JPH07270716A - Optical device - Google Patents

Abstract

PURPOSE:To provide an optical device capable of simultaneously observing an object being at two different focusing positions on the same optical axis on one image formation surface. CONSTITUTION:The image of the object placed on a focusing surface 121 is formed on the image formation surface 131 from an optical path A by way of an objective lens 123, an image formation lens 124, a half mirror 125 and a total reflection mirror 126 through a half mirror 130, and the image on a focusing surface 122 is formed on the image formation surface 131 by the half mirror 130 through the path of the objective lens 123, the image formation lens 124, the half mirror 125, a total reflection mirror 127, a correction lens 128, and a shutter 129. The focusing position of a focusing surface 122 is corrected to be the same as the focusing surface 121 by the correction lens 128, so that the images of the object on the two focusing surfaces 121 and 122 are simultaneously observed on the image formation surface 131.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device, and more particularly to an optical device capable of simultaneously observing objects at at least two different focal positions on the same optical axis on a single image plane.

[0002]

2. Description of the Related Art As an example of simultaneously observing two or more objects at different focal positions on the same optical axis, a method of bonding glass substrates shown in FIGS. 4 and 5 will be described. In FIG. 4, the wiring pattern 3 and the alignment mark 5 as shown in FIG. 5A are formed on one of the liquid crystal glass substrates 1, and the wiring pattern 3 and the alignment mark 5 have a surface. The protective film 7 is formed. The other liquid crystal glass substrate 2 is also the one liquid crystal glass substrate 1.
Similarly, the wiring pattern 4 and the alignment mark 6 shown in FIG. 5B are formed, and the surface protective film 8 is formed on the wiring pattern 4 and the alignment mark 6.

The alignment mark 5 has a circular shape, and the alignment mark 6 has a ring shape. Generally, the alignment mark 5 is made of a transparent electrode or a metal thin film such as chromium in the same process as the wiring patterns 3 and 4. .

When the liquid crystal glass substrates 1 and 2 are attached to each other, the wiring patterns 3 and 4 are arranged so that their distances are about 0.2 mm so as to face each other. In the liquid crystal display device, even if the positions of the two liquid crystal glass substrates 1 and 2 deviate from the specified position by several μm, the liquid crystal display device does not operate normally. It is necessary to perform alignment so that the alignment mark 5 is arranged. When the positioning at this point is completed, the two liquid crystal glass substrates 1 and 2 are then brought into close contact with each other to about 5 μm, and the misalignment of the alignment marks 5 and 6 is finely adjusted again.
Finally, the two liquid crystal glass substrates 1 and 2 are bonded with the adhesive 9, and the glass substrate bonding step for liquid crystal display device is completed.

When the liquid crystal glass substrates 1 and 2 are fitted together, the alignment marks 5 and 6 shown in FIG. 4 have different focal positions when viewed from above. As a method of observing such two positioning marks having different focal points, for example, the simplest method is to use an optical device having a large depth of focus and observe both alignment marks 5 and 6 within the depth of focus range. , Alternatively,
A method of adding a mechanism that moves up and down in the vertical direction to the liquid crystal glass substrates 1 and 2 to the optical device, or providing the optical device with a function of changing the focus position, and a position existing on the front surface and the back surface of the work respectively. As a method of observing the alignment mark, a method of using a method provided with two means for observing the alignment mark is considered.

[0006]

When performing the alignment as shown in FIG. 4, it is necessary to simultaneously observe the two alignment marks 5 and 6 having different focal positions. In the method described above, it is difficult to obtain high magnification and high resolution in an optical device with a large depth of focus because the aperture ratio is small, and it is possible to observe images that are slightly out of focus even within the depth of focus. It is not possible to expect high-precision observation because it cannot be observed. In the above method, it is impossible to observe the two coaxial alignment marks 5 and 6 at the same time, and it takes a switching time each time the focus position is switched, and the optical axis can be displaced when the focus position is switched. Therefore, it is difficult to guarantee accuracy. Although it is possible to observe the two positioning marks 5 and 6 respectively, the method of (2) requires two optical systems and an observing device, and connects each observed image to each relative positional relationship. It had the drawback of being difficult.

Therefore, a main object of the present invention is to provide an optical device having a relatively simple structure and capable of simultaneously observing objects at different focal positions on the same optical axis on one image plane. .

Another object of the present invention is to observe at least two alignment marks at different focal positions of at least two liquid crystal substrates on one image plane with a relatively simple structure.
It is an object of the present invention to provide an optical device for stacking liquid crystal substrates with a small displacement.

[0009]

The invention according to claim 1 is
An optical device capable of simultaneously observing objects at at least two different focal positions on the same optical axis on one imaging plane, and an objective lens provided on the optical axis and at least two focal points passing through the objective lens. A first half mirror for splitting the optical path of an image from an object at a position, and one optical path split by the first half mirror,
A second lens for combining a correction lens for changing different focal positions to the same focal position, and an optical path of the correction lens and the other optical path branched by the first half mirror
The half mirror and the observation means for observing the image formed by passing through the second half mirror.

According to a second aspect of the present invention, when at least two liquid crystal substrates each provided with a positioning mark are stacked, the positioning marks at different focal positions are simultaneously formed on one image plane. An observable optical device for holding an upper liquid crystal substrate of at least two liquid crystal substrates, a table on which the lower liquid crystal substrate is mounted, and an image of an alignment mark. Image processing for discriminating the deviation of the alignment marks provided on at least two liquid crystal substrates according to the imaging output of the imaging means, the optical system provided between the imaging means and the alignment mark, and the imaging output of the imaging means. Means and a drive means for moving the table in the horizontal direction or in the rotation direction so that the deviation determined by the image processing means is eliminated, and the optical system is the light of the imaging means. An objective lens provided above, a first half mirror for branching an optical path of an image from an alignment mark at at least two focal positions that has passed through the objective lens, and one of the first half mirrors Of the correction lens for changing different focal positions to the same focal position and the optical path of the correction lens and the other optical path branched by the first half mirror to combine at least 2 An image of one alignment mark is given to the imaging means.

The invention according to claim 3 includes a slit to be inserted into one of the optical paths according to claim 1 or 2.

The invention according to claim 4 includes an imaging lens inserted in the optical path between the objective lens according to claim 1 or 2 and the first half mirror.

[0013]

In the optical device according to the first aspect of the present invention, the optical path of the image from the object at the at least two focal positions that has passed through the objective lens is branched by the first half mirror and is inserted into one of the branched optical paths. Depending on the correction lens used,
Change different focus positions to the same focus position,
The image passing through the correction lens and the image from the other optical path branched by the first half mirror are combined by the second half mirror, and the formed image is observed by the observation means.

According to another aspect of the optical device of the present invention, the alignment marks at different focal positions of the lower liquid crystal substrate placed on the table and the upper liquid crystal substrate held by the holding means are provided. Is imaged through the same optical system as in claim 1, the deviation of each alignment mark is determined according to the imaging output, and the table is moved in the horizontal direction so as to eliminate the deviation.

[0015]

1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the optical device according to the present invention is
A device for stacking liquid crystal glass substrates so as to eliminate misalignment, which includes an XYθ table 11, an optical unit 12,
13, a CCD camera 14, 15, an image processing unit 16, a monitor 17, a control unit 18, a drive unit 19, and a holding mechanism 20. The lower liquid crystal glass substrate of the two liquid crystal glass substrates to be stacked is placed on the XYθ table 11.
The liquid crystal glass substrate can be moved in the horizontal direction, that is, in the X and Y directions, and can be rotated by an angle θ. The holding mechanism 20 is provided in the vicinity of the XYθ table 11, holds the upper liquid crystal glass substrate of the two liquid crystal glass substrates to be stacked, and is vertically movable. CCD cameras 14 and 15 and optical unit 1
2, 13 are provided above the XYθ table 11, and CC
The D cameras 14 and 15 are provided at two locations on the lower liquid crystal glass substrate placed on the XYθ table 11 and the upper liquid crystal glass substrate held by the holding mechanism 20 via the optical units 12 and 13, respectively. The alignment mark is imaged. The image output of the CCD cameras 14 and 15 is the image processing unit 1.
6, and image processing is performed. That is, when the image processing unit 16 restores the original image according to the image output, recognizes the registered shape from the original image, and calculates the positional deviation,
The control unit 18 is notified of the amount of positional deviation. As a shape recognition method, for example, there is a method in which an image is binarized in its luminance and an image matching a registered shape is recognized. Further, the image processing unit 16 includes CCD cameras 14 and 15
The image output from is supplied to the monitor 17 for monitoring.

The control unit 18 sends a processing start signal to the image processing unit 16, receives shift amount information, and calculates the shift amount of the XYθ table 11 to be actually moved from the shift amount information,
A movement command is given to the drive unit 19. The drive unit 19 moves the XYθ table 11 in the horizontal direction according to the movement command.

FIG. 2 is a flow chart for explaining the operation of the embodiment of the present invention. Next, the operation of the optical device shown in FIG. 1 will be described with reference to FIG. First, the lower liquid crystal glass substrate to be stacked is placed on the XYθ table 11, and the upper liquid crystal glass substrate is held by the holding mechanism 20.
To hold. On these liquid crystal glass substrates, the alignment marks as shown in FIG. 5 are formed at two places respectively. These alignment marks are imaged by the CCD cameras 14 and 15 via the optical units 12 and 13. The image processing unit 16 recognizes the shape from the imaged output and calculates the amount of positional deviation. When the positional deviation information is given from the image processing section 16, the control section 18 determines whether or not the positional deviation occurs, and if there is the positional deviation, sends a command signal to the driving section 19 so as to eliminate the positional deviation. Give X
The Yθ table 11 is moved. When the displacement is eliminated, the upper liquid crystal glass substrate held by the holding mechanism 20 is lowered and brought into close contact with the liquid crystal glass substrate on the XYθ table 11.

FIG. 3 is a diagram showing a specific structure of the optical section shown in FIG. In FIG. 3, the optical unit 12 divides the optical path into two, AB, and two different focal planes 121 and 122.
Is formed so as to form an image on the image plane 131. That is, the image of the object placed on the focal plane 121 is the objective lens 1
23, the image forming lens 124, the half mirror 125, and the total reflection mirror 126, and is connected to the objective lens 123 so that the images passing through the other path by the half mirror 130 are combined to form an image on the image forming surface 131. The image lens 124, the half mirror 125, the total reflection mirror 126, and the half mirror 130 are arranged to form the optical path A.

On the other hand, the image of the object placed on the focal plane 122 passes through the objective lens 123 and the imaging lens 124, is branched by the half mirror 125 and enters the optical path B, and the total reflection mirror 127, the correction lens 128, The image from the optical path A is combined by the half mirror 130 via the shutter 129 as a slit, and the image is formed on the image forming surface 131. At this time,
The refractive index and the insertion position of the correction lens 128 are determined so that light that has passed through the objective lens 123 and the imaging lens 124, which are common to the optical path A, can be correctly formed on the imaging surface 131.

Although an optical element such as a lens is not inserted in the optical path A midway, it may be inserted if necessary. Although the illumination system is not particularly shown in FIG. 3, a half mirror or the like may be provided between the objective lens 123 and the imaging lens 124 to perform coaxial epi-illumination via the half mirror. Also, the image plane 131
1, the CCD camera 14 shown in FIG. 1 is arranged, and an image is taken by the television monitor 17. Although not shown, the correction lens 128 is provided with a fine adjustment mechanism in a direction perpendicular to the optical axis, and the correction lens 128 is finely moved and adjusted with respect to the movement of the object on the focal plane 122. Is possible. The shutter 129 is used when the glass substrate for a liquid crystal display is bonded and the image needs to be observed again after the bonding is completed.
It is provided to prevent unnecessary images from being combined by closing 29.

In the optical unit 12 constructed as described above, when the optical system based on the optical path A forms an image of the object placed on the focal plane 121 on the image forming plane 131, the optical system of the object placed on the focal plane 122 is detected. Since the image is not within the depth of focus range, the image plane 13
1 does not form an image. Similarly, in the optical system based on the optical path B, the image of the object placed on the focal plane 122 is converted into the image plane 131.
However, since the image of the object placed on the focal plane 121 is not within the depth of focus range, no image is formed on the image plane 131. In this way, since the respective images that have been combined by the half mirror 130 and have passed through the two optical paths have different focal positions, the two images are formed on the image plane 131 without interfering with each other.

[0022]

As described above, according to the first aspect of the present invention, it becomes possible to form images at two or more focal positions on one image forming surface, which is disadvantageous in terms of magnification and resolution. It is possible to observe images at two or more focal positions without using an optical system with a small aperture ratio. It becomes possible to compare images on one image forming surface instead of comparing them, and it is possible to easily observe simultaneously two alignment marks having different focus positions such as bonding of glass substrates for liquid crystal display devices. it can.

According to a second aspect of the present invention, the alignment marks having different focus positions are provided on the liquid crystal substrate on the table and the liquid crystal substrate held by the holding mechanism, respectively, via the optical system of the first aspect. It is possible to pick up an image, determine the deviation of the alignment mark according to the imaging output, move the table in the horizontal direction so as to eliminate the deviation, and bring the upper liquid crystal substrate into close contact.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a flow chart for explaining the operation of the embodiment of the present invention.

FIG. 3 is a diagram showing an example of an optical section shown in FIG.

FIG. 4 is a diagram for explaining pasting of a conventional glass substrate for a liquid crystal display device.

FIG. 5 is a diagram showing an example of an alignment mark.

[Explanation of symbols]

 11 XYθ table 12, 13 Optical unit 14, 15 CDD camera 16 Image processing unit 17 Monitor 18 Control unit 19 Driving unit 20 Holding mechanism 121, 122 Focal plane 123 Objective lens 124 Imaging lens 125, 130 Half mirror 126, 127 Total reflection Mirror 128 Correction lens 129 Shutter 131 Image plane

Claims (4)

[Claims] 1. An optical device capable of simultaneously observing objects at at least two different focal positions on the same optical axis on one imaging plane, the objective lens being provided on the optical axis, A first half mirror for branching an optical path of an image from an object at the at least two focus positions that has passed through, inserted into one optical path branched by the first half mirror, and having the same different focus positions; A correction lens for changing the focus position, a second half mirror for combining the optical path of the correction lens and the other optical path branched by the first half mirror, and the second half mirror An optical device comprising an observation means for observing an image formed by passing therethrough. 2. An optical device capable of simultaneously observing alignment marks at different focal positions on one image plane when at least two liquid crystal substrates each having alignment marks are stacked. And holding means for holding the upper liquid crystal substrate of the at least two liquid crystal substrates, a table on which the lower liquid crystal substrates of the at least two liquid crystal substrates are placed, and an image of the alignment mark. Image pickup means for controlling the optical axis, an optical system provided between the image pickup means and the alignment mark, and a deviation of the alignment marks provided on the at least two liquid crystal substrates according to the image pickup output of the image pickup means. The image processing means for determining, and the table is moved in the horizontal direction or the rotating direction so as to eliminate the deviation determined by the image processing means. The optical system branches the optical path of the image from the objective lens provided on the optical axis of the image pickup means and the alignment marks at the at least two focal positions passing through the objective lens. A first half mirror, a correction lens that is inserted into one of the optical paths branched by the first half mirror, and that changes the different focus positions to the same focus position; An optical device comprising: a second half mirror that combines the optical path and the other optical path branched by the first half mirror to give an image of the at least two alignment marks to the imaging means. 3. The optical device according to claim 1, further comprising a slit inserted in the one optical path. 4. The optical device according to claim 1, further comprising an imaging lens inserted in an optical path between the objective lens and the first half mirror.