JPS59214705A - Method and device for detecting pattern for liquid crystal display element - Google Patents

Abstract

PURPOSE:To detect the pattern of a liquid crystal display element at a high contrast, by arranging a transparent mask, wherein a part, whose thickness is different in a recessed or projected shape, is provided at the central part of a Fourier transformation surface of the pattern of the liquid crystal display element, which has a uniform thickness and lighted by a spot light source. CONSTITUTION:A mask 10 is inserted in the vicinity of a Fourier transformation surface D. The thickness of only the central part of the mask 10 is increased with respect to the peripheral part by a size corresponding to 1/4 the wavelength of a light source S (i.e., different by a phase difference pi/2). At the same time, transmittance is made to be (t). The peripheral part is transparent. Here, it is important that the central part of the mask 10 is made to agree with the distribution region of the DC component (zero order component) of the spectrum of a sample 1. When the transmittance of the central part of the mask is expressed by t=1 (i.e., perfectly transparent), a phase difference component phi becomes luminance information 2phi. Thus detection becomes easy. The central part of the mask 10 is made thick in a projected shape, but the same effect can be obtained when it is made thin in a recessed shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method and apparatus for detecting patterns on a liquid crystal display element.

[Background of the invention]

Conventionally, patterns on a liquid crystal display element have been generally detected by capturing an enlarged image of serum using a bright field illumination microscope with a TV camera and processing the TV camera signal.

However, due to the low contrast of the pattern of the liquid crystal display element, there is a technical aspect in which stable detection is not easy. The lower plate 2 is shown, and (5) is a front view, however)
0 is a partially enlarged side view. Top plate 1. A pattern 4 and an alignment pattern 3 are formed on the lower plate 2 in advance. Generally, a method is adopted in which each alignment pattern is observed, alignment work is performed to correct any misalignment between the two, and the upper plate 1 is fixed with adhesive at one end.

Also, before this operation, the formation state of the pattern 4 is inspected, defects such as chips 5 and cracks 6 are inspected, and if there are any defective products, they are picked out and removed before the alignment operation.

However, it is very difficult to observe the pattern 4 and alignment pattern 3 during these operations. The reason is pattern 3
．． 4 is because it is formed of a transparent conductive thin film. The lighting pattern of the liquid crystal display element has high contrast and is easy to see, while the non-lighting pattern is difficult to see, which has commercial value, so the thin film forming pattern 6.4 is 0.05 μm thick.
It must be as thick as below and transparent.

The optical properties of pattern 3.4 configured as described above are approximately equivalent to "glass in water", and it is said to be a phase contrast sample with uniform transmittance and only a slight change in phase. be able to.

FIG. 2 is an explanatory diagram showing that the pattern 5.4 has a low contrast, and FIG. 2A shows an optical path diagram, and FIG. 2B shows a detected image.

When pattern 3.4 is expressed as a phase difference sample f(x, y'), the following equation is obtained.

f(x・y)=eXpCiφ(x, y)]−=
-(1) When the phase difference φ radian is sufficiently smaller than 2π, the above equation is approximated by the following equation.

f(x,)−)g 1+iφ(x, y) + =
= (2) Assuming that the point light source is S, the spectral distribution of the sample 1 on the Fourier transform plane of the illuminated sample 1 is expressed by equation (2)? Obtained by Fourier transform.

F(u,v)−δ(o)+i T(φ(x,)・)
]・Playing... (6) Here ""l"f ' u=
2"f'f; focal length λ of lens 7; average wavelength δ of light beam S; delta function T; symbol meaning Fourier transform.

The enlarged image of the sample 1 magnified on the frosted glass 9 by the objective lens 8 in FIG. 2 is obtained by Fourier transforming the equation (3) again.

f (x', y') = T (F (u, v):) = 1 + iφ
(x + y) ・・・・・・・・・・・・ (
4) The information obtained by the human eye and TV camera is an image ((4)
Since it is the brightness of the equation), the following equation is obtained.

I (x', y') - f (x', y') ・f(x'
, y')"= [1+iφ(x + y)']・[
1-iφ(X, y) ')n1+φz (x+y)
・・・・・・・・・・・・(5) (Here the symbol ◆
indicates conjugation. ) In the end, the contrast) C6 based on the phase difference information φ becomes the following equation.

co=φ2/1=φ2 ・・・・・・・・・・・・
・・・・・・・・・・・・・・・(6) Equation (6) becomes, for example, when φ = 1o-t, φ2 = 10”2, resulting in extremely low contrast, and detection by TV camera signal is difficult. This is extremely difficult in practice.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method and a detection device for detecting a pattern of a liquid crystal display element with high contrast.

[Summary of the invention]

In order to achieve the above object, a first method of the present invention provides a method for forming convex and concave shapes with a uniform thickness on the Fourier transform surface of a pattern for a liquid crystal display element illuminated by a point light source. It is characterized in that a transparent mask having 7 portions of different thickness is placed on either side.

A second method of the present invention is characterized in that a transparent thin film is provided at the center of the observation objective lens closest to the Fourier transform surface of the liquid crystal display element pattern illuminated by a point light source.

Further, the sixth method of the present invention includes providing a thin film (including an opaque film) that is not completely transparent at the center of the observation objective lens closest to the Fourier transform surface of the liquid crystal display element pattern illuminated by a point light source. Features.

Further, the fourth method of the present invention is to provide a uniform thickness on the Fourier transform surface of a pattern for a liquid crystal display element illuminated by a ring-shaped light source, but with a concave or convex pattern having different thicknesses in the ring-shaped portion. It is characterized by the placement of a transparent mask with locations.

A fifth method of the present invention is characterized in that a ring-shaped transparent thin film is provided on the surface of the objective lens closest to the Fourier transform surface of the liquid crystal display element pattern illuminated by the ring-shaped light source.

The sixth method of the present invention is to apply a ring-shaped thin film that is not completely transparent (including opaque film) to the surface of the lens, which is closest to the Fourier transform surface of the liquid crystal display pattern illuminated by a ring-shaped light source. It is characterized by providing.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to FIG. This figure shows an apparatus of the present invention configured to carry out the method of the present invention, and corresponds to FIG. 2 in the conventional method. The difference from Figure 2 is that there is a mask 1 near the Fourier transform surface.
This is the point where 0 was inserted. Figure A shows an optical path diagram, and Figure B shows a detected image.

In the above mask 10, only the center portion is 1/1/2 of the wavelength of the light source S.
The thickness is increased relative to the surroundings in terms of optical path length by an amount corresponding to 4 (that is, the phase difference is different by π/2), and at the same time, the transmittance is t, and the surroundings are transparent. Here, it is important that the center of the mask 10 coincides with the distribution area of δ(0) in the above equation (3) (that is, the distribution area of the DC component (zero-order component) of the spectrum of the sample 1). mask 10
Expressed numerically, it becomes the following formula.

(Here, the transmittance t is 0≦t≦1.)
The spectral distribution after passing is as follows: dG(u,v)=
F(u,v)-H(u,v)=itδ(0)+iT
[:φ(x, y))−=・−・(8) Image f
(x'Ly') becomes the following formula.

f (x'+y')=T[GCu*v)]=i
(t+φ< x * y) ] ・・・・・・・・・
(9) The brightness of the image is expressed by the following formula.

I (x', y') = f (x', y') - f (
X', y')"== i 2+φ2+2φt
(10) When the transmittance at the center of the mask is t=1 (that is, completely transparent), equation (10) becomes 1(X',)'')' 1+2φ, the phase difference component φ becomes the luminance information 2φ, and (5 ) The detection is easier than the above formula (Fig. 5A).
Although the mask 10 has a convexly thick center portion, the same effect can be obtained even if the knee portions are made thinner in a portal shape.

As shown in the above-mentioned embodiment, the first method of the present invention is to form convex and concave shapes with a uniform thickness on the Fourier transform surface of a pattern for a liquid crystal display element illuminated by a point light source. A pattern can be detected with high contrast by arranging a transparent mask having portions with different thicknesses on either side. Further, the first apparatus of the present invention includes a point light source for illuminating a liquid crystal display element as an object to be inspected, and a transparent mask disposed on the Fourier transform surface of the liquid crystal display element. By having a uniform thickness and having a convex or concave portion of different thickness in the center, the method of the invention described above can be easily carried out.

Generally, in the case of transmittance t, the DC component (background) of the sample
The highest contrast of the phase component IMAX
and the ratio of the difference △I between the minimum load rMin? Defined as contrast C, -4!・・・・・・・・・
(12) From equation (12), high contrast can be obtained when the transmittance t is small. (For example, t-10”3+
In the case of φ2 10-2 radians, C=4o. ) It is also effective to utilize this to make the transmittance near the center of the mask 10 shown in FIG. 3A smaller than the transmittance of other parts.

The above is the principle of pattern detection by the method of the present invention, which is common to the basic principle of phase microscopes used for biological applications, for example.

In the above description, for simplicity, the thickness change at the center of the mask is set to 1/4 of the optical path length, but similar results can be obtained even if this value is not necessarily selected.

FIG. 4 shows the phase difference φ that occurs when a thin film pattern with a thickness ε is illuminated with a plane wave.

2π φ””7(nl)!・・・・・・・・・・・・(1ro)
(Here, n: refractive index of the pattern) Usually, the wavelength λ of the illumination light is about 0.5 μm, 11=j2~1
．． 5 t = about 0.05 μm, so,
Equation (2) is fully satisfied.

Moreover, although only transmitted illumination by the point light source S is considered above, the same effect can be obtained by general epi-illumination using a 45° semi-transmissive mirror.

Further, although the light source S is ideally monochromatic, it is not necessary and a normal tungsten lamp, halogen lamp, or the like may be used. In this case, if the average wavelength λ of the lamp is used in the calculation formula, equation (13) approximately holds true.

FIG. 5 is an explanatory diagram of a second apparatus configured to carry out the second method of the present invention, in which FIG. 5A is a front view of the objective lens and FIG. 5B is an optical path diagram.

Instead of the mask 100, a transparent thin film 11 is pasted only in the center on the surface of the objective lens near the Fourier transform surface, and an effect approximately equivalent to that of the embodiment shown in FIG. 3 is obtained. Said thin film 1
When the transmittance of 1 is set to t (tzl), a fifth device is constructed, which facilitates the implementation of the third method and has the same effect as described above.

In the embodiment shown in FIG. 6, a thin film 13 fixed from the periphery to spoke-like thin wires (wire, etc.) 12 is placed on the Fourier transform plane, and the same effect as in the embodiment shown in FIG. 3 is obtained.

In the above, the case of illumination by a point light source S was considered, but it is generally difficult to obtain a point light source with high brightness, so the fourth method of the present invention is shown in FIG. A ring-shaped illumination using a light source, a condenser lens 14, and a ring-shaped slit 15 is used.This illumination forms the DC component of the sample 1 in a ring shape on the Fourier transform surface, and the thickness changes part in a ring shape. Even if a mask 16 having a mask 16 is arranged, the same effect as in FIG. 3 can be obtained. FIG. 7B shows the ring-shaped slit 15, and FIG. 7C shows the mask 16.

FIG. 8 shows a fifth inventive method configured to carry out the fifth invention method.
FIG. This fifth method is an approximation method of the method explained with reference to FIG. 7, and in the fourth apparatus shown in FIG. A similar effect was obtained. The person in the figure is a front view, and the figure B is a side view.

FIG. 9 is an example of a sixth apparatus configured to carry out the sixth method. Membrane 1 fixed by spokes 12
8 is placed on the Fourier transform plane, and the same effect as the embodiment shown in FIG. 7 is obtained.

In the embodiments shown in FIGS. 8 and 9, the thin films 17' and 18 can be transparent or opaque to provide high-contrast detection.

Figure 10A shows the T of the liquid crystal display element pattern according to the conventional method.
An example of an enlarged image of the V camera, B in the same figure, shows a signal waveform on a scanning line. FIG. 11A shows an example of an enlarged TV camera image of a liquid crystal display element pattern obtained by the method of the present invention, and FIG. 11B shows a signal waveform on a scanning line.

As shown in FIG. 10, the detection signal obtained with conventional bright field illumination has low contrast, is susceptible to illumination unevenness and electrical noise, and cannot be binarized.

Furthermore, visual observation on the monitor is very difficult to see, which is a burden to the above-mentioned work.

On the other hand, the detection signal obtained by the present invention has a high contrast as shown in FIG. 11, and can be easily binarized. According to the present invention, inspection of liquid crystal display element patterns and alignment of upper and lower glass plates can be easily and quickly performed.

FIGS. 10 and 11 are examples in which the enlargement ratio is large, and only the edges of the pattern have a high contrast, and the flat parts of the pattern become D'C components and are erased.

However, when the enlargement ratio is small, the high brightness signals at the right and left edges of the pattern match, and the entire pattern has a high foot last as shown in FIG. 6B.

[Effects of the Invention] As detailed above, according to the method of the present invention, a pattern of a liquid crystal display element can be detected with high contrast. Further, the apparatus of the present invention can easily carry out the above-described method of the invention and exhibit its effects.

[Brief explanation of the drawing]

Fig. 1 shows a liquid crystal display element, in which Fig. 1A is a front view, Fig. 1B is a side view, and Fig. 1C is a partially enlarged side view. FIG. 2 shows a state of detection of a liquid crystal display element pattern by a conventional method, in which A is an optical path diagram and B is a detected image. FIG. 3A shows an embodiment of the present invention, in which FIG. 3A is an optical path diagram in a pattern detection state, and FIG. 3B is a detected image. FIG. 4 is an explanatory diagram of the phase difference, and FIG. 5 is a diagram showing an embodiment different from the above. FIG. 4A is a plan view of the objective lens, and FIG. 5B is an explanatory diagram of the optical path. Figure 6A
, B are explanatory diagrams of still different embodiments, FIGS. 7A, B, and C are explanatory diagrams of still different embodiments, FIGS. 8A and B are explanatory diagrams of still further different embodiments, and FIG. It is an explanatory diagram of an example. FIG. 10A is a plan view of a pattern detection image according to the conventional method, and FIG. 10B is a chart of signal waveforms of scanning lines of the detection image. FIG. 11A is a pattern detection image by the method of the present invention;
Figure B is a chart of the signal waveform of the detected image. DESCRIPTION OF SYMBOLS 1... Liquid crystal display element glass upper plate, 2... Lower plate, 5... Alignment pattern, 4... Display pattern, 5... Chip, 6... Crack, 7...・Lens, 8... Objective lens, 9... Cloudy glass, 10... Mask, 11... Thin film,
12... Spoke, 16... Thin film, 14... Condenser lens, 15... Ring-shaped slit, 16... Mask, 17... Thin film (ring-shaped), Fig. 1 (A) 2n ( A) Fig. 7A Fig. 8 Fig. 72/3 Fig. 70 B Z (=position) (time) -〉Z. Procedural amendment (0 shots) Name of the invention Pattern detection method for liquid crystal display elements Department measurement - vq Jie 5i Person making the correction 11+'lriyamai Patent applicant and Iro'31011 formula
≦2 II: [-] Standing
B'1 Mi Subject of amendment Correct the section of the detailed description of the invention in the specification.

Claims (1)

[Claims] 1. A Fourier transform surface of a nozzle for a liquid crystal display element illuminated by a point light source has a uniform thickness and a convex or concave shape with different thicknesses in the center. A method for detecting a pattern for a liquid crystal display element, comprising: arranging a transparent mask having a plurality of locations. 2. The method for detecting a pattern for a liquid crystal display according to claim 1, wherein the transparent mask has a center portion that has a different transparency from other portions. 3. The method for detecting a pattern for a liquid crystal display element according to claim 1, wherein the transparent mask has a transparent film in the center supported by spokes from the periphery. 4. A liquid crystal display device according to claim 1, wherein the mask is supported by spokes from the periphery and has a thin film in the center that is not completely transparent. How to detect patterns. 5. Detection of a pattern for a liquid crystal display element according to claim 1, wherein the mask is a transparent mask with a uniform thickness and zero transmittance at the center. Method. 6. A method for detecting a pattern for a liquid crystal display device, characterized in that a transparent thin film is provided at the center of an observation objective lens closest to the Fourier transform surface of the pattern for a liquid crystal display device illuminated by a point light source. 2. A pattern for a liquid crystal display element, characterized in that a thin film (including opaque) that is not completely transparent is provided at the center of the observation objective lens closest to the Fourier transform surface of the pattern for a liquid crystal display element illuminated by a point light source. Detection method. 8. On the Fourier transform surface of a pattern for a liquid crystal display element illuminated by a ring-shaped light source, a concave or convex portion with a different thickness is provided in the ring-shaped portion with a uniform thickness. A method for detecting a pattern for a liquid crystal display element, the method comprising arranging a transparent mask. 9. The method for detecting a pattern for a liquid crystal display element according to claim 8, wherein the mask has a transmittance that is different from the transmittance of the upper n-ring-shaped portion than the other portions. 10□ The above mask is supported by spokes from the periphery7
9. The method for detecting a pattern for a liquid crystal display element according to claim 8, characterized in that the opening has a C-ring-shaped transparent thin film. 11. The method for detecting a pattern for a liquid crystal display element according to claim 8, wherein the mask has a ring-shaped thin film that is not completely transparent and is supported by spokes from the periphery. 12. Claim 8, characterized in that the first mask is one in which the ring-shaped portion is made opaque.
The method for detecting a pattern for a liquid crystal display element as described in 2. 16. For liquid crystal display elements illuminated by a ring-shaped light source. 1. A pattern detection method for a liquid crystal display device, characterized in that a ring-shaped transparent thin film is provided on the surface of an objective lens closest to the Fourier transform surface of the pattern. 14 A pattern for a liquid crystal display element, characterized in that a ring-shaped thin film (including opaque) that is not completely transparent is provided on the surface of the objective lens closest to the Fourier transform surface of the pattern for a liquid crystal display element illuminated by a ring-shaped light source. Detection method. 15 A point light source for illuminating a liquid crystal display element as a test object, and a transparent mask disposed on the Fourier transform surface of the liquid crystal display element, the mask having a uniform thickness. A pattern detecting device for a liquid crystal display element, further comprising a convex or concave piece 1') having a different thickness in the center. 16. The device for detecting a pattern for a liquid crystal display element according to claim 15, wherein the transparent mask has a central portion having a different transparency from other portions. 1Z The pattern detection device for a liquid crystal display element according to claim 15, wherein the transparent mask has a transparent film in the center supported by spokes from the periphery. 18. The liquid crystal according to claim 15, wherein the mask is supported by spokes from the periphery, and is not completely transparent (and has a thin film in the center). Device for detecting patterns for display elements. 19. The liquid crystal display according to claim 15, wherein the mask is a transparent mask having a uniform thickness with zero transmittance at the center. Device pattern detection device. 20. The central part of the observation objective lens, which has a point light source for illuminating the liquid crystal display element to be examined, and is located closest to the Fourier transform plane of the liquid crystal display element. 21. A detection device for a pattern for a liquid crystal display element, characterized in that a transparent thin film is provided on the surface of the liquid crystal display element. A detection device for a pattern for a liquid crystal display element, characterized in that a thin film (including an opaque film) that is not completely transparent is provided in the center of an observation objective lens located closest to the surface. A ring-shaped light source for illumination is provided, and a transparent mask is provided on the 7-layer conversion surface of the liquid crystal display element.The transparent mask has a uniform thickness and a ring-shaped convex shape in the center. , and a ring-shaped concave opening with a portion having a different thickness. 23. The above-mentioned mask has a ring-shaped portion whose transparency 23. The pattern detection device for a liquid crystal display element according to claim 22, wherein the pattern detection device for a liquid crystal display element has a different transmittance in other parts. 24. The mask is a transparent ring-shaped mask supported by spokes from the periphery. 22. The device for detecting a pattern for a liquid crystal display element according to claim 22, characterized in that the mask has a thin film.25. 23. The detection device for a pattern for a liquid crystal display element according to claim 22, characterized in that the device has a thin film. 26. The mask has a ring-shaped portion made opaque. Claim 22 characterized by
A detection device for a pattern for a liquid crystal display element as described in 2. 27. A ring-shaped light source is provided to illuminate the liquid crystal display element to be examined, and a ring-shaped transparent thin film is provided on the objective lens closest to the Fourier transform surface of the liquid crystal display element. Pattern detection device for liquid crystal display elements. 28. A liquid crystal characterized in that a ring-shaped light source is provided to illuminate a liquid crystal display element as a test object, and a ring-shaped opaque thin film is provided on the objective lens closest to the Fourier transform surface of the liquid crystal display element. Pattern detection device for display elements.