CN107085320B - Method for measuring optical path difference of liquid crystal panel - Google Patents
Method for measuring optical path difference of liquid crystal panel Download PDFInfo
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- CN107085320B CN107085320B CN201710244020.7A CN201710244020A CN107085320B CN 107085320 B CN107085320 B CN 107085320B CN 201710244020 A CN201710244020 A CN 201710244020A CN 107085320 B CN107085320 B CN 107085320B
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- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
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- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
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Abstract
The invention discloses a method for measuring optical path difference of a liquid crystal panel, which comprises the steps of obtaining brightness corresponding to at least two different optical path differences under the same preset condition; fitting to obtain a relation between the optical path difference and the brightness ratio when the reference optical path difference of the first reference liquid crystal panel is taken as the reference optical path difference according to the brightness corresponding to the different optical path differences; under the preset condition, calculating the brightness ratio of the liquid crystal panel to be tested and the first reference liquid crystal panel; and obtaining the optical path difference of the liquid crystal panel to be measured according to the brightness ratio and the relation between the optical path difference and the brightness ratio. By the mode, the optical path difference of the liquid crystal panel to be measured is obtained by utilizing the relation between the optical path difference and the brightness ratio, the measurement process of the optical path difference of the liquid crystal panel is simplified, and the measurement cost is reduced.
Description
Technical Field
The invention relates to the technical field of optics, in particular to a method for measuring optical path difference of a liquid crystal panel.
Background
Currently, liquid crystal panels are becoming an important role of consumer electronics, and are widely used in displays of devices such as mobile terminals having high-resolution color screens. The liquid crystal panel comprises a dark state which can not pass light and a bright state which can pass light, and the liquid crystal plays a role of a light valve for controlling voltage during the switching between the dark state and the bright state and the whole display process of the liquid crystal display. The transmittance of the liquid crystal panel is the ratio of the transmitted luminous flux to the incident total luminous flux of the liquid crystal display in a dark state, namely the transmittance of the liquid crystal panel represents the light leakage degree of the liquid crystal panel in the dark state; the higher the penetration rate is, the smaller the light leakage degree of the dark state of the liquid crystal panel is; the degree of light leakage in the dark state of the lcd panel is an important indicator of the lcd.
As can be seen from the formula of the transmittance of the liquid crystal panel, Tr is 0.5sin2(2 θ) sin2 (pi Δ ND/λ) (θ represents the azimuth angle between the absorption axis of the polarizer of the liquid crystal panel and the long axis of the liquid crystal molecules), when θ is 45 °, the transmittance is the highest, and at this time, the transmittance is reduced to Tr is 0.5sin2 (pi Δ ND/λ), where Δ N is the optical path difference of the liquid crystal panel and D is the cell thickness, so that the transmittance of the liquid crystal display is closely related to the optical path difference and the cell thickness, and therefore, it is very important to monitor the optical path difference in the preparation of the liquid crystal panel. In the prior art, special equipment is often adopted to measure the optical path difference of the liquid crystal panel, the polarizer of the liquid crystal panel needs to be removed in the measurement process, the measurement process is complex, and the liquid crystal panel is damaged.
Disclosure of Invention
In view of this, the present invention provides a method for measuring an optical path difference of a liquid crystal panel, which can simplify a measurement process of the optical path difference of the liquid crystal panel and reduce measurement cost.
In order to solve the technical problems, the invention provides a technical scheme that: the method for measuring the optical path difference of the liquid crystal panel comprises the following steps:
acquiring brightness corresponding to at least two different optical path differences under the same preset condition;
fitting to obtain a relation between the optical path difference and the brightness ratio when the reference optical path difference of the first reference liquid crystal panel is taken as the reference optical path difference according to the brightness corresponding to the different optical path differences;
under the preset condition, calculating the brightness ratio of the liquid crystal panel to be tested and the first reference liquid crystal panel;
and obtaining the optical path difference of the liquid crystal panel to be detected according to the brightness ratio and the relation between the optical path difference and the brightness ratio.
Wherein, under the same preset condition, acquiring the brightness corresponding to at least two different optical path differences includes:
enabling at least two second reference liquid crystal panels with different optical path differences to be matched with the same phase compensation mechanism respectively, and acquiring the brightness corresponding to the at least two second reference liquid crystal panels under the same azimuth angle and the same side visual angle;
and respectively taking the brightness corresponding to the at least two second reference liquid crystal panels as the brightness corresponding to the at least two different optical path differences.
Wherein, under the preset condition, calculating the brightness ratio of the liquid crystal panel to be measured and the first reference liquid crystal panel comprises:
respectively matching the liquid crystal panel to be tested and the first reference liquid crystal panel with the phase compensation mechanism; respectively acquiring the brightness of the liquid crystal panel to be detected and the first reference liquid crystal panel under the azimuth angle and the side visual angle;
and dividing the brightness of the liquid crystal panel to be tested by the brightness of the first reference liquid crystal panel to obtain the brightness ratio of the two.
The phase compensation mechanism comprises a first phase compensation part and a second phase compensation part which are respectively arranged on two sides of the liquid crystal panel, wherein the first phase compensation part and the second phase compensation part respectively comprise a cellulose Triacetate (TAC) layer and a Polyethylene (PVA) layer; the first phase compensation portion and/or the second phase compensation portion further include a COP layer.
Wherein the included angle between the slow axis of the COP layer and the absorption axis of the polyethylene PVA layer is 90 degrees.
Wherein the acquiring the brightness of the at least two second reference liquid crystal panels at the same azimuth angle and the same side viewing angle includes:
acquiring dark state full-view brightness distribution of the at least two second reference liquid crystal panels;
extracting brightness distributions corresponding to different side viewing angles of the at least two second reference liquid crystal panels under the same azimuth angle from the dark state full viewing angle brightness distribution;
and extracting the brightness of the at least two second reference liquid crystal panels at the same side visual angle from the brightness distribution corresponding to the different side visual angles.
Wherein, the obtaining the relationship between the optical path difference and the brightness ratio by fitting according to the brightness corresponding to the different optical path differences, the relationship taking the reference optical path difference of the first reference liquid crystal panel as the reference optical path difference, includes:
taking each optical path difference in the different optical path differences as a reference optical path difference in sequence, and fitting to obtain a relation between a plurality of optical path differences corresponding to each reference optical path difference and a brightness ratio according to the brightness corresponding to the different optical path differences;
extracting a relation between an optical path difference corresponding to a reference optical path difference with the smallest difference value of the reference optical path differences and a brightness ratio from the relation between the optical path differences corresponding to the reference optical path differences and the brightness ratio obtained through fitting;
and taking the extracted relation between the optical path difference and the brightness ratio as the relation between the corresponding optical path difference and the brightness ratio when the reference optical path difference is taken as the reference optical path difference.
Wherein, the obtaining the relationship between the optical path difference and the brightness ratio by fitting according to the brightness corresponding to the different optical path differences, the relationship taking the reference optical path difference of the first reference liquid crystal panel as the reference optical path difference, includes:
taking the optical path difference with the minimum difference value with the reference optical path difference in the different optical path differences as a reference optical path difference;
fitting according to the reference optical path difference and the brightness corresponding to the different optical path differences to obtain a relation between the corresponding optical path difference and the brightness ratio;
and taking the relation between the optical path difference and the brightness ratio as the relation between the corresponding optical path difference and the brightness ratio when the reference optical path difference is taken as the reference optical path difference.
After obtaining the optical path difference of the liquid crystal panel to be measured according to the brightness ratio and the relationship between the optical path difference and the brightness ratio, the method further comprises the following steps:
calculating the liquid crystal box thickness of the liquid crystal panel to be detected according to an optical path difference formula and the optical path difference of the liquid crystal panel to be detected;
wherein, the optical path difference formula is as follows: the optical path difference is Δ N × D, Δ N is the difference between the normal optical refractive index and the extraordinary optical refractive index of the liquid crystal material, and D is the liquid crystal cell thickness.
Has the advantages that: different from the prior art, the method for measuring the optical path difference of the liquid crystal panel provided by the invention obtains the brightness corresponding to at least two different optical path differences under the same preset condition; fitting to obtain a relation between the optical path difference and the brightness ratio when the reference optical path difference of the first reference liquid crystal panel is taken as the reference optical path difference according to the brightness corresponding to the different optical path differences; under the preset condition, calculating the brightness ratio of the liquid crystal panel to be tested and the first reference liquid crystal panel; and obtaining the optical path difference of the liquid crystal panel to be measured according to the brightness ratio and the relation between the optical path difference and the brightness ratio. In the whole measuring method, the optical path difference of the liquid crystal panel to be measured can be measured without damaging the liquid crystal panel to be measured and special measuring equipment, so that the measuring process of the optical path difference of the liquid crystal panel is simplified, and the measuring cost is reduced.
Drawings
FIG. 1 is a schematic flow chart of a method for measuring an optical path difference of a liquid crystal panel according to a first embodiment of the present invention;
fig. 2 is a schematic flow chart of step S11 in the first embodiment of the measuring method shown in fig. 1;
fig. 3 is a schematic structural diagram of the phase compensation mechanism employed in step S111 in fig. 2;
FIG. 4 is a schematic flow chart of step S111 in FIG. 2;
5 a-5 g are dark state full view luminance distribution diagrams obtained in the application example of S111 in FIG. 4;
FIG. 6 is a luminance distribution graph corresponding to different side view angles of the same azimuth angle in FIG. 5 a-FIG. 5 g;
FIG. 7 is a flowchart illustrating an embodiment of step S12 in FIG. 1;
FIGS. 8a to 8g are graphs fitted with 7 optical path differences of 317nm to 377nm, respectively, as reference optical path differences;
FIG. 9 is a schematic flow chart diagram illustrating another embodiment of step S12 in FIG. 1;
FIG. 10 is a schematic flow chart of step S13 in FIG. 1;
FIG. 11 is a flowchart illustrating a method for measuring an optical path difference of a liquid crystal panel according to a second embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a schematic flow chart of a method for measuring an optical path difference of a liquid crystal panel according to a first embodiment of the present invention. As shown in fig. 1, the measurement method of the present embodiment includes the following steps:
and S11, acquiring the brightness corresponding to at least two different optical path differences under the same preset condition.
First, it is to be noted that, since the transmittance of the liquid crystal panel represents the brightness of the liquid crystal panel in the dark state, the brightness in the present invention refers to the brightness of the liquid crystal panel in the dark state; and the optical path difference from the optical path difference to the liquid crystal layer in the invention is the optical path difference of the liquid crystal.
Under the same condition, the liquid crystal panels with different optical path differences have different brightness, and the same liquid crystal panel has different brightness at different phase angles and different side viewing angles, that is, the optical path difference of the liquid crystal panel has a close relationship with the brightness. The preset conditions in this embodiment include a phase difference, an azimuth angle, and a side viewing angle, that is, the brightness corresponding to at least two different optical path differences is obtained under the same phase difference, azimuth angle, and side viewing angle.
And S12, fitting according to the brightness corresponding to the different optical path differences to obtain the relation between the optical path difference and the brightness ratio when the reference optical path difference of the first reference liquid crystal panel is taken as the reference optical path difference.
In this embodiment, the optical path difference of the first reference liquid crystal panel is a reference optical path difference, and the reference optical path difference may be the same as or different from a certain optical path difference of the at least two second reference liquid crystal panels. And fitting to obtain a relation between the optical path difference and the brightness ratio by taking the reference optical path difference as a reference optical path difference and combining the brightness corresponding to the at least two different optical path differences obtained in the step S11.
S13, under the preset condition, calculating the brightness ratio of the liquid crystal panel to be tested and the first reference liquid crystal panel.
The preset condition in this step is the same as the preset condition in step S11. And respectively obtaining the brightness of the liquid crystal panel to be tested and the first reference liquid crystal panel under the preset condition, and further obtaining the brightness ratio of the liquid crystal panel to be tested and the first reference liquid crystal panel.
And S14, obtaining the optical path difference of the liquid crystal panel to be measured according to the brightness ratio and the relation between the optical path difference and the brightness ratio.
Substituting the brightness ratio of the liquid crystal panel to be tested and the first reference liquid crystal panel obtained in the step S13 into the relational expression between the optical path difference and the brightness ratio obtained in the step S12, the optical path difference of the liquid crystal panel to be tested can be calculated.
In this embodiment, according to the relation between the optical path difference and the brightness, the optical path difference of the liquid crystal panel to be measured is calculated by calculating the relation between the optical path difference and the brightness and further using the brightness of the liquid crystal panel to be measured.
Further, referring to fig. 2, as shown in fig. 2, the step S11 includes the following steps:
and S111, respectively matching the at least two second reference liquid crystal panels with different optical path differences with the same phase compensation mechanism, and acquiring the brightness corresponding to the at least two second reference liquid crystal panels under the same azimuth angle and the same side visual angle.
The optical path difference exists depending on the liquid crystal panel, and therefore, the brightness corresponding to at least two different optical path differences is obtained, that is, the brightness corresponding to the liquid crystal panel obtaining at least two different optical path differences is obtained. In this embodiment, at least two second reference liquid crystal panels are used to obtain the brightness corresponding to at least two different optical path differences, and the optical path differences of the at least two second reference liquid crystal panels are known and are different from each other. In this embodiment, the at least two second reference liquid crystal panels are liquid crystal panels of the same type, for example, both are vertical alignment liquid crystal panels. The selection of the at least two second reference liquid crystal panels is selected according to the range of the optical path difference of the currently common liquid crystal panel, the range of the optical path difference of the currently common liquid crystal panel is between 317nm and 377nm, and therefore, the liquid crystal panel with the optical path difference between 317nm and 377nm can be selected as the second reference liquid crystal panel. In other embodiments, liquid crystal panels with other optical path differences can be selected as the second reference liquid crystal panel.
Because the phase difference of the liquid crystal molecules under different side viewing angles is different, when the liquid crystal panel is in a dark state, the brightness under different side viewing angles has difference; in order to make at least two identical liquid crystal panels have the same phase difference, in the embodiment, at least two second reference liquid crystal panels are matched with a phase compensation mechanism. Further, an azimuth angle and a side view angle are determined, and corresponding brightness is extracted from the obtained brightness distribution corresponding to the at least two liquid crystal panels with different optical path differences respectively, so that the brightness corresponding to the at least two second reference liquid crystal panels is obtained.
The phase compensation mechanism employed in the present embodiment includes, as shown in fig. 3, a first phase compensation portion and a second phase compensation portion respectively provided on both sides of the liquid crystal panel, each of the first phase compensation portion and the second phase compensation portion includes a TAC layer of triacetylcellulose, a PVA layer of polyethylene, and a COP layer, and the COP layer is located at a layer closest to the liquid crystal panel. Wherein the included angle between the slow axis of the COP layer and the absorption axis of the polyethylene PVA layer is 90 degrees. In other embodiments, only one of the first phase compensation portion and the second phase compensation portion may include the COP layer; in addition, in other embodiments, the arrangement order of the TAC layer, PVA layer and COP layer may be in other arrangement order. The parameters of the phase compensation mechanism in this embodiment are as follows:
wherein R0 is an in-plane retardation compensation value; rth is an out-of-plane optical path difference compensation value; d is the thickness of the compensating mechanism.
And S112, respectively taking the brightness of the at least two second reference liquid crystal panels as the brightness corresponding to the at least two different optical path differences.
Each second reference liquid crystal panel corresponds to one optical path difference, and therefore the luminance of at least two second reference liquid crystal panels obtained in step S111 can be respectively taken as the luminance corresponding to at least two optical path differences.
Further, referring to fig. 4, as shown in fig. 4, step S111 includes the steps of:
and S1111, acquiring dark state full-view brightness distribution of at least two second reference liquid crystal panels.
By obtaining the dark-state full-view brightness distribution of the at least two second reference liquid crystal panels, the different optical path differences correspond to the dark-state full-view brightness distribution one by one, namely the dark-state full-view brightness distribution of the at least two optical path differences is obtained.
In this embodiment, the at least two second reference liquid crystal panels with corresponding optical path differences may be directly used to obtain the dark-state full-view luminance distribution of the at least two second reference liquid crystal panels, and the dark-state luminance measurement may be performed on the second reference liquid crystal panels, so as to obtain the dark-state full-view luminance distribution of the at least two second reference liquid crystal panels with different optical path differences. However, this method has a high requirement for the liquid crystal panel, and requires to manufacture panels with different optical path differences and monitor the panels, and the process is complicated, and because the process fluctuation of the liquid crystal panel is large and there is also an error when the optical path difference is measured by the optical path difference measuring station, there is a large error in the finally obtained dark-state full-view luminance distribution of the at least two second reference liquid crystal panels.
In addition, the embodiment may further obtain the dark-state full-viewing-angle luminance distribution of the at least two second reference liquid crystal panels in an analog manner. The same analog architecture is adopted, the optical path difference of the liquid crystal panels in the analog architecture is set, and then the dark-state full-view-angle brightness distribution of at least two second reference liquid crystal panels is simulated. Errors of calculation results due to errors of the liquid crystal panel can be eliminated through a simulation mode, and measurement cost can be reduced. In this embodiment, the optical path difference of the liquid crystal panel in the analog architecture is set between 317nm and 377nm, the light source is a lambertian light source, and the central brightness is 100 nit. In other embodiments, the optical path difference of the liquid crystal panel and the light source can be set according to actual requirements.
S1112 extracts, from the dark full-view luminance distribution, luminance distributions corresponding to different side-view angles of the at least two second reference liquid crystal panels at the same azimuth angle, respectively.
From the dark-state full-view brightness distributions corresponding to the at least two second reference liquid crystal panels obtained in step S1111, brightness distributions of each optical path difference at the same azimuth angle are respectively extracted, that is, brightness distributions corresponding to different side-view angles of the at least two second reference liquid crystal panels at the same azimuth angle are obtained.
In this embodiment, the azimuth angle is selected according to an empirical value, that is, from several azimuth angles with the highest brightness in the dark-state full-viewing-angle brightness distribution of the common liquid crystal panel.
S1113, extracting the luminances of the at least two second reference liquid crystal panels at the same side viewing angle from the luminance distributions corresponding to the different side viewing angles.
The brightness of the at least two second reference liquid crystal panels acquired in step S1112 at the same azimuth angle and in the brightness distribution corresponding to different side viewing angles is further proposed, that is, the brightness of the at least two second reference liquid crystal panels at the same azimuth angle and the same side viewing angle is obtained.
In this embodiment, the selected side viewing angle is selected according to an empirical value, that is, the side viewing angle range with the highest brightness in the dark-state full-viewing-angle brightness distribution of the common liquid crystal panel is selected.
The contents of the above steps S1111 to S1113 are further explained by an application:
selecting 7 second reference liquid crystal panels with optical path differences of 317nm, 327nm, 337nm, 347nm, 357nm, 367nm and 377nm respectively, and obtaining dark-state full-viewing-angle luminance distributions of the 7 second reference liquid crystal panels, as shown in fig. 5a to 5g, it can be seen from fig. 5a to 5g that azimuth angles with higher luminance in the dark-state full-viewing-angle luminance distributions of the 7 second reference liquid crystal panels are all 45 °, 135 °, 225 ° and 315 °. Selecting 45 ° as the determined azimuth angle (selecting other azimuth angles in other application examples), the luminance distributions corresponding to different side viewing angles of the 7 second reference liquid crystal panels at the azimuth angle can be obtained, as shown in fig. 6, the abscissa is the side viewing angle, and the ordinate is the luminance, which represents the luminance distributions corresponding to different side viewing angles of the 7 second reference liquid crystal panels at the azimuth angle of 45 °. It can be seen from fig. 6 that the side viewing angles include 0 ° to 80 °, where 0 ° is the side viewing angle when the liquid crystal panel is viewed frontally; as can also be seen from fig. 6, the side viewing angle range where the luminance is highest in the dark-state full-viewing-angle luminance distribution is between 60 ° and 70 °, and 60 ° is selected as the determined side viewing angle in the present embodiment. The brightness corresponding to each second reference liquid crystal panel at 60 ° is extracted. The extracted brightness at this time is the brightness corresponding to the above-mentioned 7 optical path differences.
Further, referring to fig. 7, as shown in fig. 7, the step S12 includes the steps of:
and S121, sequentially taking each optical path difference in different optical path differences as a reference optical path difference, and fitting to obtain the relation between a plurality of optical path differences corresponding to each reference optical path difference and the brightness ratio according to the brightness corresponding to the different optical path differences.
The method comprises the steps of obtaining at least two optical path differences, respectively setting each optical path difference as a reference optical path difference, dividing the brightness of each optical path difference in the at least two optical path differences by the brightness of the reference optical path difference to obtain brightness ratios corresponding to the optical path differences, and performing linear fitting according to the obtained brightness ratios and the optical path differences of the optical path differences to obtain a relation between the corresponding optical path differences and the brightness ratios when the corresponding optical path differences are the reference optical path differences. The relationship between the optical path difference and the luminance ratio obtained by the linear fitting is characterized by a relational expression, in other words, the relationship between a plurality of optical path differences and the luminance ratio, which is the same as the number of the optical path differences, is obtained in this step.
And S122, extracting the relation between the optical path difference corresponding to the reference optical path difference with the minimum difference value and the brightness ratio from the relation between the optical path difference corresponding to the plurality of reference optical path differences obtained through fitting and the brightness ratio.
And performing difference value calculation on at least two optical path differences and the reference optical path difference of the first reference liquid crystal panel, extracting one optical path difference with the smallest difference value from the at least two optical path differences, and further extracting a relational expression between the optical path difference and the brightness ratio obtained by fitting when the optical path difference is taken as the reference optical path difference from the relational expressions between the optical path differences and the brightness ratios obtained in step S121.
And S123, taking the relation between the extracted optical path difference and the brightness ratio as the relation between the corresponding optical path difference and the brightness ratio when the reference optical path difference is taken as the reference optical path difference.
The relation between the optical path difference and the luminance ratio extracted in step S122 is used as the relation between the corresponding optical path difference and the luminance ratio when the reference optical path difference is used as the reference optical path difference.
The contents of step S121 to step S122 are further explained by an application example:
at this time, the relationship between the optical path difference and the luminance is the luminance obtained in the application examples of step S1111 to step S1113. Taking 317nm as a reference optical path difference for example, dividing the extracted luminance of 7 optical path differences by the luminance corresponding to 317nm, respectively, to obtain 7 luminance ratios of each corresponding optical path difference with respect to the reference optical path difference, and then fitting by combining the optical path differences to obtain a curve graph in which the optical path difference and the luminance ratio are linearly fitted when 317nm is taken as the reference optical path difference, as shown in fig. 8a (in fig. 8a, the abscissa is the luminance ratio, and the ordinate is the optical path difference), thereby obtaining a relation between the optical path difference and the luminance ratio:
y＝0.2267x3-3.8137x2+26.815x +295, where x is the luminance ratio and y is the path difference.
Continuing to make 327nm as the reference optical path difference, dividing the extracted luminance of the 7 optical path differences by the luminance corresponding to 327nm, respectively, to obtain 7 luminance ratios of each corresponding optical path difference relative to the reference optical path difference, and fitting by combining the optical path differences to obtain a linear fitting curve graph of the optical path difference and the luminance ratio when 327nm is used as the reference optical path difference, as shown in fig. 8b, thereby obtaining a relational expression between the optical path difference and the luminance ratio:
y＝0.6345x3-7.5735x2+37.788x +295, where x is the luminance ratio and y is the path difference;
by analogy, when 337nm is taken as the reference optical path difference, a curve graph of linear fitting of the optical path difference and the brightness ratio is shown in fig. 8c, and the relation between the optical path difference and the brightness ratio is as follows:
y＝2.0602x3-16.606x2+55.955x+295；
when 347nm is taken as the reference optical path difference, the curve graph of linear fitting of the optical path difference and the brightness ratio is shown in fig. 8d, and the relation between the optical path difference and the brightness ratio is as follows:
y＝6.3147x3-35.04x2+81.281x+295；
when 357nm is the reference optical path difference, the curve of linear fitting between the optical path difference and the brightness ratio is shown in fig. 8e, and the relationship between the optical path difference and the brightness ratio is:
y＝17.291x3-68.582x2+113.71x+295；
when 367nm is taken as the reference optical path difference, a curve graph of linear fitting of the optical path difference and the brightness ratio is shown in fig. 8f, and the relation between the optical path difference and the brightness ratio is as follows:
y＝42.275x3-124.47x2+153.19x+295；
when 377nm is taken as the reference optical path difference, the curve graph of linear fitting of the optical path difference and the brightness ratio is shown in fig. 8g, and the relation between the optical path difference and the brightness ratio is as follows:
y＝93.562x3-211.38x2+199.63x+295；
namely, each of the 7 optical path differences is used as a reference optical path difference to obtain a relation between the corresponding optical path difference and the brightness ratio.
Further, assuming that the reference optical path difference of the first reference liquid crystal panel is 320nm, and the difference between 317nm and 320nm is the smallest, the relation between the optical path difference and the brightness ratio obtained when 317nm is used as the reference optical path difference is used as the relation between the optical path difference and the brightness ratio corresponding to the reference liquid crystal panel when the reference optical path difference is used as the reference optical path difference.
It can be seen that, in the embodiments corresponding to steps S121 to S123, when the optical path differences of all the second reference liquid crystal panels are required to be fitted to be respectively used as the reference optical paths, the corresponding relational expressions between the optical path differences and the luminance ratios are required, and then the required relational expression between one optical path difference and the luminance ratio is extracted from the corresponding relational expression between the optical path difference and the luminance ratio according to the reference optical path difference of the first reference liquid crystal panel. In this embodiment, the fitted relation between all the optical path differences and the luminance ratios can be reused, and when the first reference liquid crystal panel is replaced, the relation between the optical path differences and the luminance ratios does not need to be fitted again, and the appropriate relation between the optical path differences and the luminance ratios can be selected directly according to the reference optical path differences.
Referring to fig. 9, as shown in fig. 9, in another embodiment, step S12 further includes the following steps:
s124, using the optical path difference with the smallest difference from the reference optical path difference as the reference optical path difference.
And respectively calculating difference values of the at least two optical path differences and the reference optical path difference, and extracting one optical path difference with the minimum difference value from the at least two optical path differences and the reference optical path difference to make the optical path difference be the reference optical path difference.
And S125, fitting according to the reference optical path difference and the brightness corresponding to the different optical path differences to obtain the relation between the corresponding optical path difference and the brightness ratio.
Dividing the brightness of each optical path difference in the at least two optical path differences by the brightness of the reference optical path difference respectively to obtain the brightness ratios corresponding to the plurality of optical path differences, and performing linear fitting according to the obtained brightness ratios of the optical path differences and the reference optical path difference to further obtain the relation between one optical path difference and the brightness ratios.
And S126, taking the relation between the optical path difference and the brightness ratio as the relation between the corresponding optical path difference and the brightness ratio when the reference optical path difference is taken as the reference optical path difference.
The relation between the optical path difference and the luminance ratio obtained by fitting in step S125 is used as the relation between the corresponding optical path difference and the luminance ratio when the reference optical path difference is used as the reference optical path difference.
The contents of step S124 to step S126 are further explained by another application:
at this time, the relationship between the optical path difference and the luminance is the luminance obtained in the application examples of step S1111 to step S1113. Assuming that the reference optical path difference of the first reference liquid crystal panel is 320nm, the difference between 317nm and 320nm is the smallest, then 317nm is taken as the reference optical path difference, the extracted luminance of the 7 optical path differences is divided by the luminance corresponding to 317nm, and 7 luminance ratios of each corresponding optical path difference relative to the reference optical path difference can be obtained, and then fitting is performed by combining the optical path differences, so that the relational expression between the optical path difference and the luminance ratios when 317nm is taken as the reference optical path difference can be obtained: 0.2267x3-3.8137x2+26.815x +295, where x is the luminance ratio and y is the path difference. The above-mentioned relational expression obtained when 317nm was used as the reference optical path difference was used as the relation between the optical path difference and the luminance ratio corresponding to the reference liquid crystal panel when the reference optical path difference was used as the reference optical path differenceIs represented by the following formula.
It can be seen that, in the embodiment corresponding to steps S124 to S126, only one required relationship between the optical path difference and the luminance ratio needs to be fitted each time, but when the first reference liquid crystal panel is replaced, the relationship between the optical path difference and the luminance ratio needs to be fitted again because the reference optical path difference changes. Further, referring to fig. 10, as shown in fig. 10, the step S13 includes the following steps:
s131, respectively matching the liquid crystal panel to be tested and the first reference liquid crystal panel with a phase compensation mechanism; and respectively acquiring the brightness of the liquid crystal panel to be detected and the first reference liquid crystal panel under the azimuth angle and the side view angle.
In this step, the phase compensation mechanism, the azimuth angle, and the side view angle are the same as those employed in the above step.
The liquid crystal panel to be tested and the first reference liquid crystal panel are respectively matched with the same phase compensation mechanism to obtain dark state full view angle brightness distribution of the liquid crystal panel to be tested and the first reference liquid crystal panel, and then brightness corresponding to the same azimuth angle and the same side view angle is respectively extracted from the dark state full view angle brightness distribution of the liquid crystal panel to be tested and the first reference liquid crystal panel.
S132, dividing the brightness of the liquid crystal panel to be tested by the brightness of the first reference liquid crystal panel to obtain the brightness ratio of the two.
Dividing the brightness of the liquid crystal panel to be tested extracted in the step S131 by the brightness of the first reference liquid crystal panel to obtain the brightness ratio of the liquid crystal panel to be tested to the first reference liquid crystal panel.
Further, referring to fig. 11, as shown in fig. 11, after step S14, the method further includes the following steps:
and S15, calculating the liquid crystal box thickness of the liquid crystal panel to be measured according to the optical path difference formula and the optical path difference of the liquid crystal panel to be measured.
The formula of the optical path difference is as follows: the optical path difference is Δ N × D, Δ N is the difference between the normal optical refractive index and the extraordinary optical refractive index of the liquid crystal material, and D is the liquid crystal cell thickness. Δ N is a known parameter, and is a material property of the liquid crystal. The optical path difference calculated in step S14 is substituted into the optical path difference formula to calculate the liquid crystal cell thickness D.
It should be noted that, since the refractive index of the liquid crystal is affected by the external ambient temperature, and Δ N of the liquid crystal panel is different at different temperatures, there is a certain requirement for the ambient temperature in the process of calculating the optical path of the liquid crystal panel, that is, the ambient temperature of the liquid crystal panel does not change in the whole process. Optionally, the ambient temperature of the liquid crystal panel is kept at room temperature.
In summary, it is easily understood by those skilled in the art that in the method for measuring an optical path difference of a liquid crystal panel according to the embodiment of the present invention, under the same preset condition, according to the relationship between the optical path difference and the brightness, the relationship between the optical path difference and the brightness is calculated, and then the optical path difference of the liquid crystal panel to be measured is calculated by using the brightness of the liquid crystal panel to be measured, so that the measurement process of the optical path difference of the liquid crystal panel is simplified, and the measurement cost is reduced.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (7)
1. A method for measuring optical path difference of a liquid crystal panel is characterized by comprising the following steps:
acquiring brightness corresponding to at least two different optical path differences under the same preset condition;
fitting to obtain a relation between the optical path difference and the brightness ratio when the reference optical path difference of the first reference liquid crystal panel is taken as the reference optical path difference according to the brightness corresponding to the different optical path differences;
under the preset condition, calculating the brightness ratio of the liquid crystal panel to be tested and the first reference liquid crystal panel;
obtaining the optical path difference of the liquid crystal panel to be detected according to the brightness ratio and the relation between the optical path difference and the brightness ratio;
under the same preset condition, acquiring the brightness corresponding to at least two different optical path differences comprises:
enabling at least two second reference liquid crystal panels with different optical path differences to be matched with the same phase compensation mechanism respectively, and acquiring the brightness corresponding to the at least two second reference liquid crystal panels under the same azimuth angle and the same side visual angle;
respectively taking the brightness corresponding to the at least two second reference liquid crystal panels as the brightness corresponding to at least two different optical path differences;
the fitting obtaining of the relationship between the optical path difference and the brightness ratio when the reference optical path difference of the first reference liquid crystal panel is taken as the reference optical path difference according to the brightness corresponding to the different optical path differences includes:
taking each optical path difference in the different optical path differences as a reference optical path difference in sequence, and fitting to obtain a relation between a plurality of optical path differences corresponding to each reference optical path difference and a brightness ratio according to the brightness corresponding to the different optical path differences;
extracting a relation between an optical path difference corresponding to a reference optical path difference with the smallest difference value of the reference optical path differences and a brightness ratio from the relation between the optical path differences corresponding to the reference optical path differences and the brightness ratio obtained through fitting;
and taking the extracted relation between the optical path difference and the brightness ratio as the relation between the corresponding optical path difference and the brightness ratio when the reference optical path difference is taken as the reference optical path difference.
2. The method according to claim 1, wherein the calculating the luminance ratio of the liquid crystal panel to be measured and the first reference liquid crystal panel under the preset condition comprises:
respectively matching the liquid crystal panel to be tested and the first reference liquid crystal panel with the phase compensation mechanism; respectively acquiring the brightness of the liquid crystal panel to be detected and the first reference liquid crystal panel under the azimuth angle and the side visual angle;
and dividing the brightness of the liquid crystal panel to be tested by the brightness of the first reference liquid crystal panel to obtain the brightness ratio of the two.
3. The measuring method according to claim 1 or 2, wherein the phase compensation mechanism includes a first phase compensation portion and a second phase compensation portion respectively provided at both sides of the liquid crystal panel, the first phase compensation portion and the second phase compensation portion each including a TAC layer of cellulose triacetate and a PVA layer of polyethylene; the first phase compensation portion and/or the second phase compensation portion further include a COP layer.
4. The measurement method according to claim 3, characterized in that the slow axis of the COP layer is at an angle of 90 ° to the absorption axis of the polyvinyl PVA layer.
5. The method according to claim 1, wherein the acquiring the brightness of the at least two second reference liquid crystal panels at the same azimuth angle and the same side viewing angle comprises:
acquiring dark state full-view brightness distribution of the at least two second reference liquid crystal panels;
extracting brightness distributions corresponding to different side viewing angles of the at least two second reference liquid crystal panels under the same azimuth angle from the dark state full viewing angle brightness distribution;
and extracting the brightness of the at least two second reference liquid crystal panels at the same side visual angle from the brightness distribution corresponding to the different side visual angles.
6. The method according to claim 1, wherein the fitting of the brightness corresponding to the different optical path differences to obtain the relationship between the optical path difference and the brightness ratio when the reference optical path difference of the first reference liquid crystal panel is taken as the reference optical path difference comprises:
taking the optical path difference with the minimum difference value with the reference optical path difference in the different optical path differences as a reference optical path difference;
fitting according to the reference optical path difference and the brightness corresponding to the different optical path differences to obtain a relation between the corresponding optical path difference and the brightness ratio;
and taking the relation between the optical path difference and the brightness ratio as the relation between the corresponding optical path difference and the brightness ratio when the reference optical path difference is taken as the reference optical path difference.
7. The method according to claim 1, wherein after obtaining the optical path difference of the liquid crystal panel to be measured according to the brightness ratio and the relationship between the optical path difference and the brightness ratio, the method further comprises:
calculating the liquid crystal box thickness of the liquid crystal panel to be detected according to an optical path difference formula and the optical path difference of the liquid crystal panel to be detected;
wherein, the optical path difference formula is as follows: the optical path difference is Δ N × D, Δ N is the difference between the normal optical refractive index and the extraordinary optical refractive index of the liquid crystal material, and D is the liquid crystal cell thickness.
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| JP7230271B2 (en) * | 2019-07-26 | 2023-02-28 | マジック リープ， インコーポレイテッド | Panel phase difference measurement |
| CN111028808B (en) * | 2019-12-24 | 2021-10-08 | 惠州市华星光电技术有限公司 | Method, device and system for adjusting brightness and visual angle of liquid crystal panel and display device |
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