TWI391652B - Edge sensor and defect inspection device - Google Patents

Description

Edge sensor and defect inspection device

The present invention relates to an edge sensor suitable for detecting defects or cracks such as edges of liquid crystal glass and a defect inspection device using the edge sensor.

The present inventors first focused on Fresnel diffraction of monochromatic parallel light at the edge of an object, and proposed by using a line type sensor in which a plurality of light-receiving unit cells are arranged at predetermined intervals. The light amount distribution pattern is analyzed, and the edge position of the object can be detected with high precision by the accuracy of the arrangement interval of the light receiving unit cells of the line sensor (refer to Japanese Patent No. 3858998).

In addition, a transparent body or a translucent body such as a liquid crystal glass is also proposed in which the edge position is detected with high precision, and a method of detecting the edge position with high precision has been proposed (refer to Japanese Laid-Open Patent Publication No. 2007-64733).

However, when there is a defect or a crack at the edge of the vitreous body, the defect portion due to the aforementioned defect or crack in the inside of the vitreous body is affected by the reflected light. Therefore, it is extremely difficult to correctly detect the edge from the light amount distribution pattern of the freonai diffraction described above. And, even if there is an edge position of the vitreous body with a defect or crack at the edge, along The edge is detected while moving the line sensor, and it is not easy to accurately detect the change in the edge position. Therefore, it is extremely difficult to define defects in the vitreous that cause defects or cracks.

The present invention has been made in order to solve the above-described circumstances, and an object of the invention is to provide an edge sensor for detecting an edge position of an object from a light amount distribution pattern generated by a franena diffraction of an edge of an object. An edge sensor such as a liquid crystal glass that defects such as defects or cracks generated by a transparent or translucent object is reliably detected.

Moreover, another object of the present invention is to provide a defect inspection apparatus capable of accurately detecting a defect portion such as a liquid crystal glass such as a defect or a crack generated by a transparent or translucent object by using the edge sensor described above. .

In order to achieve the foregoing object, the edge sensor of the present invention is provided with: a line type sensor in which a plurality of light receiving unit cells are arranged at predetermined intervals; a light source that projects monochromatic parallel light toward the line type sensor; The edge sensor of the calculation unit that analyzes the output of the line sensor and detects the specific position (edge) of the object positioned in the optical path of the monochromatic parallel light, and the calculation unit searches for the line type sensing by the free space side, for example. The output of the device analyzes the light quantity distribution pattern on the line sensor, and particularly includes: <A> searching for the amount of light generated from the edge of the transparent or translucent object from one end to the other end The amount of light when distributing the pattern is reduced to the first The first position detecting means obtained by determining the position of the light amount threshold as the first detecting position of the object, the first light amount threshold is determined based on the amount of light in the free space; <B> will be detected in the first When the detection position is further lowered, the second position detecting means is obtained as the second detection position of the object by the position of the second light amount threshold set based on the amount of light in the free space.

Further, the first and second light amount thresholds may be individually set, but the same value may be given.

Further, the defect inspection device of the present invention includes the device comprising the edge sensor having the above-described configuration, and is characterized in that: <a> scanning means for causing the line sensor of the edge sensor Moving along the edge of the aforementioned transparent or translucent object, or moving a transparent or translucent object in a direction crossing the line sensor of the edge sensor; <b> defect detection means, which is accompanied by the foregoing The linear sensor or the scan of the object monitors the change of the first and second detection positions detected by the first and second position detecting means of the edge sensor, and the first or second detection When the amount of change in the position exceeds a threshold set in advance, a predetermined process of issuing a warning class is executed.

Further, the other defect inspection apparatus of the present invention includes the edge sensor having the above-described configuration, and is characterized in that: <c> a light-shielding width detecting means for the first one of the edge sensors And the first and the second detected by the second position detecting means 2 detecting the difference in position as the shading width; <a> scanning means, which is to move the aforementioned line sensor of the edge sensor along the edge of the transparent or translucent object, or to make transparent or The translucent object moves in a direction crossing the line sensor of the edge sensor; and <d> a defect detecting means, which is accompanied by the scanning of the line sensor or the object, and is monitored by the aforementioned shading The light-shielding width obtained by the width detecting means issues a warning when the light-shielding width exceeds a predetermined threshold.

Incidentally, the transparent or translucent object is a glass plate, and the defect detecting means is configured to detect a defect or a crack of the edge of the glass plate, and a recess (a defect that deforms the edge line), and display a display defect. Warning.

According to the edge sensor of the above configuration, the amount of light is reduced from the light amount distribution pattern generated at the edge of the object to the position of the first light amount threshold set based on the amount of light in the free space (the amount of light is large) The change position is detected as the first detection position (for example, the edge position) of the object, and since the object is transparent or translucent, as described above, the first detection position is closer to the object side than the detected first detection position. The portion where the amount of light generated is large is detected by the first detection position being further lowered, and then increased to the second detection position of the second light amount threshold set based on the amount of light in the free space. From these two By detecting the relationship of the positions, it is possible to determine whether or not the edge of the object is defective.

That is, when there are defects such as defects or cracks at the edge of the object, the transmission of light inside the transparent or translucent object is changed by these defects, and the amount of light generated at the normal edge without defects is formed. Since the light amount distribution patterns having different patterns are distributed, it is easy to discriminate the change in the light amount distribution pattern from the above two detection positions. As a result, it is easy to determine whether or not the edge of the object is defective from the relationship between the two detection positions.

Further, according to the defect inspection apparatus of the present invention, the linear sensor of the edge sensor is moved along the edge of the transparent or translucent object or the transparent or translucent object tide and the aforementioned edge feeling are caused. When the linear sensor of the detector moves in the direction in which the detector crosses, the first and second detection positions are respectively obtained, and the detected detection position is determined. Therefore, the change of the two detection positions can be detected. The defect of the defect or the crack, and the information of the detection position (scanning position information) of the aforementioned detection position at the time of detecting the defect can easily determine the existence position of the defect.

Therefore, it is possible to detect the change in the light amount distribution pattern at the edge of the transparent or translucent object, and it is possible to easily and easily detect the presence of a defect such as a defect or a crack of the edge of the object, and thus it is extremely practical. advantage.

Hereinafter, an edge sensor according to an embodiment of the present invention and a defect inspection device using the edge sensor will be described with reference to the drawings.

1 is a transparent or translucent object A for detecting, for example, liquid crystal glass or the like The edge sensor 10 of a specific position (for example, an edge position) and the position detection target portion of the object A detected by the edge sensor 10 are scanned while monitoring the output of the edge sensor 10 A schematic configuration diagram of the defect inspection device for the presence or absence of the object A.

The edge sensor 10 is configured to: a line type sensor 11 that arranges a plurality of light receiving unit cells on a straight line at a predetermined pitch; and a light source 12 that projects a monochromatic parallel light toward the line type sensor 11; An optical head 13 in which the sensor and the light source are disposed opposite each other with a predetermined distance; and an output of the line sensor 11 is analyzed to detect a specific position of the object A placed in the optical path of the monochromatic parallel light The operator 14 (e.g., edge position).

In addition, the basic structure (structure) of the optical head 13 is described in the above-mentioned Japanese Patent No. 3,958,994, and JP-A-2007-64733. Further, the scanning of the position detecting target portion of the object A by the edge sensor 10 is performed by causing the aforementioned line sensor 11 (optical head 13) of the edge sensor 10 to be along the aforementioned transparent or translucent The edge of the object A is moved to perform. Or conversely, by moving the transparent or translucent object A toward the direction intersecting the line sensor 11 of the edge sensor 10, specifically, the direction intersecting the arrangement direction of the plurality of light receiving cells, To perform the scan.

Further, the operator 14 is realized by, for example, a CPU, and analyzes the light amount distribution pattern generated on the line sensor 11 at the edge of the object A described above from the output of the line sensor 11. ,Come The functions 15, 16 of the specific position of the object A (including, for example, the first and second detection positions described later at the edge position) are calculated. Here, the light amount distribution pattern is generally a pattern of the Fresnel diffraction generated by the monochromatic parallel light.

Incidentally, the configuration of the arithmetic unit 14 is basically erecting the light amount distribution pattern when the light receiving amount of the line sensor 11 which is not freed by the object A is normalized to [1]. In the part, the position at which the received light amount is [0.25] is detected as the detection position (edge position) of the object A. In other words, the arithmetic unit 14 is a position at which the light amount is a predetermined light amount threshold value [0.25] defined by the light amount [1] in the free space on the light amount distribution pattern of the freon. The specific position (edge position) of A is detected.

The present invention is directed to the fact that the object A to be detected is transparent or translucent, and the output of the line sensor 11 is as shown in FIG. 2, not only in the free space in which the object A is not positioned, but also in the aforementioned amount. The portion of the object A that has been positioned, the monochromatic parallel light that has passed through the object A also reaches the line sensor 11, so that the amount of light received is large. Further, in the case where the object A is a light-shielding body, attention is paid to the fact that the amount of received light does not largely decrease at the edge portion, but in the case where the object A is transparent or translucent, only the edge portion of the object A is subjected to the freon. The amount of light received will be somewhat reduced by the effect of the shot. Further, when there is a defect such as a defect or a crack at the edge of the object A, attention is paid to the random diffraction, refraction, scattered reflection, and the like of the monochromatic parallel light of the defect portion. here In other cases, the width of the portion where the amount of received light is lowered (lower) becomes wider than when the fringe is generated at the edge of the straight line (the blade edge).

That is, the output of the line sensor 11 when the detection position of the liquid crystal glass as the transparent object is detected using the optical head 13, as shown in Figs. 3(a) to (d), respectively, depending on whether or not the edge of the liquid crystal glass exists. Defects can cause differences in the distribution pattern of the amount of light received. Further, Fig. 3(a) shows the light-receiving pattern of the edge portion where the defect is not present, and Fig. 3(b) shows the light-receiving pattern when there is a minute defect in the edge portion, and Fig. 3(c) shows the edge portion. There is a distribution pattern when there is a crack, and FIG. 3(d) is a distribution pattern when there is a depression due to a defect at the edge portion.

As shown in the distribution patterns of the received light amounts shown in FIGS. 3(a) to 3(d), compared with the case where there is no defect at the edge of the object A, in the case where defects such as defects or cracks exist, the edge is present. The portion of the amount of light becomes large, and the width of the amount of light becomes wider. However, the position of the low amount of light detected on the free space side is not affected by the presence or absence of the defect, and hardly changes. Further, the position of the low amount of light detected on the object side largely changes depending on the type and degree of the defect, and various types of changes occur in the low-profile type (pattern in which the amount of light changes). Further, when there is a defect in the detection position, a large distribution is generated in the amount of received light on the object A side through which the original light is substantially transmitted.

Therefore, the edge sensor 10 of the present invention includes the first position detecting means 15 and the second position detecting means 16. The first position detecting means 15 is when the free space side of the object A is never positioned When the output of the line sensor 11 is searched for, the first detection position α of the object A is obtained from the portion where the amount of light is drastically lowered due to the freon diffraction generated at the edge of the object A. The second position detecting means 16 obtains the second detection position β of the object A, and the second detection position β is the first detection position α obtained from the first position detecting means 15, and the amount of received light is further increased. After the reduction, the position where the amount of received light increases again.

By the way, in this embodiment, for example, the amount of received light is reduced to a position of [0.825] from the normalized light amount [1.0] on the free space side, that is, to a position where the first and second light amount thresholds are set in advance as a position. The first and second detection positions α and β are detected, respectively. Here, the first and second light amount threshold values are set to the same value [0.825], but may be set to mutually different values. Further, in this embodiment, in particular, by searching for the output of the line sensor 11 from the free space side, it is not affected by the irregularity of the amount of received light generated on the object A side due to the defect, and can be separately The first and second detection positions α, β necessary for defining the low portion of the received light amount corresponding to the detection position (edge position) of the object A are surely detected. However, the output of the aforementioned line sensor 11 can also be searched from the object A side. In addition, when the amount of received light is normalized, the amount of light in the free space can be measured and stored in the state where the object A is not provided, and when it is detected, it can be measured and stored in free space. The amount of light is normalized, and it is also possible to use the area where the amount of received light is small as a free space from the detection result.

Use of the inspection of the object A detected by such an edge sensor 10 The defect inspection device that performs the defect inspection of the object A by the information of the measurement position (the first and second detection positions α, β) includes a detection target portion of the detection position of the object A using the optical head 13 A scanning means (scanning mechanism) 21 for moving the edge of the object A. The scanning means 21 may be an object supporting mechanism (not shown) having a function of moving the object A in parallel along its edge, and conversely, the optical head 13 may be along the edge of the object A. A moving mechanism (not shown) that moves in parallel. That is, the scanning means 21 may be a person who moves the object A in a direction in which the object A intersects with the line sensor 11, and conversely, the line sensor 11 may be moved in parallel along the edge of the object A.

In addition to the scanning means 21, the defect inspection apparatus further includes a defect detecting means (prone determination means) 22 for sequentially executing the use of the arithmetic unit (CPU) 14 in association with the scanning of the position detecting target portion. The above-described detection processing of the first and second detection positions α, β monitors the change in the output (the first and second detection positions α, β), thereby detecting the presence or absence of a defect such as a defect or a crack at the edge of the object A. Furthermore, in this embodiment, the information of the first and second detection positions α, β detected by the edge sensor 10 is temporarily stored in the memory 23, and the first and second detection positions are The change pattern (the tendency to change) is read out from the defect detecting means 22 described above, and the defect inspection is performed.

Then, when the change width of the first detection position α or the second detection position β described above exceeds the allowable width set in advance, for example, the defect detection means (prone determination means) 22 determines that the state is "defective". At the same time, the defect inspection of the aforementioned object A when it is judged as "defective" The part (scanning position) is detected as a defective portion. Further, the allowable width of the change width of the first detection position α or the second detection position β is set in accordance with the degree of linearity required for the edge of the object A.

Further, the defect detecting means (trend determining means) 22 may detect, for example, a difference between the first detecting position α and the second detecting position β as a low width (light blocking width) of the light amount of the light amount distribution pattern, and monitor The difference between the aforementioned detection positions α, β (the drop width of the light amount) when the edge of the object A is scanned. Then, when the difference in the detected position (the low width of the light amount) exceeds the allowable value set in advance, the state is judged as "defective". Even in this case, the defect inspection portion (scanning position) of the object A when it is determined to be "defective" is detected as a defective portion. Further, the allowable value of the difference (the low width of the light amount) of the above-described detection position is set in accordance with the degree of linearity required at the edge of the object A.

In the above-described defect inspection apparatus, the detection position of the transparent or translucent object A is detected as the first and second detection positions α and β, respectively, by the edge sensor 10 described above. The position detection target portion is moved along the edge, and the change state (the tendency of change) of the first and second detection positions α and β is monitored. Therefore, according to the present device, when the change of the first or second detection position α, β exceeding the preset allowable value is detected, or the difference between the first detection position α and the second detection position β exceeds the allowable width At this time, it is possible to confirm this situation as a defect such as a defect or a crack at the edge of the object A. Ground detection. Further, according to the present device, it is possible to detect at any of the edges of the object A whether or not there is a defect such as a defect or a crack.

Fig. 4 (a) shows a state in which the first and second detection positions α, β are changed when the edge detection is performed using the liquid crystal glass having the defect as an example. In this example, almost no change is observed with respect to the first detection position α, but a large change is seen in the width range of the portion corresponding to the defect with respect to the second detection position β. Moreover, FIG. 4(b) shows a state in which the first and second detection positions α and β are changed when the edge detection is performed by using the liquid crystal glass having cracks as an example. In this example, almost no change is observed in the first detection position α. However, as for the second detection position β, a large change is also seen in the width range of the portion corresponding to the crack.

In addition, FIG. 4(c) shows a state in which the first and second detection positions α and β are changed when the edge detection is performed on the liquid crystal glass which is recessed due to the defect. In this example, with respect to the first detection position α, a few changes can be seen in the concave portion, but with respect to the second detection position β, a large change can be seen in the range corresponding to the width of the concave portion. 5(a) to (c) are diagrams corresponding to those of Figs. 4(a) to 4(c), respectively, and the amount of movement of the edge sensor 10 or the translucent body A is plotted as the horizontal axis, and the first display is displayed. And the state of the change of the second detection position α, β. Even if the edge detection result is displayed as described above, the tendency to change is the same as that shown in the above-described FIGS. 4(a) to 4(c).

Therefore, as described above, the edge of the object A is monitored by monitoring the edge sensor 10 of the present invention which is added to the first detection position α detected by the general edge sensor and detects the second detection position β. Scanning In the defect inspection device of the present invention in which the first and second detection positions α and β are changed, it is possible to reliably detect a minute defect such as a defect or a crack generated at the edge of the object A such as liquid crystal glass. Further, since the detection can be performed on the portion where the defect is present, it is extremely excellent in practicality in managing the quality of, for example, liquid crystal glass.

Further, in the case of detecting a defect, it is desirable to perform a predetermined action in response to the situation. In the predetermined operation, an operation instruction such as a warning or an alarm is issued, or a removal device for removing the defective object A by the process is provided, and a means for performing an instruction to perform the removal process may be employed. Thereby, the correspondence to the defective product can be easily performed.

Further, when there is a defect such as a defect or a crack at the edge of the object A, as described with reference to FIGS. 3(a) to 3(d), a change in the amount of received light occurs even on the object A side. Therefore, in the case where the transparent or semi-transparent object A is not contaminated, and the amount of light in the object A portion (inside the object) is stabilized, for example, the inner side of the normal object A can be obtained in advance. As shown in FIG. 3( a ), the light amount distribution on the inner side of the object A to be inspected is compared with the light amount distribution described above to perform defect inspection. Further, as shown in Figs. 3(b) to 3(d), the light amount distribution on the inner side of the object A to be inspected can be obtained, and the light amount distribution of the normal object A shown in Fig. 3(a) can be obtained. At the same time, this condition is judged to be a defect such as a defect or a crack. Moreover, if this method is used in combination with the method of determining the change of the second detection position described above, it is possible to further perform the inspection of the minute defect of the edge of the object A. Measurement.

Furthermore, the present invention is not limited to the above embodiment. For example, the first and second light amount threshold values at the time of detecting the first and second detection positions α and β are not limited to the above-mentioned [0.825], and the detection position of the transparent or translucent object A at the edge is detected. The degree of lightness of the edge portion can be set. Further, the detection width by the line sensor 11 may be determined in accordance with the distance (working distance) between the line sensor 11 and the object A. Further, various changes and modifications can be made without departing from the spirit and scope of the invention.

10‧‧‧Edge sensor

11‧‧‧Linear sensor

12‧‧‧Light source

13‧‧‧ Optical head

14‧‧‧Operator (CPU)

15‧‧‧1st position detection means

16‧‧‧2nd position detection means

21‧‧‧Scanning means (scanning mechanism)

22‧‧‧ Defect detection means (trend identification means)

23‧‧‧ memory

Fig. 1 is a schematic block diagram showing an edge sensor and a defect detecting device according to an embodiment of the present invention.

2 is a view showing a relationship between a light amount distribution pattern of a line type sensor and a detection position detected by the aforementioned edge sensor.

Fig. 3 is a graph showing a change in the light amount distribution pattern in which the edge has a defect or a change thereof.

Fig. 4 is a view showing a state of a change in the first and second detection positions of the scan with respect to the inspection site.

Fig. 5 is a view showing a state in which the amount of movement of the edge sensor or the translucent body is changed by the first and second detection positions.

10‧‧‧Edge sensor

11‧‧‧Linear sensor

12‧‧‧Light source

13‧‧‧ Optical head

14‧‧‧Operator (CPU)

15‧‧‧1st position detection means

16‧‧‧2nd position detection means

21‧‧‧Scanning means (scanning mechanism)

22‧‧‧ Defect detection means (trend identification means)

23‧‧‧ memory

Claims (7)

An edge sensor comprising: a line type sensor in which a plurality of light receiving unit cells are arranged at a predetermined interval; a light source that projects a monochromatic parallel light toward the line type sensor; and an output of the line type sensor An edge sensor of the calculation unit that detects the specific position (edge) of the object positioned in the optical path of the monochromatic parallel light, and the calculation unit includes: a first position detecting means that is The position where the light amount at the time when the one end portion searches for the light amount distribution pattern generated at the edge of the transparent or translucent object toward the other end portion is lowered to the first light amount threshold value is obtained as the first detection position of the object, and the first The light amount threshold is defined based on the amount of light in the free space; and the second position detecting means increases the amount of light in the free space after the detected first detection position is further lowered. The position of the second light amount threshold set as a reference is obtained as the second detection position of the object. The edge sensor according to claim 1, wherein the calculation unit analyzes the light amount distribution pattern on the line sensor by the output of the free space side search line sensor. A defect inspection device characterized by comprising: an edge sensor according to claim 1 of the patent application; wherein the line sensor of the edge sensor is moved along an edge of the transparent or translucent object Scanning means; and With the scanning of the line sensor, the first or second detection position is monitored by the first and second detection positions obtained by the first and second position detecting means of the edge sensor. A defect detection means that issues a warning when the amount of change exceeds a predetermined threshold. A defect inspection device comprising: an edge sensor according to claim 1 of the patent application; and the first and second position detection means detected by the edge sensor a light-shielding width detecting means for determining a difference between the second detecting positions as a light-shielding width; and a scanning means for moving the line-shaped sensor of the edge sensor along an edge of the transparent or translucent object; The scanning of the line sensor monitors the light-shielding width obtained by the light-shielding width detecting means, and when the light-shielding width exceeds a predetermined threshold value, a defect detecting means for issuing a warning is issued. A defect inspection device characterized by comprising: an edge sensor according to claim 1; moving the transparent or translucent object toward a line sensor of the edge sensor; a scanning means; and a scan of the object to monitor a change in the first and second detection positions obtained by the first and second position detecting means of the edge sensor, and the first or second A defect detecting means that issues a warning when the amount of change in the detected position exceeds a threshold set in advance. A defect inspection device comprising: an edge sensor according to claim 1 of the patent application; and the first and second detections respectively detected by the first and second position detecting means of the edge sensor a detection means for detecting a difference in position as a light-shielding width; and a scanning means for moving the transparent or translucent object toward a line sensor intersecting the line sensor; The scanning monitors the light-shielding width obtained by the light-shielding width detecting means, and when the light-shielding width exceeds a predetermined threshold value, a warning detecting means for issuing a warning is issued. The defect inspection device according to any one of claims 3 to 6, wherein the transparent or translucent object is a glass plate, and the defect detecting means is a defect or a crack for detecting an edge of the glass plate.