JPH0968705A - Alignment mark and alignment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide alignment marks suitable for alignment of hologram color filters and the pixels of liquid crystal display elements and an alignment method. SOLUTION: The alignment marks are constituted by forming the alignment marks 14 composed of interference fringes or diffraction gratings on the same substrate 11 as a main hologram 13, such as hologram color filters. These alignment marks are aligned with the counter alignment marks of the substrate to be aligned of the liquid crystal display elements, etc., by using a method for visualizing the alignment marks 14. The simultaneous formation of the alignment marks 14 in the same manner as in the stage for producing the main hologram 13 is possible. The alignment marks 14 which are normally invisible are easily visualized by the method for visualizing the alignment marks 14, by which the exact positioning is made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment mark and an alignment method, and more particularly to an alignment mark of a hologram color filter and an alignment method of a hologram color filter and a black matrix.

[0002]

2. Description of the Related Art As a color filter for a color liquid crystal display device, each wavelength component of a backlight can be incident on each liquid crystal cell without waste and absorption, as compared with a conventional wavelength absorption type filter. The present applicant has proposed a hologram color filter in Japanese Patent Application No. 5-12170 or the like to significantly improve the hologram color filter. The structure is composed of an eccentric Fresnel zone plate-shaped micro hologram array. The hologram color filter will be briefly described below.

A liquid crystal display device using this hologram color filter will be described with reference to the sectional view of FIG. In the figure, a hologram array 5 constituting this hologram color filter is arranged at a distance from the backlight 3 incident side of a liquid crystal display element 6 which is regularly divided into liquid crystal cells 6 '(pixels). On the back of the liquid crystal display element 6,
A black matrix 4 provided between the liquid crystal cells 6'is arranged. In addition to the above, polarizing plates (not shown) are arranged on both sides of the liquid crystal display element 6. An absorption type color filter that transmits light of colors corresponding to the R, G and B color separation pixels is additionally arranged between the black matrixes 4 as in the conventional color liquid crystal display device. You may do it.

The hologram array 5 has a repetition period of R, G, and B color separation pixels, that is, a set of three liquid crystal cells 6 ′ adjacent to each other in the direction of the liquid crystal display element 6 in the plane of the paper. The micro holograms 5 'are arranged in an array at the same pitch as the repetition pitch. The micro holograms 5' are aligned with each set of three liquid crystal cells 6 'adjacent to each other in the direction of the plane of the liquid crystal display element 6, and each hologram 5' Each of the micro holograms 5 ′ corresponds to the light of the green component in the backlight 3 that enters at an angle θ with respect to the normal to the hologram array 5 and corresponds to the micro hologram 5 ′. It is formed in a Fresnel zone plate shape so that light is condensed on the liquid crystal cell G at the center of the three color separation pixels R, G, and B. The micro hologram 5 ′ has a relief type, which has no or little wavelength dependence of the diffraction efficiency.
It consists of transmission holograms such as phase type and amplitude type. Here, the fact that there is no or little wavelength dependence of the diffraction efficiency is not a type that diffracts only a specific wavelength and does not diffract other wavelengths like a Lippman hologram,
Means that one diffraction grating diffracts any wavelength,
The diffraction grating having a small wavelength dependence of the diffraction efficiency diffracts at different diffraction angles according to the wavelength.

[0005] With such a configuration, when the white backlight 3 that enters at an angle θ with respect to the normal line from the surface of the hologram array 5 opposite to the liquid crystal display element 6 is incident, the wavelength is reduced. Accordingly, the diffraction angle of the minute hologram 5 'is different, and the light condensing position for each wavelength is dispersed in a direction parallel to the hologram array 5 surface. Among them, the red wavelength component is located at the position of the liquid crystal cell R displaying red, the green component is located at the position of the liquid crystal cell G displaying green, and the blue component is located at the position of the liquid crystal cell B displaying blue. By arranging the hologram array 5 so as to diffract and collect light, each color component passes through each liquid crystal cell 6 ′ with almost no attenuation in the black matrix 4 and the liquid crystal cell 6 ′ at the corresponding position. Color display can be performed according to the state.

As described above, by using the hologram array 5 as a color filter, each wavelength component of the conventional color filter backlight can be made incident to each liquid crystal cell 6'without being absorbed, and its utilization efficiency is improved. Can be significantly improved.

Such a hologram color filter 5
Manufactures a computer generated hologram lens array and duplicates it. That is, the hologram interference fringes of the minute hologram 5'is calculated by a computer, and the interference fringes are drawn by an electron beam on an electron beam resist coated on a glass substrate on which chromium is deposited, and then developed, and the relief type computer is calculated. Hologram (CG
H: Computer Generated Holo
The chrome pattern of the gram) array is first made. Next, the glass substrate is ion-etched using this chrome pattern as a mask to prepare a CGH array original plate. Next, a hologram photosensitive material is brought into close contact with or superposed on the relief surface of the CGH array thus manufactured, with a slight gap therebetween, and laser light is incident from the CGH array side at an angle θ corresponding to the backlight 3 in FIG. Then, the convergent diffracted light generated by each CGH of the CGH array and the linearly transmitted light are caused to interfere with each other in the hologram photosensitive material to duplicate the CGH array. This duplicated hologram is used as the hologram array 5 in FIG. Further, a duplicated copy of this duplicated hologram as an original plate may be used as the hologram array 5.

[0008]

By the way, in order to incorporate such a hologram color filter 5 into a liquid crystal display device, the hologram array 5 is accurately positioned (aligned) on the black matrix 4 arranged on the rear surface of the liquid crystal display element 6. )Must.

However, the black matrix 4
, Its position can be confirmed as a contrast image, but since the hologram array 5 is usually composed of a phase hologram, its position cannot be confirmed as a contrast image by a normal observation method. Moreover, as is clear from the arrangement of FIG. 8, since the hologram array 5 and the black matrix 4 are arranged apart from each other by about the focal length of the minute hologram 5 ', both are arranged in the alignment method for observing the same plane. It cannot be aligned accurately.

The present invention has been made in view of such circumstances, and an object thereof is to provide an alignment mark of a phase hologram such as a hologram color filter and an alignment method using the same. An object of the present invention is to provide an alignment mark and an alignment method suitable for alignment between a hologram color filter and a pixel of a liquid crystal display element.

[0011]

The alignment mark of the present invention which achieves the above object is an alignment mark provided on the same substrate as a hologram or a diffraction grating.
It is characterized in that the alignment mark is composed of an interference fringe or a diffraction grating.

In this case, the hologram or the diffraction grating is composed of an array in which condensing element holograms are periodically arranged, and each element hologram records white light incident at an angle with respect to the normal to the recording surface. It is possible to use a hologram color filter that disperses wavelengths in the direction along the surface and disperses the light.

As the interference fringes or the diffraction grating of the alignment mark, a phase interference fringe or a phase diffraction grating can be used.

In this case, the hologram or the diffraction grating can also be composed of the phase interference fringes or the phase diffraction grating similar to the alignment mark.

As the alignment mark, either a converging phase hologram or a constant-pitch phase diffraction grating may be used.

Further, according to one alignment method of the present invention, one substrate provided with an alignment mark made of a condensing hologram on the same substrate as the hologram or the diffraction grating and the other substrate provided with an opposing alignment mark. In the alignment method for positioning with the substrate, the alignment mark of one substrate is illuminated from a predetermined direction, the convergence point of the diffracted light is imaged, and the image of the opposing alignment mark of the other substrate is imaged. Is displayed on the same screen and the relative positions of the two substrates are adjusted.

According to another alignment method of the present invention, one substrate provided with an alignment mark made of a condensing hologram on the same substrate as the hologram or diffraction grating,
In the alignment method for positioning the other substrate provided with the facing alignment mark, the alignment mark of one substrate is illuminated from a predetermined direction, and the converging point of the diffracted light is formed in the vicinity of the facing alignment mark of the other substrate, The method is characterized in that an image in the vicinity of the facing alignment mark on the other substrate is captured, the captured image is displayed on the same screen, and the relative positions of the both substrates are adjusted.

Another alignment method of the present invention is
In the alignment method for positioning one substrate having alignment marks made of a diffraction grating with a constant pitch on the same substrate as the hologram or diffraction grating and the other substrate having opposing alignment marks, the alignment of one substrate The mark is illuminated from a predetermined direction, and the vicinity of the alignment mark is imaged by the straight traveling component or the diffracted component, and the image of the facing alignment mark on the other substrate is also captured, and both the captured images are displayed on the same screen. In the method, the relative positions of the two substrates are adjusted.

In still another alignment method of the present invention, the hologram or the diffraction grating is provided on the same substrate by using an alignment mark formed of interference fringes or a diffraction grating provided in a fixed relationship with the hologram or the diffraction grating. In the alignment method for detecting the position of, the alignment mark is illuminated from a predetermined direction in order to form a contrast image, and the convergence point of the diffracted light is imaged,
The method is characterized in that the vicinity of the alignment mark is imaged by a straight-moving component or a diffracting component, and the substrate is subjected to predetermined processing based on the position of the obtained contrast image.

In the present invention, since an alignment mark composed of interference fringes or a diffraction grating provided on the same substrate as the hologram or the diffraction grating is used, the alignment mark is similarly formed in the main hologram or the diffraction grating at the same time. Can be formed.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the alignment mark and the alignment method of the present invention will be described below with reference to the drawings, taking a hologram color filter as an example. FIG. 1 shows a perspective view of a hologram 10 of an embodiment to be aligned. The hologram 10 comprises a hologram layer 12 provided on a glass substrate 11, and the hologram layer 12
, A main hologram 13 composed of the hologram array 5 is provided in a substantially central region, and alignment marks 14 are provided at four corners of the main hologram 13 in a predetermined positional relationship. Main hologram 13 is also alignment mark 1
Both 4 are also phase type holograms, and are usually transparent and invisible.

As an example of the alignment mark 14,
As shown in the schematic plan view of FIG. 2, there is a phase Fresnel zone plate shape for collecting obliquely incident parallel light as in the case of the minute hologram 5 '. Further, as shown in a schematic plan view in FIG. 3, a phase diffraction grating having a constant grating pitch can be used. 2 and 3, the black portion and the white portion mean the high refractive index portion and the low refractive index portion having a phase difference with respect to the incident light, or the opposite portion. Each of these alignment marks 14 is composed of a phase grating or phase interference fringes, and there is an advantage that they can be similarly formed at the same time in the manufacturing process of the main hologram 13. Further, in the case of using a phase Fresnel zone plate shape as shown in FIG. 2 and having the same focal length as the minute hologram 5 '(in the case of FIG. 6 described later), the alignment mark 14
Can be created by using a part of the main hologram 13 or the same drawing data.

Now, in the above example, the hologram 10 having the alignment mark 14 on the periphery is black on the back surface.
In order to accurately position on the target substrate 15 such as the liquid crystal display element 6 (FIG. 8) provided with the matrix 4, as shown in FIG. 4, the hologram 10 and the target substrate 15 are separated by a predetermined distance d.
The alignment mark 14 provided on the hologram 10 and the facing alignment mark 16 provided on the target substrate 15 are opposed to each other by a distance (substantially equivalent to the focal length of the minute hologram 5'in the case of FIG. 8). Deploy. When the target substrate 15 is like the liquid crystal display element 6 provided with the black matrix 4, the opposing alignment mark 16 is made of an opaque pattern of metal or the like and is a mark having contrast. Of course, the facing alignment mark 16 may also be a pattern that is invisible to the eye and is made of a transparent phase pattern like the alignment mark 14. A transparent glass plate or the like may be interposed between the hologram 10 and the target substrate 15 so as to be spaced apart from each other by a predetermined distance d.

The following method can be used to accurately align the hologram 10 and the target substrate 15 using the alignment mark 14 and the facing alignment mark 16.

In the case of FIG. 5, as the alignment mark 14 provided in the periphery of the hologram 10, a phase Fresnel zone plate shape for converging the obliquely incident illumination light 17 as shown in FIG. 2 is used. Then, hologram 10
When the illumination light 17 having a predetermined wavelength is incident from the target substrate 15 side at a predetermined angle, it is diffracted by the alignment mark 14 and the diffracted light is once converged in the air. An image of this convergence point is picked up by a camera 18 including an objective lens and an image pickup device such as a CCD. On the other hand, the facing alignment mark 16 on the target substrate 15 is appropriately illuminated and an image is picked up by a camera 19 including an objective lens and an image pickup device such as a CCD. When both captured images are electronically combined and displayed on the monitor screen 20, the alignment mark 1 indicating the position of the hologram 10 is displayed.
The image 14 ′ of No. 4 becomes a bright spot on the monitor screen 20, while the image 16 ′ of the facing alignment mark 16 representing the position of the target substrate 15 is displayed as it is. Therefore, by adjusting the relative positions of the hologram 10 and the target substrate 15 so that the centers of the image 14 'and the image 16' coincide with each other, they are accurately positioned. Although the alignment mark 14 has a phase-Fresnel zone plate shape that condenses light in the above description, it may have a phase-Fresnel zone plate shape that diverges like a negative lens. In this case, the camera 18 is installed so that the focus position is aligned with the divergence point of the virtual image. The alignment mark 14 may be a reflective type instead of a transmissive type. However, in this case, the incident direction of the illumination light 17 needs to be opposite to that shown in the figure.

Next, in the case of FIG. 6, as the alignment mark 14 provided around the hologram 10, a phase Fresnel zone plate shape for converging the obliquely incident illumination light 17 as shown in FIG. 2 is used. This corresponds to the case where the focal length d is used and the same hologram as the minute hologram 5 ′ (FIG. 8) forming the main hologram 13 (FIG. 1) is used. In this case, when the illumination light 17 having a predetermined wavelength is incident from the opposite side of the hologram 10 to the target substrate 15, the diffracted light diffracted by the alignment mark 14 converges on the facing alignment mark 16 of the target substrate 15. To do. Therefore, when the counter alignment mark 16 area is imaged by the camera 19 including the objective lens and the image sensor such as CCD and displayed on the monitor screen 20 while appropriately illuminating the counter alignment mark 16 of the target substrate 15, the position of the hologram 10 is determined. The image 14 ′ of the alignment mark 14 representing the image becomes a bright spot on the monitor screen 20, while the image 16 ′ of the counter alignment mark 16 representing the position of the target substrate 15 is displayed in the same pattern. Therefore, by adjusting the relative positions of the hologram 10 and the target substrate 15 so that the centers of the image 14 'and the image 16' coincide with each other, they are accurately positioned.

Now, the case of FIG. 7 described below is a case where the alignment mark 14 is a phase diffraction grating having a constant grating pitch as shown in FIG. In this case, the illumination light 21 including multiple wavelengths is emitted from the target substrate 15 side of the hologram 10.
When the vicinity of the alignment mark 14 is illuminated with, a part of the light becomes the diffracted light 22 at the alignment mark 14, and the straight-ahead component decreases. Therefore, when the camera 18 captures an image of the vicinity of the alignment mark 14 due to the straight-ahead component, an image 14 'of the diffraction grating region appears darker than the periphery of the alignment mark outside the alignment mark recording region. On the contrary, when the camera 18 images the vicinity of the alignment mark 14 with the diffracted light 22, the diffraction grating region appears as an image 14 'brighter than the surroundings. On the other hand, as in the case of FIG.
Is appropriately illuminated, the image is captured by the camera 19, and both captured images are electronically combined and displayed on the monitor screen 20,
The image 14 ′ of the alignment mark 14 representing the position of the hologram 10 is displayed with the diffraction grating region darker or brighter than the surroundings as described above, while the image 16 ′ of the counter alignment mark 16 representing the position of the target substrate 15 is displayed. 'Is displayed as it is. Therefore, image 14 'and image 1
By adjusting the relative positions of the hologram 10 and the target substrate 15 so that the centers of the 6'are aligned with each other, they are accurately positioned. The same applies when the illumination light 21 is incident from the opposite side of the hologram 10 to the target substrate 15.

In the case of FIGS. 5 to 7, the opposing alignment mark 16 is premised to be made of an opaque pattern of metal or the like, but like the alignment mark 14, it is made of a transparent phase pattern. Even in this case, an image showing the position can be obtained in the same manner.

Further, the alignment mark 14 composed of the above phase grating or phase interference fringes is provided in a predetermined positional relationship with respect to the main hologram 13, and the position thereof is visualized in the same manner as described above, and its detected position. It is also possible to perform processing such as cutting on the hologram 10 based on the detected position data, instead of aligning with another substrate or the like with reference to.

In the above description, the main hologram 13 is also included.
Although the hologram color filter as shown in FIG. 8 is assumed as an example, this is merely an example, and the present invention is not limited to this, and other various phase holograms such as a hologram lens array, alignment of phase diffraction gratings, etc. It is obvious that the present invention can be applied to the positioning, the position detection.

[0031]

As is apparent from the above description, according to the alignment mark of the present invention, since the alignment mark composed of the interference fringes or the diffraction grating provided on the same substrate as the hologram or the diffraction grating is used, There is an advantage that the marks can be formed at the same time in the process of manufacturing the main hologram or the diffraction grating. Moreover, based on the alignment method of the present invention, such an alignment mark that is normally invisible can be easily visualized,
Accurate positioning is possible.

[Brief description of drawings]

FIG. 1 is a perspective view of a hologram provided with an alignment mark according to the present invention.

FIG. 2 is a schematic plan view of an example of an alignment mark.

FIG. 3 is a schematic plan view of an example of another alignment mark.

FIG. 4 is a diagram showing a relative arrangement position of a hologram and a target substrate.

FIG. 5 is a diagram for explaining one alignment method of a hologram and a target substrate.

FIG. 6 is a diagram for explaining another alignment method of the hologram and the target substrate.

FIG. 7 is a diagram for explaining still another alignment method of the hologram and the target substrate.

FIG. 8 is a cross-sectional view of a liquid crystal display device using a hologram color filter.

[Explanation of symbols]

 3 ... Backlight 4 ... Black matrix 5 ... Hologram array (hologram color filter) 5 '... Micro hologram 6 ... Liquid crystal display element 6' ... Liquid crystal cell 10 ... Hologram 11 ... Glass substrate 12 ... Hologram layer 13 ... Main hologram 14 ... Alignment mark 14 '... Alignment mark image 15 ... Target substrate 16 ... Opposing alignment mark 16' ... Opposing alignment mark image 17 ... Illumination light 18, 19 ... Camera 20 ... Monitor screen 21 ... Illumination light 22 ... Diffraction light

Claims (9)

[Claims] 1. An alignment mark provided on the same substrate as a hologram or a diffraction grating, wherein the alignment mark is composed of interference fringes or a diffraction grating. 2. The hologram or diffraction grating comprises an array in which condensing element holograms are periodically arranged,
2. The alignment mark according to claim 1, wherein each element hologram is composed of a hologram color filter for wavelength-dispersing white light incident at an angle with respect to a normal line of the recording surface in a direction along the recording surface to disperse the white light. . 3. The alignment mark according to claim 1, wherein the interference fringes or the diffraction grating of the alignment mark comprises a phase interference fringe or a phase diffraction grating. 4. The alignment mark according to claim 3, wherein the hologram or the diffraction grating is also composed of the same phase interference fringes or phase diffraction grating as the alignment mark. 5. The alignment mark according to claim 3, wherein the alignment mark is formed of a condensing phase hologram. 5. The alignment mark comprises a phase diffraction grating with a constant pitch.
The described alignment mark. 6. An alignment method for positioning one substrate provided with an alignment mark made of a condensing hologram on the same substrate as a hologram or a diffraction grating and the other substrate provided with an opposing alignment mark, The alignment mark on one substrate is illuminated from a predetermined direction, the convergence point of the diffracted light is imaged, the image of the opposing alignment mark on the other substrate is imaged, and both images are displayed on the same screen. And adjusting the relative positions of the two substrates. 7. An alignment method for positioning one substrate provided with an alignment mark made of a condensing hologram on the same substrate as a hologram or a diffraction grating and the other substrate provided with an opposing alignment mark, The alignment mark on one substrate is illuminated from a predetermined direction, the convergent point of the diffracted light is formed near the opposing alignment mark on the other substrate, and the image near the opposing alignment mark on the other substrate is taken. Is displayed on the same screen and the relative position of the two substrates is adjusted. 8. An alignment method for positioning one substrate provided with alignment marks made of a diffraction grating having a constant pitch on the same substrate as a hologram or a diffraction grating and the other substrate provided with opposing alignment marks, The alignment mark on one substrate is illuminated from a predetermined direction, and the vicinity of the alignment mark is imaged by the straight-moving component or the diffractive component, and the image of the facing alignment mark on the other substrate is also captured, and both captured images are displayed on the same screen. An alignment method characterized by adjusting the relative position of the two substrates displayed above. 9. An alignment method for detecting the position of the substrate using an alignment mark composed of interference fringes or a diffraction grating provided on the same substrate as the hologram or the diffraction grating in a fixed relationship with the hologram or the diffraction grating, The alignment mark is illuminated from a predetermined direction in order to form a contrast image, and the convergence point of the diffracted light is imaged, or the vicinity of the alignment mark is imaged by a straight component or a diffractive component, and based on the position of the obtained contrast image. An alignment method comprising subjecting the substrate to a predetermined process.