KR101721557B1 - A structure of making a moire interference pattern for anti-counterfeiting - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fabricating a moire interference pattern, and more particularly, to a method for fabricating a moire interference pattern for preventing forgery whose cycle, color, and phase vary according to viewing position, distance and time.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a moire interference pattern for anti-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fabricating a moire interference pattern, and more particularly, to a method for fabricating a moire interference pattern for preventing forgery whose cycle, color, and phase vary according to viewing position, distance and time.

The history of counterfeit goods designed to deceive as genuine has been very long, but the number of counterfeit goods has increased in recent years and is expected to continue in the future. There is a conventional technique for preventing such counterfeit goods, such as a serial number or a method of attaching a specially manufactured hologram to the product. However, the number of counterfeit products is not reduced in this method. Also, It is difficult to distinguish.

In the case of hologram, which is the most widely used anti-countermeasure tool, it is possible to discriminate a counterfeit product with the naked eye through color change and composite pattern depending on the viewing direction. However, many experts share knowhow to make this hologram , There are many manufacturers that can produce such holograms, and even if a special color pattern is used instead of these holograms, it is difficult to distinguish the color from the true color.

Accordingly, it is required to develop a new anti-counterfeiting technology that is easy for a general person, not an expert, to identify a counterfeit by the naked eye, and which is difficult to counterfeit.

Moiré is one of the well-known interferograms formed by superimposing two sheets of periodic patterns on a printed film or plate. Typical applications of this moire interference fringe are a metrology field such as a shape recognition of a subject using a moire interference fringe formed on an image captured by projecting a single pattern on a subject and placing another one of the patterns close to the camera , But the use of anti-counterfeiting technology in the 1990s was also proposed. [Cited Documents 1 and 2].

In the case of such anti-counterfeiting technology, there is no technology to manufacture a moire pattern with high resolution. However, recently, a high-resolution pattern making technique which can not print with a conventional printing machine has been developed, Moire technology for anti-counterfeiting using multi-view image arrangement method has been introduced [cited document 3].

The feature of the anti-counterfeiting technology using moiré is that the cycle of the moire interferogram pattern greatly changes to the fine cycle change of the pattern, so that a small pattern period change of the printing process is amplified and the observer can easily identify the counterfeit product. However, the solution to the problem of periodic change is directly related to the development of high-resolution printing technology and needs a lot of improvement.

Therefore, the present invention makes it possible to fabricate a new anti-fake pattern which can replace the hologram by using the characteristics of the chirped moiré, which is a new moiré phenomenon which has not been known so far.

Cited document 1. A. Schilling, W.R. Tompkin and R, Staub, " Diffractive moire features for optically variable devices, " Proc SPIE, V6075, pp 60750V1-12 (2006) &Quot; Unison Micro-optic Security Film, " Proc. SPIE V 5310, pp. 321-327 (2004), by R. A. Steenblik, M. J. Hurt, Citations 3. Victor J Cadarso. et al. High-resolution 1D moires as counterfeit security features. Light: Science & Applications, 2, e86 (2013) Citing Documents 4. I. Amidror, The Theory of the Moire Phenomenon, Kluwer Academic Publishers, 2000 5. O. Kafri and I. Glatt, The Physics of Moire Metrology, John Wiley and Sons, New York, 1989 References 6. F. A. Jenkins. et al. Fundamental of Optics, Korean Student Edition. (McGraw-Hill, New York, 1976)

It is an object of the present invention to provide a hologram recording method and a hologram recording method in which a hologram used for anti-falsification is replaced with a hologram, a hologram interference pattern for preventing falsification in which the hologram varies in color, And the like.

In order to achieve the above object, the present invention provides a structure for generating a chirped Moiré interference fringe in which a period of an interference fringe is continuously reduced or increased, wherein a periodic first grating pattern having a refractive index of 1 is made of a transparent medium, An upper grating pattern plate formed on one surface or both surfaces; A lower grid pattern medium having a grid pattern in which a second grid pattern is formed on an upper side of the upper grid pattern and has a direction of 0 to 90 degrees with respect to a direction of the first grid pattern; .

At this time, the lower grid pattern medium may be closely attached to the upper grid pattern plate without a gap, or may be inserted at a predetermined interval, but a transparent medium insertion or air layer may be formed between the gap.

Alternatively, the gap between the upper grid pattern plate and the lower grid pattern medium may be continuously changed in one direction in accordance with a rule, and a transparent medium insertion or air layer may be formed between the gap.

Further, the thickness of the upper grating pattern plate can be continuously changed in one direction according to a rule.

In addition, the refractive index of the upper grating pattern plate can be continuously changed in one direction according to a rule.

The lattice pattern may be a linear lattice pattern having a uniform period and a line width, a variable periodic lattice pattern in which a line width is constant but a period is reduced or extended with a predetermined rule, a variable linewidth lattice pattern in which a line is constant, , And a simultaneous variable grating pattern in which the period and the line width are simultaneously varied.

It is preferable that the grid pattern has a continuous arrangement in which one line having a specific contour is different in width in one direction, and the specific contour has a symmetrical or arbitrary shape.

In addition, each line forming the grid pattern can be selectively colored or a part of each line can be colored.

The upper grid pattern plate may further include a transparent protective layer formed to protect the grid pattern.

In addition, the grid pattern displayed on the lower grid pattern medium may be continuously arranged with red, green, blue, and white bands such as sub-pixels of a general display panel.

At this time, it is preferable that red, green, blue and white bands are arranged in the form of a chirp signal in the grid pattern displayed on the lower grid pattern medium.

The chirped Moiré interferogram according to the present invention changes its period and phase depending on the viewing position, distance and time, changes in color, and responds very sensitively to a very minute pattern period change. The periodic pattern used for the generation of such moiré is a function of the refractive index and thickness of the film, the plate or the medium filling the space between the two patterns, and the phase of the interference fringe is transferred according to the viewing direction and distance, Because it is different, it can be easily distinguished by eyes.

In addition, since the cycle of the moire interference fringe itself is chirped and digitized, and the color change between each color can be gradually or rapidly displayed, there is an advantage that close-up reproduction is hardly possible, and the film related to the generation of the moire interference fringe It is necessary to know the exact thickness and refractive index of the plate and the line width of the lines constituting the recorded periodic pattern.

In addition, since the shapes of the lines can be deformed, the shapes of the moire interference patterns can be variously modified. Therefore, the chirped moiré interference pattern is a very simple and effective technique for preventing forgery.

1 is a view showing the principle of forming a moire interference fringe by superposition of a general linear grating,
2 is a view showing a moiré interference pattern formed by superimposing linear gratings having different linewidths on red, green, and blue periodic array plates,
3 shows a lattice superposition structure for generating the chirped moiré of the present invention,
4 shows a possible grid pattern of the upper and lower layer grid patterns shown in FIG. 3,
FIG. 5 is a diagram showing a geometrical optical generation principle of a chirped moire interference fringe generated in the structure of FIG. 3;
6 is a diagram showing an example of a chirped pattern of the present invention and an example of a phase change according to a viewing direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a generation structure of a moire interference fringe for preventing falsification of the present invention will be described in detail with reference to the accompanying drawings.

Moire is a phenomenon often observed in daily life as a natural interference phenomenon that is formed when a plate with two periodic patterns is overlapped.

Moire interference fringes formed by overlapping two sheets having a linear periodic pattern exhibit very sensitive characteristics in which the interference fringe pattern is changed even by a small difference in the period. However, some assumptions are required to express it by a mathematical expression.

First, assume that two sheets of film are assumed to be films without consideration of the thickness of the plate. For the periodic patterns recorded on the two plates, approximate to the cosine function considering only the period irrespective of the thickness of the lines, The Moire function is expressed as a function product.

The empirical expression is obtained by irradiating a pattern of one of two plates with a subject to be inspected, taking a pattern deformed by the shape of the subject to be photographed through a periodic pattern of another plate, It is possible to measure the surface shape or deformation of the object to be measured, which has become the basis for industrial application of the moire.

However, in the representation of the empirical function, a color moire pattern (Color Moire Pattern) appears in a contact-type three-dimensional image display in which a display panel and a viewing zone forming optics are overlapped. The method for reducing or eliminating the moiré pattern, which is the most serious factor for hindering the image quality in the three-dimensional image, has not been proposed.

According to the empirical function, it is impossible to predict the moiré pattern in the contact type three-dimensional image display because the moiré pattern is accompanied by the color and the period of the color is different from the period predicted by the empirical function.

The reason for this can be summarized in two ways. First, there is a non-zero finite thickness of the lines representing the boundaries of each Elemental Optics element constituting the optical plate for viewing area formation. And the second is that the thickness of the optical plate for forming the field-of-view is not zero but a certain thickness.

FIG. 1 is a view showing the principle of forming a moire interference fringe by superimposing a general linear grating, and shows the influence of the thickness of the lines representing the boundary on the moire pattern.

First, as shown in FIG. 1 (a), when the first linear grid 3 having a constant line width 1 and the period 2 is longer than the first linear grid 3 and the line width is narrower than the second linear grid 4, The portion 6 in which the lines of the first linear grating 3 and the second linear grating 4 are completely or nearly overlapped in the moire first interference fringe 5 formed is the portion in which the moire first interference fringe 5 is whitened And the portion 7 where the lines of the first linear grating 3 and the second linear grating 4 are arranged so as not to overlap each other but to the left and to the right is given to the moire first interference fringe 5 in black.

If the first linear grating 3 is formed by overlapping with the third linear grating 8 having the same period as the second linear grating 4 but having a much larger line width as shown in FIG. 1 (b) 2 interference fringe 9 exhibits the same period 10 as the moiré first interference fringe 5 in the overlap with the second linear grating 5 described above but the first linear grating 3 and the thin third linear fringe 5, The portion 11 in which the lines of the grating 8 are completely or almost overlapped is much narrower in width than the overlapping portion 6 and the portions 12 in which the lines are not nearly overlapped and are arranged horizontally to each other, The width of the arrangement portion 7 is much longer than that of the arrangement portion 7 in the overlapping manner with the substrate 5.

Therefore, even if the linewidth of the linear grating becomes thick, the period of the moire interferogram does not change, but in one period, whitish portions decrease and black portions increase.

FIG. 2 is a view showing a moire interference pattern formed when a linear grid having a different line width is superimposed on a periodic array plate of red, green, and blue.

If sub-pixels of red, green, and blue, such as the display panel, are continuously arranged instead of the period of monochrome in the first linear grating 3, if the line width of the overlapped forming grating is changed, The color also changes. In this case, in general, the grating direction 58 in the linear grating is perpendicular to the grating arrangement direction 59.

First, a third interference fringe 14, which is a moire interference fringe obtained when the first linear grating 3 is superimposed on the color film plate 13 in which red, green, and blue are periodically arranged as shown in FIG. 2 (a) Is obtained by superposing a fourth linear grating 15 having a line width twice the line width 1 of the first linear grating 3 on the color film plate 13 as shown in Fig. 2 (b) And has the same period 17 as the fourth moire interference pattern 16, but its color arrangement is different.

In the case of the moire third interference fringe 14, each color stripe is made up of two to three colors, but the fourth moire interference fringe 16 has one or two colors of each color stripe .

Therefore, if the linewidth of the linear grating is changed, the color composition of the Moire interference pattern changes. If the overlying linear grating has a certain thickness, the underlying linear grating pattern passes through the thickness of the overlying linear grating and overlaid with the above linear grating pattern, and this overlaid pattern is incident on the observer's eye .

In this case, however, the pattern of the underlying linear grating is not transmitted as it is, but is refracted by the refractive index of this thickness while being transmitted, so that the original period is given differently depending on the viewing angle.

FIG. 3 is a diagram illustrating a lattice superposition structure for generating the chirped moiré of the present invention.

3 (a) shows an example in which the upper pattern plate 19 having a specific thickness 18 is placed on the upper side of the periodic grid pattern 20 and the lower grid pattern plate 21 ) Is spaced apart from the bottom surface 23 of the upper side grid pattern plate 19 by a predetermined distance 24 with the grid pattern 22 on the drawn side up.

In this case, the thickness 18 of the upper grid pattern 19 does not have to be constant in left and right and up and down. As shown in the figure, the thickness is changed from left to right (or right to left) It is possible to correspond to the function 60, that is, the form 60 continuously changing according to the rule, and the form 61 simultaneously changing the left and right.

At this time, the specific distance 24, which is the distance between the bottom surface 23 of the upper grid plate 19, may be the same as the thickness 18 of the upper plate 19 and may be zero. The upper grid pattern plate 19 is preferably transparent and the larger the refractive index is, the smaller the thickness 18 of the upper grid pattern 19 can be. Therefore, the larger the refractive index, the better.

Instead of changing the thickness 18 of the upper grating pattern 19 by a specific function, the refractive index may be changed from left to right (or right to left) or from top to bottom (or from top to bottom) to a specific function It is also possible to vary it.

At this time, the transparent protective film 27 or the protective window 27 for protecting the grid pattern 20 on the upper grid pattern 19 does not affect the characteristics of the moire interference pattern formed. This is because the moire interference pattern is formed at the position of the grid pattern 20.

In addition, if the lower layer grating pattern plate 21 is transparent, it is possible to observe the moire interference pattern in all of the lower layers. In this case, there is no difference in that the grid pattern 22 of the lower grid pattern plate 21 is directly displayed on the bottom surface 23 of the upper grid pattern plate 19 as shown in FIG. 3 (b) The material to be held serves as a protective film for protecting the bottom surface 23 of the upper grid pattern plate. In this case, the relative difference in the lattice direction between the upper grid pattern 20 and the lower grid pattern 22 should be 90 ° or less.

FIG. 4 is a diagram showing possible grid patterns of the upper and lower layer grid patterns shown in FIG. 3 of the present invention.

4A shows a periodic upper grid pattern 20 given to the upper grid pattern plate 19 in a linear grid pattern 28 in which the period 25 and the line width 26 are constant and FIG. A variable period type grid pattern 29 in which a period 26 is constant but a period 25 is reduced or increased with a predetermined rule. 4 (g) shows a variable line width type grid pattern 30 in which the line width 26 is constant or decreasing with a constant rule, and FIG. 4 (h) And the line width 26 are simultaneously variable, the four basic grid patterns are possible. At this time, a pattern such as the variable periodic grating pattern 29, the variable linewidth grating pattern 30, and the simultaneous variable grating pattern 31 is referred to as a chirped pattern.

The shape of each line in each lattice pattern may be an arrow tip shape 32, a crescent shape 33, a trapezoid shape, or the like corresponding to the thickness of each line as shown in Figs. 4 (c) (34), a pillar form (35), and the like.

At this time, in each grid pattern, the grid has a width, so the overall outline is represented. The shape of this contour is symmetrical and may be random. Therefore, each of the grid patterns has a line having a specific outline, such as a linear grid pattern 28, a variable periodic grid pattern 29, a variable line width grid pattern 30, or a simultaneous variable grid pattern 31 ).

It is possible to selectively color each line of these grid patterns 28, 29, 30 and 31 as shown in Figs. 4 (i) to 4 (k), colorize only a part of each line, .

The lower grid pattern plate 21 may have the same pattern as the grid pattern 20 of the upper grid pattern plate 19 but is not of the same black and white interference pattern as the upper grid pattern plate 19, a continuous color pattern 36 composed of periodic band-shaped color arrangements having the same size as red, green, and blue on the display panel such as the display panel (i), or a chirp-like arrangement A color pattern 37 of FIG. 4A, and a non-bar-shaped color array 38 such as an arrowhead-type color pattern that is not a stripe pattern as shown in FIG. 4 (k). Thus, the upper and lower grid pattern plates are applicable not only to the linear grid pattern plate but also to all the grid pattern plates having a periodic pattern.

Fig. 5 is a diagram showing the geometrical optics generation principle of a chirped moire interference fringe generated in the structure of Fig. 3 (b). In FIG. 5, the thickness 18 of the upper grid plate is assumed to be t, and the specific gap 24, which is the gap between the bottom layer of the upper grid plate and the lower layer grid pattern, is assumed to be zero.

으로 주어지는 n번째 격자선(40)의 멀리 있는 측면 점(41)을 보는 시각(42)이

, 그리고 가까이 있는 측면 점(43)을 보는 시각(44)이

이다. 여기서

는 관측거리(Viewing Distance)이며,

는 격자패턴(20)의 주기이다.In the observer's eye 39,

The time 42 at which the far side point 41 of the n-th grid line 40 is viewed

, And the time 44 (44) of viewing the near side point 43

to be. here

Is the viewing distance,

Is the period of the grid pattern 20.

과

은 관측거리의 함수임을 알 수 있다. 이 경우 n번째 격자선의 시선에서 멀리 있는 측면 점(41)은 상측 격자패턴 판(19)의 두께(18)에 의해 굴절되어 하층 격자패턴 판의 격자패턴(22)과 측면 점(41)의 격자패턴(22)에 있어 대응점(45)에서 만나며, n번째 격자선의 시선에서 가까이 있는 측면 점(43)은 측면 점(43)의 격자패턴(22)에 있어 대응점(46)에서 만난다.therefore

and

Is a function of the observed distance. In this case, the side points 41 far from the line of sight of the n-th grating line are refracted by the thickness 18 of the upper grating pattern 19, and the grating pattern 22 of the lower grating pattern plate and the lattice of the side points 41 The side points 43 that meet at the corresponding points 45 in the pattern 22 and are closer to the line of sight of the nth lattice meet at the corresponding points 46 in the lattice pattern 22 of the side points 43.

, 그리고 n번째 격자선의 시선에서 멀리 있는 측면 점(41)과 n번째 격자선의 시선에서 가까이 있는 측면 점(43)의 굴절각을 각각

(48) 과

(49)이라면,

그리고

으로 주어진다.The distance between the two corresponding points 45, 46 is

, And the refraction angles of the side point (41) far from the line of sight of the n-th grid line and the side point (43) near the line of sight of the n-th grid line are respectively

(48) and

(49)

And

.

그리고

으로 주어진다. 이들 식에서

(48) 과

(49)은 굴절률이 적을수록 시각에 가까워진다.Also, according to Snell's law [6]

And

. In these equations

(48) and

(49) is closer to the visual angle as the refractive index is smaller.

Therefore, if the thickness of the upper grid pattern plate 18 is air, the refractive index of the air is 1.0, so that no refraction occurs. Therefore, in the lower grid pattern 22 of the side point 41 far from the line of sight of the n-th grid line, Is given as a corresponding point 50 in the lower layer lattice pattern 22 of the side point 41 when the refractive index is 1.0 and the side point 43 near the line of sight of the nth lattice line is given as a point ) Correspond to the corresponding point 51 in the lower layer lattice pattern 22 of the lower layer.

에 대응하므로

로 주어진다.Therefore, when the refractive index is 1.0 due to the refraction, the corresponding point 50 in the grid pattern 22 of the side point 41 is reduced in the lower grid pattern 22 of the side point 41 by the distance from the corresponding point 45 And the corresponding point 51 in the grid pattern 22 of the side point 43 is reduced by the distance from the corresponding point 46 in the lower layer grid pattern 22 of the side point 43 when the refractive index is 1.0 The effect appears. In other words, the lower layer grid pattern 22 is relatively reduced by the refraction compared to the upper layer grid pattern 20, and the reduced ratio is the line width 40 of the upper layer grid pattern 20 The width (47) of the lower layer lattice pattern (22)

To

.

>

(

>

)이 항상 성립되므로,

이

보다 항상 크다. 그리고

은 n이 적을수록 커지므로, 그 축소비율도 n이 적을수록 커진다.

은 n이 적을수록 값이 적어진다. 그리고

은 1보다 클 수 없다.In this equation

>

(

>

) Is always established,

this

It's always bigger. And

Becomes smaller as n becomes smaller, the reduction ratio becomes larger as n becomes smaller.

The smaller n is, the smaller the value. And

Can not be greater than one.

Therefore, the lower layer lattice pattern 22 becomes a chirped-type pattern in which the period is reduced from a place far from the line of sight, that is, from a place where the time is large to a place where the time is small. If the lower grid pattern plate is transparent in FIG. 5, the upper grid pattern plate 19 is viewed through the lower grid pattern plate. In this case, the interference pattern has a chirped pattern .

FIG. 6 shows an example of the chirped pattern of the present invention and an example of the phase change according to the viewing direction. In Fig. 6, a printing paper on which a grid pattern of a certain period was printed was used as a lower layer pattern, and a lenticular plate made of polycarbonate having a thickness of 2.4 mm was used as an upper lattice pattern plate. The refractive index of the polycarbonate is 1.589. In Fig. 6, two moire interference fringes are given. The upper part is taken with the camera optical axis on the right side, and the lower part is taken with the camera optical axis in the center. First, in these two moire interferograms, the first black line 52 on the right side of the upper interference pattern is shifted to the left by approximately half a cycle of the first interference period 54 from the right side of the upper moire interference pattern below And is given by a line 53. This proves that the phase varies depending on the direction in which the moire interferogram looks.

Also, the period of the lower moire interferogram is the same as the first interferogram period 54 to the right of the upper moire interferogram. This means that the chaperone moiré is difficult to recognize when there is little vision.

Comparing the seventh, seventh, and eighth periods 55, 58, and 57 of the upper Moiré interferogram with the interferogram period 54, the interferogram period decreases from left to right. . Although the reduction ratio does not appear linearly, it shows a chirpy-like behavior in which the period of interference fringes decreases continuously.

It is to be understood that the invention is not limited to the disclosed embodiment, but is capable of many modifications and variations within the scope of the appended claims. It is self-evident.

1: Line width 2: Period
3: first linear lattice 4: second linear lattice
5: Moire first interference pattern obtained by superimposing first and second linear gratings
6: the portion of the first interference fringe that is completely or nearly overlapping
7: a portion where the lines of the first interference fringe are arranged almost side by side without being overlapped with each other
8: Third linear grid
9: Moire second interference pattern obtained by superimposing the first and third linear gratings
10: the period of the second interference pattern and the period of the second interference pattern
11: a portion where the lines are completely or nearly overlap in the second interference pattern
12: a portion where the lines are not overlapped in the second interference fringe but are arranged laterally to each other
13: Color film plate
14: Moire third interference pattern formed by overlapping the color film plate and the first linear grating
15: Fourth linear grid with line width twice the line width
16: a fourth moire interference pattern formed when the color film plate and the fourth linear grating are superimposed;
17: Cycle of third and fourth interference fringes of moire
18: Thickness of the upper grid plate
19: upper grid pattern plate 20: upper grid pattern
21: lower layer lattice pattern plate 22: lower layer lattice pattern
23: bottom surface of the upper grid pattern plate
24: space between the bottom surface of the upper grid pattern plate and the lower grid pattern
25: Period of upper grid pattern 26: Line width of upper grid pattern
27: Transparent protective film (protective window) 28: Linear lattice pattern with constant period and line width
29: Variable Periodic Grid Pattern 30: Variable Linear Grid Pattern
31: Simultaneously variable grid pattern 32: Arrow-shaped line
33: Crescent line 34: Trapezoidal line
35: Column-shaped line
36: Continuous color pattern consisting of color stripes
37: Colored pattern with reduced or enlarged line width
38: Non-barrel color array such as an arrowhead color pattern
58: Grid direction 59: Array direction of the grating

Claims (11)

As a structure for generating a chirped moire interference fringe in which the period of the interference fringes continuously decreases or increases,
A first grating pattern having a refractive index of 1 and a periodic first grating pattern having a directional property is formed on one or both surfaces thereof and the refractive index of the upper grating pattern plate ;
A lower grid pattern medium having a grid pattern in which a periodic second grid pattern is recorded on an upper side of the upper grid pattern and having a direction of 0 to 90 degrees with respect to a direction of the first grid pattern; Lt; / RTI >
The grid pattern has a variable periodic grid pattern in which the line width is constant but the period is reduced or increased with a predetermined rule, a variable line width grid pattern in which the line width is reduced or extended with a constant rule, And a variable grating pattern is selected from the plurality of grating patterns.
The method according to claim 1,
Wherein the lower lattice pattern medium is in close contact with or spaced from the upper lattice pattern plate at a predetermined interval, wherein a transparent medium is inserted between the spaces or an air layer is formed. rescue.
The method according to claim 1,
Characterized in that the distance between the upper lattice pattern plate and the lower lattice pattern medium is changed in one direction continuously in accordance with a rule, and a transparent medium is inserted or air layer is formed between the intervals, the generation structure of the moire interference pattern .
delete delete delete delete The method according to claim 1,
Wherein each line constituting the grid pattern is selectively colored or a part of each line is colored. ≪ RTI ID = 0.0 > 15. < / RTI >
The method according to claim 1,
Wherein the upper grid pattern plate further comprises a transparent protective layer formed to protect the grid pattern. ≪ RTI ID = 0.0 > 18. < / RTI >
The method according to claim 1,
Wherein the grid pattern displayed on the lower grid pattern medium is formed by continuously arranging red, green, blue and white bands such as the sub-pixels of a general display panel.
11. The method of claim 10,
Wherein the grid pattern displayed on the lower grid pattern medium has red, green, blue, and white bands arranged in the form of a chirp signal.

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