Test light path and test method of polarizing film

Abstract

The application discloses a test light path and a test method of a polarizing film, which are used for detecting the durability of the polarizing film and comprise a tunable quantum cascade laser controller used for triggering an electric signal, a tunable quantum cascade laser connected with the tunable quantum cascade laser controller in an electric signal mode and used for emitting an optical signal corresponding to the electric signal, a beam splitter arranged on the path of the optical signal and used for dividing the optical signal into a first light beam and a second light beam, a high-time-resolution infrared detector arranged on the path of the first light beam and used for detecting the luminous intensity of the first light beam after the first light beam transmits through the polarizing film and converting the luminous intensity into an electric signal, an optical reflecting lens arranged on the path of the second light beam and used for reflecting the second light beam, and a signal collection system connected with the high-time-resolution infrared detector in an electric signal mode and used for collecting the data of infrared transmittance. The test light path of the polarizing film can detect the durability of the polarizing film in situ in the production process of the polarizing film.

Description

Technical Field

[0001] This invention relates to the field of polarizing film testing, specifically to a test optical path and test method for a polarizing film. Background Technology

[0002] Polarizing film is a key component that determines display quality. In liquid crystal displays (LCDs), the liquid crystal cell and the polarizing films on both sides form a light switch that determines whether light can pass through. In organic light-emitting diode displays (OLEDs), the combination of polarizing film and quarter-wave plate can eliminate the interference of ambient light on the display.

[0003] In the performance testing of polarizing films, their optical performance can be tested and fed back in a timely manner using online optical performance testing devices; however, their durability performance can currently only be obtained by sampling and then using aging chambers with damp heat, high temperature, and low temperature for up to 500 hours. Due to the long testing cycle of polarizing film durability, if process fluctuations cause the durability to deteriorate, it cannot be directly fed back to the production line, which will cause serious material and labor losses.

[0004] However, it is currently impossible to test the durability of polarizing films in situ during the production process. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a test optical path and test method for polarizing film, aiming to solve the problem that it is currently impossible to detect the durability of polarizing film in situ during the production process of polarizing film.

[0006] To achieve the above objectives, the present invention proposes a test optical path for a polarizing film, comprising: a tunable quantum cascade laser controller for triggering an electrical signal; a tunable quantum cascade laser connected to the controller for emitting an optical signal corresponding to the electrical signal; a beam splitter disposed in the path of the optical signal for splitting the optical signal into a first beam and a second beam; a high time-resolution infrared detector disposed in the path of the first beam for detecting the luminous intensity of the first beam after passing through the polarizing film under test and converting the luminous intensity into an electrical signal; an optical reflector disposed in the path of the second beam for reflecting the second beam; and a signal collection system connected to the detector for collecting infrared transmittance data.

[0007] Optionally, after being reflected by the optical reflector, the second beam and the first beam converge at the same point on the polarizing film under test.

[0008] Optionally, the ratio of the luminous intensity of the first beam to that of the second beam is 1:9.

[0009] Optionally, the first beam is used to collect infrared transmittance data.

[0010] Optionally, the second beam is used to resonate and heat the polarizing film.

[0011] To achieve the above objectives, the present invention also proposes a testing method for polarizing films, which uses the above-mentioned testing optical path for polarizing films to detect the durability of polarizing films.

[0012] Optionally, the method includes: connecting a test optical path to the polarizing film; using an infrared testing method in the test optical path of the polarizing film to obtain the infrared transmittance of different polarizing films with known durability specifications, as calibration data; using an infrared testing method in the test optical path of the polarizing film to obtain the infrared transmittance data of the polarizing film to be tested; comparing the infrared transmittance data of the polarizing film to be tested with the calibration data to obtain the durability test result of the polarizing film to be tested.

[0013] Optionally, the step of "connecting the test optical path of the polarizing film" includes: forming an electrical signal connection between the tunable quantum cascade laser controller and the tunable quantum cascade laser; forming an electrical signal connection between the high time-resolution infrared detector and the signal collection system; and forming an optical signal connection between the tunable quantum cascade laser controller and the high time-resolution infrared detector.

[0014] Optionally, the testing method is in-situ detection.

[0015] Optionally, the test method is applied during the production process of polarizing film.

[0016] The beneficial effects of this invention are as follows: The test optical path for the polarizing film provided by this invention utilizes a tunable quantum cascade laser controller, a tunable quantum cascade laser, a beam splitter, optical reflecting mirrors, a high time-resolution infrared detector, and a signal collection system to construct the optical path. The tunable quantum cascade laser controller controls the tunable quantum cascade laser to emit infrared light, which is then split into two beams by the beam splitter. The second beam rapidly and precisely heats the hydroxyl groups on the PVA molecular chains in the polarizing film, while the first beam provides the hydroxyl signal to the high time-resolution infrared detector. The intensity of the complexation between the hydroxyl groups and iodine is detected, directly reflecting the stability of the internal chemical structure of the polarizing film. This allows for in-situ testing of the durability of the polarizing film during its production process. Furthermore, the beam energy of the infrared light can be adjusted according to the speed of the polarizing film production line, ensuring in-situ testing without damaging the polarizing film product. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the test optical path of a polarizing film according to one embodiment;

[0019] Figure 2 This is a schematic diagram of the normalized intensity of Examples 1-4.

[0020] Table 1. Meaning of the labels in the test optical path diagram of the polarizing film

[0021] 1 Tunable quantum cascade laser 5 Polarizing film 2 Tunable quantum cascade laser controller 6 High time-resolution infrared detector 3 Beam splitter 7 Signal collection system 4 Optical reflector

[0022] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0024] Unless otherwise specified, all technical and scientific terms used herein have their usual meaning within the field to which the subject matter is claimed.

[0025] To facilitate understanding of this embodiment, the symbols, instruments, and terms are explained below:

[0026] PVA stands for polyvinyl alcohol.

[0027] A quantum cascade laser is a semiconductor laser that emits laser light in the mid-infrared and far-infrared frequency bands. Tunable means that the output wavelength of the laser can be continuously changed within a certain range.

[0028] A time-resolved infrared detector is an infrared detector that takes only microseconds to acquire a complete spectrum.

[0029] Polarizing film is a key component that determines display quality. In liquid crystal displays (LCDs), the liquid crystal cell and the polarizing films on both sides form a light switch that determines whether light can pass through. In organic light-emitting diode displays (OLEDs), the combination of polarizing film and quarter-wave plate can eliminate the interference of ambient light on the display.

[0030] In the performance testing of polarizing films, their optical performance can be tested and fed back in a timely manner using online optical performance testing devices; however, their durability performance can currently only be obtained by sampling and then using aging chambers with damp heat, high temperature, and low temperature for up to 500 hours. Due to the long testing cycle of polarizing film durability, if process fluctuations cause the durability to deteriorate, it cannot be directly fed back to the production line, which will cause serious material and labor losses.

[0031] However, it is currently impossible to test the durability of polarizing films in situ during the production process.

[0032] To address the aforementioned problems, this invention proposes a test optical path for a polarizing film, comprising: a tunable quantum cascade laser controller for triggering an electrical signal; a tunable quantum cascade laser, electrically connected to the controller, for emitting an optical signal corresponding to the electrical signal; a beam splitter disposed in the path of the optical signal for splitting the optical signal into a first beam and a second beam; a high time-resolution infrared detector disposed in the path of the first beam for detecting the luminous intensity of the first beam after passing through the polarizing film under test and converting the luminous intensity into an electrical signal; an optical reflector disposed in the path of the second beam for reflecting the second beam; and a signal collection system electrically connected to the detector for collecting infrared transmittance data.

[0033] In one embodiment, after setting the frequency, infrared wavenumber, and energy, the tunable quantum cascade laser controller 2 triggers an electrical signal to the tunable quantum cascade laser 1. The tunable quantum cascade laser 1 emits a corresponding optical signal, which serves as the incident light for the beam splitter 3. The beam splitter 3 splits the incident beam emitted by the tunable quantum cascade laser 1 into two beams with a certain intensity ratio: a transmitted beam and a reflected beam. The transmitted beam serves as the first beam, and the reflected beam serves as the second beam. The first beam is used to detect the pulsed light signal of hydroxyl groups. After passing through the polarizing film 5, it is detected by the high time-resolution infrared detector 6, which converts the optical signal into an electrical signal. This signal is collected and stored by the signal collection system 7 as infrared transmittance data. The second beam is reflected by the optical reflector 4 and, through resonant absorption, rapidly heats the hydroxyl groups on the PVA molecular chains in the polarizing film under test. Since the polarization properties of polarizing films originate from polyiodide ions complexed with PVA, and these complexes are formed by the hydroxyl groups on the PVA molecular chain, as the durability of the polarizing film improves, the interaction between the hydroxyl groups and iodine strengthens, leading to a decrease in the OH dipole moment, reduced infrared light absorption, and consequently, increased transmittance. Therefore, detecting the infrared transmittance of the OH bonds reveals the state of the OH bond dipole moment, and thus the strength of the complexation between the hydroxyl groups and iodine. The stability of the hydroxyl-iodine complex further reflects the durability of the polarizing film.

[0034] In one embodiment, the tunable quantum cascade laser controller 2 is set to a frequency of 100 kHz and an infrared wavelength of 3300 cm⁻¹. -1 The set energy is 100mW. The emitted wavelength of a quantum cascade laser can be adjusted by changing the energy between two excited states of a semiconductor. In the specific production of polarizing films, the beam energy can be adjusted according to the speed of the polarizing film production line to avoid damage to the polarizing film product during testing.

[0035] Furthermore, after being reflected by the optical reflector, the second beam converges with the first beam at the same point on the polarizing film under test. After the second and first beams converge at the same point on the polarizing film 5 under test, the second beam is absorbed by the hydroxyl groups on the PVA molecular chain, causing the molecular motion to become more intense, resulting in an increase in temperature. This creates conditions for the first beam to accurately detect the vibrational frequency of the hydroxyl groups at a specific point and the amount of infrared light absorbed, thus obtaining the final infrared transmittance of the polarizing film 5 under test.

[0036] Furthermore, the ratio of the luminous intensity of the first beam to the second beam is 1:9. In one embodiment, one side of the beam splitter 3 is coated with a dielectric beam-splitting film, and the other side is coated with an anti-reflection film. When the infrared beam emitted by the tunable quantum cascade laser 1 is incident on the surface of the beam-splitting film 3 at a 45-degree angle of incidence, a beam splitting ratio of 1:9 for transmitted light intensity to reflected light intensity can be achieved. This beam splitting ratio can both meet the high-speed detection of infrared transmittance by the high-time-resolution infrared detector 6 and promote the heating of the hydroxyl group by the second beam.

[0037] Furthermore, the first beam is used to collect infrared transmittance data. The intensity of the tunable quantum cascade laser is more than four orders of magnitude greater than that of ordinary blackbody radiation. The first beam is 1 / 10 of the initial infrared light emitted by the tunable quantum cascade laser 1. After being detected by the high time-resolution infrared detector 6, it is converted into an electrical signal. The first beam accurately detects the vibration frequency of the fixed-point hydroxyl group and the amount of infrared light absorbed, thereby obtaining the infrared transmittance of the polarizing film 5, which is finally collected by the signal collection system 7.

[0038] Furthermore, the second beam is used to resonantly heat the polarizing film. The intensity of the tunable quantum cascade laser is more than four orders of magnitude greater than that of ordinary blackbody radiation. The second beam is 9 / 10 of the initial infrared light emitted by the tunable quantum cascade laser 1. The high intensity causes the molecules on the polarizing film to move violently, thus effectively heating the hydroxyl groups.

[0039] To address the aforementioned issues, this invention also proposes a testing method for polarizing films, utilizing the aforementioned testing optical path to detect the durability of the polarizing film. Compared to traditional polarizing film durability testing, which requires sampling followed by aging chamber tests involving humidity, high temperature, and low temperature for up to 500 hours, the testing method proposed in this invention eliminates the need for sampling and can detect the durability performance of the polarizing film in just 10μs.

[0040] Furthermore, the testing method includes: connecting the test optical path of the polarizing film; using infrared testing in the test optical path of the polarizing film to obtain the infrared transmittance of different polarizing films with known durability specifications, as calibration data; using infrared testing in the test optical path of the polarizing film to obtain the infrared transmittance data of the polarizing film to be tested; comparing the infrared transmittance data of the polarizing film to be tested with the calibration data to obtain the durability test result of the polarizing film to be tested.

[0041] In one embodiment, in the above optical path, polarizing films of different durability specifications that have completed durability testing are collected. For example, five low-durability polarizing films, five medium-durability polarizing films, five high-durability polarizing films, and five ultra-high-durability polarizing films are collected. The infrared transmittance of each film is measured using an infrared testing method. The average value of the infrared transmittance of polarizing films of different durability specifications is then taken as calibration data. Next, a polarizing film with unknown durability is selected, and the film is guided through the film to measure its infrared transmittance. The infrared transmittance of the film is then compared with the calibration data to obtain the durability test result of the polarizing film.

[0042] Furthermore, the step of "connecting the test optical path of the polarizing film" includes: forming an electrical signal connection between the tunable quantum cascade laser controller and the tunable quantum cascade laser; forming an electrical signal connection between the high time-resolution infrared detector and the signal collection system; and forming an optical signal connection between the tunable quantum cascade laser controller and the high time-resolution infrared detector. The test optical path of the polarizing film includes two transformations: an electrical signal to an optical signal, and then the optical signal back to an electrical signal. After the tunable quantum cascade laser controller and the tunable quantum cascade laser form an electrical signal connection, the frequency, wavenumber, and energy of the initially emitted infrared light can be controlled. After the tunable quantum cascade laser controller and the high time-resolution infrared detector form an optical signal connection, the resulting optical path provides a detection position for the durability testing of the polarizing film. After the high time-resolution infrared detector and the signal collection system form an electrical signal connection, the optical signal is converted into an electrical signal, which is collected and stored by the signal collection system as infrared transmittance data.

[0043] Furthermore, the testing method is in-situ testing. The polarizing film durability testing method of this scheme can achieve in-situ testing, that is, the polarizing film under test is inspected and tested at its original installation and assembly position, without the need for sampling, and the polarizing film under test is not damaged during the testing process.

[0044] Furthermore, the aforementioned testing method is applied to the production process of polarizing film. This polarizing film durability testing method enables durability testing during the production process, providing timely feedback to the production line regarding process compliance. This avoids the need for subsequent long-term testing and feedback to the production line if durability deteriorates due to process fluctuations, thus preventing significant material and labor losses.

[0045] Example 1:

[0046] The trigger signal of the tunable quantum cascade laser controller is sent to the tunable quantum cascade laser, setting its frequency to 100kHz and its infrared wavelength number to 3300cm. -1The light signal emitted by the 100mW tunable quantum cascade laser is split into two beams by a beam splitter. The intensity of the first beam is 10% of the initial intensity, and the intensity of the second beam is 90% of the initial intensity. Before passing through the film, the light intensity I0 detected by the high time-resolution infrared detector is collected when there is no sample in the optical path. Twenty low-durability polarizing films are taken and guided through the film. The transmittance I of the 20 samples is measured, and the infrared transmittance data is calculated using the formula and then the average value is taken.

[0047] Example 2:

[0048] The trigger signal of the tunable quantum cascade laser controller is sent to the tunable quantum cascade laser, setting its frequency to 100kHz and its infrared wavelength number to 3300cm. -1 The light signal emitted by the 100mW tunable quantum cascade laser is split into two beams by a beam splitter. The intensity of the first beam is 10% of the initial intensity, and the intensity of the second beam is 90% of the initial intensity. Before passing through the film, the light intensity I0 detected by the high time-resolution infrared detector is collected when there is no sample in the optical path. Twenty medium-durability polarizing films are selected and guided through the film. The transmittance I of the 20 samples is measured, and the infrared transmittance data is calculated using the formula and then averaged.

[0049] Example 3:

[0050] The trigger signal of the tunable quantum cascade laser controller is sent to the tunable quantum cascade laser, setting its frequency to 100kHz and its infrared wavelength number to 3300cm. -1 The light signal emitted by the 100mW tunable quantum cascade laser is split into two beams by a beam splitter. The intensity of the first beam is 10% of the initial intensity, and the intensity of the second beam is 90% of the initial intensity. Before passing through the film, the light intensity I0 detected by the high time-resolution infrared detector is collected when there is no sample in the optical path. Twenty high-durability polarizing films are taken and guided through the film. The transmittance I of the 20 samples is measured, and the infrared transmittance data is calculated using the formula and then the average value is taken.

[0051] Example 4:

[0052] The trigger signal of the tunable quantum cascade laser controller is sent to the tunable quantum cascade laser, setting its frequency to 100kHz and its infrared wavelength number to 3300cm. -1The light signal emitted by the 100mW tunable quantum cascade laser is split into two beams by a beam splitter. The intensity of the first beam is 10% of the initial intensity, and the intensity of the second beam is 90% of the initial intensity. Before passing through the film, the light intensity I0 detected by the high time-resolution infrared detector is collected when there is no sample in the optical path. Twenty ultra-durable polarizing films are taken and guided through the film. The transmittance I of the 20 samples is measured, and the infrared transmittance data is calculated using the formula and then the average value is taken.

[0053] Furthermore, the infrared transmittance T is calculated using the following formula:

[0054]

[0055] Where I represents the light intensity detected by the high time-resolution infrared detector when there is a polarizing film in the transmittance optical path; and I0 represents the light intensity detected by the high time-resolution infrared detector when there is no film in the optical path.

[0056] The infrared transmittance data from Examples 1-4 were converted into normalized intensity, and data with the same characteristic were normalized to a distribution with a mean of 0 and a variance of 1, resulting in... Figure 2 .

[0057] Furthermore, we tested the polarizing film with unknown durability, and after the tests, we compared its normalized intensity data with... Figure 2 By comparison, we can conclude that: polarizing films with a normalized intensity in the range of 0.34-0.47 are low-durability samples; polarizing films with a normalized intensity in the range of 0.47-0.60 are medium-durability samples; polarizing films with a normalized intensity in the range of 0.60-0.70 are high-durability samples; and polarizing films with a normalized intensity exceeding 0.7 are ultra-high-durability samples.

[0058] The above experiments clearly demonstrate that the present invention utilizes a test optical path for the polarizing film constructed from a tunable quantum cascade laser controller, a tunable quantum cascade laser, a beam splitter, optical reflecting lenses, a high time-resolution infrared detector, and a signal collection system. By testing the infrared transmittance of Examples 1-4, calibration data for the polarizing film's durability can be obtained. The test optical path for the polarizing film relies on the high-energy characteristics of the tunable quantum cascade laser and the high-speed, microsecond-level spectrum detection of the high-time-resolution infrared detector, achieving a 10μs time resolution and an in-situ method for measuring the durability of the polarizing film. Using this test method in industrial production allows for the integration of polarizing film durability testing with the production process, enabling timely feedback of problems to the production line. Furthermore, the energy of the initial beam can be adjusted according to the speed of the polarizing film production line, ensuring in-situ testing without damaging the polarizing film product, thus possessing significant industrial application value.

[0059] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A test optical path of a polarizing film, characterized by, include: A tunable quantum cascade laser controller for triggering electrical signals; A tunable quantum cascade laser is electrically connected to the tunable quantum cascade laser controller to emit an optical signal corresponding to the electrical signal. A beam splitter is positioned in the path of the optical signal to split the optical signal into a first beam and a second beam. A high time-resolution infrared detector is positioned in the path of the first beam to detect the luminous intensity of the first beam after it passes through the polarizing film under test, and converts the luminous intensity into an electrical signal. An optical reflecting mirror is positioned in the path of the second beam to reflect the second beam. Additionally, a signal collection system is electrically connected to the high time-resolution infrared detector for collecting infrared transmittance data; After being reflected by the optical reflector, the second beam converges with the first beam at the same point on the polarizing film. The ratio of the luminous intensity of the first beam to that of the second beam is 1:

9.

2. The test light path of a polarizing film according to claim 1, wherein The first beam is used to collect infrared transmittance data.

3. The test optical path of a polarizing film according to claim 1, wherein The second beam is used to resonate and heat the polarizing film.

4. A method of testing a polarizing film, characterized by, The durability of the polarizing film is tested using the test optical path of the polarizing film as described in claims 1 to 3.

5. The method of testing a polarizing film according to claim 4, wherein include: Test optical path connecting to the polarizing film; Infrared testing was used in the test optical path of the polarizing film to obtain the infrared transmittance of different polarizing films with known durability specifications, which was used as calibration data. Infrared testing method is used in the test optical path of the polarizing film to obtain infrared transmittance data of the polarizing film under test; The infrared transmittance data of the polarizing film under test is compared with the calibration data to obtain the durability test results of the polarizing film under test.

6. The testing method for the polarizing film as described in claim 4, characterized in that, The step of "connecting the test optical path of the polarizing film" includes: The tunable quantum cascade laser controller is electrically connected to the tunable quantum cascade laser. The high time-resolution infrared detector is electrically connected to the signal collection system to generate an electrical signal. A tunable quantum cascade laser controller is connected to a high time-resolution infrared detector to form an optical signal connection.

7. The testing method for the polarizing film as described in claim 4, characterized in that, The testing method is in-situ detection.

8. The testing method for the polarizing film as described in claim 4, characterized in that, The test method is applied in the production process of polarizing film.

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