation unit makes the resistor R of ITO electrode of CTSP unit 500 _pWith capacitor C _pBeing connected to is basic LC _RefThe LC tank circuit 200 of parallel circuit, this LC tank circuit 200 is converted into as LC _RefThe resistor R of parallel circuit and ITO electrode _pWith capacitor C _pSerial circuit between the LC resonant circuit of modification of parallel circuit.In this case, impedance Z ₁And Z ₂Represent by following equality 2:

$Z_1=\frac{-\mathrm{i\ωL}}{{\mathrm{\ω}}^{2}L{C}_{\mathrm{ref}}-1}$ $Z_2=R_p+\frac{1}{{\mathrm{i\ωC}}_p}---\left(2\right)$

The resulting impedance Z of this circuit can obtain through following equality 3:

$\frac{1}{Z}=\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="Z"\; filenames="HSA00000580461200012.png"\; state="\{\{state\}\}">Z</figure-callout>}}_1}+\frac{1}{Z_2}=\frac{R_p}{\frac{1}{{C_p}^2{\mathrm{\&omega;}}^2}+{R_p}^2}+i(C_{\mathrm{ref}}\mathrm{\&omega;}+\frac{1}{C_p\mathrm{\&omega;}(\frac{1}{{C_p}^2{\mathrm{\&omega;}}^2}+{R_p}^2)}-\frac{1}{\mathrm{L\&omega;}})---\left(3\right)$

Because under the imaginary part of impedance (Z) is 0 condition, confirm the resonant frequency among the resulting impedance Z, therefore, resonant frequency is the frequency of the equality 4 below satisfying:

$C_{\mathrm{ref}}\mathrm{\&omega;}+\frac{1}{C_p\mathrm{\&omega;}(\frac{1}{{C_p}^2{\mathrm{\&omega;}}^2}+{R_p}^2)}-\frac{1}{\mathrm{L\&omega;}}=0---\left(4\right)$

At this, at C _RefC _pLR _pUnder ≠ 0 the situation, obtain positive real root through following equality 5:

$\mathrm{\&omega;}={\left(\frac{1\sqrt{4L{C}_{\mathrm{ref}}{R_p}^2{C_p}^2+{({\mathrm{LC}}_{\mathrm{ref}}+{\mathrm{LC}}_p-{R_p}^2{C_p}^2)}^2}-{\mathrm{LC}}_{\mathrm{ref}}-{\mathrm{LC}}_p+{R_p}^2{C_p}^2}{{\mathrm{LC}}_{\mathrm{ref}}{R_p}^2{C_p}^2}\right)}^{1/2}---\left(5\right)$

At this, can find out, in resistor R _pUnder=0 the situation, fundamental resonant appears, and at R _p--under the situation of＞∞, resonance frequencies converge does

Can not only use such scheme to obtain resistance and electric capacity in the CTSP unit 500 simultaneously.But, when resistor r and resistor R with known resistance _pBe connected in series, measure the data of the variation of the resonant frequency that changes in response to resistance r, during then with the equality 6 below the data substitution, can obtain resistance and electric capacity simultaneously.

$\mathrm{\&omega;}={\left(\frac{1}{2}\frac{\sqrt{{4\mathrm{LC}}_{\mathrm{ref}}{(R_p+r)}^2{C_p}^2+{({\mathrm{LC}}_{\mathrm{ref}}+{\mathrm{LC}}_p-{(R_p+r)}^2{C_p}^2)}^2}-{\mathrm{LC}}_{\mathrm{ref}}-{\mathrm{LC}}_p+{(R_p+r)}^2{C_p}^2}{{\mathrm{LC}}_{\mathrm{ref}}{(R_p+r)}^2{C_p}^2}\right)}^{1/2}---\left(6\right)$

Fig. 3 is the figure that illustrates in response to the variation of the resonant frequency of the changes in resistance of resistor r.Fig. 3 illustrates at L=R _Ref=R _p=C _pUnder=1 the situation, the figure of the variation of the resonant frequency in the scope of 0.001＜r＜10.According to Fig. 3, can find out that along with resistance (r) increases, resonant frequency increases in preset range (0.01＜r＜5) internal linear.

In Fig. 1, when comprising resistor R _pWith capacitor C _pThe time constant of series connection RC circuit be defined as " τ _p", and will comprise inductor L and capacitor C _pThe resonant frequency of tank circuit be defined as " ω _p" time, through following equality 7 expression τ _pAnd ω _p

τ _p＝R _pC _p ${\mathrm{\&omega;}}_{p^{\&prime;}}=\frac{1}{\sqrt{{\mathrm{LC}}_p}}---\left(7\right)$

Now, the equality that resonated originally is by 8 expressions of following equality, and it is separated by 9 expressions of following equality.

${\left(\frac{\mathrm{\&omega;}}{{\mathrm{\&omega;}}_p}\right)}^2\frac{1}{1+{\mathrm{\&omega;}}^2{{\mathrm{\&tau;}}_p}^2}=1-{\left(\frac{\mathrm{\&omega;}}{{\mathrm{\&omega;}}_0}\right)}^2---\left(8\right)$

$\mathrm{\&omega;}=\frac{{\mathrm{\&omega;}}_0}{\sqrt{2}}{(-(\frac{1}{{{\mathrm{\&tau;}}_p}^2{{\mathrm{\&omega;}}_0}^2}+\frac{1}{{{\mathrm{\&tau;}}_p}^2{{\mathrm{\&omega;}}_p}^2}-1)+\sqrt{{(\frac{1}{{{\mathrm{\&tau;}}_p}^2{{\mathrm{\&omega;}}_0}^2}+\frac{1}{{{\mathrm{\&tau;}}_p}^2{{\mathrm{\&omega;}}_p}^2}-1)}^2-\frac{4}{{{\mathrm{\&tau;}}_p}^2{{\mathrm{\&omega;}}_0}^2}})}^{1/2}---\left(9\right)$

Simultaneously, when for ω _pWhen finding the solution the resonance equality, it is separated through 10 expressions of following equality.

${\mathrm{\&omega;}}_p=\frac{{\mathrm{\&omega;}}_0\mathrm{\&omega;}}{\sqrt{({{\mathrm{\&omega;}}_0}^2-{\mathrm{\&omega;}}^2)({{\mathrm{\&tau;}}_p}^2{\mathrm{\&omega;}}^2+1)}}---\left(10\right)$

In equality 10, for obtaining ω _pAnd τ _p, change ω ₀, and therefore according to ω ₀Variation and measure ω.For this reason, connect the switch (SW2) that resonant frequency changes unit 300, and with other capacitor C ₁Be parallel to resonance unit 200, thereby change resonant frequency.That is the switch of closed Fig. 2 (SW2) and, with capacitor C ₁Be connected in parallel to resonant circuit 200, thereby change ω ₀, and, in this case, when passing through to measure ω ₀Variation obtain ω ₀With two or more whens value of ω, can obtain value and two equalities of two the unknowns, thereby obtain ω _pAnd τ _pThereby the equality 11 below using obtains resistance and electric capacity.

τ _p＝R _pC _p ${\mathrm{\&omega;}}_p=\frac{1}{\sqrt{{\mathrm{LC}}_p}}---\left(11\right)$

In above-mentioned equality 11,, therefore can and change the condition (changing position of pointing or the like) that touches through fixed resistance and come accurately to measure each instantaneous electric capacity because with respect to the electric capacity of CTSP unit 500, resistance is non-variable value.With this mode, can make up and to check whether defectiveness and can confirm the equipment of the bulk property of CTSP of CTSP unit 500.

As stated, according to the equipment that is used to check the capacitance touch screen panel of the present invention, can be through simple LC resonant circuit being connected to traditional CTSP and using the resonant frequency characteristic to come easily to check the electrical specification of CTSP (resistance and electric capacity) then.In addition, this is used for checking that the device of capacitance touch screen can easily be used to analyze the defective of CTSP, and this is because can use relation between LC resonant circuit and the resonant frequency to obtain the actual capacitance between the ITO electrode of CTSP.

Though described the preferred embodiments of the present invention in the above, the invention is not restricted to above-mentioned specific embodiment.Promptly; Those skilled in the art will be appreciated that; Under the situation that does not depart from disclosed scope of the present invention and spirit in the claim, various modifications, interpolation and replacement all are possible, and the equivalent of all so suitable variations and modification all should be regarded as belonging to scope of the present invention.

Claims (4)

1. one kind is used for using the resonance frequency displacement to check the device of the electrical specification of capacitance touch screen panel (CTSP), comprising:

Power supply unit is constructed to make to circuit supply voltage or electric current;

The CTSP unit is constructed to make the resistor R of the ITO electrode of CTSP _pAnd the capacitor C between the ITO electrode of CTSP _pConnection is one another in series;

The resonance unit is constructed to comprise the LC resonant circuit that is connected with said power supply unit and produces electric resonance;

Resonant frequency changes the unit, is connected to said resonance unit and is constructed to change the resonant frequency of said resonance unit; And

Operating unit is arranged in said CTSP unit and said resonant frequency and changes between the unit to connect said CTSP unit and said resonant frequency change unit;

Wherein be connected under the situation of said resonance unit, side by side measure resistance and electric capacity in response to the said CTSP unit of the change of resonant frequency through operating said operating unit in said CTSP unit.

2. device according to claim 1 is wherein through the resistor R of change with said CTSP unit _pThe resistance of the resistor r that can change arbitrarily of series connection causes the change of resonant frequency.

3. device according to claim 1 wherein changes the switch of unit and therefore extra capacitor is parallel-connected to said resonance unit through connecting said resonant frequency, thereby changes the electric capacity that resonant frequency is measured said CTSP unit.

4. device according to claim 3, wherein, under the situation of the electric capacity of fixing said CTSP unit, measurement is in response to the electric capacity of the said CTSP unit of the change of resonant frequency.

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