KR101339040B1 - Solid-state NMR probe of analyzing the structure of LCD panel - Google Patents

Abstract

The present invention relates to a solid NMR probe for structural analysis of the LCD panel, the LCD panel fragment sample is inserted, the main coil unit for applying a magnetic field to the LCD panel fragment sample; A C channel tuning unit connected to one end of the main coil unit; A trap unit connected in parallel to the C channel tuning unit; An F channel tuning unit connected to the other end of the main coil unit; And a coaxial cable part connected between the F channel tuning part and the main coil part, applying a first pulse to the first terminal connected to the C channel tuning part and the trap part, and then measuring the emission signal and connecting the F channel tuning part to the F channel tuning part. After applying the second pulse to the second terminal, the emission signal is measured, and the F nuclear magnetic resonance spectrum is obtained from the measured emission signal, providing a spectrum of the LCD panel sample with improved signal-to-noise ratio, and bulk of the liquid crystal. Areas and surface areas can be distinguished.

Description

Solid-state NMR probe of analyzing the structure of LCD panel

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state NMR probe, and more particularly, to an LCD panel sample having an improved signal-to-noise ratio (S / N ratio) and to distinguishing bulk and surface areas of liquid crystals. A solid NMR probe for structural analysis.

Liquid crystal display (LCD) panels operate by controlling the transmission of light through liquid crystal molecules. These liquid crystal molecules are affected by the electric field passing through the liquid crystal. The liquid crystal molecules are arranged according to the electric field when the electric field is turned on, and when the electric field is turned off, the arrangement of the liquid crystal is controlled by interaction with the surface of the polyimide resin (alignment layer).

In order to fully understand the characteristics of LCD panel operation, it is necessary to understand the interaction between liquid crystal material molecules and the alignment layer. Determining the three-dimensional arrangement of liquid crystal molecules is very important as the first step for this purpose. The crystal rotation method is currently the most basic method of determining the alignment direction of the liquid crystal. However, it only shows the average alignment direction by finding the standard deviation angle that maximizes light transmission, and does not provide any quantitative information about how many “how many” ratios of liquid crystal molecules are aligned in a particular orientation.

NMR (Nuclear Magnetic Resonance) technique is the most widely used analytical technique along with X-Ray Diffraction (XRD) technique to analyze the structure of molecules. Related fields include liquid NMR, solid NMR and MRI. Solid NMR technique is an experimental technique applied when the sample to be analyzed is a solid.

Solid NMR spectroscopy is widely used to explain the structure of cell membrane proteins that cannot be sufficiently obtained by X-ray diffraction or liquid NMR spectroscopy. .

Dipole-dipole coupling and chemical shift anisotropy values are the two major measures of cell membrane protein structure determined by solid-state NMR experiments. When protein molecules are oriented in a particular direction in the cell membrane environment, bipolar coupling and chemical transfer anisotropy have different values depending on the orientation of the molecules, and these values are used to determine the spatial structure of the protein. For example, bipolar coupling of nitrogen-hydrogen bonds in protein backbones gives information about the orientation of nitrogen-hydrogen bonds and this information is used to determine the round spine structure of the protein. However, there is no development of a solid NMR probe for analyzing the structure of the LCD panel itself.

Accordingly, an object of the present invention is to provide a spectrum of an LCD panel sample with an improved signal-to-noise ratio (S / N ratio), and a solid NMR probe for structural analysis of an LCD panel capable of distinguishing between bulk and surface regions of liquid crystals. To provide.

The present invention, in order to achieve the above object, the LCD panel piece sample is inserted, the main coil unit for applying a magnetic field to the LCD panel piece sample; A C channel tuning unit connected to one end of the main coil unit; A trap unit connected in parallel to the C channel tuning unit; An F channel tuning unit connected to the other end of the main coil unit; And a coaxial cable part connected between the F channel tuning part and the main coil part, applying a first pulse to a first terminal connected to the C channel tuning part and the trap part, and measuring an emission signal. After applying a second pulse to the second terminal connected to the channel tuning unit, and measuring the emission signal, F nuclear magnetic resonance spectrum is obtained from the measured emission signal solid NMR probe for structural analysis of the LCD panel to provide.

According to an embodiment of the present disclosure, the trap unit may be configured by connecting an inductor and a capacitor in series.

In addition, it is preferable that the length of the coaxial cable part is determined using the resonance frequency of ¹⁹ F and the electric constant of the coaxial cable.

The coaxial cable part may be a coaxial cable having a quarter length of a resonance wavelength between the other end of the main coil part and the ground.

According to another embodiment of the present invention, the C channel tuning unit includes: a first variable capacitor connected in series between the first terminal and one end of the main coil unit; And a second variable capacitor connecting the node and the ground between the first variable capacitor and one end of the main coil unit.

On the other hand, the F channel tuning unit includes a third variable capacitor connected to the second terminal; A sixth fixed capacitor connected to the other end of the main coil unit; And a fourth variable capacitor connecting the node and the ground between the third variable capacitor and the sixth fixed capacitor.

Further, the signals of the bulk liquid crystal and the surface liquid crystal of the LCD panel piece sample can be distinguished from the F nuclear magnetic resonance spectrum.

According to the present invention, it is possible to provide a solid-state NMR (nuclear magnetic resonance) spectrum of a liquid crystal by putting an LCD panel sample inside a flat square coil, and provide a spectrum of an LCD panel sample having an improved signal-to-noise ratio (S / N ratio). have. Further, according to the present invention, the bulk region and the surface region of the liquid crystal can be distinguished. Furthermore, according to the present invention, it can help to identify the characteristics of the three-dimensional arrangement of liquid crystal (LC) molecules in the LCD panel.

1 is a block diagram of a solid NMR probe for structural analysis of an LCD panel according to an exemplary embodiment of the present invention.
FIG. 2 shows a ¹⁹ F- ¹³ C double resonance home built probe for a 500 MHz narrowbore magnet.
FIG. 3 shows ¹⁹ F NMR (nuclear magnetic resonance) spectra obtained by experimenting a sealing liquid crystal sample in a glass capillary in a 500 MHz narrowbore magnet.
FIG. 4 shows a ¹⁹ F spectrum of an LCD panel obtained from a HomeBuild ¹⁹ F- ¹³ C double resonance solid-state probe according to an embodiment of the present invention with a square coil flattened in a 500 MHz narrowbore magnet. .
FIG. 5 shows ¹⁹ F solid-state NMR (nuclear magnetic resonance) spectra of a liquid crystal and an LCD panel sample sealed in a glass capillary tube.

Prior to the description of the concrete contents of the present invention, for the sake of understanding, the outline of the solution of the problem to be solved by the present invention or the core of the technical idea is first given.

Solid NMR probe for structural analysis of the LCD panel according to an embodiment of the present invention is inserted into the LCD panel fragment sample, the main coil unit for applying a magnetic field to the LCD panel fragment sample; A C channel tuning unit connected to one end of the main coil unit; A trap unit connected in parallel to the C channel tuning unit; An F channel tuning unit connected to the other end of the main coil unit; And a coaxial cable part connected between the F channel tuning part and the main coil part, applying a first pulse to a first terminal connected to the C channel tuning part and the trap part, and measuring an emission signal. After applying a second pulse to the second terminal connected to the channel tuning unit, the emission signal is measured, and the F nuclear magnetic resonance spectrum is obtained from the measured emission signal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art, however, that these examples are provided to further illustrate the present invention, and the scope of the present invention is not limited thereto.

The configuration of the invention for clarifying the solution to the problem to be solved by the present invention will be described in detail with reference to the accompanying drawings based on the preferred embodiment of the present invention, the same in the reference numerals to the components of the drawings The same reference numerals are given to the components even though they are on different drawings, and it is to be noted that in the description of the drawings, components of other drawings may be cited if necessary. In the following detailed description of the principles of operation of the preferred embodiments of the present invention, it is to be understood that the present invention is not limited to the details of the known functions and configurations, and other matters may be unnecessarily obscured, A detailed description thereof will be omitted.

In addition, in the entire specification, when a part is referred to as being 'connected' to another part, it may be referred to as 'indirectly connected' not only with 'directly connected' . In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, "comprises" or "comprising" excludes the presence or addition of one or more other components, steps, operations, or elements other than the components, steps, operations, or elements mentioned. I never do that.

The orientation or dynamic behavior of liquid crystal molecules on the alignment film surface is very important for the performance of LCDs. However, there is little method for experimentally measuring the interaction between the alignment film and the liquid crystal. Cell membrane proteins in the lipid bilayer and liquid crystals in LCD panels are naturally and technically very similar. Thus, solid NMR methods, originally developed for the study of cell membrane proteins in the lipid bimolecular layer, can be used for analysis of LCD panel conditions.

The present invention discloses the application of a solid-state NMR probe using a flat square coil for the analysis of liquid crystal samples in an LCD panel. In particular, in the present invention, a sample analysis of an LCD panel is performed using a square coil probe flat on a ¹⁹ F- ¹³ C double resonance home built 500 MHz narrowbore (NB) solid NMR.

LCD liquid crystals comprise oligofluorophenyl regions. The oligo fluorophenyl region moiety can interact with the electric field to effectively control the alignment. Therefore, the following describes a solid-state NMR probe targeting fluorine ( ¹⁹ F) nuclei adjacent to carbon.

1 is a block diagram of a solid NMR probe for structural analysis of an LCD panel according to an exemplary embodiment of the present invention.

The solid NMR probe according to the present embodiment shown in FIG. 1 is a design of an in-situ solid phase NMR probe for an LCD panel sample, and is a 500 MHz narrowbore ¹⁹ F- ¹³ C home resonance probe. In particular, the circuit is optimized by making a flat rectangular coil probe with a ¹⁹ F- ¹³ C double resonance circuit in a 500 MHz narrow bore magnet to directly observe an LCD panel sample.

Referring to FIG. 1, the solid NMR probe according to the present exemplary embodiment may include a main coil unit 110, a C channel tuning unit 120, a trap unit 130, an F channel tuning unit 140, and a coaxial cable unit 150. It consists of.

The main coil parts 110 and L1 are shaped to surround the shape of the sample so that the LCD panel piece sample is inserted. The main coil part 110 is a copper material plated with gold and has a flat rectangular coil shape of five wheels. The overall size of the main coil unit 110 (width 14 mm, height 1 mm, length 16 mm) is preferably made to fit the size of the LCD panel piece sample (width 10 mm, length 15 mm). The LCD panel piece samples are placed in a magnetic field.

The C channel tuning unit 120 tunes and matches the ¹³ C channel with the C1 and C2 capacitors. C1 and C2 are variable capacitors (1-10 pF) for tuning and matching ¹³ C channels (125 MHz).

The trap 130 is composed of an L2 coil and a C5 capacitor, which act to prevent the high frequency signal from interfering with the low frequency channel.

The ¹⁹ F channel connected to the second terminal is a high frequency channel and the ¹³ C channel connected to the first terminal is a low frequency channel. When a second pulse having a high frequency is applied to the second terminal, a trap 130 is used to prevent the second pulse from affecting the first terminal having a low frequency.

The inductor L2 and the fixed value capacitor C5 constituting the trap unit 130 are used as traps for removing reflected pulses in the high frequency region. The inductor L2 can be made by twisting 1/2 of the 2.5mm copper wire. L2-C5 trap allows always enables an efficient tuning of the ¹³ C-channel, increasing the separation (Isolation) between ¹³ C and ¹⁹ F-channel channel.

The first terminal applies a first pulse to the C channel tuning unit 120 and measures the emitted signal. At this time, the trap unit 130 is connected to the first terminal to remove the unwanted extra pulse signal emitted from the high frequency region.

The second terminal applies a second pulse to the F channel tuning unit 140 and measures the emitted signal. The signal reflected back to the first terminal and the second terminal is input to the computer in the form of digitized free induction decay (FID), and converted into an NMR signal.

The F channel tuning unit 140 tunes and matches the ¹⁹ F channel with C3, C4, and C6 capacitors. C3 and C4 are variable capacitors (1-10 pF) for tuning and matching the ¹⁹ F channel (470 MHz).

In addition to capacitors C3, C4 and C6 for high frequency ¹⁹ F channels, λ / 4 coaxial cable is used. λ represents the resonance wavelength, and the method of calculating λ / 4 (the length of the coaxial wavelength cable) is shown in Equation 1. The length of λ / 4 line calculated by Equation 1 is about 10.6 cm.

The length of the coaxial cable part 150 (λ / 4 line) is calculated as the ¹⁹ F resonance frequency at the magnetic field strength of the 500 MHz resonance frequency as shown in Equation 1 below. The coaxial cable part 150 is connected to the ground.

In Equation 1, c denotes the speed of light, ν denotes the resonance frequency of the ¹⁹ F channel, and ε denotes the dielectric constant of the coaxial cable.

Pulses are applied to the second terminal to obtain ¹⁹ F nuclear magnetic resonance spectra from the solid NMR probe according to the embodiment of the present invention. When a pulse is applied to the second terminal, the pulse goes to the main coil unit 110, and the sample in the main coil unit 110 reacts to a specific frequency to emit a reflected signal. The reflected signal is detected by the computer and received in FID form (a function that represents the amount of energy released over time). After that, a FT (fourier transform) can be used to obtain the spectrum in Hz. However, for ¹³ C nuclear magnetic resonance, both pulses are used to prevent coupling with ¹⁹ F.

As described above, C1, C2, C3, and C4 are variable capacitors (1-10 pF), which are used for tuning and matching ¹³ C channels and ¹⁹ F channels. At this time, C5 and C6 is preferably a capacitor (capacitor) fixed to 33 pF, 2 pF, respectively. The impedance of all probe circuits was set to 50Ω and tuned with a network analyzer (Hewlett Packard 85046A).

Meanwhile, the preparation of the LCD panel sample for analyzing the structure of the LCD panel by the solid NMR probe according to the embodiment of the present invention may be performed as follows.

First, LCD panel samples were obtained by carving out a 40-inch liquid crystal panel 10 mm x 15 mm. A panel piece (containing liquid crystal between the panel pieces) is placed on the probe head. The spacing between the glass plates is generally about several micrometers, so that about 0.5 microliter of liquid crystal material is placed on the probe head. Most of the liquid crystal component is made up of difluorophenyl, and this part arranges liquid crystals in the electric field when the electric field is turned on. The rest of the liquid crystal component consists only of carbon, hydrogen, and oxygen.

FIG. 2 shows a ¹⁹ F- ¹³ C double resonance home built probe for a 500 MHz narrowbore magnet.

Figure 2 (a) shows the components of the ¹⁹ F- ¹³ C double resonance home built probe before assembly.

Figure 2 (b) shows a flat square coil made of gold plated copper located on a ceramic plate. It is desirable to use fluorine-free materials such as ceramics to minimize the probe background signal.

Figure 2 (c) shows the upper part of the assembled pro part.

Figure 2 (d) shows the overall view of the probe is covered.

FIG. 3 shows ¹⁹ F NMR (nuclear magnetic resonance) spectra obtained by experimenting a sealing liquid crystal sample in a glass capillary in a 500 MHz narrowbore magnet.

Figure 3 (a) is obtained by vertically placing the sample in a commercially produced ¹ H- ¹⁹ F double resonance probe (probe), Figure 3 (b) is a home built solid phase ¹⁹ F- according to an embodiment of the present invention Spectra were obtained by placing the sample horizontally in a ¹³ C double resonance probe. At this time, the number of transient is 16 times and the line broadening is 5Hz.

In the present invention, the spectrum analysis of the LCD panel sample was performed as follows.

After optimizing the probe position in the magnet, ¹⁹ F NMR (nuclear magnetic resonance) spectra obtained by horizontally placing a glass capillary in which a liquid crystal is placed inside a flat rectangular coil are shown in FIG. 3 (b). Referring to FIG. 3 (b), three distinct signals appear without a background signal from the probe material in the spectrum.

These ¹⁹ F signals come from the region of difluorophenyl, which accounts for most of the liquid crystal component.

FIG. 4 shows a ¹⁹ F spectrum of an LCD panel obtained from a HomeBuild ¹⁹ F- ¹³ C double resonance solid-state probe according to an embodiment of the present invention with a square coil flattened in a 500 MHz narrowbore magnet. . The number of transients is 20k, the recycle delay is 5 seconds, and the line broadening is 0.3 Hz.

In addition, in Fig. 4, ¹⁹ F NMR (nuclear magnetic resonance) spectra of the liquid crystal in the LCD panel were obtained while the panel sample was horizontally placed inside the flat rectangular coil and the panel was placed in a plane parallel to the magnetic field. Sharp signals similar to those in the liquid crystal (LC) spectrum were observed, with additional broad signals at 100-150 ppm upfield.

FIG. 5 shows the ¹⁹ F solid-state NMR (nuclear magnetic resonance) spectra of liquid crystal and LCD panel samples sealed to glass capillaries.

The ¹⁹ F solid-phase NMR (nuclear magnetic resonance) spectrum shown above in FIG. 5 is the spectrum for the liquid crystal, and the ¹⁹ F solid-phase NMR (nuclear magnetic resonance) spectrum shown below is for the LCD panel sample.

In LCD panels, the signals of bulk and surface liquid crystals can be distinguished in the spectrum. The method of distinguishing a bulk liquid crystal from a surface liquid crystal can be distinguished by measuring a bulk liquid crystal sample separately and measuring an LCD panel sample which is considered to contain a bulk liquid crystal and a surface liquid crystal.

In the ¹⁹ F NMR (nuclear magnetic resonance) spectrum shown in FIGS. 3 to 5, the chemical shift value of fluorine was measured after sealing by putting triflouroethanol (TFE) into a glass capillary. Corrected by the signal from. The signal of the TFE can be measured and used to determine the reference value of the chemical shift value, which is the x-axis in the solid NMR spectrum.

The features of the present invention discussed above are as follows.

First, a ¹⁹ F- ¹³ C solid-state NMR (nuclear magnetic resonance) probe developed for use in 500 MHz narrowbore magnets was optimized.

In other words, we optimized the performance of the home built probe developed with ¹⁹ F signal of TFE, an external standard material. When adjusting the vertical position of the probe in the magnet bore, a flat rectangular coil was placed on a ceramic plate to minimize the background signal of the probe from probe components containing fluorine.

Second, the spectra of the LCD panel sample were optimized.

The liquid crystal sample (LC) in the glass capillary was measured in two different directions. The vertical direction was measured with a commercially prepared liquid phase NMR (nuclear magnetic resonance) probe. The horizontal direction was observed with a home built solid phase NMR (nuclear magnetic resonance) probe according to the present invention. The corresponding spectra are as shown in FIG. 3. It can be seen that the spectra of FIGS. 3 (a) and 3 (b) are basically the same and the signal-to-noise ratio (S / N ratio) is better when observed with the home built solid state NMR probe according to the present invention. This means that the home built solid phase NMR (nuclear magnetic resonance) probe according to the present invention is well made and fully optimized. Optimization of liquid crystal (LC) spectra in LCD panel samples is much more difficult than normal ¹⁹ F NMR (nuclear magnetic resonance) experiments. This is due to the very low signal-to-noise ratio (S / N) due to the small sample volume.

To obtain a signal-to-noise ratio similar to that of normal ¹⁹ F NMR experiments, an LCD panel sample requires approximately 1000 times the experiment time of a liquid crystal (LC) sample.

On the other hand, since the alignment layer of the LCD panel is made of polyimide resin, liquid crystal (LC) molecules are arranged in a particular direction due to the interaction of molecules when the electric field is turned off. The LCD panels used in the present invention are in "vertical alignment" mode. In this mode, the functional groups of the polyimide resin align the liquid crystal LC perpendicular to the panel. Since it is not applicable when the electric field passes through the panel, it can be assumed that the liquid crystal (LC) molecules are arranged in parallel in the magnetic field at least on the surface of the alignment layer, and it can be seen that this is the case in actual LCD panels which normally operate.

In the liquid crystal (LC) sample, the surface modification group of the alignment layer has no interaction with the surface, and the arrangement of the liquid crystal LC is only affected by the magnetic field. Therefore, the liquid crystals LC will be uniformly arranged in the horizontal direction of the liquid crystal LC sample. In the LCD panel sample, bulk liquid crystals (LC) far from the alignment layer are mainly arranged in the magnetic field.

On the other hand, the arrangement of the liquid crystal LC on the alignment surface is mainly influenced by the surface strain group. Thus the liquid crystal LC will be arranged parallel to the magnetic field. Referring to FIG. 5, these two movements in the bulk liquid crystal LC and the surface liquid crystal LC appear in the LCD panel spectrum.

The ¹⁹ F- ¹³ C solid-state NMR (nuclear magnetic resonance) probe developed for use in 500 MHz narrowbore magnets has been successfully developed through comparison and optimization with commercial probes. In addition, the LCD panel sample was placed inside a flat rectangular coil to obtain a solid-state NMR (nuclear magnetic resonance) spectrum of the liquid crystal. From the spectrum, the bulk region and the surface region of the liquid crystal (LC) were distinguished. Furthermore, the application of solid-state NMR (nuclear magnetic resonance) technology will help to identify the properties of the three-dimensional arrangement of liquid crystal (LC) molecules in LCD panels.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

¹⁹ F- ¹³ C solid NMR probe for 500 MHz NB for structural analysis of LCD panel itself

110: main coil unit 120: C channel tuning unit
130: trap unit 140: F channel tuning unit
150: coaxial cable part

Claims (8)

A main coil part inserted into the LCD panel piece sample or the liquid crystal to apply a magnetic field to the LCD panel piece sample or the liquid crystal;
A C channel tuning unit connected to one end of the main coil unit;
A trap unit connected in parallel to the C channel tuning unit;
An F channel tuning unit connected to the other end of the main coil unit; And
A coaxial cable part connected between the F channel tuning part and the main coil part,
After applying a first pulse to the first terminal connected to the C channel tuning unit and the trap unit, the reflected signal is measured, and after applying a second pulse to the second terminal connected to the F channel tuning unit, the reflected signal is measured. And obtaining an F nuclear magnetic resonance spectrum from the measured reflected signal,
The coaxial cable unit,
A solid NMR probe for structural analysis of an LCD panel characterized in that the length is determined using the resonance frequency of ¹⁹ F and the dielectric constant of the coaxial cable. The method according to claim 1,
The trap unit,
Solid NMR probe for structural analysis of LCD panel, characterized in that the inductor and capacitor are connected in series. delete The method according to claim 1,
The coaxial cable unit,
And a coaxial cable having a quarter length of a resonant wavelength between the other end of the main coil part and the ground. The method according to claim 1,
The C channel tuning unit,
A first variable capacitor connected in series between the first terminal and one end of the main coil unit; And
And a second variable capacitor connecting the node and the ground between the first variable capacitor and one end of the main coil unit. The method according to claim 1,
The F channel tuning unit,
A third variable capacitor connected to the second terminal;
A sixth fixed capacitor connected to the other end of the main coil unit; And
And a fourth variable capacitor connecting the node and the ground between the third variable capacitor and the sixth fixed capacitor. The method according to claim 1,
Solid NMR probe for structural analysis of the LCD panel, characterized in that the signal of the bulk liquid crystal and surface liquid crystal of the LCD panel sample is distinguished from the F nuclear magnetic resonance spectrum. The method according to any one of claims 1 to 2, and 4 to 7,
Structure analysis method of the LCD panel, characterized in that to obtain the F nuclear magnetic resonance spectrum using the solid NMR probe.

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