JP3379606B2 - Defect detection method for transparent plate material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect detecting method for a transparent plate-like material for detecting defect positions such as bubbles and scratches generated on a transparent plate glass or the like.

[0002]

2. Description of the Related Art It is necessary to remove various defects such as bubbles, scratches, foreign substances, cracks and chips from the glass plate in the step of cutting glass plates manufactured by various manufacturing methods into plate glass of a desired size. For this reason, when cutting a glass plate into a glass plate of a desired size, in a previous step, an operator applies marks (hereinafter referred to as defect marks) at various defect positions of the glass plate in advance. Then, the plate glass is cut out by removing the portion to which the defect mark is applied, or the plate glass including the defect mark is extracted and discarded from the cut plate glass without removing the defect mark portion.

For example, if the flat glass production line is automated, defect mark detector is disposed on the flat glass production line and automatically reads the defect mark defect mark detector, extracting the flat glass containing drawbacks mark Discard or input the read defect mark position data to the cutting machine to remove the portion where the defect mark is applied and cut out the plate glass.

By the way, when a glass plate is manufactured by the float method , the back surface in contact with the surface of tin is the bottom surface, and the surface facing the bottom surface is the top surface. The foam glass material plate in a float process, scratches, and detects the foreign matter, when applied drawbacks mark automatically mark coater defect mark is applied to the top surface of the glass workpiece. And <br/> was either glass element plate manufactured by the float method, the case is transported to the top surface of the glass material plate on the upper surface in a subsequent step,
It may be conveyed with the bottom surface of the glass plate facing upward. Therefore, when the defect mark applied to the top surface of the glass substrate is read by the defect mark detector, the defect mark may be on the upper surface side or the lower surface side of the glass substrate. For example, when the glass substrate applied to the top surface of the glass substrate is transported to the cutting process in the float process in the glass substrate manufacturing line, the case where the glass substrate is transported with the top surface facing upward and the top surface facing downward It may be transported in the form of.

Here, when the top surface of the glass plate is conveyed downward, the operator detects a defect mark applied to the top surface (lower surface) by visual inspection and based on this defect mark. A defect mark is newly added to the bottom surface (that is, the upper surface) of the glass substrate, and the defect mark is applied to the upper faces of all the glass substrates conveyed in the cutting process. Therefore, the defect mark detector only needs to detect the defect mark applied to the upper surface of the glass plate.

[0006] However, if abolished visual inspection by the operator in a production line, there is a drawback marks are applied to the glass element plate and the lower surface, which is applied to the top surface glass element plate.
Therefore, the defect mark detector needs to detect both the defect mark applied on the upper surface of the glass plate and the defect mark applied on the lower surface of the glass plate. And conventionally,
The defect mark applied on the upper surface of the glass plate has been detected by a reflection type defect mark detector, and the defect mark applied on the lower surface of the glass plate has been detected by a transmission type defect mark detector. It was technically difficult to detect the marks on the upper and lower surfaces only by the reflection type.

A reflection type defect mark detector 10 shown in FIG.
Is provided with a light source 14 for projecting light and an imaging camera 16 above the glass substrate 12, and irradiation light 18 projected from the light source 14 for projecting is reflected by the glass substrate 12 and enters the imaging camera 16. To do. And the defect mark 2 with the irradiation light 18 on the upper surface
When 0 (see FIG. 6) is irradiated, the light amount S ₁ of the reflected light of the defect mark 20 entering the imaging camera 16 in the a range becomes substantially 0 (see FIG. 7).

Therefore, the light quantity S of the reflected light of the defect mark 20
₁ and the light amount S ₂ of the reflected light of the glass plate 12 other than the defect mark 20 become large (generally, the defect mark 20
The reflected light amount S ₁ of the glass substrate 12 is the reflected light amount S ₂ of the glass plate 12.
It is known to be reduced to about 5 to 10%. ).
Accordingly, by setting the predetermined light amount S as the threshold value, it is possible to recognize the position where the light amount S ₁ is smaller than the threshold value S as the coordinate position of the defect mark 20.

In this case, the size Y ₁ (see FIGS. 5 and 6) of the defect mark 20 is obtained by repeating the above-described detection process while the glass plate 12 is being conveyed in the Y direction (see FIG. 6). When the size of Y ₁ is larger than a predetermined value, the defect mark 20 is finally recognized. On the other hand, as shown in FIG. 8, when the defect mark 20 is applied to the lower surface of the glass substrate 12, the imaging camera 16 of the reflective defect mark detector 10 is used.
When the light amount S ₃ (see FIG. 9) of the reflected light (front surface reflected light + back surface reflected light) from the defect mark 20 is detected, the light amount S ₃ has a light amount difference from the light amount S ₄ of the reflected light of the glass substrate 12. small.
That is, the light amount S ₃ of the reflected light of the defect mark does not significantly decrease as compared with the light amount S ₄ of the reflected light of the glass plate 12 other than the defect mark 20. Therefore, when the defect mark 20 is applied to the lower surface of the glass plate 12, in order to detect the defect mark 20 with the reflective defect mark detector 10, the threshold value S is set to a value close to S _4. There is a need.

On the other hand, the fluorescent lamp used for the light source 14 of the reflection type defect mark detector 10 has a rapid change in the amount of light over time.
It decreases by 30-40% in 000-2000 hours. Moreover, the light amount sharply decreases in the first 100 hours, and thereafter gradually decreases. Therefore, when a fixed value threshold S, when the first lapse of 100 hours, the reflected light quantity S ₄ of the glass substrate 12 is smaller than the threshold S, no longer can exactly Detect disadvantages mark 20 .

Therefore, when the defect mark 20 is applied to the lower surface of the glass plate 12, the transmission type defect mark detector 30 shown in FIG. 10 is used. The transmissive defect mark detector 30 has a light source 34 for projecting light disposed below the glass substrate 12 and an imaging camera 36 above the glass substrate 12. The irradiation light 38 projected from the light source 34 for projecting passes through the glass substrate 12 and enters the imaging camera 36.

In this case, when the light beam 38 irradiates the defect mark 20, the irradiation light 38 is blocked by the defect mark 20, so that the irradiation light 38 irradiating the defect mark 20 does not enter the imaging camera 36. On the other hand, the irradiation light 38 irradiating the glass base plate 12 other than the defect mark 20 passes through the glass base plate 12 and enters the imaging camera 36. Therefore, the defect mark 20
The difference between the transmitted light quantity becomes larger the amount of light and glass substrate 12 of the irradiation light irradiated to, by setting an appropriate light intensity as a threshold value, cutting the defect mark 20 in discovery.

Further, according to the transmission type defect mark detector 30 and cut the disadvantage marks 20 applied to the lower surface or upper surface of the glass substrate 12 in detection knowledge.

[0014]

By the way, the glass substrate 1
When the plate glass is cut from 2 and folded, the cut and folded plate glass may be cracked or chipped. Is However, if the transmission type defect mark detector 30,
Even when a crack or chip of the plate glass is detected, the light amount is hardly reduced, so that the transmissive defect mark detector 30 cannot detect the crack or chip.

On the other hand, in the case of the reflection type defect mark detector 10, by setting the binarization level of the reflected light amount in two steps, cracks and chips generated in the glass plate 12 and the glass plate 12 are generated.
Detection knowledge to distinguish and disadvantages mark 26A applied to the upper surface of the
Kill at. It was only, defect mark detector 10 of conventional reflective
In this case, the defect mark 26B applied to the lower surface of the glass plate 12 cannot be detected.

Therefore, the defect mark 20 applied to the lower surface or the upper surface of the glass base plate 12 is detected, and the glass base plate 12 is further detected.
In order to detect cracks, chips, and the like that occur during cutting, folding, and the like, two types of defect mark detectors, a reflective defect mark detector 10 and a transmissive defect mark detector 30, are required. However, there is a problem that the cost is increased because of the equipment cost.

The present invention has been made in view of the above circumstances, and a transparent plate-like material capable of reducing the cost by detecting the defect mark applied to the lower surface or the upper surface of the glass plate by one system. It aims at providing the defect detection method of.

[0018]

DISCLOSURE OF THE INVENTION The present invention provides a defect detecting method for a transparent plate-shaped material, which detects a defect mark applied to a defect position such as a bubble or a scratch generated on the transparent plate-shaped material. Surface reflected light by the defect mark applied to the surface of the transparent plate-like material, which is projected from a light source installed on the front side of the material, and back surface by the defect mark applied on the back surface of the transparent plate-like material. The reflected light is reflected on the surface side of the transparent plate-like material.
The image pickup camera installed in the
A method for detecting a defect of a transparent plate-shaped material for detecting nothing, comprising:
The amount of light reflected from the front surface and the amount of light reflected from the back surface are
Compared to the case without a mark, the surface reflected light is 5 to 1
It is characterized in that the position of the defect mark applied to the front surface and the back surface of the transparent plate-like material is detected by using a defect mark material that is reduced to 0% to 60% or less by the back surface reflected light. There is.

Further, the present invention is characterized in that the secular change of the light quantity projected from the light source is detected and the detected secular change is corrected.

[0020]

According to the present invention, the back surface reflected light reflected by the defect marks applied to the rear surface and surface reflected light discouraged reflected by the defect marks applied to the surface of the transparent plate-shaped material is below the respective setpoint A defect mark material that reduces is used. Thus, by measuring the surface reflected light Contact and light reflected by the lower surface of the transparent plate-shaped member, for detecting the surface and the position of the applied defect mark on the back surface of the transparent plate-shaped member, respectively.

Therefore, the defect mark applied to the transparent plate-shaped material is applied to both the case where the application surface of the defect mark is located on the light source side and the case where the application surface of the defect mark is located on the opposite side of the light source. kill in the discovery. Further, according to the present invention, the secular change in the light amount of the light source for projecting light is detected, and the detected secular change is corrected. Therefore, even when the light quantity of the light source projecting light changes over time, wear detection sensitivity constant maintenance.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the method for detecting defects in a transparent plate material according to the present invention will be described below with reference to the accompanying drawings. The glass plate transporting means 40 shown in FIG.
The carrier conveyor 46 is stretched over the second and driven rollers 44, and the drive roller 42 is rotated by a drive motor (not shown) to move the carrier surface of the carrier conveyor 46 in the arrow Y direction. As a result, the glass base plate 48 placed on the transport conveyor 46 moves in the arrow Y direction.

Defect marks 60 are applied to the upper surface and the lower surface of the glass plate 48, respectively. As a mark material for applying the defect mark 60 to the glass plate 48, the defect mark 60A has a surface reflectance of 0.05 and the defect mark 6 is an example.
A water-based pen with a 0 backside reflectance of 0.55 is used. Here, as the selection criteria of the mark material, those having a front surface reflectance of 5 to 10% and a back surface reflectance of 55 to 60% or less are suitable, but are not limited thereto, and the front surface reflectance and the back surface reflectance are not limited thereto. It is possible to use a mark material having a small reflectance for both of the above.

The plate glass defect detecting device 50 includes a light source 52 for projecting light, an image pickup camera 54, and a light quantity correcting means 56. The light source 52 for projecting light is arranged above the glass plate 48, and the irradiation light 58 projected from the light source 52 for projecting light is the glass plate 48.
It is reflected by and enters the imaging camera 54. In this case, the imaging camera 54 is arranged above the glass plate 48. The image pickup camera 54 converts the input light quantity of the reflected light into an electric signal and inputs it to the average light quantity calculation circuit 56A of the light quantity correction means 56.

The average light amount calculation circuit 56 of the light amount correction means 56
A averages the light amount in the central portion b range (see FIG. 3) from the input reflected light, and inputs the averaged light amount value X signal to the multiplication circuit 56B. The multiplication circuit 56B has a light amount value X
And the amplification setting voltage Y input from the D / A converter 56C described later are multiplied, and the signal of the calculated value A (A = X · Y) is passed through the buffer amplifier 56D and the A / D converter 56E. Input to the digital processing unit 58.

The digital processing unit 58 compares the calculated value A with the target value T stored in advance and obtains the amplification setting voltage Y so that the calculated value A becomes the target value T. Then, the signal of the obtained amplification degree setting voltage Y is D / A converted by the above-mentioned D / A converter 56C and fed back to the multiplication circuit 56B. Therefore, even if the light amount of the fluorescent light of the light source 52 for projecting decreases due to secular change, the average light amount value in the central portion b range (see FIG. 3) in the reflected light output from the imaging camera 54 is the target value T. To be kept constant.

When the defect mark 60 is not applied to the position of the glass substrate 48 irradiated with the irradiation light 58, or when the glass substrate 48 does not exist at the position irradiated with the irradiation light 58, the amount of reflected light is increased. Changes greatly. Therefore, the average value X of the light amount calculated by the average light amount calculation circuit 56A greatly changes, but in this case, the change in the average value X is ignored in order to distinguish it from the change in the light amount of the light source 52 for projecting due to aging. Take measures.

The operation of the plate glass defect detecting apparatus used in the defect detecting method for the transparent plate-shaped member constructed as described above will be described. First, as shown in FIG. 1, the case of detecting the defect mark 60 applied on the upper surface of the glass plate 48 will be described. Irradiation light 58 is projected from the light source 52 for projecting light. In this case, the irradiation light 58 simultaneously irradiates the defect mark 60 and the glass plate 48 other than the defect mark 60. The reflected light reflected by the defect mark 60 and the defect mark 60
The reflected light reflected by the glass plate 48 other than the above enters the imaging camera 54.

In this case, the amount of reflected light reflected by the defect mark 60 is S ₁ , and the amount of reflected light reflected by the glass plate 48 other than the defect mark 60 is S ₂ (graph G _{1 in} FIG. 3). reference). Then, the reflected light amount S of the defect mark 60
₁ decreases to about 5 to 10% of the reflected light amount S ₂ reflected by the glass plate 48 other than the defect mark 60. Next, FIG.
The case where the defect mark 60 applied to the lower surface of the glass plate 48 as shown in FIG. in this case,
The amount of light reflected by the defect mark 60 is S ₃ ,
The amount of light reflected by the glass plate 48 other than the defect mark 60 is S ₂ (see graph G _{2 in} FIG. 3). And
The reflected light amount S ₃ of the defect mark 60 is 55 to 6 of the reflected light amount S ₂ reflected by the glass plate 48 other than the defect mark 60.
It only drops to about 0%.

On the other hand, the light quantity of the fluorescent lamp of the light source 52 for projecting decreases with the lapse of time, and the average light quantity value X in the range b in the reflected light
When the light intensity decreases, the light amount correction means 56 calculates the calculated value A obtained by multiplying the average light amount value X and the amplification degree setting voltage Y by the multiplication circuit 56B. Further, the light amount correction means 56 compares the calculated value A with the target value T, obtains the amplification degree setting voltage Y so that the calculation value A becomes the target value T, and the obtained amplification degree setting voltage Y is multiplied by the multiplication circuit 56B. Give feedback to.

As a result, even if the light amount of the fluorescent lamp of the light source 52 for projecting decreases due to secular change, the average light amount value in the central range b of the reflected light (see FIG. 3) becomes constant so as to reach the target value T. Is corrected to . Even when the light quantity of the fluorescent light of the light source 52 for projecting decreases due to secular change, the decreased light quantity is represented by the graph G shown in FIG.
It is corrected to ₁ and G ₂ . Therefore, by setting the threshold value S to about 0.8 × S ₂ , the glass substrate 48
By a tree in the drawbacks marks 60 the upper surface and coated on the lower surface of at discovery <br/>.

Next, the plate glass is cut from the glass plate 48,
A case will be described in which, when folded, a chip generated around the plate glass and the defect mark 60 applied to the lower surface side of the plate glass are detected separately. First, when the irradiation light 58 projected from the projection light source 52 of the plate glass defect detection device 50 irradiates the defect mark coated on the lower surface side around the plate glass, the amount of reflected light incident on the imaging camera 54. Is the graph G
₃ (see Figure 4) . In this case, as described above, the reflected light amount S ₃ of the defect mark is reduced to about 55 to 60% of the reflected light amount S ₂ of the plate glass other than the defect mark.

On the other hand, when the light projected from the light projecting light source 52 irradiates a chip generated around the plate glass, the amount of the reflected light entering the image pickup camera 54 is graph G ₄ (see FIG. 4).
become that way. In this case, the reflected light amount S ₄ of the chip generated around the plate glass is smaller than the reflected light amount S ₃ of the defect mark. Therefore, a defect mark detection threshold value S _m is set between the light amount S ₃ and the light amount S _2, and a defect detection threshold value S _k is set between the light amount S ₃ and the light amount S _4. it allows kills with discovery distinguishes between chipping that occurred drawbacks marks and flat glass around coated on the lower surface side of the peripheral flat glass.

By the way, the defect mark is applied to bubbles, scratches, etc. generated on the glass plate in the glass plate manufacturing process (for example, float manufacturing process), and the chip of the peripheral edge of the plate glass is cut off. It occurs in the folding process. Therefore, it is significant for cost analysis to detect the defect mark applied on the lower surface side of the plate glass and the defect generated around the plate glass separately.

That is, for example, the production and cutting of a glass plate,
In the case where the folding process is performed by another company, when the defect mark is detected, it is a defect on the glass plate manufacturing side, and when the defect mark is detected, it is a cut and a folding process defect. In this way, the cause of defective products off the production side of the glass material plate, since the cut in the processing side and the secondary district by folding, help to cost analysis.

[0036]

As described above, according to the defect detection method for a transparent plate-like material according to the present invention, when the application surface of the defect mark is located on the light source side and the application surface of the defect mark is opposite to the light source. in both when located on the side, it cuts the disadvantages marks applied to the transparent plate-shaped member in discovery. Accordingly, since the wear disadvantage mark both applied to the side opposite to the light source side and the light source in the defect detecting device of flat glass of one system with detection knowledge, the cost can be reduced.

Further, according to the present invention, since the secular change of the light quantity emitted from the light source for light projection is detected and the detected secular change is corrected, even when the light quantity of the light source for light projection changes with time, The detection sensitivity can be maintained constant. Therefore, cut with stable detection known disadvantages marks applied to the rear surface of the transparent plate-shaped member.

[Brief description of drawings]

FIG. 1 is a schematic view of a plate glass defect detection device used in a transparent plate-shaped material defect detection method according to the present invention.

FIG. 2 is an explanatory diagram illustrating a case where a defect mark applied to the lower surface of a glass plate is detected by the defect detecting method for a transparent plate material according to the present invention.

FIG. 3 is a graph when a defect mark applied to the upper surface of a glass plate is detected by the defect detecting method for a transparent plate material according to the present invention, and a defect mark applied to the lower surface of the glass plate is detected. Diagram showing the case graph

FIG. 4 is a graph showing a case where a glass plate chipping is detected by the transparent plate-like material defect detection method according to the present invention and a graph when a defect mark applied to the lower surface of a glass plate is detected.

FIG. 5 is a schematic view showing a conventional reflection type defect mark detector.

FIG. 6 is an explanatory diagram illustrating a case where a conventional defect mark detector of a reflection type detects a defect mark applied on the upper surface of a glass plate.

FIG. 7 is a diagram showing a graph when a defect mark applied on the upper surface of a glass plate is detected by a conventional reflection type defect mark detector.

FIG. 8 is an explanatory diagram illustrating a case where a conventional reflective defect mark detector detects a defect mark applied to the lower surface of a glass plate.

FIG. 9 is a diagram showing a graph when a defect mark coated on the lower surface of a glass plate is detected by a conventional reflection-type defect mark detector.

FIG. 10 is a schematic diagram showing a conventional transmission type defect mark detector.

[Explanation of symbols]

48 ... Plate glass (transparent plate material) 50 ... Plate glass defect detection device 52 ... Light source 58 ... Irradiation light 60 ... Defect mark

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 21/84-21/958 C03C 15/00-35/26 B41M 5/20

Claims (3)

(57) [Claims] 1. A method for detecting a defect of a transparent plate-shaped material, which detects a defect mark applied to a defect position such as a bubble or a scratch generated on the transparent plate-shaped material. The light reflected from the defect mark, which is projected from the light source and is applied to the surface of the transparent plate member, and the back surface reflected light, which is applied to the back face of the transparent plate member, is reflected by the defect plate.
Defects caused by light received by an imaging camera installed on the front side of the material
A method for detecting defects in transparent plate-shaped materials that detects the presence or absence of marks.
I, the light quantity and the light quantity of the light reflected by the lower surface of the surface reflected light is the
Compared with the case where there is no defect mark, 5
The defect mark applied to the front surface and the back surface of the transparent plate-shaped material is adjusted to 10% to 10% by using the defect mark material which is reduced to 60% or less by the back surface reflected light. A method for detecting a defect of a transparent plate-shaped material, which is characterized by detecting. Wherein said detecting the aging of projected light quantity from the light source, according to claim 1 Symbol placement transparent plate-shaped material defect detecting method for correcting the secular change that the detection. 3. The set value is set in two stages, and the reflected light amount of a chip generated around the transparent plate-like material and the reflected light amount of the defect mark are set based on the set values set in the two stages. The method for detecting defects of a transparent plate-like material according to claim 1, wherein the defects are detected separately.