JPH11148902A - Apparatus for inspecting surface flaw of flat substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform not only surface inspection by rapidly performing the feed of a substrate to be inspected substantially by the point contact of both side edges but also to adapt respective surface inspections by a reflected light system, a scattered light system and a transmitted light system and to enable the surface inspection of the substrate to be inspected different in width dimension. SOLUTION: A feed mechanism 11 wherein each one set of taper rollers 12 wherein the small diameter side end surfaces thereof are mutually opposed at a required interval are arranged in a feed direction in one row to feed a substrate A to be inspected so as to straddle the opposed taper rollers 12, 12 and an inspection space part 13 is set at the required position between the taper roller rows, air floating mechanisms 21 arranged within the required width range along the feed center between the respective one set of the taper rollers 12, 12 excepting the inspection space part 13 and floating the center part in the feed direction of the fed substrate A to be inspected by ejected air 22 from a lower part to exclude the effect of gravity, a CCD camera 41 for continuously optically detecting the surface state of the substrate A to be inspected passed through the inspection space part 13 in the unidimensional direction crossing the feed direction at a right angle, a signal processor 42 and a CPU 43 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting surface defects of various substrates formed in a flat plate shape, and more particularly, to a flat plate product having a relatively large area, for example, a type of display element. An oxide film (SiO ₂
Liquid crystal display substrate on which a transparent film (IT film) is formed.
One-dimensional CCD (Charge Coup) is used to measure the surface condition of large-sized flat products such as plasma display substrates on which silicon film (O film) has been formed and silicon wafers that have been cut from other raw materials.
The present invention relates to an improvement of an inspection apparatus which picks up an image with a camera and detects the state of the surface, here a surface defect, etc., from the imaged image signal.

[0002]

2. Description of the Related Art Generally, with respect to various flat substrate products, a defect inspection of the surface has been performed so far mainly by visually observing the surface condition. Recently, with the rapid improvement in the performance of CCD cameras, automatic inspection means using the CCD cameras have been widely adopted. In particular, with respect to flat substrates applied to liquid crystal display devices and the like, in recent years, gradually Due to the tendency to increase in size, defect inspection by a one-dimensional CCD camera has begun to be used for more rigorous and rapid automatic inspection of such large-sized substrates.

In a conventional surface defect inspection of a large-sized substrate using a one-dimensional CCD camera, a large-sized substrate to be inspected is usually set on a flat inspection stage serving as a support table. In this state, one or both of the one-dimensional CCD camera and the inspection stage are relatively moved, so that the large-sized substrate to be inspected is closely attached to the flat inspection stage here. Since the substrate to be inspected is placed in a state, the flatness of the substrate to be inspected is easily ensured, and highly accurate detection of a surface defect or the like becomes possible.

[0004] In this case, however, it is necessary to frequently repeat the work of placing the corresponding large-sized substrate on the inspection stage and then performing the inspection, and removing the substrate from the inspection stage after the inspection. Besides, there is a concern that the board surface may be stained or scratched.
The workability is poor and lacks in speed, and furthermore, the handling mechanism for handling the substrate to be inspected has the disadvantage of being complicated, and the overall throughput of the inspection process is significantly reduced. As a problem, this method cannot be used for effective and quick defect inspection of such a large-sized substrate.

On the other hand, means for transporting the substrate to be inspected by rollers without placing the substrate to be inspected on the inspection stage as described above can easily cope with the enlargement of the substrate to be inspected. Although it is widely used because it can be transported at high speed, defect inspection using a one-dimensional CCD camera leaves the possibility of dirt and scratches caused by the contact of the transport roller with the corresponding large-sized substrate. In order to cope with the problem, a non-contact transport system is desired as much as possible.

On the other hand, as a non-contact large-size substrate transfer system, for example, as shown in FIG. 4, a pair of tapered rollers 51, 51 having small-diameter side end faces opposed to each other at a required interval are used. It is conceivable to arrange them in parallel in the transport direction, and to support the transported side edges of the enlarged substrate A to be inspected between the tapered rollers 51 of each set in a point contact state.

However, when the transfer means shown in FIG. 4 is applied, the size of the substrate A to be inspected is increased due to the weight of the substrate A itself. However, there is a possibility that the surface of the substrate to be inspected A at the inspection point may not be detected in a proper manner because it sinks downward and curves around the gravitational portion and is relatively largely warped. It is necessary to convey while maintaining the original flatness without the influence of gravity.

Therefore, generally, in order to correct the downward warpage caused by the own weight of the substrate A to be inspected which is transported while being supported in a point contact state between the tapered rollers 51, 51, for example, as shown in FIG. As shown in the drawing, an air floating mechanism 61 having a large number of air ejection holes on its surface is disposed below the transporting means, and the whole of the inspection target substrate A is ejected by the ejection air 62 from each of the air ejection holes. Is possible to eliminate the influence of gravity by raising the surface of the inspection target substrate A when the inspection point is on the air floating mechanism 61. Therefore, in the surface inspection by the reflected light method or the scattered light method, the surface portion of the air floating mechanism 61 is easily affected, and in the surface inspection by the transmitted light method, Since the air floating mechanism 61 itself is to interrupt the transmission of irradiated light, there is a problem that can not be applied to each. Further, in the case of this type of defect inspection, since the interval between the tapered rollers 51 is fixedly set to a specific facing distance, it is impossible to correspond to the inspection target substrate 52 having a different width dimension. It also had disadvantages.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to provide a method for transporting a substrate to be inspected in a substantially non-contact and rapid manner. A flat substrate that enables surface inspection and, in addition, makes it possible to apply each surface inspection by the reflected light method, the scattered light method, and the transmitted light method, and enables the surface inspection of substrates to be inspected having different width dimensions. To provide a surface defect inspection apparatus.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a tapered roller having a pair of tapered rollers whose small-diameter side end faces are opposed to each other at a required interval. A transport mechanism arranged in a row in the transport direction so that the substrate to be inspected can be transported across the opposing tapered rollers, and a transport mechanism in which an inspection space is set at a required position between the tapered roller rows, Arranged within the required width range along the transport center between the tapered rollers of each set, except for the inspection space, and the center of the transport direction of the inspected substrate to be transported is floated by jet air from the lower side. An air floating mechanism that eliminates the influence of gravity by gravity, and a unit that optically continuously detects the surface condition of the inspection target substrate passing through the inspection space in a one-dimensional direction orthogonal to the transport direction. A surface defect inspection apparatus of the flat substrate to symptoms.

According to a second aspect of the present invention, in the apparatus for inspecting a surface defect of a flat substrate according to the first aspect, the optical detecting means uses the linear band-shaped irradiation light to perform the inspection. An irradiation light source that irradiates the surface of the inspection target substrate passing through the space, a one-dimensional CCD camera that receives reflected light or transmitted light of the irradiation light, and a one-dimensional direction such as a one-dimensionally arranged optical fiber sensor array. Characterized by comprising a light receiving detector, a signal processor and a central processing unit for detecting the presence / absence of a surface defect of a substrate to be inspected from a change in the amount of reflected light or transmitted light received. It is.

Further, according to a third aspect of the present invention, in the apparatus for inspecting a surface defect of a flat substrate according to the first aspect, the opposed interval of the tapered rollers for each set of the transport mechanism is set as follows. It is characterized in that it can be adjusted in accordance with the width of the substrate to be inspected in the transport direction.

Therefore, in the apparatus for inspecting the surface of a flat substrate according to the present invention, the substrate to be inspected is transported by point contact before and after the inspection space set on the transport mechanism in the required width along the transport direction. It is levitated by each air floating mechanism arranged in the range and is made in a flat state eliminating the influence of gravity, so it is possible to quickly transport while maintaining its own flatness, as a result, The surface state of the inspection target substrate passing through the inspection space can be easily detected by the optical detection means.

In addition, since the inspection space portion is set in the middle of the transportation for detecting the surface condition of the inspection target substrate, each surface inspection by the reflected light method, the scattered light method and the transmitted light method can be easily applied. obtain.

Further, by adjusting the facing distance between the tapered rollers of each set constituting the transport mechanism, it becomes possible to inspect the surface of the substrate to be inspected having different width dimensions.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a flat substrate surface defect inspection apparatus according to the present invention in which an optical detection means based on a reflected light method is applied will be described in detail with reference to FIGS. Will be described.

FIG. 1 is an explanatory side view schematically showing an overall outline of a surface defect inspection apparatus to which a point contact support transport mechanism according to the embodiment is applied. FIG. 2 is an explanatory side view schematically showing a relationship between an inspection space set on the transport mechanism and the air floating mechanism. FIG. 3 is an explanatory side view schematically showing the arrangement of the air floating mechanism with respect to the transport mechanism and the adjustment of the facing distance between the tapered rollers of each set.

That is, in the apparatus configuration of the embodiment shown in FIG. 1 to FIG. 3, the present surface defect inspection apparatus includes a set of tapered rollers 12 having small-diameter side end faces facing each other at a required interval. , 12, the sets of tapered rollers 12, 12 are arranged in a row at required intervals in the transport direction, and a transport mechanism 11 in which an inspection space 13 is set at a required position between the tapered roller rows is provided.

Further, each of the sets of tapered rollers 12,
An air floating mechanism 21 is arranged at a lower portion between the 12 and within a required width range along the transport center and in a corresponding portion except the position of the inspection space portion 13. In this case, a large number of air ejection holes are formed in the (upper surface), not shown again.

Further, on the upper side of the transport mechanism 11, a substrate A to be inspected transported by the transport mechanism 11 is irradiated on the inspection space 13 at a position facing the inspection point 13 a in the inspection space 13. An irradiation light source 31 and a one-dimensional CCD camera 41 as a one-dimensional light receiver are arranged in advance, and a linear band of irradiation light 3 from the irradiation light source 31 is provided.
2 is projected to the inspection point 13a, and the reflected light 33 reflected at the inspection point 13a can be received by the one-dimensional CCD camera 41. A change in the amount of light 33 can be processed by a signal processor 42 at the next stage, and a CPU (Central Processing Unit: Central Processing Unit) 43 such as a microcomputer can detect the state of the surface, for example, the presence or absence of a surface defect. To In addition, as the one-dimensional direction light receiving detector, an optical fiber sensor array or the like separately arranged in one-dimensional direction may be applied.

Therefore, in the case of the apparatus configuration according to the present embodiment, each set of the tapered rollers 12, 12 of the transport mechanism 11 is used.
The board A to be inspected, which is transported with both side edges supported in a point contact state, is floated by a required amount by the jet air 22 from each air floating mechanism 21 at the transport position before and after excluding the inspection space 13. Thus, the effect of gravity is eliminated, and the sheet is quickly conveyed while maintaining its own flatness. Next, at the time of passing through the inspection space 13, the inspection point 13 a is constantly illuminated by the linear band-shaped irradiation light 32 emitted from the irradiation light source 31, and the surface of the inspection target substrate A (the inspection target The reflected light reflected on the surface) is sequentially and continuously received by the one-dimensional CCD camera 41,
As a result, as described above, the surface condition of the inspection target substrate A, and thus the current state of the target surface defect, can be easily detected by optical means.

One embodiment of the defect inspection in this case is specifically described as follows. That is, the taper rollers 12, 12 of each set are arranged in a row at an interval of 80 mm as the transport mechanism 11, and the interval between the air floating mechanisms 21 arranged before and after in correspondence with the inspection space 13 is 50 mm. And 550 mm in width in the transport direction as a substrate to be inspected A × 650 mm in length × 1.1 mm in thickness
Transfer speed of 1m by the transfer mechanism 11
/ Min, and the material glass substrate was irradiated with a linear band of irradiation light 32 by a halogen lamp as an irradiation light source 31 at an inspection point 13a on the inspection space 13 to perform a defect inspection.

In this case, the air ejection holes of each air floating mechanism 21 disposed before and after the inspection space portion 13 are formed in a grid shape at intervals of 25 mm, and the air ejection holes are formed from the air ejection holes. , Clean and dry blast air through a dust filter 22
The substrate A to be inspected conveyed is floated as expected. Here, in the case of the substrate A to be inspected of this size, usually, when the substrate is transported by merely supporting both side edges, as described above, the center portion sinks down by about 10 mm due to the influence of gravity and warps. However, even if the air floating mechanism 21 having a width of 300 mm as an intermediate air floating area within a range corresponding to approximately 50% of the width direction size 550 mm of the inspection target substrate A, the inspection target substrate A It was confirmed that sufficient flatness could be maintained.

As a result of the irradiation inspection in the above state, typical air bubbles on the surface of the inspection target substrate A,
Defects such as foreign matter and scratches could be detected stably. In addition, for more accurate inspection in this state,
Interposing an auxiliary roller between the front and rear air floating mechanisms 21 is also one effective method.

The interval K between the rear end of the front air floating mechanism 21 and the inspection point 13a in the inspection space 13 is not necessary because there is no air floating means in the corresponding portion. It is preferable that the value of the interval K be kept below a certain value. Table 1 shows the results of measuring the floating difference (warpage) of the glass substrate according to the size and the value of the interval K according to the size of the substrate.

[0026]

[Table 1]

From this measurement result, the value of the interval K is 50
mm or less, preferably, the floating difference (warpage) is 100 μm.
It is understood that it is effective to set the length to 30 mm or less, which is equal to or less than m.

Further, each of the tapered rollers 12, 1
As described above, since the facing distance L between the two needs to correspond to the inspection target substrate A of various widths, for example, 250 mm to 570
It is preferable that the distance can be adjusted within a range of about mm.

One specific example in this case is as follows. That is, 150 mm / 550 mm = 3/11 as compared with the case where the material glass substrate having a width of 550 mm × length 650 mm × thickness 1.1 mm is transported by the transport mechanism 10 at a transport speed of 1 m / min. It was confirmed that sufficient flatness could be obtained even with the ratio of (the width of the air floating mechanism 21 / the width of the inspection target substrate A). That is, the facing distance L between the tapered rollers 12, 12
Is set to 250 mm, and a width of 250 mm × length of 300 mm × thickness of 0.
Even when the glass substrate A of 7 mm was transferred at a transfer speed of 1 m / min, sufficient flatness was obtained. From these results, it is determined that the width of the air floating region in the transport direction is preferably set to an air floating width equal to or less than the maximum width of the inspection target substrate A, and more preferably to 50% or less.

In the above-described embodiment, the case where the optical detection means based on the reflected light method is applied has been described. However, the present invention is applicable to other optical detection means based on the scattered light method or the transmitted light method. Of course.

[0031]

As described above in detail in the embodiment, according to the apparatus of the present invention, a pair of tapered rollers whose small-diameter side end faces face each other at a required interval are arranged in a row in the transport direction. By using a transport mechanism configured as described above, it is possible to transport in a substantially non-contact state in which both side edges of the substrate to be inspected are supported across the respective tapered rollers, and transport by point contact of the substrate to be inspected is performed. Before and after the inspection space set on the transport mechanism, the air is floated by each air floating mechanism arranged within a required width range along the transport direction, so that it is formed in a flat state eliminating the influence of gravity. As a result, it is possible to carry out quickly while maintaining its own flatness, and as a result, it is possible to easily and accurately detect the surface condition of the inspection target substrate passing through the inspection space by the optical detection means. obtain There is a point. In addition, in order to detect the surface condition of the inspection target substrate, since the inspection space is set on the way of transport, each surface inspection by the reflected light method, the scattered light method and the transmitted light method can be easily applied, At the same time, since the opposing interval of the tapered rollers of each set constituting the transport mechanism is adjustable, various useful effects such as the surface inspection of each inspection target substrate having different width dimensions can be performed. It has an excellent feature that it has a relatively simple structure and can be easily implemented.

[Brief description of the drawings]

FIG. 1 is an explanatory side view schematically showing an overall outline of a surface defect inspection apparatus to which a point contact support transport mechanism according to an embodiment of the present invention is applied.

FIG. 2 is an explanatory side view schematically showing a relationship between an inspection space set on the transport mechanism and an air floating mechanism.

FIG. 3 is an explanatory side view schematically showing an arrangement of an air floating mechanism with respect to the transport mechanism and an adjustment of an interval between tapered rollers in each set.

FIG. 4 is an explanatory side view schematically showing an outline of a conventional point contact support transport mechanism.

FIG. 5 is an explanatory side view schematically showing an arrangement of an air floating mechanism when the same point contact support transport mechanism is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Conveying mechanism 12 Taper roller 13 Inspection space part 13a Inspection point 21 Air floating mechanism 22 Jet air 31 Irradiation light source 32 Irradiation light 33 Reflection light 41 CCD camera 42 Signal processor 43 CPU (Central processing unit) A Inspection board

Claims (3)

[Claims] 1. A set of tapered rollers whose small-diameter side end faces are opposed to each other at a required interval are arranged in a row in the transport direction, and the substrate to be inspected can be transported across the opposed tapered rollers. In addition to the above, a transport mechanism in which an inspection space is set at a required position between the tapered roller rows, and excluding the inspection space within a required width range attached to a transport center between the tapered rollers of each set. An air floating mechanism that is disposed and lifts a central portion in the transport direction of the inspected substrate to be transported by jet air from below to eliminate the influence of gravity, and a surface condition of the inspected substrate passing through the inspection space portion Means for continuously and optically detecting in a one-dimensional direction orthogonal to the transport direction. 2. An irradiation light source for irradiating a surface portion of a substrate to be inspected passing through the inspection space with a linear band of irradiation light, and a one-dimensional light receiving reflected light or transmitted light of the irradiation light. A one-dimensional light receiving detector such as a CCD camera, a one-dimensional optical fiber sensor array, and a signal processor that detects the presence or absence of surface defects on the inspection target substrate from changes in the amount of reflected light or transmitted light received. 2. The apparatus according to claim 1, wherein the apparatus comprises a central processing unit. 3. The surface defect of the flat substrate according to claim 1, wherein an interval between the tapered rollers in each set of the transport mechanism is adjustable in accordance with a width of the inspection target substrate in the transport direction. Inspection equipment.