JPH10149110A - Image display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the image display device and its manufacture which evade decreases in pixel aperture rate and light convergence rate due to a defect in the precision of the sticking of a driving substrate and a counter substrate provided with macrolenses and increase the light convergence efficiency and production efficiency. SOLUTION: At an arbitrary position in a non-display area 20B on the counter substrate 22, a cylindrical lens 25 as a light converging means is formed and on the side of the driving substrate 21, for example, a scale type alignment mark 26 is provided corresponding to the lens. With light convergence characteristics of this cylindrical lens 25, a linear light-converged image 30 is formed on the driving substrate 21, so the light converged image 30 and a graduation line of the alignment mark 26 are positioned through a microscope. The microscope is put in focus on only the alignment mark 26 on the side of the driving substrate 21 and even when the counter substrate 22 and driving substrate 21 are at a large distance from each other in the direction of the depth focus, they can be observed through a single-focus microscope, thereby putting the driving substrate 21 and counter substrate 22 one over the other with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device used for, for example, a camera-integrated VTR (Video Tape Recorder) or a liquid crystal projector and a method of manufacturing the same.
In particular, the present invention relates to an image display device in which a fine alignment method is improved in a step of superposing (positioning) substrates of a liquid crystal display device formed by bonding two substrates, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the spread of electronic equipment having a liquid crystal display device such as a liquid crystal projector, demands for higher performance of the liquid crystal display device have increased, and the liquid crystal display device has been improved in definition and brightness. Improvements are in progress. This liquid crystal display device generally includes a substrate (hereinafter, referred to as a driving substrate) on which a thin film transistor (hereinafter simply referred to as a “TFT”) for controlling each pixel, a storage capacitor, and the like are formed, and a color filter (a color filter). Substrate on which a liquid crystal panel) or a black matrix are formed
(Referred to as a counter substrate).

[0003] The driving substrate of the liquid crystal display device is the TF described above.
It is composed of a T portion and an opening for displaying an image, and as a result of the TFT portion occupying an area, a sufficient transmittance may not be ensured in some cases. For this reason, a structure in which a micro condenser lens for pixels (hereinafter simply referred to as “micro lens”) is provided in the opening of each pixel so that light originally radiated to the TFT part is condensed in the opening. Has been adopted. As a method of forming a microlens, there is known a method of independently creating a microlens array and bonding the microlens array to a counter substrate.

[0004] In such a liquid crystal display device, the driving substrate and the opposing substrate are superposed (positioned) on the basis of the alignment mark by a superposition device, and then bonded to each other. Hereinafter, the method of superposing the driving substrate and the counter substrate will be further described with reference to FIG.

FIG. 1 is a top view of a state in which a driving substrate 2 and a counter substrate 3 of a liquid crystal display device 1 are superimposed. In addition, as shown in FIG. 7, the superposing apparatus places one substrate (for example, the driving substrate 2) on the XY-θ table 11 and faces the other substrate (for example, the opposing substrate 3). With the microscope 12 in place,
And alignment marks 7 on each of the substrates 2 and 3
The substrate 2 on the XY-θ table 11 is relatively moved so that the substrates 8 are brought together.

The liquid crystal display device 1 has a display area 4 for displaying an image, and a peripheral portion of the display area 4 such as Al.
It generally comprises a guard ring portion 5 on which a metal film of (aluminum) is formed, and external connection pads 6 for inputting necessary information from an external IC (integrated circuit) (not shown). Alignment marks (alignment marks) 7 and 8 are formed at arbitrary positions of the guard ring portion 5. The alignment mark 7 is formed on the drive substrate 2 side, and the alignment mark 8 is formed on the counter substrate 3 side. In this figure, the driving substrate 2 and the opposing substrate 3
Are overlapped. An opening 9 excluding the TFT portion is attached to the driving substrate 2 side, and a number of microlens arrays 10 for condensing light to the opening 9 are attached to the counter substrate 3 side.

[0007] The drive substrate 2 and the counter substrate 3 are superimposed on the basis of the alignment marks 7 and 8. Here, it is required that the opening 9 and the microlens array 10 be overlapped in an optimum state in order to secure a sufficient transmittance. After superposition,
The periphery between the driving substrate 2 and the opposing substrate 3 is sealed and fixed with a sealing material (not shown), and a gap between the driving substrate 2 and the opposing substrate 3 is filled with a liquid crystal composition. , 3
The liquid crystal display device 1 can be manufactured by integrally laminating the polarizing plates on both sides of the liquid crystal display device.

[0008]

In a liquid crystal display device as described above, when a color filter or a black matrix is formed on a counter substrate, an alignment mark is formed at the same time, and the driving substrate is formed using the alignment mark. Is generally performed. Therefore, when the microlenses are provided on the counter substrate side, the gap between the surface on which the alignment marks on the drive substrate side are formed and the surface on which the microlenses are provided on the counter substrate side is increased.
The microlens cover glass (not shown) is separated in the depth of focus direction by the thickness of the cover glass (not shown) (100 to 200 μm), and the alignment mark on the drive substrate and the alignment mark on the counter substrate are simultaneously observed with a normal microscope. Was difficult. Further, there is a problem that "shift" easily occurs between the microlens and the pixel portion, and the light collection rate is reduced. In addition, in a configuration in which a microlens array is independently created and attached to an opposing substrate, not only a new alignment mark for position alignment between the color filter and the like of the opposing substrate and the microlens array is required, but also a microlens array is similarly formed. In this case, there is a problem that a "shift" occurs and the light collection rate is reduced.

Further, for example, when a black matrix is formed on the drive substrate side to be used as a black and white panel for application to a liquid crystal projector, only the microlenses are provided on the opposing substrate. In this case, as a position alignment means, a method of newly forming an alignment mark on the opposing substrate and aligning it (No. 1), or a method in which a light beam is incident on a microlens and a focused spot is made to match a pixel and transmitted. A method such as a method (2) for maximizing the amount of light is adopted.

[0010] However, in the first method described above,
It is necessary to newly form an alignment mark on the opposing substrate, which not only causes a new manufacturing cost but also increases the lead time and lowers the production efficiency. In addition, when there is a “shift” in the relative position with respect to the microlens when forming the alignment mark, there is a problem that the “shift” between the opening and the microlens is further enlarged, and the light collection efficiency is reduced. . Next, in the second method, it is necessary to prepare a light source that matches the optical system to be used, and bond the light source while aligning the positions of the driving substrate and the counter substrate. Costly,
There is a problem that production efficiency is reduced. For example, if light is incident from a direction inclined several degrees in accordance with the rubbing direction, not from the normal direction, or if a Kayla optical system is used instead of a telecentric optical system, prepare a light source suitable for them. And there is a problem that the apparatus is enlarged accordingly.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the pixel aperture ratio and the light collection ratio due to poor precision in bonding a drive substrate and a counter substrate provided with microlenses. In addition, an image display device and a method of manufacturing the image display device capable of avoiding a decrease in production efficiency due to an increase in complexity of an apparatus for aligning light beams incident on microlenses and improving light collection efficiency and production efficiency are provided. Is to do.

[0012]

According to the present invention, there is provided an image display apparatus comprising a pixel portion including a plurality of pixels and having an alignment mark serving as a reference for superposition formed thereon.
And a lens group consisting of a plurality of micro-condensing lenses corresponding to the pixel portions on the first substrate side, and condensing light for converging incident light to an alignment mark on the first substrate side. And a second substrate opposed to the first substrate with a predetermined gap therebetween.

According to the method of manufacturing an image display device of the present invention, there is provided a first substrate having a pixel portion including a plurality of pixels and having an alignment mark serving as a reference for superposition formed thereon;
A lens group including a plurality of micro condenser lenses is provided corresponding to the pixel portion on the first substrate side, and a light condensing means for condensing incident light on an alignment mark on the first substrate side is provided. Facing the second substrate with a predetermined gap between the first substrate and the second substrate with reference to the alignment mark on the first substrate and the light collected by the light collecting means on the second substrate. And moving the two substrates relative to each other to overlap the two substrates.

In the image display device and the method of manufacturing the same according to the present invention, an alignment mark serving as a reference for superposition is formed on a first substrate having a pixel portion, and a second substrate forming a pair with the first substrate is formed. A focusing means for focusing incident light on an alignment mark on the first substrate side, and the alignment of the first substrate by the alignment mark is performed with reference to a focused image by the focusing means. .

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIGS. 1 (a) and 1 (b)
2 and 3 show a configuration of the liquid crystal display device 20 according to the first embodiment of the present invention. These figures show a display area 20A of the liquid crystal display device 20 and the display area 2A.
It shows a partial area including a non-display area (guard ring portion) 20B provided around 0A. The liquid crystal display device 20 has a first TFT in which a TFT for controlling each pixel and the like are formed.
And a counter substrate 22 as a second substrate on which micro lenses and the like are formed. FIG. 2A shows the counter substrate 22 and FIG.
FIG. 2B is a view of the driving substrates 21 as viewed from above, and shows a state in which the liquid crystal display device 20 is viewed from the side after the driving substrates 21 and the opposing substrate 22 are overlapped. FIG.

The opposing substrate 22 is directly and integrally formed with a lens group composed of a number of microlenses 24 for condensing light on an opening 23 in a display area 20A on the driving substrate 21 side. A cover glass plate 22a is adhered to the surface of the lens group, forming a so-called on-chip micro lens (OCL). Each micro lens 24 has, for example, a hexagonal shape when viewed from above. At an arbitrary position in the non-display area 20B of the counter substrate 22, a semi-cylindrical lens (hereinafter, referred to as a cylindrical lens) 25 as a light condensing means is formed. As shown in FIG. 3, for example, the cylindrical lens 25 is a lens that refracts the incident light 28 only in one axial direction and transmits the same. When parallel light is incident on the cylindrical lens 25, it is linearly collected on the focal plane. It becomes light and becomes a linear condensed image 29. In the present embodiment, this cylindrical lens 2
No. 5 utilizes the light-collecting characteristics (lens characteristics). That is, this cylindrical lens 25 is
By simultaneously forming the microlenses 24 designed to focus on each of the upper pixels, the light can be linearly focused on the alignment marks 26 on the drive substrate 21. Although not shown, a black matrix and a color filter for the purpose of shielding light are formed on the counter substrate 22 as necessary.

On the other hand, the driving substrate 21 is provided with a display area 20A.
A TFT section (not shown) for controlling each pixel and an opening 23 for projecting an image are provided in the inside, and the cylindrical lens 2 on the counter substrate 22 side is provided in the non-display area 20B.
For example, a scale-like alignment mark 26 corresponding to 5
Is provided. In the manufacturing process of the driving substrate 21, the alignment mark 26
When the metal layer 27 such as l (aluminum) and Ti (titanium) is formed, they are formed in the same step.

The driving substrate 21 and the opposing substrate 22 having such a configuration are superimposed on the basis of the alignment mark 26 and the condensed image by the cylindrical lens 25 in a superimposing apparatus similar to that shown in FIG. That is, as shown in FIG.
Is refracted in a uniaxial direction by the light condensing property of the cylindrical lens 25, whereby a linear condensed image 30 is formed on the drive substrate 21. By aligning the condensed image 30 with the graduation line 26a of the alignment mark 26, the two substrates 21 and 22 can be easily overlapped. At this time, it is sufficient to focus the microscope only on the drive substrate 21 side, and it is not necessary to directly look at the cylindrical lens 25 on the counter substrate 22 side.

As described above, the drive substrate 21 and the opposing substrate 22 are aligned by superposing the alignment mark 26 and the condensed image 30 of the cylindrical lens 25 on each other. As shown in FIG. 24 will be accurately aligned on the corresponding openings 23.

As described above, in this embodiment, the opposing substrate 2
Instead of using the cylindrical lens 25 on the second side as an alignment mark, a linear condensed image 30 is formed using its condensing characteristics, and the condensed image 30 is formed on the alignment mark 26 on the drive substrate 21 side. Since the superimposition is performed, only the alignment mark 26 on the drive substrate 21 needs to focus the microscope. Therefore, the opposite substrate 22
And the drive board 21 are far apart in the depth of focus direction,
Observation is possible with a single focus microscope. Therefore, the driving substrate 21 and the counter substrate 22 can be accurately overlapped, and automation can be easily realized.

In this embodiment, since the scale-like alignment marks 26 are formed on the drive board 21 side, the two substrates 21 and 2 are intentionally laid along the scale lines.
2 can be shifted (offset), and the degree of freedom of positioning can be increased.

FIG. 5 shows a modification of the shape of the cylindrical lens, and is an enlarged view of a main part in a state where the condensed image of the cylindrical lens and the alignment mark on the driving substrate overlap each other.

That is, a cross-shaped alignment mark 42 is provided on the drive substrate 21 side. On the other hand, on the counter substrate 22 side, a cylindrical lens 40 in which two semi-cylindrical lenses are assembled in a cross shape is provided. Due to the light-collecting characteristics of each semi-cylindrical lens of the cylindrical lens 40, a cross-shaped light-collected image 41 is formed on the alignment mark 42 on the drive substrate 21 side. By superimposing the condensed image 41 of the cylindrical lens 40 on the alignment mark 42, the two substrates 21 and 22 can be easily superimposed.

Although the present invention has been described with reference to various embodiments, the present invention is not limited to the above-described embodiments, and can be variously modified within an equivalent range. For example, in the above-described embodiment, as an example, a mode in which a microlens is integrally formed on a counter substrate and then the counter substrate and the driving substrate are overlapped with each other using the cylindrical lens and the alignment mark has been described. It is also possible to apply the method of superimposing the microlens substrate separately formed thereon after superimposing the microlens substrate and the counter substrate using the above-described cylindrical lens and the alignment mark.

In the above-described embodiment, the superimposition is performed based on the linear or cross-shaped condensed image formed by the cylindrical lenses 25 and 40 as the light condensing means on the second substrate side. It is also possible to perform superposition using a point-like condensed image by a plurality of lenses. Note that the present invention is suitable for a case where two substrates are automatically superimposed using a visual sensor or the like, but it is also applicable to a case where the two substrates are manually supervised visually.

[0027]

As described above, according to the image display device and the method of manufacturing the same of the present invention, an alignment mark is formed on a first substrate having a pixel portion, and a second substrate having a plurality of microlenses is formed. , A light collecting means for condensing incident light on an alignment mark on the first substrate side is provided, and superimposition is performed based on an image collected by the light collecting means and the alignment mark. So even if the two substrates are far apart in the depth of focus direction,
By observing with a single focus microscope, it is possible to perform superposition with high accuracy, to achieve alignment between the pixel portion and the micro focusing lens, and to improve the pixel aperture ratio and the lens focusing ratio. Play.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of a liquid crystal display device of the present invention. FIG. 1A is a top view showing a counter substrate, and FIG. 1B is a top view showing a driving substrate.

FIG. 2 is a side view showing a state in which a counter substrate and a driving substrate of the embodiment shown in FIG. 1 are overlaid.

FIG. 3 is a perspective view for explaining light-collecting characteristics of the cylindrical lens shown in FIG.

FIG. 4 is a view showing a theoretical appearance when a converged image of the cylindrical lens shown in FIG. 1 and an alignment mark are superimposed.

FIG. 5 is a view for explaining a modification of the cylindrical lens shown in FIG. 1;

FIG. 6 is a top view illustrating a state in which two substrates of a conventional liquid crystal display device are superimposed.

FIG. 7 is a side view illustrating a schematic configuration of a superposition apparatus.

[Explanation of symbols]

20: liquid crystal display device, 21: drive substrate (first substrate),
22: Counter substrate (second substrate), 23: Opening, 24:
Microlens, 25, 40 ... cylindrical lens (light collecting means), 26, 42 ... alignment mark

Claims (6)

[Claims] A first substrate having a pixel portion including a plurality of pixels and having an alignment mark serving as a reference for superposition formed thereon; and a plurality of micro-collections corresponding to the pixel portion on the first substrate side. A lens group including an optical lens is provided, and a light condensing unit for condensing incident light on the alignment mark on the first substrate side is provided, and the light converging unit is opposed to the first substrate at a predetermined gap. An image display device comprising: a second substrate disposed thereon. 2. The method according to claim 1, wherein the alignment mark on the first substrate side is a scale mark, and the light condensing means is a lens that forms a linear condensed image on the surface of the first substrate. The image display device according to claim 1. 3. The method according to claim 2, wherein the alignment mark on the first substrate side is a cross-shaped mark, and the condensing means is a lens that forms a cross-shaped condensed image on the surface of the first substrate. The image display device according to claim 1. 4. A first substrate having a pixel portion composed of a plurality of pixels and having an alignment mark serving as a reference for superposition formed thereon, and a plurality of micro-collections corresponding to the pixel portion on the first substrate side. A step of facing a second substrate provided with a lens group including an optical lens and provided with a light condensing means for condensing incident light on the alignment mark on the first substrate side at a predetermined gap; And an alignment mark on the first substrate and the second
A step of relatively moving the first substrate and the second substrate on the basis of a condensed image formed by the light condensing means on the first substrate and superimposing the two substrates. A method for manufacturing an image display device. 5. The method according to claim 1, wherein the alignment mark on the first substrate side is a scale mark, and the condensing means is a lens for forming a linear condensed image on the surface of the first substrate. The method for manufacturing an image display device according to claim 4. 6. The method according to claim 1, wherein the alignment mark on the first substrate is a cross-shaped mark, and the condensing means is a lens for forming a cross-shaped condensed image on the surface of the first substrate. The image display device according to claim 4, wherein