A method for measuring optical properties of a polymer-stabilized vertical-alignment alignment agent

Abstract

This invention discloses a method for measuring the optical properties of a polymer-stabilized vertical alignment agent. Step 1: A PSVA-type alignment agent film is coated on a substrate with an ITO semiconductor layer. After pre-baking to remove solvent, the alignment agent film undergoes high-temperature dehydration and cyclization in an oven to impart liquid crystal alignment properties. Step 2: The PSVA-type alignment agent film is rubbed to give its side chain structure a fixed orientation. Step 3: The rubbed substrate is assembled with a frame adhesive to obtain a test cell. A negative VA liquid crystal mixed with RM monomers and a suitable amount of photoinitiator is injected under vacuum. Step 4: A voltage greater than Vth is applied to the test cell after liquid crystal injection, causing the liquid crystal molecules to tilt in the direction of the electric field. Ultraviolet light irradiation causes the RM monomers to polymerize and deposit on the surface of the PI film, fixing the liquid crystal angle to obtain a complete test cell. The liquid crystals are neatly arranged with a fixed orientation. This method overcomes the problems of high design precision, high cost, and relatively difficult fabrication associated with fishbone substrates.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal display technology, specifically relating to a method for measuring the optical properties of a polymer-stabilized vertical alignment agent. Background Technology

[0002] In the modern display industry, dominated by TFT-LCDs, polymer-stabilized vertical alignment (PSVA) display panels are widely used in high-end display fields such as aerospace, medical, and graphics processing due to their superior performance, including wide viewing angles, ultra-high contrast, high transmittance, and fast response times.

[0003] Polymer Stable Vertical Alignment (PSVA) display panels mainly rely on TFT / ITO electrodes with gaps to control the tilting of liquid crystal. Photosensitive polymers are added to the liquid crystal material. After the panel is turned on, the liquid crystal tilts in the direction of the electric field. Then, ultraviolet light is used to cause the photosensitive monomers in the liquid crystal to undergo a polymerization reaction, so that the liquid crystal generates a pretilt angle pointing in the direction of the driving electric field, achieving the characteristics of a multi-domain structure.

[0004] However, for alignment agent material developers, the TFT / ITO gaps in PSVA display panels need to be designed in a fishbone shape, and the linewidth and line spacing need to be within 3.5μm. Compared to other glass substrates on the market used for fabricating test cells, PSVA fishbone glass substrates require higher design precision, are more expensive, and are relatively difficult to manufacture. Therefore, it is necessary to provide a new method to measure the various optical properties of PSVA-type liquid crystal alignment agents without using PSVA fishbone glass substrates to solve the above problems. Summary of the Invention

[0005] In order to solve the above-mentioned problems in the prior art, the present invention aims to provide a method for measuring the optical properties of polymer-stabilized vertical alignment agents.

[0006] The technical solution adopted in this invention is as follows:

[0007] A test box includes a display area and a non-display area located outside the display area; wherein the non-display area is made of a single borosilicate glass material; the display area includes a borosilicate substrate and an N-type oxide semiconductor ITO layer, the semiconductor ITO layer being connected to an external power supply via pins for applying voltage to form an interlayer electric field, driving liquid crystal, and serving as a test box for demonstrating optical performance as an alignment agent material.

[0008] As a preferred embodiment of the present invention, the test box is composed of two substrates, wherein a PSVA-type liquid crystal alignment agent film is coated on the substrate, and a frame adhesive and spacer particles are disposed between the upper and lower substrates. The frame adhesive is filled with 3.5μm silicon balls, and the ratio of the frame adhesive to the silicon balls is 100:1. The spacer particles are made of a resin composition with a particle size of 3.5μm.

[0009] As a preferred embodiment of the present invention, both the upper and lower layers of the test box are provided with external voltage input ports, which are connected to the ITO electrode layer and are made of the same material, N-type oxide semiconductor.

[0010] A method for measuring the optical properties of a polymer-stabilized vertical alignment agent, comprising the following steps:

[0011] Step 1: A PSVA-type alignment agent film is coated on a substrate with a semiconductor ITO layer. After the alignment agent film is pre-baked to remove the solvent, it needs to be dehydrated and cyclized in an oven at high temperature to make the alignment agent film have liquid crystal alignment properties.

[0012] Step 2: During the coating process of the PSVA-type alignment agent film, the PSVA-type alignment agent film is rubbed to give its side chain structure a fixed orientation, and the pretilt angle is changed from 90° to below 90°.

[0013] Step 3: After the substrate is polished, it is assembled with the frame adhesive to obtain the test empty cell. The height of the test empty cell is set to 3.5μm. The frame adhesive leaves a liquid crystal injection port. Negative VA liquid crystal mixed with RM monomer and an appropriate amount of photoinitiator is injected in a vacuum environment. Then the injection port is closed to obtain the PSVA test cell.

[0014] Step 4: Apply a voltage greater than Vth to the test box to make the liquid crystal molecules tilt in the direction of the electric field. Then, use ultraviolet light to irradiate the RM monomers to polymerize and deposit them on the surface of the PI film. Fix the liquid crystal angle and arrange the liquid crystals in a fixed direction. A pretilt angle of 88° to 88.5° is obtained. After the RM monomers react, they form a fixed angle with the substrate and the liquid crystal. This angle is maintained after the voltage is removed.

[0015] Step 5: The PSVA PI optical parameters evaluated for the above test panel include:

[0016] Apply a continuous voltage of 0V to 10V and measure the transmittance distribution curve as a function of voltage, i.e., V-TCure;

[0017] Measure the panel brightness at 0V and Vth voltages, and calculate the contrast ratio: CR = brightness in the on state / brightness in the black state.

[0018] Apply a voltage greater than Vth and measure the response time when the transmittance increases from 10% to 90%.

[0019] Apply an AC voltage greater than Vth and allow the ΔAngle to age continuously at room temperature or high temperature for a certain period of time.

[0020] As a preferred embodiment of the present invention: the PSVA type alignment agent film can be coated with INKJET or spincoating, and the thickness of the PSVA type alignment agent film is 80-120 nm; the pre-baking temperature is 80-95°C and the time is 100-130 seconds; the baking temperature is 220-240°C and the time is 1200-1800 seconds.

[0021] As a preferred embodiment of the present invention: the PSVA type orientation agent film thickness is 100nm; the pre-baking temperature is 90℃ and the pre-baking time is 120 seconds; the baking temperature is set to 230℃ and the time is set to 1200 seconds.

[0022] Preferred in this invention, the pretilt angle is modified between 0.4° and 0.6°. Under normal conditions, the retardation rate remains unaffected, no light leakage occurs, and a completely black state is achieved. In the open state, the pretilt angle φ of the liquid crystal is 45°, thereby obtaining maximum transmittance.

[0023] As a preferred embodiment of the present invention, the friction cloth used to abrade the PSVA-type alignment agent film is made of COTTON material, and the fiber density should be less than 10,000 fibers / cm². 2 The fabric length is 2.5mm to ensure that the initial pretilt angle of the liquid crystal is between 89.4° and 89.6°.

[0024] As a preferred embodiment of the present invention: the grinding step uses low-intensity grinding, the pressing amount is set to 0.2mm~0.3mm, the friction machine platform speed is set to 33.3mm / s, and the roller speed is set to 1000rpm.

[0025] As a preferred embodiment of the present invention, the PSVA type alignment agent film is rubbed in a 180° anti-parallel direction, and both the upper and lower substrates are rubbed in a 180° horizontal direction, so that after the upper and lower substrates are flipped and bonded, the orientation vectors of all liquid crystal molecules are in the same direction, and the liquid crystal twist angle is 0°.

[0026] As a preferred embodiment of the present invention, the applied voltage Vth is set to a range of 15V to 25V, a square wave, and a frequency set to 30Hz to 64Hz.

[0027] As a preferred embodiment of the present invention, the ultraviolet irradiation process should be carried out in a heated environment with a temperature set at 40℃~70℃, and a 313nm wavelength UV lamp tube should be used for ultraviolet irradiation polymerization, with the UV irradiation time not exceeding 200 seconds.

[0028] As a preferred embodiment of the present invention, the voltage of Vth is set to 20V, the frequency is set to 64Hz, and the heating environment is set to 60℃.

[0029] The beneficial effects of this invention are as follows:

[0030] This method applies a voltage to the test box to orient the RM monomers and liquid crystal molecules according to the electric field direction; under heating conditions, ultraviolet light irradiation causes the liquid crystals to align neatly in a fixed direction. After the RM monomers have reacted completely, the angle is maintained after the voltage is removed, and the angle can be controlled by controlling the applied voltage. This overcomes the problems of high design precision, high cost, and relatively difficult fabrication of fishbone substrates. Attached Figure Description

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific implementation methods.

[0032] Figure 1 This is a schematic diagram of the structure of the test panel of the present invention;

[0033] Figure 2 This is the manufacturing process of the test kit of the present invention;

[0034] Figure 3 This is the liquid crystal alignment and power-on sequence of the test box of the present invention;

[0035] Figure 4 This is a transmittance distribution curve diagram from Embodiment 1 of the present invention;

[0036] Figure 5 This is a transmittance distribution curve diagram from Embodiment 2 of the present invention;

[0037] Figure 6 This is a transmittance distribution curve in Embodiment 3 of the present invention.

[0038] In the diagram: 1-substrate, 2-semiconductor ITO layer, 3-frame adhesive, 4-pin. Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0040] The following is combined with Figure 1-6 This invention describes specific embodiments.

[0041] A test box includes a display area and a non-display area located outside the display area; wherein the non-display area is made of a single borosilicate glass material; the display area includes a borosilicate substrate 1 and an N-type oxide semiconductor ITO layer 2, the semiconductor ITO layer 2 being connected to an external power supply via pins 4 for applying voltage to form an interlayer electric field, driving liquid crystal, and serving as a test box for demonstrating optical performance as an alignment agent material.

[0042] As a preferred embodiment of the present invention, the test box is composed of two substrates, wherein a PSVA-type liquid crystal alignment agent film is coated on the substrate, and a frame adhesive 3 and spacer particles are disposed between the upper and lower substrates. The frame adhesive 3 is filled with 3.5μm silicon balls, and the ratio of the frame adhesive 3 to the silicon balls is 100:1. The spacer particles are made of resin composition and have a particle size of 3.5μm.

[0043] As a preferred embodiment of the present invention, both the upper and lower layers of the test box are provided with external voltage input ports, which are connected to the ITO electrode layer and are made of the same material, N-type oxide semiconductor.

[0044] A method for measuring the optical properties of a polymer-stabilized vertical alignment agent, comprising the following steps:

[0045] Step 1: A PSVA-type alignment agent film is coated on a substrate with a semiconductor ITO layer. After the alignment agent film is pre-baked to remove the solvent, it needs to be dehydrated and cyclized in an oven at high temperature to make the alignment agent film have liquid crystal alignment properties.

[0046] Step 2: During the coating process of the PSVA-type alignment agent film, the PSVA-type alignment agent film is rubbed to give its side chain structure a fixed orientation, and the pretilt angle is changed from 90° to below 90°.

[0047] Step 3: After the substrate is polished, it is assembled with the frame adhesive to obtain the test empty cell. The height of the test empty cell is set to 3.5μm. The frame adhesive leaves a liquid crystal injection port. Negative VA liquid crystal mixed with RM monomer and an appropriate amount of photoinitiator is injected in a vacuum environment. Then the injection port is closed to obtain the PSVA test cell.

[0048] Step 4: Apply a voltage greater than Vth to the test box to make the liquid crystal molecules tilt in the direction of the electric field. Then, use ultraviolet light to irradiate the RM monomers to polymerize and deposit them on the surface of the PI film. Fix the liquid crystal angle and arrange the liquid crystals in a fixed direction. A pretilt angle of 88° to 88.5° is obtained. After the RM monomers react, they form a fixed angle with the substrate and the liquid crystal. This angle is maintained after the voltage is removed.

[0049] Step 5: The PSVA PI optical parameters that can be evaluated for the above test panel include:

[0050] Apply a continuous voltage of 0V to 10V and measure the transmittance distribution curve as a function of voltage, i.e., V-TCure;

[0051] Measure the panel brightness at 0V and Vth voltages, and calculate the contrast ratio: CR = brightness in the on state / brightness in the black state;

[0052] Apply a voltage greater than Vth and measure the response time when the transmittance increases from 10% to 90%.

[0053] Apply an AC voltage greater than Vth and allow the ΔAngle to age continuously at room temperature or high temperature for a certain period of time.

[0054] As a preferred embodiment of the present invention, the PSVA type alignment agent film can be coated with INKJET or spincoating, and the thickness of the alignment agent film is 80-120 nm; the pre-baking temperature is 80-95°C and the time is 100-130 seconds; the baking temperature is 220-240°C and the time is 1200-1800 seconds.

[0055] Specifically: the PSVA type alignment agent film thickness is 100nm; the pre-baking temperature is 90℃ and the pre-baking time is 120 seconds; the baking temperature is set to 230℃ and the time is set to 1200 seconds.

[0056] Furthermore, the pretilt angle can be modified between 0.4° and 0.6°. Under normal conditions, the retardation rate remains unaffected, no light leakage occurs, and a completely black state is achieved. In the open state, the liquid crystal's pretilt angle φ = 45°, thus obtaining maximum transmittance.

[0057] As a preferred embodiment of the present invention, the friction cloth used for rubbing the PSVA-type alignment agent film is made of COTTON material, and the fiber density should be less than 10,000 fibers / cm². 2 The fabric length is 2.5mm to ensure that the initial pretilt angle of the liquid crystal is between 89.4° and 89.6°.

[0058] Specifically: the grinding step uses low-intensity grinding, the pressing amount is set to 0.2mm~0.3mm, the friction machine platform speed is set to 33.3mm / s, and the roller speed is set to 1000rpm.

[0059] As a preferred embodiment of the present invention, the PSVA type alignment agent film is rubbed in a 180° anti-parallel direction, and both the upper and lower substrates are rubbed in a 180° horizontal direction, so that after the upper and lower substrates are flipped and bonded, the orientation vectors of all liquid crystal molecules are in the same direction, and the liquid crystal twist angle is 0°.

[0060] As a preferred embodiment of the present invention, the applied voltage Vth is set to a range of 15V to 25V, a square wave, and a frequency set to 30Hz to 64Hz.

[0061] Specifically: the ultraviolet irradiation process should be carried out in a heated environment with a temperature set between 40℃ and 70℃. 313nm wavelength UV lamps should be used for ultraviolet irradiation polymerization, and the UV irradiation time should not exceed 200 seconds.

[0062] Furthermore: Vth voltage is set to 20V, frequency to 64Hz, and heating environment to 60℃.

[0063] Example 1

[0064] In one embodiment, a conventional PSVA-type orientation agent material (PSVA PI A) was selected, and a test cell was fabricated according to the method described in this invention. The following parameters were obtained from the test:

[0065] (1) Initial pretilt angle data under different friction indentation amounts:

[0066]

[0067] (2) UV irradiation alignment was performed on a test cell with a grinding and pressing depth of 0.2 mm, and the resulting pretilt angle data were obtained:

[0068]

[0069] (3) VT Cure was tested using a test cell with a UV irradiation time of 85 seconds: (see the relevant document for details) Figure 4 ).

[0070] (4) Based on the VT data, the threshold voltage of PSVA PI A is 4.8V. Using V0 and V4.8 to test the brightness values, the contrast ratio of the test cell is calculated as follows:

[0071]

[0072] (5) Apply a 5V voltage and test the response time of the test cell:

[0073] Response time Data 1 Data 2 Data 3 Data 4 Data 5 Ton 5.3ms 5.2ms 5.3ms 5.6ms 5.4ms Toff 4.6ms 4.4ms 4.4ms 4.7ms 4.5ms

[0074] (6) Apply AC 14V voltage and test the angle change of the test cell at room temperature (25℃):

[0075] Time T24 T48 T72 T168 T268 △Angle 0.024° 0.057° 0.081° 0.102° 0.139°

[0076] (7) Apply AC 14V voltage and test the angle change of the test cell in a high temperature environment of 60℃:

[0077] Time T24 T48 T72 T168 T268 △Angle 0.055° 0.079° 0.096° 0.133° 0.175°

[0078] Example 2

[0079] In one embodiment, a high-angle PSVA type alignment agent material (PSVA PI B) was selected, and a test cell was fabricated according to the method described in this invention. The following parameters were obtained from the test:

[0080] (1) Initial pretilt angle data under different friction indentation amounts:

[0081]

[0082] (2) UV irradiation alignment was performed on a test cell with a grinding and pressing depth of 0.3 mm, and the resulting pretilt angle data were obtained:

[0083]

[0084] (3) VT Cure was tested using a test cell with a UV irradiation time of 125 seconds: (see the relevant document for details) Figure 5 ).

[0085] (4) Based on the VT data, the threshold voltage of PSVA PI A is 8.1V. Using V0 and V8.1 to test the brightness values, the contrast ratio of the test cell is calculated as follows:

[0086]

[0087] (5) Applying an 8.1V voltage, the response time of the test cell is:

[0088] Response time Data 1 Data 2 Data 3 Data 4 Data 5 Ton 6.5ms 6.7ms 6.3ms 6.5ms 6.6ms Toff 4.2ms 4.3ms 4.2ms 4.1ms 4.3ms

[0089] (6) Apply AC 14V voltage and test the angle change of the test cell at room temperature (25℃):

[0090] Time T24 T48 T72 T168 T268 △Angle 0.022° 0.045° 0.076° 0.098° 0.127°

[0091] (7) Apply AC 14V voltage and test the angle change of the test cell in a high temperature environment of 60℃:

[0092] Time T24 T48 T72 T168 T268 △Angle 0.043° 0.062° 0.088° 0.115° 0.135°

[0093] Example 3

[0094] In one embodiment, a low-angle PSVA type alignment agent material (PSVA PI C) was selected, and a test cell was fabricated according to the method described in this invention. The following parameters were obtained from the test:

[0095] (1) Initial pretilt angle data under different friction indentation amounts:

[0096]

[0097] (2) UV irradiation alignment was performed on a test cell with a grinding and pressing depth of 0.2 mm, and the resulting pretilt angle data were obtained:

[0098]

[0099] (3) VT Cure was tested using a test cell with a UV irradiation time of 65 seconds: (see the relevant document for details) Figure 6 ).

[0100] (4) Based on the VT data, the threshold voltage of PSVA PI A is 4.2V. Using V0 and V4.2 to test the brightness values, the contrast ratio of the test cell is calculated as follows:

[0101]

[0102]

[0103] (5) Apply a voltage of 4.2V and test the response time of the test cell:

[0104] Response time Data 1 Data 2 Data 3 Data 4 Data 5 Ton 4.7ms 4.5ms 4.5ms 4.6ms 4.6ms Toff 5.9ms 6.2ms 6.1ms 5.9ms 6.0ms

[0105] (6) Apply AC 14V voltage and test the angle change of the test cell at room temperature (25℃):

[0106] Time T24 T48 T72 T168 T268 △Angle 0.065° 0.108° 0.135° 0.222° 0.314°

[0107] (7) Apply AC 14V voltage and test the angle change of the test cell in a high temperature environment of 60℃:

[0108] Time T24 T48 T72 T168 T268 △Angle 0.088° 0.147° 0.259° 0.471° 0.645°

[0109] This invention is not limited to the above-described optional embodiments. Anyone can derive other various forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that falls within the scope of the claims of this invention shall be protected by this invention.

Claims

1. A method for measuring the optical properties of a polymer-stabilized vertical alignment agent, comprising the following steps: Step 1: A PSVA-type alignment agent film is coated on a substrate with a semiconductor ITO layer. After the alignment agent film is pre-baked to remove the solvent, it needs to be dehydrated and cyclized in an oven at high temperature to make the alignment agent film have liquid crystal alignment properties. Step 2: During the process of coating the PSVA type alignment agent film, the side chain structure of the PSVA type alignment agent film is rubbed to make it have a fixed orientation vector, and the pretilt angle is changed from 90° to less than 90°. Step 3: After the substrate is polished, it is assembled under the bonding effect of the frame adhesive to obtain the test empty cell. The height of the test empty cell is set to 3.5μm. The frame adhesive pattern has a liquid crystal injection port. Negative VA liquid crystal mixed with RM monomer and an appropriate amount of photoinitiator is injected in a vacuum environment. Then the injection port is closed to obtain the PSVA test cell. Step 4: Apply a voltage greater than Vth to the test box to make the liquid crystal molecules tilt in the direction of the electric field, and use ultraviolet light to irradiate the RM monomers to polymerize and deposit them on the surface of the PI film. Fix the liquid crystal angle and arrange the liquid crystals neatly in a fixed direction. Step 5: The PSVA PI optical parameters that can be evaluated for the test panel include: Apply a continuous voltage of 0V to 10V and measure the transmittance distribution curve as a function of voltage, i.e., V-TCure; Measure panel brightness at OV and Vth voltages, calculate contrast ratio, and brightness in both on and black states. Apply a voltage greater than Vth and measure the response time when the transmittance increases from 10% to 90%. Apply an AC voltage greater than Vth and age it continuously at room temperature or high temperature for a certain period of time, resulting in ΔAngle. The PSVA type alignment agent film can be coated using INKJET or spin coating. The thickness of the PSVA type alignment agent film is 80-120 nm. The pre-baking temperature is 80-95℃ and the time is 100-130 seconds. The baking temperature is 220-240℃ and the time is 1200-1800 seconds. The friction cloth used to rub the PSVA type alignment agent film is made of COTTON material, with a fiber density of less than 10,000 fibers and a cloth length of 2.5 mm, to ensure that the initial pretilt angle of the liquid crystal is between 89.4° and 89.6°. The grinding step uses low-intensity grinding, with the pressing amount set to 0.2mm~0.3mm, the friction machine platform speed set to 33.3mm / s, and the roller speed set to 1000rpm; The alignment agent film is rubbed in a 180° anti-parallel direction. Both the upper and lower substrates are rubbed in a 180° horizontal direction. After the upper substrate is flipped and bonded, the orientation vectors of all liquid crystal molecules are in the same direction, and the liquid crystal twist angle is 0°.

2. The method for measuring the optical properties of a polymer-stabilized vertical alignment agent according to claim 1, characterized in that: The PSVA-type alignment agent film thickness is 100nm; the pre-baking temperature is 90℃ and the pre-baking time is 120 seconds; the baking temperature is set to 230℃ and the time is set to 1200 seconds.

3. The method for measuring the optical properties of a polymer-stabilized vertical alignment agent according to claim 1, characterized in that: The change in the pre-tilt angle is between 0.4° and 0.6°.

4. The method for measuring the optical properties of a polymer-stabilized vertical alignment agent according to claim 1, characterized in that: The applied voltage Vth is set to a range of 15V to 25V, a square wave, and a frequency set to 30Hz to 64Hz.

5. The method for measuring the optical properties of a polymer-stabilized vertical alignment agent according to claim 4, characterized in that: The ultraviolet irradiation process should be carried out in a heated environment with the temperature set between 40℃ and 70℃. 313nm wavelength UV lamps should be used for ultraviolet irradiation polymerization, and the UV irradiation time should not exceed 200 seconds.

6. The method for measuring the optical properties of a polymer-stabilized vertical alignment agent according to claim 5, characterized in that: The voltage Vth is set to 20V, the frequency to 64Hz, and the heating environment to 60℃.

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