JPH09264727A - Inspecting instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accomplish discrimination between the adherence of a foreign matter to an overcoated layer and the formation of a protrusion made by the foreign matter included into the overcoated layer by identifying transmission light or reflected light from an object to be inspected as bright defect or dark defect. SOLUTION: When any foreign matter 36 adheres to an overcoated layer c, light is scattered on the foreign matter 36 to be dissipated to make an input signal into a sensor 8 dark in level. On the other hand, when a sunk part 37 is formed in the overcoated layer C, the light is scattered at the sunk part 37 to make the input signal into the sensor bright in level. When a foreign matter 35 is rolled into the overcoated layer C to form a protrusion, the protrusion part of the overcoated layer C functions as microlens so that the light passing through the layer is condensed slightly before the protruded defect and detected by a sensor as bright dot. On the other hand, the light surrounding the condensed part decreases thereby allowing detecting of the bright defect and the dark defect in a pair.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a CCD linear image sensor or the like to optically and electrically detect defects in a light-transmitting overcoat layer formed on the surface thereof, such as a color filter for liquid crystal. The present invention relates to an inspection device for detecting.

[0002]

2. Description of the Related Art Conventionally, there has been provided an apparatus for detecting defects such as foreign matters and pinholes by using reflected light or transmitted light from an object to be inspected such as a glass plate and a compact disk using a CCD sensor. For example, in the device disclosed in Japanese Unexamined Patent Publication No. 6-18439, by utilizing the fact that an opaque defect that does not transmit light and a defect that transmits light such as a pinhole output different signals, Defects such as holes are detected.

[0003]

By the way, defects such as color filters for liquid crystals having a translucent overcoat layer formed on the surface thereof, as shown in FIG. When the foreign matter 36 is attached to the layer C (a), when the foreign matter 35 is caught in the overcoat layer C to form a protrusion (b), the overcoat layer C is peeled off to form a concave portion 37. (C) etc. When this is attempted to be discriminated by the conventional inspection device, (c) can be discriminated because it induces a bright defect signal similar to a pinhole, but (a) and (b) are both opaque defects. Since the dark defect signal is induced, it is not possible to determine whether the foreign matter 36 is attached (a) or the foreign matter 35 is projected (b).

The present invention has been made to solve the above-mentioned conventional drawbacks, and an object thereof is to detect a protrusion when foreign matter is attached to the overcoat layer and when the foreign matter is caught in the overcoat layer. An object of the present invention is to provide an inspection device capable of surely discriminating between the case where it is formed.

[0005]

Therefore, in the inspection apparatus according to the first aspect, transmitted light or reflected light from the inspection object A having the light-transmitting overcoat layer C is passed through the optical system 7 including the imaging lens. The sensor 8 which receives light and the output signal from this sensor 8 are used to determine whether the defect is a bright defect having a bright signal level, a dark defect having a dark signal level, or a protrusion defect having a mixture of bright and dark signal levels. The image forming position of the optical system is set slightly before the surface of the object A to be inspected.

In this inspection apparatus, in the case where the foreign matter 36 adheres to the overcoat layer C in FIG.
Since the light is scattered and dissipated by, the input signal level to the sensor 8 becomes dark, and this is recognized as a dark defect. On the other hand, in FIG. 2C in which the overcoat layer C is peeled off to form the concave portion 37, light is scattered by the concave portion 37, so that the input signal level to the sensor 8 becomes clear. Is recognized as a bright defect. By the way, Figure 2
When the foreign matter 35 is caught in the overcoat layer C as shown in FIG.
The projection part of (2) functions as a microlens, and the light passing through this layer is condensed slightly before the projection defect (upper side in the figure). In this case, since the optical system 7 including the imaging lens projects a light-converging point slightly in front of the substrate surface (upper side in the drawing) onto the sensor 8, the foreign matter 35 causing the projection defect is black. However, the sensor 8 will detect it as a bright spot. Further, for this reason, the light around the condensing portion is reduced, and it is detected as a dark defect around the bright defect. That is, in the case of a protrusion defect, a bright defect and a dark defect are detected as a pair, and therefore, only a bright defect such as peeling of the overcoat layer and a dark defect such as adhesion of the foreign matter 36. And can be selected by a single measurement operation.

The inspection apparatus according to a second aspect of the invention is characterized in that, when a protrusion defect is determined in the above, the protrusion height is determined based on the bright defect level.

Since there is a relatively good correlation between the amount of condensed light and the height of the protrusion, the inspection apparatus according to the second aspect makes it possible to estimate the height of the protrusion.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, specific embodiments of the inspection apparatus of the present invention will be described in detail with reference to the drawings. First, the overall schematic configuration of the inspection apparatus of the present invention and the principle of signal processing will be described with reference to FIGS.

In FIG. 3, A is an object to be inspected, and this object to be inspected A has a translucent overcoat layer C formed on its surface like a color filter for liquid crystal, for example. The present invention irradiates the surface of the inspection object A with light and optically and electrically detects defects on the surface from the reflected light. The light from the lamp 1 is totally reflected by the reflection mirror 3 via the projection optical system 2 and projected onto the surface of the inspection object A. The light reflected on the surface of the inspection object A is totally reflected by the reflection mirror 6 and is received by the CCD sensor 8 via the light receiving optical system 7. Here, for example, a tungsten halogen lamp is used as the lamp 1, and for example, a condenser lens system or a collimator lens system is used for the optical systems 2 and 7. A high speed drive type CCD linear image sensor is used as the CCD sensor 8.

In the above description, the image forming position of the light receiving optical system 7 is set not at the surface of the inspection object A but at a predetermined distance L (upper side in the drawing) from the surface of the inspection object A. That is, by the CCD sensor 8, the inspection object A
Rather than observing the surface of the
The upper part is observed (for example, about 0.3 mm). Such an image forming position can be set accurately by setting the image forming position of the light receiving optical system 7 on the surface of the inspection object A and then relatively lowering the inspection object A by a certain distance L. is there.

The output of the CCD sensor 8 is signal-amplified by the CCD driver 9 and input to the A / D converter 10 and the low-pass filter (LPF) 13 in the next stage. The output signal of the CCD driver 9 fluctuates up and down with respect to the reference level when a foreign substance or a pinhole is detected. The threshold level is used to detect the signal that fluctuates up and down. However, since the detection signal itself fluctuates, if the threshold level is set to an absolute constant value, there is a risk of erroneous detection. Therefore, the threshold level is also changed according to the change of the detection signal from the CCD sensor 8.

A low pass filter 13 is used to generate the varying threshold level. That is, C
Since the output of the CD sensor 8 includes a pulse-like signal that projects vertically when a pinhole or a foreign substance is detected, a low-pass filter 13 is used to control the threshold level that smoothly changes in order to suppress this sharp fluctuation. Is generating.

By using the low-pass filter 13 to generate the threshold level, the threshold level will be delayed in time. Therefore C
The output signal from the CD sensor 8 does not correspond to the threshold level compared with this output signal.

Therefore, a delay circuit (digital delay line) 11 is provided at the next stage of the A / D converter 10, and C
By eliminating the time delay between the output signal of the CD sensor 8 and the threshold level, the two are accurately corresponded. The digital signal output from the delay circuit 11 is converted into an analog signal by the D / A converter 12, and the output signal of the D / A converter 12 and the signal from the low pass filter 13 are sent to the signal processing circuit 14. Each of the above circuits 10
The control unit 31 is constituted by 14.

The signal processing circuit 14 composed of a microcomputer or the like has a structure as shown in FIG. 4, and includes a level setting section 15 for setting the threshold level to a predetermined value and a level setting section 15. Comparators 16 and 17 for comparing the set threshold level with the output signal from the CCD sensor 8 and determination for obtaining binarized pulses corresponding to the defects of the inspection object A by obtaining outputs from the comparators 16 and 17. In the input / output interface (I / O) 22 for inputting / outputting data to / from the unit 20, the determination result of the determination unit 20, the position of the defect of the inspection object, and the personal computer 23. It is configured.

The binarized pulse train data of the judgment result of the judging unit 20 is stored in the memory 21, and the personal computer 23 sequentially reads it to perform data arithmetic processing.
The color CRT 24 displays the defective portion in a mapping display almost at the same time as the above determination result, so that the image of the defect can be instantly known. Further, the printer 26 can output the above determination result and the like. 25
Is a keyboard. 3 corresponds to that in FIG.

Next, the gist of the present invention will be described in more detail. Since the sensor 8 is located further away from the image forming position of the optical system 7 by L, the condensing point of the upper part of the inspection object A is projected on the sensor 8. In that case, FIG.
Shows a case where the particles are caught in the overcoat layer C to form a projection, and the reflected light at the portion of the foreign matter 35 is CCD.
The light is received by the sensor 8. And CCD sensor 8
The output signal from is sent to the detection means 41. Here, the detecting means 41 is composed of the level setting section 15, the comparators 16 and 17 and the judging section 20 shown in FIG.

In FIG. 1B, the AK mode video waveform is a waveform input from the CCD sensor 8,
Based on the input from the low-pass filter 13, a K mode threshold waveform (a range of 100% or more and less than 200% of the background level of the A / K mode video waveform) and an A mode threshold waveform (A / K mode video waveform background) A range of 100% or less with respect to the ground level) is generated by the level setting unit 15 and compared by the comparators 16 and 17, respectively.

By the way, when a projection in which the foreign matter 35 is caught is formed in the overcoat layer C as shown in FIG. 1A, the projection portion of the overcoat layer C functions as a microlens and passes through this layer. The light is focused slightly before the projection defect (upper side in the figure). In this case, since the optical system 7 including the imaging lens projects a light-converging point slightly in front of the substrate surface (upper side in the drawing) onto the sensor 8, the foreign matter 35 causing the projection defect is black. However, the sensor 8 will detect it as a bright spot. Further, for this reason, the light around the condensing portion is reduced, and it is detected as a dark defect around the bright defect. That is, in the case of a protrusion defect, a bright defect and a dark defect are detected as a pair, so that the signal level fluctuates up and down as shown in FIG. Therefore, the vertically oscillated signal is detected by the upper and lower threshold waveforms, and the K-mode binarization pulse as shown in FIG. 1D is provided between the A-mode binarization pulse as shown in FIG. Is detected, the determination unit 20 determines that the overcoat layer C has a protrusion defect involving the foreign matter 35. That is, a certain distance (for example, 100
The projection defect is determined on the assumption that there is a pair of A-mode binarization pulses within μm) and that there is a K-mode binarization pulse between them. At this time, there is a good correlation between the condensed light quantity, for example, the peak value of the A / K mode video waveform in FIG. 1B and the projection height, so the projection height is estimated based on the peak value. be able to.

On the other hand, when the foreign matter 36 adheres to the overcoat layer C as shown in FIG.
Since it is scattered and dissipated in the image, the image position is slightly displaced, the signal level becomes dark, and the signal changes only in one direction. Therefore, as shown in FIG. 1 (f), for example, the AK mode video waveform swings only to the lower side, becomes lower than the A mode threshold waveform, and the binarized pulse as shown in (g) is generated. Accordingly, the determination unit 20 detects that the foreign matter 36 is attached to the overcoat layer C.

Further, as shown in FIG. 1H, when the overcoat layer C is peeled off to form the concave portion 37,
Since the light is scattered by the concave portion 37, although the image forming position is slightly displaced, the signal level becomes clear and the signal changes only in one direction. Therefore, as shown in FIG.
For example, the A / K mode video waveform swings only to the upper side,
It becomes higher than the mode threshold waveform, and a binarized pulse as shown in (j) is generated.
Then, it is detected that the overcoat layer C is peeled off.

In the block diagram shown in FIG. 3, the inspection of the inspection object A by light is shown as a so-called reflection type, but it may be configured as a transmission type. Further, although the incident angle on the inspection object A is inclined with respect to the vertical (for example, 10 degrees with respect to the vertical), the incident angle may be vertical and the inspection may be of a reflection type or a transmission type.

[0024]

According to the inspection apparatus of the first aspect, the image forming position of the optical system is arranged slightly away from the surface of the object to be inspected, and any one of the bright defect, the dark defect and the protrusion defect is generated based on the output signal. Therefore, it is possible to distinguish with high probability a defect in which a foreign substance is attached to the overcoat layer and a defect in which the foreign substance is caught in the overcoat layer and forms a protrusion. Further, it is possible to discriminate a defect in which the overcoat layer is peeled off and recessed.

Since there is a relatively good correlation between the amount of condensed light and the height of the protrusion, the inspection apparatus according to the second aspect makes it possible to estimate the height of the protrusion.

[Brief description of drawings]

FIG. 1 is an explanatory diagram when a defect is determined in an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing each defect in the inspection object.

FIG. 3 is a schematic system configuration diagram of an entire inspection apparatus according to the embodiment.

FIG. 4 is a block diagram of a signal processing circuit according to an embodiment.

[Explanation of symbols]

 A inspection object 7 optical system 8 sensor 41 detecting means

Claims (2)

[Claims] 1. A sensor (8) for receiving transmitted light or reflected light from an object to be inspected (A) having a translucent overcoat layer (C) through an optical system (7) including an imaging lens. ,
A detection unit that receives an output signal from the sensor (8) and determines whether the defect is a bright defect having a bright signal level, a dark defect having a dark signal level, or a protrusion defect having a mixture of bright and dark signal levels. (41), and the image forming position of the optical system is set slightly before the surface of the inspection object (A). 2. The inspection apparatus according to claim 1, wherein when the protrusion defect is determined in the above, the protrusion height is determined based on the bright defect level.