JPH05332944A - Optical system for detecting for foreign matter on color filter - Google Patents

Abstract

PURPOSE:To simplify the conventional optical system of a drive for detecting foreign matters on a color filter. CONSTITUTION:A set of light projection system 3 and light reception system 4 are provided and a light projection angle thetaT of the light projection system 34 and a light reception angle thetaR of the light reception system 4 are set to an identical angle within 75 deg.-85 deg. for the surface of a color filter 1. A half mirror 42 is provided at the light reception system 4 for applying one part of the reflection light on the surface which is divided into two portions, a first space filter 43 which eliminated a regular reflection light LR is provided, a first light receiver 44 which receives axis-deviated reflection lights LR' and LR'' whose axis deviated for the regular reflection light LR and then detects an angular protrusion which is formed by a buried foreign object and a second space filter 45 which applies the other of the divided reflection light and allows only the regular reflection light LR to be transmitted are provided, and then a second light receiver 4 which detects an adhering object by detecting reduction in intensity of the regular reflection light LR which is transmitted through it is provided, thus forming only a simple set of light projection/reception system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter detecting optical system for a color filter for a color display liquid crystal panel.

[0002]

2. Description of the Related Art With the progress of liquid crystal and its control technology, a liquid crystal panel capable of color display on a screen of considerable size with a small amount of power has been developed, and a color filter is used for this. FIG. 3A shows an example of the color filter 1, in which a chrome thin film 12 is deposited on the surface of a glass plate 11,
A large number of fine square holes are formed in a regular array in this, and pixels 13 of three primary colors indicated by R, G, and B are cyclically planted in each square hole. Although there are various methods for arranging the pixels 13, the drawing shows a delta array in which RGB is the apex of a triangle. (b) shows a cross section of the color filter 1, and a transparent film such as polyimide or acrylic is coated with a very small thickness on the entire surface of the color filter 1 in which each pixel is implanted. Is formed. Although not shown in the drawing, an alignment film, a liquid crystal film, a thin film transistor (TFT) and the like having a minute thickness are laminated on the color filter 1 to form a color liquid crystal panel.

When a foreign substance exists in the color filter and the size thereof is, for example, several μm or more, the pixel is not obscured, and the foreign substance continuously breaks through the alignment film or the liquid crystal film. It may damage the TFT. Although the number of TFTs corresponding to each pixel is arranged, each of them is not independent in a circuit, and a large number of TFTs are connected to each other.
The damage of one TFT is not limited to one, and causes a malfunction of a series of connected TFTs. Foreign matter existing in the color filter 1 will be described with reference to FIG. (a) shows the state before the top coat 14 is coated, where the foreign matter is p, p ₁ is the middle of the pixel 13, p ₂ is the foreign matter attached to the surface of the pixel, and p ₃ is the inside of the pixel. It is a buried foreign substance buried in. What should be noted here is that the surface of the pixel rises upward due to p ₃ to form the protrusion 2. Next, in (b), the foreign matter p ₁ , p ₂ , and p ₃ are buried in the top coat in a state where the top coat 14 is coated, and in this case also, the protrusions 2 are formed on the top coat.
In addition, the foreign matter p'is a top coat after the coating is completed.
It is attached to 14. In the above, each foreign matter p ₁
Although it is assumed that ~ p ₃ and p'are spherical, in general, they are not spherical but have irregular shapes of various shapes, but the projection 2 has a simple mountain shape or a shape close to this, and this is called a mountain projection. I will call it.

Conventionally, before and after the top coat is coated on each of the above-mentioned foreign matters, 100% inspection of the color filters is performed by visual observation, and the detected foreign matters are removed as much as possible, and it is regarded as a good product. However, the visual inspection is inefficient, and there is uneven detection due to individual differences. On the other hand, it is conceivable to apply a surface inspection device that has been conventionally used for inspecting foreign substances such as a semiconductor IC wafer. However, the conventional surface inspection apparatus is a method of receiving scattered light of a foreign substance, and the foreign substance buried in the pixel 13 or the top coat 14 as shown by p ₁ , p ₂ and p ₃ in FIG. 4B above. Experiments have found that is difficult to detect because it does not scatter scattered light. On the other hand, the inventor of the present invention has devised a method for detecting a buried foreign matter, and as a prior art, “flat 2-
No. 324029, “Built-in foreign matter detection method for color filter and foreign matter inspection apparatus” has been applied for a patent. The buried foreign matter detection method according to the above patent application will be described with reference to FIG. Figure 5
In (a), a white light flux L _T is projected onto the surface of the color filter 1 at a projection angle θ _T. If the surface is smooth, the regular reflection light L _R has a direction of the regular reflection angle θ _R equal to the projection angle θ _T , but if the chevron projection 2 is present, the reflection direction changes and the axially displaced reflection light L _R ' And its reflection angle becomes θ _R '. An experiment was conducted to determine the optimum light-receiving angle θ _r of the light-receiver with respect to the projection angle θ _T by installing a light-receiver in the direction of the reflection angle θ _R '. The results show that when the projection angle θ _T is 78 °, the light-receiving angle is It was found that the axially displaced reflected light L _R 'received when θ _r was 83 ° had a peak value. FIG. 5B shows a detection signal of the photodetector obtained by scanning the surface of the color filter 1 with the white light flux L _{T. In} the waveform in which the amplitude changes by each pixel 13, the pulse p for the chevron projection 2 is shown. It is projected, and the embedded foreign matter p is indirectly detected by detecting this with an appropriate threshold value.

Since the chevron projection 2 is a three-dimensional chevron, its cross section has inclined surfaces on the left and right sides and the front and back sides. On the other hand, in the above experiment, the optimum light receiving angle θ _r of the off-axis reflected light L _R ′ with respect to the left tilted surface was described, but it is considered that other tilted surfaces cannot always be detected at this light receiving angle θ _r . .. Therefore, a buried foreign matter inspection apparatus that has not been put into practical use is provided with two sets of light emitters / receivers for the left and right inclined surfaces,
Further, the color filter 1 is rotated to receive light in four directions of 0 ° and 90 °, and the chevron projection 2 is detected in either direction. FIG. 6 shows a schematic configuration of an optical system of a practical buried foreign matter inspection apparatus, which shows two projectors 3a and 3b.
And a light receiving system 4 having two light receivers 4a and 4b are provided. The light emitting system 3a and the light receiver 4a are provided for the left inclined surface of the chevron projection 2 and the right light is provided for the right inclined surface. The light projector 3b and the light receiver 4b receive the respective axis-shifted reflected light L _R '. The color filter 1 is mounted on the mounting table 5, and the moving and rotating mechanism 6 alternately moves in the X and Y directions to scan the entire surface with the white light L _T , and the inspection is performed in the left and right directions. Then, the moving and rotating mechanism 6 rotates the color filter 1 by 90 °, and
Direction is being checked.

[0006]

The above-mentioned optical system requires two sets of light projecting and receiving systems, and thus has a drawback that the configuration is rather complicated. In order to simplify this, as a result of further studying the optimum light receiving angle θ _r of the above-mentioned light receiver, if the light projecting system and the light receiving system have the same and appropriate high angle, in the case of the above two sets, It was found that the chevron projections can be detected by a pair of light emitting and receiving systems as in the above. However, for the left-right direction and the front-back direction, the color filter 1
Rotate and measure in two directions, 0 ° and 90 °. In addition,
The foreign matter inspection device also needs to detect the adhered foreign matter, and for this purpose also serves as a light projecting system, and a light receiver for the adhered foreign matter is separately provided to receive light in two directions. The detection in this case can be performed by utilizing the fact that the intensity of the specular reflection light is reduced due to the scattered light of the adhering foreign matter. The present invention has been made to simplify the optical system of a foreign substance inspection device for a color filter, and based on the above-mentioned examination results, a set of a light projecting and receiving system for detecting the chevron projections 2 and a light receiving system attached thereto. A light detector for foreign matter is added, and the color filter is rotated in two directions of 0 ° and 90 ° by the moving / rotating mechanism 6 of the inspection device, thereby providing a foreign matter detection optical system capable of detecting both embedded foreign matter and adhered foreign matter in good condition. The purpose is to do.

[0007]

SUMMARY OF THE INVENTION The present invention is a foreign matter detection optical system for a color filter, comprising: (1) one set of a light projecting system and a light receiving system, They are arranged symmetrically with respect to the surface normal, and the projection angle θ _T of the projection system and the reception angle θ _R of the reception system are 7 with respect to the surface of the color filter.
Set to the same angle within the range of 5 ° to 85 °. (2) For the light receiving system, a half mirror that splits the reflected light on the surface that is input to the light receiving system and one that is split by the half mirror, and the first space that removes the specularly reflected light on the surface. A first light receiver that has a filter, transmits the first spatial filter, receives the off-axis reflected light that is off-axis with respect to the regular reflected light, and detects the protrusion formed by the embedded foreign matter, and two divisions. A second spatial filter that transmits only the specularly reflected light that is input to the other of the two, and detects the adhered foreign matter by detecting a decrease in the intensity of the specularly reflected light that has passed through the second spatial filter. And two light receivers.

[0008]

In the above foreign matter detection optical system, the projection angle θ _T
And the acceptance angle θ _R are 75 ° with respect to the surface of the color filter.
A set of light projecting system and light receiving system are arranged symmetrically with respect to the normal to the surface, with the same angle in the range of ~ 85 °. A white light flux from the projection system is projected on the surface, and the color filter is rotated in two directions of 0 ° and 90 ° by the moving and rotating mechanism,
The entire surface is scanned respectively. The reflected light received by the light receiving system includes specular reflected light on the surface and axially displaced reflected light on the left and right or front and rear inclined surfaces of the chevron projection, which are divided into two by a half mirror. .. One of the two parts is specularly reflected light is removed by the first spatial filter,
The off-axis reflected light is received by the first photodetector, and chevron projections are detected in either the 0 ° or 90 ° direction, or in both directions. On the other hand, the second spatial filter removes the axially reflected light due to the chevron protrusions or the scattered light due to the adhered foreign matter, and only the specularly reflected light is transmitted and received by the second light receiver. Since the intensity of the specularly reflected light received by the second light receiver is reduced due to the axially displaced reflected light or scattered light, a pulse for this reduction appears in the received light signal,
Adhering foreign matter is detected by detecting this. In the above, the color filter is rotated in two directions of 0 ° and 90 °, and the projection system and the first photoreceiver are used for the chevron projections, and the projection system and the second projection system are also used for the adhering foreign matter. Since the optical receiver performs inspection in two directions and detects each in either direction or both directions, the optical system is significantly simplified as compared with the conventional one.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of detecting a buried foreign matter in the foreign matter detecting optical system of the present invention will be described with reference to FIG. In the color filter 1 of FIG. 1, the foreign matter p buried in the pixel 13 or the top coat 14 causes the mountain-shaped projections 2 to occur on the surface thereof. When the white light flux L _T is projected onto the chevron projection 2 at a projection angle θ _T , the apex of the chevron projection 2 is horizontal, and as shown by the chain double-dashed line, a reflection angle θ _R equal to the projection angle θ _T. The specularly reflected light L _R is reflected at. On the other hand, the reflected light L _R 'from the inclined surface on the left side of the chevron protrusion 2 is axially displaced to the left by twice the inclination angle of the inclined surface (varies depending on the position), and the reflected light on the inclined surface on the right side. L _R ″ is offset to the right by twice the tilt angle. Therefore, the spread angle of the off-axis reflected lights L _R ′ and L _R ″ is four times the maximum value of the tilt angle. Looking at this inclination angle numerically, the size of the chevron protrusion 2 is such that the bottom surface is, for example, about 100.
When it is μm, the height is about several μm, and the maximum value of the inclination angle is 3 to 4 degrees at most. Therefore, the spread angle is 2
It becomes 0 degrees or less, and this can be received by one light receiver, which is the principle of detection of the embedded foreign matter of the present invention. However, the regular reflected light L _R is the axially displaced reflected light L _R ', L _r ``
Therefore, it is necessary to remove it.
In addition, in order to ensure detection, 0 ° and 90
It shall be inspected in two directions. As described above, the first light receiver is provided in the direction of the light receiving angle θ _{R that} is the same as the light projecting angle θ _T ,
By removing the regular reflection light L _R and receiving the axially displaced reflection lights L _R ′ and L _R ″, the chevron projection 2 can be detected. However, if θ _T and θ _R are made small, the scattered light at the edge of the pixel 13 is input to the light receiving system and also becomes noise. Therefore, it is desirable to make them large within a range that does not interfere with the configuration of the optical system. From the above, θ _T and θ _R are from 75 ° to
A range of 85 ° is suitable. Next, although illustration of the adhered foreign matter is omitted, focusing on the specular reflection light L _{R that} has become noise in the above, since L _R is scattered by the adhered foreign matter (the same applies to the buried foreign matter), the intensity decreases. A second photodetector is provided to detect the adhering foreign matter by the lowering pulse included in the photodetection signal. in this case,
The scattered light of the adhering foreign matter and the off-axis reflected light L _R ′ and L _R ″ become noise and therefore need to be removed.

2A and 2B show an embodiment of the foreign matter detecting optical system of the present invention. FIG. 2A is an overall configuration diagram and FIG. 2B is a partial view. In FIG. 2 (a), the foreign matter detection optical system is constructed by arranging a set of a light projecting system 3 and a light receiving system 4 symmetrically with respect to a vertical line C on the surface of the color filter 1. The light projecting system 3 and the light source 31 of a halogen lamp, made from a slit plate 33 to projection lens 32 for collimating the white light, and white light with the light beam L _T, through a slit plate 33, mounted on the mounting table 5 Further, the white light flux L _T is projected onto the surface of the color filter 1 at the projection angle θ _T , and is also used for detecting the embedded foreign matter and the adhered foreign matter. The light receiving system 4 includes a condenser lens 41 that collects the reflected light on the surface and a half mirror 42 that divides the collected reflected light into two.
And. Further, one of the two divided light beams is input, and the first spatial filter 43 that removes the specular reflection light L _R and the first spatial light filter 43 that receives the axially displaced reflection lights L _R ′ and L _R ″ that have passed through the first spatial filter 43 are received. the photodetector 44 is provided, also by entering two other split portion, a second spatial filter 45 which only specularly reflected light L _R is transmitted through the second light that receives the specularly reflected light L _R transmitted through this It is configured by providing a container 45. Each of the light receivers 44 and 46 is arranged at the image forming point of the condenser lens 41 by using a CCD linear sensor, and the first and second spatial filters 43 and 45 are arranged immediately before them. FIG. 2B shows an example of the slit plate 33 and the first and second spatial filters 43, 45. The slit 331 of the slit plate 33 has a width W _{X in the} scanning direction as an interval corresponding to the irradiation width, The length W _Y in the Y direction is set to a length corresponding to the CCD sensor, but if these are too large compared to the size of the chevron protrusion or the adhered foreign matter, the detection sensitivity will decrease, and if it is too small, the scanning time will be long. Since they conflict with each other, set to an appropriate value through experiments. Further, the first and second spatial filters 43, 45 are provided with notches 431, 432 for transmitting only the axis-shifted reflected light L _R ′, L _R ″ and a notch 451 for transmitting only the specularly reflected light L _R , respectively. Set up. In the figure, the shapes of these notches are rectangular, but the shape and dimensions greatly affect the detection performance of the chevron protrusions and adhered foreign matter, so the shape is not limited to a rectangle.
Similar to the above, each is set appropriately by experiments or the like so that these can be detected well. In the foreign matter detection optical system described above, the white light flux L _T from the light projecting system 3 is projected on the surface of the color filter 1, and is moved in the X and Y directions by the moving and rotating mechanism 6 to scan the entire surface to 0 °. Rotate in two directions of 90 ° and inspect each. The reflected light on the surface is received by the light receiving system 4, and the first and second light receivers 44, 4
Predetermined processing is performed on each received light signal of 6,
Buried foreign matter and adhering foreign matter are detected in either or two directions.

[0011]

As described above, in the foreign matter detecting optical system according to the present invention, the buried foreign matter buried in the pixels of the color filter or the top coat, or the foreign matter adhered to the surface of the foreign matter is 0 ° in the color filter. And 90 °
In either direction or both directions, the first photodetector of the light projecting system and the photoreceiver system causes the buried foreign matter to rotate.
In addition, the second light receiver, which also serves as a light emitting system and a light receiving system, can detect adhering foreign matter satisfactorily. The optical system is remarkably simpler than the conventional inspection device using two sets of light emitting and receiving systems. There is a great effect in being realized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a principle of detecting a buried foreign matter in a foreign matter detection optical system of the present invention.

2A and 2B show an embodiment of a foreign matter detection optical system of the present invention, wherein FIG. 2A is an overall configuration diagram and FIG. 2B is a partial view.

FIG. 3A is a diagram showing an example of a color filter, and FIG.
FIG. 3 is an explanatory diagram of a top coat coated on a color filter.

FIG. 4 is an explanatory diagram of foreign matter existing in a color filter,
(a) is the state before the top coat is coated,
(b) shows the coated state, respectively.

5A and 5B are explanatory views of a prior art buried foreign matter detection method according to a patent application, in which FIG. 5A is an explanatory view of a chevron protrusion due to the buried foreign matter and a reflection angle of reflected light due to the projection, and FIG. It is a figure which shows an example of the waveform of a signal.

FIG. 6 is a schematic configuration diagram of an optical system of a conventional buried foreign matter inspection apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Color filter, 11 ... Glass plate, 12 ... Chrome thin film, 13 ... 3 Primary color pixels 14 ... Top coat, 2 ... Angle projection, 3 ... Projection system, 3a, 3
b ... Emitter, 31 ... Light source, 32 ... Emitter lens, 33 ... Slit plate, 331 ... Slit, 4 ... Light receiving system, 4a, 4b ... Light receiver,
41 ... Condensing lens, 42 ... Half mirror, 43 ... First spatial filter, 431, 432 ... Notch, 44 ... First light receiver, 45 ...
Second spatial filter, 451 ... Notch, 46 ... Second light receiver, 5 ... Mounting table, 6 ... Moving and rotating mechanism, p, p _{1 to} p ₃ ,
p '... foreign matter, L _T ... white light flux, L _R ... specular reflection light, L _R ',
L _R ″ ... Axis off reflected light, θ _T ... Projection angle, θ _R ... Reflection angle.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yutaka Kumazawa, 2-6-2 Otemachi, Chiyoda-ku, Tokyo, inside Nitrate Electronics Engineering Co., Ltd. (72) Tadahiro Furukawa, 4-12-12 Koishikawa, Bunkyo-ku, Tokyo Kyodo Printing Co., Ltd. (72) Inventor Ichiro Betsumiya 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Kyodo Printing Co., Ltd. (72) Inventor Shinji Mizumoto 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Joint printing Within the corporation

Claims (1)

[Claims] 1. A color filter, in which pixels of three primary colors are arranged, is targeted, and the color filter is mounted on the X or Y axis.
A moving and rotating mechanism that moves in a direction and rotates by 90 °, a light projecting system that projects a white light beam on the surface of the color filter to scan, and a light receiving system that receives the reflected light of the surface. The color filter is rotated by a rotating mechanism, the reflected light is received by the light receiving system in two directions of 0 ° and 90 °, and the embedded foreign matter is embedded in the pixel or the top coat coated on the color filter. Alternatively, in a foreign matter inspection device for detecting adhered foreign matter, (1) one set of the light projecting system and the light receiving system are symmetrically arranged with respect to the surface normal, and the light projecting angle θ _T and the light receiving angle of the light projecting system are received. The light receiving angle θ _{R of the} system is set to the same angle within the range of 75 ° to 85 ° with respect to the surface of the color filter, and (2)
A half mirror that splits the reflected light of the surface that is input to the light receiving system into two and one of the reflected light that is split into two by the half mirror are input to the light receiving system, and specularly reflected light of the surface is removed. A first spatial filter that transmits the first spatial filter, receives the axially displaced reflected light that is axially displaced from the specularly reflected light, and detects the chevron protrusion formed by the embedded foreign matter. The first light receiver and the second of the reflected light divided into two are inputted, and the second light transmitting only the specularly reflected light
A second photodetector for detecting the adhering foreign matter by receiving the specular reflection light transmitted through the second spatial filter and detecting a decrease in intensity of the received light signal. A foreign matter detection optical system for a color filter, which is configured to be provided.