JP4110640B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device in which two substrates are bonded together to form a liquid crystal panel and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, along with the widespread use of electronic devices with liquid crystal display devices such as personal computers, small televisions, and liquid crystal projectors, the demand for higher functionality in liquid crystal display devices has increased. Improvements are being made to achieve higher brightness and higher brightness.
[0003]
In general, a panel of a liquid crystal display device (liquid crystal panel) includes a driving substrate on which a pixel-controlled thin film transistor (hereinafter referred to as “TFT”) and a storage capacitor are formed, a color filter (in the case of a color liquid crystal panel), and a black matrix. And so on. Of these, the drive substrate has a TFT portion and an opening for taking incident light. However, as a result of the area occupied by the TFT portion, sufficient light transmittance may not be ensured. Therefore, a structure is adopted in which light is condensed on each pixel by forming a microlens on the counter substrate corresponding to the opening of each pixel. As a method for forming a microlens, a method of forming a glass substrate using a transparent resin is known.
[0004]
In such a liquid crystal display device, the drive substrate and the counter substrate described above are bonded to each other in the assembly stage. When the bonding is performed, for example, a relative position between the corresponding microlens and the pixel is shifted. The desired luminance cannot be obtained. For this reason, when bonding substrates together, high positioning accuracy is required.
[0005]
Therefore, in the prior art, as shown in FIGS. 6A and 6B, alignment marks 52a and 52b are formed in advance on both sides of the drive substrate 51, and correspondingly on both sides of the counter substrate 53. Alignment marks 54a and 54b are formed, and in actual bonding, each mark position is observed from above with a microscope (not shown) while the driving substrate 51 and the counter substrate 53 are overlapped. The other substrate (for example, the counter substrate 53) is moved relative to the other substrate (for example, the driving substrate 51) together with the stage. At this time, by aligning the alignment marks 52a, 54a and 52b, 54b of the respective substrates, the drive substrate 51 and the counter substrate 53 are aligned, so that both substrates are in a predetermined gap (cell gap) in that state. It sticks together with a sealing material through. Incidentally, the gap between the substrates is secured by the spacers scattered on the drive substrate 51 or the counter substrate 53 prior to the bonding of the substrates.
[0006]
[Problems to be solved by the invention]
By the way, when the alignment of the substrate is performed using the microscope as described above, if the alignment marks 52a, 52b and 54a, 54b provided on both sides of each substrate are put in one field of view and are simultaneously confirmed, the lens Must be set low. However, when the magnification of the lens is lowered, it is impossible to confirm minute displacements of the alignment marks 52a, 54a and 52b, 54b, so that high positioning accuracy cannot be obtained.
[0007]
On the other hand, when the magnification of the lens is increased to obtain high positioning accuracy, only one side alignment mark 52a, 54a or 52b, 54b can be held in one field of view. In this case, it is necessary to move the stage frequently until the alignment marks 52a, 54a and 52b, 54b on both sides are completely matched, and it is necessary to repeat this many times, so that it takes time to align the substrates.
[0008]
Further, in the state where the driving substrate 51 and the counter substrate 53 with microlenses are overlapped, the mark position of each substrate in the optical axis direction of the microscope is different, so that, for example, the microscope is focused on the driving substrate 51 side. When aligned with the alignment marks 52a and 52b, the images of the alignment marks 54a and 54b on the counter substrate 53 side are blurred.
[0009]
Under these circumstances, the microscopes can simultaneously confirm the alignment marks 52a, 54a and 52b, 54b provided on both sides of each substrate with a high magnification, and can confirm all the mark images in a just-focus state. Units have been developed and put into practical use.
[0010]
As shown in FIG. 7, this microscope unit includes a pair of left and right double focus microscopes (hereinafter simply referred to as “microscopes”) 55a and 55b, and each of the microscopes 55a and 55b has a double focus function, that is, driving. The alignment mark 52a, 52b on the substrate 51 side and the alignment mark 54a, 54b on the counter substrate 53 side can be focused at the same time. Further, CCD cameras 56a and 56b are mounted on the upper ends of the microscopes 55a and 55b, respectively, and images (mark images) captured by these CCD cameras 56a and 56b are displayed on the monitor.
[0011]
By the way, when the substrate is aligned using the microscope unit having the above-described configuration, the distance Lr between the optical axes of the left and right microscopes 55a and 55b is set to the alignment marks 52a and 52b provided on both sides of each substrate. By adjusting the distance La (see FIG. 6) between 54a and 54b, simultaneous observation of the alignment marks 52a and 54a and 52b and 54b is realized.
[0012]
However, in the above-described microscope unit, the lens barrel sizes of the left and right microscopes 55a and 55b are increased by the addition of the double focus function, and as a result, the minimum adjustment value of the optical axis distance Lr between the microscopes 55a and 55b is the mutual mirror. Strong restrictions on tube size. For this reason, the double focus microscope cannot cope with the case where the distance La between the alignment marks 52a, 52b and 54a, 54b provided on both sides of each substrate is less than the minimum adjustment value of the inter-optical axis distance Lr. is there. Incidentally, at present, only a liquid crystal panel having a size of 1.3 inches or more can be supported.
[0013]
[Means for Solving the Problems]
The present invention has been made to solve the above problems,
The two substrates forming a quadrangle are bonded to each other to form a liquid crystal panel, alignment marks for alignment are formed on the two substrates, and the alignment marks are diagonally aligned with each other. A method of manufacturing a liquid crystal display device, wherein each of the two substrates is moved relative to one of the two substrates by an xy-θ stage. When aligning the two substrates, the x-axis direction or the y-axis direction of the movement direction of the other substrate by the xy-θ stage is substantially matched with the diagonal direction of the substrate. The substrate is aligned.
[0014]
In the manufacturing method of the liquid crystal display device, the alignment marks for alignment are arranged and formed at the corresponding diagonal positions of the respective substrates, so that the distance between the alignment marks is longer than that of the conventional substrate even with the same size substrate. Become. As a result, the substrate can be aligned even with a smaller-sized substrate with a double focus microscope.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram for explaining an embodiment of a liquid crystal display device according to the present invention.
First, as shown in FIG. 1A, the drive substrate 1 on which each pixel control TFT and the like are formed is formed in a quadrangular shape. A wiring pattern portion 2 that is electrically connected to a TFT driving circuit is provided on one side portion (upper side portion in the figure) of the driving substrate 1. In addition, two alignment marks 3 a and 3 b are formed on the drive substrate 1. Each of the alignment marks 3 a and 3 b has a cross shape, for example, and is arranged and formed at a diagonal position of the drive substrate 1.
[0016]
On the other hand, as shown in FIG. 1B, the counter substrate 4 on which color filters, microlenses, and the like are formed is also formed in a quadrangular shape. The counter substrate 4 constitutes a liquid crystal panel by being bonded to the drive substrate 1. In the counter substrate 4, alignment marks 5 a and 5 b are arranged and formed at diagonal positions corresponding to the mark formation position on the drive substrate 1 side. Each alignment mark 5a, 5b has, for example, a shape in which a square having a smaller diameter is drawn in a square frame and a straight line is drawn from each corner of the square having a small diameter to each side of the square having a large diameter. There is no.
[0017]
Incidentally, the alignment marks 3a and 3b on the drive substrate 1 side and the alignment marks 5a and 5b on the counter substrate 4 side are each made of a conductive material (metal or the like) on a transparent glass substrate made of non-alkali glass or the like in each substrate manufacturing process. ) And insulating materials (resins, etc.) are used to construct various functional parts (TFTs, microlenses, etc.) at the same time (in the same process) as those functional parts.
[0018]
When a liquid crystal panel is configured by using the driving substrate 1 and the counter substrate 4 having the above-described configuration, first, in the state where these two substrates 1 and 4 are overlapped with each other, the respective mark positions are viewed from above with a microscope (not shown). The other substrate (for example, the counter substrate 4) is moved relative to one substrate (for example, the driving substrate 1) while observing with the illustration. At this time, by aligning the alignment marks 3a, 5a and 3b, 5b of each substrate, the drive substrate 1 and the counter substrate 4 are aligned, so that both substrates are in a predetermined gap (cell gap) in this state. It sticks together with a sealing material through. Further, after the liquid crystal is filled between the drive substrate 1 and the counter substrate 4 (cell gap), which have been bonded together, by, for example, a vacuum injection method, the injection port is closed with a sealing material. Complete.
[0019]
Here, in this embodiment, the alignment marks 3a, 3b and 5a, 5b are arranged and formed at the diagonal positions corresponding to the two substrates, that is, the driving substrate 1 and the counter substrate 4, respectively. Therefore, the distance Lb between the alignment marks 3a, 3b and 5a, 5b is a conventional distance between marks (distance La in FIG. 6) as compared with the conventional one in which alignment marks are formed on both sides of each substrate. Can be secured more widely.
[0020]
Thus, when the drive substrate 1 and the counter substrate 4 are aligned using a double focus microscope, conventionally, as shown in FIG. 2, two microscopes (2 When two double-focus microscopes are arranged, the positions of the lens barrels (shown by broken lines in the figure) that interfere with each other in the hatched portions are the alignment marks 3a, 3b and 5a, 5b as shown in this embodiment. If they are respectively arranged at the diagonal positions MPb of the substrates 1 and 4, the lens barrel positions (indicated by solid lines in the figure) of the two microscopes do not interfere with each other.
[0021]
As a result, it is possible to deal with a smaller-sized substrate (liquid crystal panel) with a double focus microscope. Incidentally, as a compatible size of the double focus microscope, a liquid crystal panel that was conventionally only compatible with a liquid crystal panel having a size of 1.3 inches or more can be applied to a liquid crystal panel having a size of about 0.9 inches by adopting this embodiment. It becomes possible.
[0022]
By the way, in the case of a microscope unit including a pair of left and right microscopes (see FIG. 7), the direction for adjusting the distance between the optical axes of the two microscopes (distance Lr in FIG. 7) is orthogonal to the optical axis of the microscope and the optical axis. It is restricted only in the direction (uniaxial direction) that connects them. On the other hand, when the size (inch size) of the liquid crystal panel changes, the distance Lb (see FIG. 1) between the alignment marks 3a, 3b and 5a, 5b formed at the diagonal positions of each substrate correspondingly. Change. Therefore, in order to deal with liquid crystal panels of various sizes with a common microscope unit, the adjustment direction of the distance between the optical axes is a line segment connecting the alignment marks 3a, 3b and 5a, 5b, that is, the diagonal lines of the substrates 1, 4 Must match the direction.
[0023]
In such a case, for example, if the alignment marks 3a and 3b on the drive substrate 1 side are formed in a cross shape in accordance with the xy coordinates where the horizontal direction of the substrate is the x direction and the vertical direction is the y direction, the mark image is formed with a CCD camera or the like. When the image is taken in and displayed on the monitor, the cross-shaped mark shape appears as an x (cross) shape as shown in FIG. Then, when the operator aligns the substrate while viewing the mark image displayed on the monitor, the “×” shape is more difficult to align than the cross shape due to the relationship between the mark angle and the visibility. Become. The same can be said for the alignment marks 5a and 5b formed on the counter substrate 4 side.
[0024]
Therefore, in the present embodiment, as shown in FIGS. 3A and 3B, the alignment marks 3a and 3b on the drive substrate 1 side and the alignment marks 5a and 5b on the counter substrate 4 side are respectively set to diagonal lines of the respective substrates. It is formed obliquely along K. Specifically, assuming that the lateral direction of each substrate is the x-axis direction and the diagonal line K of each substrate forms an angle α with respect to the x-axis, the alignment marks 3, 3b and 5a are the same angle α. , 5b are inclined.
[0025]
Thereby, even when the adjustment direction of the distance between the optical axes of the microscope unit is matched with the diagonal direction of the substrate as described above, for example, the cross-shaped alignment marks 3a and 3b formed on the drive substrate 1 side are shown in FIG. As shown in (b), since it is displayed in a cross shape on the monitor screen, it is easy to perform the alignment work while looking at the monitor screen, and the work efficiency is improved.
[0026]
In general, the positioning of the driving substrate 1 and the counter substrate 4 is performed by moving the other substrate (for example, the counter substrate 4) relative to the one substrate (for example, the driving substrate 1), thereby each substrate 1 , 4 are made by matching the alignment marks 3a, 3b and 5a, 5b, and the relative movement of the other substrate is carried out using an xy-θ stage.
[0027]
At this time, a coordinate system of the liquid crystal panel, that is, a coordinate system in which the horizontal direction of each substrate (the driving substrate 1 and the counter substrate 4) is the x-axis direction and the vertical direction is the y-axis direction is used (substrate by an xy-θ stage). The x direction is aligned with the horizontal direction of the substrate and the y direction is aligned with the vertical direction of the substrate), and the adjustment direction of the distance between the optical axes of the microscope unit is matched with the diagonal direction of the substrate as described above. In some cases, the following problems occur. That is, when the operator operates the adjustment knob of the xy-θ stage to move the stage in the x direction (or y direction), the mark position on the monitor moves in an oblique direction. As a result, a sensory shift occurs between the actual stage movement and the mark movement on the monitor, and the work efficiency deteriorates.
[0028]
Therefore, in this embodiment, an alignment coordinate system as shown in FIG. 5 is adopted. In FIG. 5, the x direction, the y direction, and the θ direction indicate the movement directions of the substrate by the xy-θ stage. In this alignment coordinate system, the x-axis direction, which is one of the movement directions of the substrate by the xy-θ stage, is made to coincide with the diagonal direction of the substrates 1 and 4 passing the alignment mark formation position MP.
[0029]
Specifically, for example, when the counter substrate 4 is placed on the xy-θ stage, the axial direction passing through the alignment marks (mark centers) 5a and 5b formed at the diagonal positions of the counter substrate 4 is x. The xy-θ stage is inclined by the diagonal angle α of the substrate (see FIG. 3) in the θ direction so that the −y-θ stage substantially coincides with the x-axis direction.
[0030]
By aligning the substrate in such a state, when the substrate (for example, the counter substrate 4) is moved in the x direction (or y direction) by the xy-θ stage, the mark position on the monitor Moves in the horizontal direction (or vertical direction). As a result, the actual movement of the stage and the movement of the mark on the monitor sensuously coincide with each other, so that the alignment of the substrate is facilitated and the working efficiency is improved.
[0031]
In the alignment of the substrate, the same effect as described above can be obtained even if the y-axis direction orthogonal to the x-axis direction of the substrate movement direction by the xy-θ stage coincides with the diagonal direction of the substrate. Can do.
[0032]
【The invention's effect】
As described above , according to the present invention , the alignment mark for alignment is arranged and formed at the corresponding diagonal position of each substrate. Therefore, even with the same size substrate (panel), the alignment mark The distance between them can be secured longer than before. As a result, even when the substrate is aligned, even a smaller-sized substrate can be handled by the double focus microscope, and therefore, a particularly small liquid crystal display panel can be assembled with high accuracy in a short time.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an embodiment of a liquid crystal display device according to the present invention.
FIG. 2 is a diagram for explaining a relationship between a mark formation position and a microscope barrel position;
FIG. 3 is a diagram illustrating an inclination state of an alignment mark with respect to a substrate.
FIG. 4 is a diagram showing a display state of alignment marks on a monitor.
FIG. 5 is a diagram for explaining a method of manufacturing a liquid crystal display device according to the present invention.
FIG. 6 is a diagram for explaining a conventional example.
FIG. 7 is a diagram illustrating a configuration of a microscope unit for substrate alignment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Drive board, 3a, 3b, 5a, 5b ... Alignment mark, 4 ... Counter board

Claims (2)

The two substrates forming a quadrangle are bonded to each other to form a liquid crystal panel, alignment marks for alignment are respectively formed on the two substrates, and the alignment marks are diagonally opposite to each other. A method of manufacturing a liquid crystal display device formed by arranging each at a position,
When aligning the two substrates by moving the other substrate relative to one of the two substrates by an xy-θ stage,
Of the moving direction of the other substrate by the xy-θ stage, the substrate is aligned in a state where the x-axis direction or the y-axis direction is substantially coincident with the diagonal direction of the substrate.
A method for manufacturing a liquid crystal display device. The substrates are aligned in a state where the adjustment direction of the distance between the optical axes of the pair of microscopes used for the alignment of the two substrates is aligned with the diagonal direction of the substrates.
  The method of manufacturing a liquid crystal display device according to claim 1.

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