JP3984264B2 - Apparatus for determining physical characteristics of nematic liquid crystal material and method for determining physical characteristics of nematic liquid crystal material having negative dielectric anisotropy - Google Patents

Description

  The present invention relates to a device for determining physical properties of a nematic liquid crystal material and a method for determining physical properties of a nematic liquid crystal material having negative dielectric anisotropy.

  Currently, liquid crystal displays are widely used in applications such as flat TVs and computer monitors. The liquid crystal materials used for this liquid crystal display are roughly classified into two types: positive dielectric anisotropy (Δε> 0) and negative dielectric anisotropy (Δε <0). In particular, liquid crystal materials with negative dielectric anisotropy are used for TV applications. In order to improve the responsiveness of the liquid crystal material, it is an important issue to reduce the rotational viscosity of the liquid crystal material.

It is known that the rotational viscosity of a liquid crystal material having a positive or negative dielectric anisotropy is determined by a rotating magnetic field method (see Non-Patent Document 1).
Rotating magnetic field method [FJ Bock, H. Kneppe, F. Schneider, Liquid Crystals 1 (1986), 239]

  However, the experimental equipment using the rotating magnetic field method has a problem that the structure is relatively complicated and it takes time to measure the rotational viscosity, and a large amount of liquid crystal is necessary for the measurement. .

  Further, only the rotational viscosity of a liquid crystal material having a positive anisotropy in magnetic susceptibility anisotropy Δχ is measured.

  The present invention has been made in view of the above points, and its purpose is to determine the physical characteristics of a nematic liquid crystal material having positive and negative dielectric anisotropy regardless of the polarity of magnetic susceptibility anisotropy. Apparatus for determining nematic liquid crystal materials capable of determining the physical characteristics of nematic liquid crystal materials having positive and negative dielectric anisotropy irrespective of the polarity of magnetic anisotropy It is to provide a method.

An apparatus for determining physical properties of a nematic liquid crystal material according to claim 1, wherein a liquid crystal test cell sandwiching a nematic liquid crystal material having negative dielectric anisotropy on a vertically aligned substrate, and applying to the liquid crystal test cell a voltage output means for outputting the one or more single pulse voltage for a filter means for removing noise superimposed on the single pulse voltage outputted by said voltage output means by said filter means A voltage amplifying means for amplifying the single pulse voltage from which noise has been removed and applying the amplified voltage to the liquid crystal test cell; a changeover switch means for performing a switching operation for flowing an inrush current flowing through the liquid crystal test cell; measuring means for measuring the transient current waveform flowing in the liquid crystal test cell single pulse voltage is applied, the single pulse voltage The liquid crystal and calculating means for theoretically calculating the transient waveform of the current flowing through the test cell, a transient current waveform measured by the measuring means, theoretically calculated by the calculating means when the are applied to the liquid crystal test cell such a transient current waveform is aligned while changing the physical properties of the liquid crystal material of the liquid crystal test cell, determine the physical properties of when both transient current waveform is aligned, a physical property of the liquid crystal material of the liquid crystal test cell characterized by comprising determination means for, the.

The invention described in claim 2 is the apparatus for determining physical properties of a nematic liquid crystal material according to claim 1 , wherein the determining means determines a rotational viscosity γ ₁ that is a physical property of the liquid crystal material. .

According to a third aspect of the present invention, there is provided the apparatus for determining physical properties of a nematic liquid crystal material according to the first or second aspect , wherein the determining means determines a shear viscosity η ₂ which is a physical property of the liquid crystal material. Features.

According to a fourth aspect of the present invention, there is provided the device for determining a physical property of a nematic liquid crystal material according to any one of the first to third aspects , wherein the determining means is a pretilt angle that is a physical property of the liquid crystal material. It is characterized in that θ ₀ is determined.

6. A method for determining a physical property of a nematic liquid crystal material having a negative dielectric anisotropy according to claim 5, wherein the liquid crystal test cell includes a nematic liquid crystal material having a negative dielectric anisotropy sandwiched between vertically aligned substrates. and the voltage output step of outputting one or more of the single pulse voltage for applying to the filtering step for removing noise superimposed on the single pulse voltage outputted in the voltage output step A voltage amplifying step for amplifying the single pulse voltage from which noise has been removed by the filtering step and applying the same to the liquid crystal test cell; and a switching operation for flowing an inrush current flowing through the liquid crystal test cell to the ground. a switching step, the transient current waveform flowing in the liquid crystal test cell the single pulse voltage is applied measurement A measurement step of measuring by means, the a calculation step of the transient waveform of the current flowing through the liquid crystal test cell theoretically calculated, the measuring step when the one or more single pulse voltage is applied to the liquid crystal test cell a transient current waveforms measured at, the calculated theoretical transient current waveform at said computing step, a transient current waveform matching step of Ru aligned while changing the physical properties of the liquid crystal material of the liquid crystal test cell, said transient the physical properties of when both transient current waveform is matched in the current waveform matching step, characterized by having a a determination step of determining that the physical properties of the liquid crystal material of the liquid crystal test cell.

A sixth aspect of the present invention is the method for determining physical characteristics of a nematic liquid crystal material having negative dielectric anisotropy according to claim 5 , wherein, in the determining step, the rotational viscosity is a physical characteristic of the liquid crystal material. and determining a gamma _1.

A seventh aspect of the invention is a method for determining physical characteristics of a nematic liquid crystal material having negative dielectric anisotropy according to claim 5 or claim 6 , wherein the determining step uses the physical characteristics of the liquid crystal material. It is characterized in that a certain shear viscosity η ₂ is determined.

The invention according to claim 8 is the method for determining physical properties of a nematic liquid crystal material having negative dielectric anisotropy according to any one of claims 5 to 7 , wherein the determining step includes: The pretilt angle θ ₀ which is a physical characteristic of the liquid crystal material is determined.

The invention according to claim 9 is the physical property determination method for a nematic liquid crystal material having negative dielectric anisotropy according to any one of claims 5 to 8 , wherein the determining step includes: In addition, at least one of Leslie's viscosity coefficients α _{1 to} α ₅ which is a physical characteristic of the liquid crystal material is determined.

A tenth aspect of the present invention is an apparatus for determining physical properties of a nematic liquid crystal material, wherein the liquid crystal test cell sandwiches a nematic liquid crystal material having a positive dielectric anisotropy on a horizontally aligned substrate, and the liquid crystal Voltage output means for outputting one or more single pulse voltages to be applied to the test cell; and filter means for removing noise superimposed on the single pulse voltage output by the voltage output means; A voltage amplifying means for amplifying the single pulse voltage from which noise has been removed by the filter means and applying it to the liquid crystal test cell; and a switching for performing a switching operation for flowing an inrush current flowing through the liquid crystal test cell to the ground. Switch means; measuring means for measuring a transient current waveform flowing in the liquid crystal test cell to which the single pulse voltage is applied; A calculation means for theoretically calculating a transient current waveform flowing in the liquid crystal test cell when a single pulse voltage is applied to the liquid crystal test cell, and a positive value based on a peak value of the transient current waveform measured by the measurement means. A computing means for computing the rotational viscosity γ ₁ of a nematic liquid crystal material having a dielectric anisotropy of
Characterized by including the.

According to the first to fourth aspects of the present invention, the rotational viscosity γ ₁ , shear viscosity η ₂ , and pretilt angle θ ₀ of a nematic liquid crystal material having negative dielectric anisotropy can be determined.

According to the fifth to ninth aspects of the present invention, the rotational viscosity γ ₁ , shear viscosity η ₂ , and pretilt angle θ ₀ of the nematic liquid crystal material having negative dielectric anisotropy can be determined.

According to the tenth aspect of the present invention, the rotational viscosity γ ₁ of a nematic liquid crystal material having a positive dielectric anisotropy can be determined.

  Embodiments of the present invention will be described below with reference to the drawings and mathematical expressions. A nematic liquid crystal material determining apparatus capable of determining physical characteristics of a nematic liquid crystal material having a negative dielectric anisotropy will be described with reference to FIG.

  In FIG. 1, reference numeral 11 denotes a function generator that generates one single pulse voltage as described in the block. A single pulse output from the function generator 11 is supplied to one end of the liquid crystal test cell 14 via an adaptive low-pass filter 12 and an amplifier 13. The adaptive low-pass filter 12 is a low-pass filter that can vary the frequency band with time. The time when polarity inversion occurs is a high-frequency band low-pass filter, and the time when the pulse voltage does not change is a substantially DC-band low-pass filter. Using this function, a stable pulse voltage can be supplied to the sample.

  The TTL signal synchronized with the single pulse voltage output from the function generator 11 is input to the adaptive low-pass filter 12 and the changeover switch 15. The frequency band of the adaptive low-pass filter 12 is switched according to the TTL signal output from the function generator 11.

  The contact a of the changeover switch 15 is connected to the current-voltage converter 16. The current-voltage converter 16 converts the input current into a voltage. The point b of the changeover switch 15 is to prevent the inrush current from the function generator 11 generated when the polarity of the pulse voltage is reversed from flowing into the current-voltage converter 16 and destroying the current-voltage converter 16 in advance. Is provided. That is, the inrush current flows to the ground via the b contact.

  The voltage signal output from the current-voltage converter 17 is amplified via the amplifier 17 and input to the A / D converter 19 via the low-pass filter (LPF) 18. The voltage signal E output from the A / D converter 19 is a voltage signal corresponding to a transient current flowing through the liquid crystal test cell 14.

  The voltage signal E is input to the control unit 20. The control unit 20 controls the apparatus as a whole, and includes a CPU, a ROM, a RAM, and the like. Further, the ROM matches the theoretical transient current waveform while changing the physical characteristics of the liquid crystal material of the liquid crystal test cell, and the physical characteristics when both transient current waveforms are matched match the liquid crystal material of the liquid crystal test cell. A program having a determination function means for determining the physical characteristics of each of them is stored.

  It is connected to the ground line 21 of the A / D converter 19. The ground line 21 is connected to the other end of the function generator 11, the contact b of the changeover switch 15, and one input terminal of the amplifier 17.

  Here, reference numeral 22 denotes a display unit connected to the control unit 20.

First, the rotation viscosity gamma ₁ from the peak current I _P flowing when applying a single pulse voltage to the liquid crystal test cell 14 sandwiching a nematic liquid crystal material having a positive dielectric anisotropy in the substrate subjected to horizontal orientation A calculation method will be described.

The rotational viscosity is calculated using equations (1) and (2).

Where γ ₁ is the rotational viscosity of the liquid crystal, S is the electrode area of the liquid crystal cell, Δε is the dielectric anisotropy of the liquid crystal, I _p is the measured peak current value, L is the gap of the liquid crystal cell, V is the applied voltage, V ₀ is the threshold voltage of the liquid crystal material, and K ₁₁ is the splay elastic constant of the liquid crystal.

  Next, when a single pulse voltage output from the function generator 11 is applied to a liquid crystal test cell 14 having a liquid crystal material having a negative dielectric anisotropy, a transient current flowing in the liquid crystal test cell 14 is theoretically calculated. The calculation method is described below.

The dynamic behavior of nematic liquid crystals considering the flow effect is formulated by Ericksen and Leslie and is described by the law of conservation of mass, equations of motion and angular momentum equations. The equation for mass conservation is expressed by equation (3).

Where v is the flow rate of the fluid.

The equation of motion is expressed by equation (4).

Here, ρ represents density, i, j represents x, y or z coordinates, comma represents partial differentiation based on spatial coordinates, and a dot on the head represents total differentiation based on time. Also, for the index that appears repeatedly, take the sum. σ _ij is a stress tensor and is given by equation (5).

Where p is pressure, n _i is component i of the director n of the nematic liquid crystal,
A _ij = (ν _{i, j} + ν _{j, i} ) / 2, Equation 6 and α _i (i = 1 to 6) are Leslie's viscosity coefficients. f is the free energy density of the nematic liquid crystal when the electric field E is applied, and is given by equation (6).

Here, K ₁₁ , K ₂₂ and K ₃₃ are the splay elastic constant, twist elastic constant and bend elastic constant of the nematic liquid crystal, respectively, and D is the electric flux density.

The angular momentum equation is expressed by equation (7).

Here, ρ ₁ is the moment of inertia per unit volume, γ ₁ = α ₃ −α ₂ is the rotational viscosity, and γ ₂ = α ₃ + α ₂ . h is a molecular field and is given by equation (8).

Substituting into Eqs. (3) to (8) the conditions when an electric field E is applied in the vertical direction to the substrate for a vertically aligned nematic liquid crystal cell, the equations of motion and angular momentum equations under these conditions are Eqs. (9) and (9), Guided as in (10).

Where θ is the angle between the director and the axis perpendicular to the substrate, v is the flow velocity in the direction parallel to the substrate in the plane of rotation of the director, σ is the integration constant, ε _o is the dielectric constant in vacuum, and Δε is the dielectric constant of the liquid crystal It is rate anisotropy. a and b are given by equations (11) and (12), respectively.

Using equations (9) and (10), we derive an analytical solution for the transient current that flows when an electric field is applied to a vertically aligned nematic liquid crystal cell. It is assumed that the alignment state of the liquid crystal cell is a strong anchoring state, and the director is always fixed at θ = θ _o on the substrate. Here, θ ₀ is the pretilt angle. At this time, the integral constant σ on the right side of Equation (9) can be regarded as a shear stress generated on the substrate surface. Assume that σ = 0. This indicates that the liquid crystal molecules move freely on the substrate surface. Further, it is assumed that the tilt angle θ _b of the director in the bulk region of the liquid crystal cell rotates uniformly in the electric field response process, and the electric field E _b in the bulk region is always constant regardless of time. At this time, equations (9) and (10) can be solved analytically, and equations (13) and (14) are derived.

Here, β ₁ = α ₁ ² + γ ₂ ² + 2α ₁ (α ₃ + α ₄ + α ₅ ),
β ₂ = γ ₁ ² + γ ₂ ² -2γ ₁ (α ₃ + α ₄ + α ₅ )
β ₃ = α ₂ -α ₄ -α ₅ , β ₄ = α ₂ + 2α ₃ + α ₄ + α ₅
β ₅ = γ ₂ ² + α ₁ (α ₃ + α ₄ + α ₅ ), β ₆ = α ₁ γ ₁ + γ ₂ ² ,
β ₇ = α ₁ + α ₃ + α ₄ + α ₅
It is.

Assuming that α ₁ ≠ 0 and β ₁ > 0 as the conditions for deriving equation (13) and α ₁ ≠ 0 and β ₁ <0 as the conditions for deriving equation (14), this is generally true for many liquid crystal materials. It is a condition. The transient current I is derived as follows:

Here, S is an electrode area. Equation (13), (14) (beta ₁ dependent on the sign), and by then simultaneous equation (15) performs fitting with the experimental results (Fig. 5), a nematic liquid crystal having a negative dielectric anisotropy The Leslie viscosity coefficient and θ _o of the material can be estimated.

Furthermore, the rotational viscosity (γ ₁ ) and the viscosity coefficient of Leslie of nematic liquid crystal material with negative dielectric anisotropy and The shear viscosity (η ₂ ) can be estimated.

This assumption for determining the shear viscosity (η ₂ ) of the liquid crystal material is a great advantage of this measurement method. This is because some liquid crystal materials have been determined by classical flow experiments so far [for example, H. Kneppe, F. Schneider, Molecular Crystals and Liquid Crystals, 65 (1981), 23].

  In recent years, it has been proposed to measure the time dependence of the optical response of liquid crystals (observation of decay flow) [SV Pasechnik, VG Chigrinov, DV Shmeliova, VA Tsvetkov, AN Voronov, Liquid Crystals 31 (4), 2004, 585]. However, this method has low accuracy, and the accuracy is particularly low for a liquid crystal material having a refractive index anisotropy of 0.2 or less. Therefore, this method is not suitable for measuring a liquid crystal material having a refractive index anisotropy of 0.15 or less used for a liquid crystal display.

(Experimental result)
Table 1 shows the measurement results of the rotational viscosity of three liquid crystal materials with negative dielectric anisotropy. The measurement temperature was 20 ° C., and SE-1211 (Nissan Chemical) was used as the vertical alignment film. The gap of the test cell used for the measurement is about 22um, and there are two types of applied voltages: 90V and 100V.

“Γ ₁ mag” in Table 1 is determined by measuring the torque of the liquid crystal in the rotating magnetic field described in “Merck Liquid Crystals”, Physical Properties of Liquid Crystals, Stat. Nov. 1997, Merck KGaA. This is for comparison with the measured value.

Next, the operation for determining the rotational viscosity γ ₁ of a nematic liquid crystal material that actually has a negative dielectric anisotropy will be described.

  First, a liquid crystal test cell 14 holding a nematic liquid crystal material having a negative dielectric anisotropy on a vertically aligned substrate is installed as shown in FIG. At this time, the liquid crystal test cell 14 is vertically aligned. That is, as shown in FIG. 3, the liquid crystal molecules of the liquid crystal test cell 14 are vertically aligned. By the way, when an electric field is applied to the liquid crystal test cell 14, the liquid crystal molecules of the liquid crystal test cell 14 are aligned as shown in FIG.

  Next, the function generator 11 starts to operate in response to a control signal from the control unit 20. That is, the function generator 11 outputs one single pulse voltage.

  When a single pulse voltage is applied to the liquid crystal test cell 14 made of a nematic liquid crystal material having negative dielectric anisotropy, a transient current I as shown in FIG. 2 flows.

  The transient current I is converted into a voltage signal corresponding to the transient current I via the current-voltage converter 16, the amplifier 17, and the A / D converter 19, and is input to the controller 20. Then, the transient current I is displayed on the display unit 22 as shown by the solid line in FIG. The display example of FIG. 5 shows a state where the waveform of the actually measured transient current I is matched with the transient current I ′ calculated theoretically as in the equations (13) to (15). .

That is, the control unit 10 changes the physical characteristics (α _{1 to} α ₅ , γ ₁ , γ _2, etc.) existing in the equation (15) while changing the waveform of the transient current I actually measured and the equation (13). ) To (15) have a function of matching the transient current I ′ calculated theoretically.

Of the physical characteristics when matching is achieved, the rotational viscosity (γ ₁ ) and the shear viscosity (η ₂ ) are obtained.

Further, the pretilt angle θ ₀ is also obtained by this matching.

Next, a description actually the positive dielectric constant operation of determining the rotational viscosity gamma ₁ of the nematic liquid crystal material having anisotropic.

  First, a liquid crystal test cell 14 holding a nematic liquid crystal material having a positive dielectric anisotropy on a horizontally oriented substrate is installed as shown in FIG. At this time, the liquid crystal test cell 14 is horizontally aligned. That is, as shown in FIG. 7, the liquid crystal molecules of the liquid crystal test cell 14 are horizontally aligned. By the way, when an electric field is applied to the liquid crystal test cell 14, the liquid crystal molecules of the liquid crystal test cell 14 are aligned as shown in FIG.

  Next, the function generator 11 starts to operate in response to a control signal from the control unit 20. That is, the function generator 11 outputs one single pulse voltage.

  When a single pulse voltage is applied to the liquid crystal test cell 14 made of a nematic liquid crystal material having a positive dielectric anisotropy, a transient current I as shown in FIG. 6 flows.

  The transient current I is converted into a voltage signal corresponding to the transient current I via the current-voltage converter 16, the amplifier 17, and the A / D converter 19, and is input to the controller 20.

Then, the control unit 20 obtains the peak current _Ip of the transient current I.

By substituting this peak current _Ip into equation (1), the rotational viscosity γ ₁ of the nematic liquid crystal material having positive dielectric anisotropy is determined.

  In the above-described embodiment, the single pulse voltage is output from the function generator 11. However, two or more single pulse voltages may be output.

  Furthermore, in the above embodiment, the program is stored in the ROM, but it may be stored in a hard disk device or other recording medium.

The system block diagram which shows the structure of the determination apparatus of the nematic liquid crystal material which concerns on one embodiment of this invention. FIG. 6 is a waveform diagram of a transient current that flows when a single pulse voltage is applied to a liquid crystal test cell made of a liquid crystal material having negative dielectric anisotropy according to the same embodiment. The figure which shows the state which performed the vertical alignment of the liquid crystal test cell which consists of a nematic liquid crystal material with the negative dielectric constant anisotropy which performed the vertical alignment based on the embodiment. The figure which shows the change of the state of the liquid crystal test cell which applied the electric field to the liquid crystal test cell which concerns on the embodiment. The figure which shows the state which matched the transient current which flows into the liquid crystal test cell calculated theoretically according to the embodiment, and the transient current actually measured. FIG. 4 is a waveform diagram of a transient current that flows when a single pulse voltage is applied to a liquid crystal test cell made of a liquid crystal material having a positive dielectric anisotropy according to the embodiment. The figure which shows the state which gave the horizontal alignment the liquid crystal test cell which consists of a nematic liquid crystal material with the positive dielectric constant anisotropy concerning the embodiment. The figure which shows the change of the state of the liquid crystal test cell which applied the electric field to the liquid crystal test cell which concerns on the embodiment.

Explanation of symbols

11 ... function generator, 12 ... adaptive low-pass filter,
DESCRIPTION OF SYMBOLS 13 ... Amplifier, 14 ... Liquid crystal test cell, 15 ... Changeover switch, 16 ... Current-voltage conversion part,
17 ... Amplifier, 18 ... Low-pass filter, 19 ... A / D comparator,
20: Control unit.

Claims (10)

A liquid crystal test cell sandwiching a nematic liquid crystal material having negative dielectric anisotropy on a vertically aligned substrate;
Voltage output means for outputting one or more single pulse voltages for application to the liquid crystal test cell;
Filter means for removing noise superimposed on the single pulse voltage output by the voltage output means;
Voltage amplifying means for amplifying the single pulse voltage from which noise has been removed by the filter means and applying it to the liquid crystal test cell;
Changeover switch means for performing a switching operation for flowing an inrush current flowing through the liquid crystal test cell to the ground;
Measuring means for measuring the transient current waveform flowing in the liquid crystal test cell the single pulse voltage is applied,
A calculating means for calculating theoretically the transient current waveforms flowing in the liquid crystal test cell when the single pulse voltage is applied to the liquid crystal test cell,
A transient current waveform measured by the measuring means, said been a theoretical transient current waveform calculated by the calculating means, is aligned while changing the physical properties of the liquid crystal material of the liquid crystal test cell, both transient current waveform matching was physical characteristic when the, determining means for determining said a physical property of the liquid crystal material of the liquid crystal test cell,
Physical characterization device of nematic liquid crystal material characterized by comprising a. It said determining means, the physical characterization device of nematic liquid crystal material according to claim 1, wherein the determining the rotational viscosity gamma ₁ is a physical property of the liquid crystal material. 3. The apparatus for determining physical characteristics of a nematic liquid crystal material according to claim 1, wherein the determining means determines a shear viscosity η ₂ which is a physical characteristic of the liquid crystal material. The device for determining physical characteristics of a nematic liquid crystal material according to any one of claims 1 to 3, wherein the determining means determines a pretilt angle θ ₀ which is a physical characteristic of the liquid crystal material. And the voltage output step of outputting one or more of the single pulse voltage for applying to the liquid crystal test cell sandwiching a nematic liquid crystal material having a negative dielectric anisotropy substrate subjected to vertical alignment,
A filter processing step for removing noise superimposed on the single pulse voltage output in the voltage output step;
A voltage amplifying step of amplifying the single pulse voltage from which noise has been removed by the filtering step and applying it to the liquid crystal test cell;
A switching step for performing a switching operation for flowing an inrush current flowing through the liquid crystal test cell to the ground;
A measurement step of measuring by the measuring means the transient current waveforms flowing in the liquid crystal test cell the single pulse voltage is applied,
A calculation step for theoretically calculating a transient current waveform flowing in the liquid crystal test cell when one or more single pulse voltages are applied to the liquid crystal test cell ;
A transient current waveforms measured at the measuring step, has been a theoretical transient current waveform calculated in the calculation step, a transient current waveform matching step of Ru aligned while changing the physical properties of the liquid crystal material of the liquid crystal test cell ,
A determining step of determining a physical characteristic when both transient current waveform is aligned in the transient current waveform matching step, a physical property of the liquid crystal material of the liquid crystal test cell,
A method for determining physical properties of a nematic liquid crystal material having negative dielectric anisotropy, characterized by comprising: In the determination step, the physical characterization method of the nematic liquid crystal material having a negative dielectric anisotropy according to claim 5, wherein the determining the rotational viscosity gamma ₁ is a physical property of the liquid crystal material. 7. The physical property determination of a nematic liquid crystal material having a negative dielectric anisotropy according to claim 5 or 6, wherein said determination step determines a shear viscosity η ₂ which is a physical property of the liquid crystal material. Method. 8. The negative dielectric anisotropy according to claim 5, wherein a pretilt angle θ ₀ which is a physical characteristic of the liquid crystal material is determined in the determining step. 9. A method for determining the physical properties of nematic liquid crystal materials. In the determination step, in any one of the claims 5 to 8, characterized in that determining at least one of Leslie viscosity coefficients alpha ₁ to? ₅ is the physical properties of the liquid crystal material A method for determining physical properties of a nematic liquid crystal material having negative dielectric anisotropy as described. A liquid crystal test cell holding a nematic liquid crystal material having a positive dielectric anisotropy on a horizontally oriented substrate;
Voltage output means for outputting one or more single pulse voltages for application to the liquid crystal test cell;
Filter means for removing noise superimposed on the single pulse voltage output by the voltage output means;
Voltage amplifying means for amplifying the single pulse voltage from which noise has been removed by the filter means and applying it to the liquid crystal test cell;
Changeover switch means for performing a switching operation for flowing an inrush current flowing through the liquid crystal test cell to the ground;
Measuring means for measuring a transient current waveform flowing in the liquid crystal test cell to which the single pulse voltage is applied;
Calculation means for theoretically calculating a transient current waveform flowing in the liquid crystal test cell when the single pulse voltage is applied to the liquid crystal test cell;
Calculation means for calculating the rotational viscosity γ ₁ of the nematic liquid crystal material having positive dielectric anisotropy based on the peak value of the transient current waveform measured by the measurement means ;
Physical characterization device of nematic liquid crystal material characterized by comprising a.

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