JP6953446B2 - Particle detection method and device on the upper surface of glass, and incident light irradiation method - Google Patents

Description

Cross-reference of related applications

The present application claims the priority benefit of Korean Patent Application No. 10/2016/0064134 filed May 25, 2016, the content of which is relied upon and incorporated herein by reference in its entirety.

The present disclosure relates to a particle detection method and an apparatus on the upper surface of glass, and an incident light irradiation method.

Generally, the microcircuit pattern is formed on only one surface (eg, top surface) of the flat glass used in the flat panel display device, and the microcircuit pattern is formed on the other surface (eg, bottom surface) of the flat glass. Does not form. If the microcircuit pattern is formed on particles present on the top surface of flat glass, the microcircuit pattern can have some defects. Therefore, it is necessary to inspect for the presence of particles on the top surface of flat glass before forming a microcircuit pattern.

In order to detect only the particles on the upper surface of the flat glass, the conventional flat glass particle detection device is configured to irradiate the upper surface and the lower surface of the flat glass with light from above the flat glass at different angles. Includes first and second illuminators, and first and second cameras configured to capture images of the top illuminated area and the bottom illuminated area, respectively.

Since the flat glass has a predetermined thickness, the particles on the upper surface are shown as bright parts and the particles on the lower surface are shown as dark parts on the image. The conventional device is configured to compare and analyze the acquired images by the first and second cameras, respectively, and detect the particles existing on the upper surface.

However, since the conventional device includes two irradiation devices and two cameras, not only the manufacturing cost of flat glass but also the manufacturing cost of the device increases. Further, recently, since the transport speed of flat glass has continued to increase, there is a demand for increasing the detection speed of particles on the upper surface of flat glass. Nevertheless, conventional devices have to compare and analyze images acquired by two cameras, making it difficult to meet such demands. The present disclosure seeks to provide a solution to at least one of the above problems.

The present disclosure provides a method and apparatus for detecting particles on a glass surface that can use only one light source and only one camera, and a method for irradiating incident light.

One aspect of the present disclosure provides a method for detecting particles on the upper surface of glass. The method involves arranging a rotatable mirror in the optical path of the light emitted from the light source so that the mirror reflects the light and irradiates the upper surface with the incident light, and the incident angle of the incident light is set to the incident light. The process of calculating so that the first region where light intersects the upper surface of the glass and the second region where light passes through the glass and intersects the lower surface of the glass do not overlap each other when viewed from above, and the mirror. , A step of rotating based on the calculated incident angle, a step of acquiring an image of the first region with a camera arranged above the first region, and detecting particles by analyzing the acquired image. Including the process of The detected particles are considered to be present on the upper surface.

In one embodiment, the angle of incidence is calculated based on the index of refraction and thickness of the glass.

In one embodiment, the angle of incidence is calculated based on the maximum value of the horizontal distance between the right edge of the first region and the left edge of the second region.

In one embodiment, the maximum value of the horizontal distance is calculated based on the following formula:

However,
L'is the horizontal distance,
d is the thickness of the glass,
n is the refractive index of glass,
θ is the incident angle of the incident light and
W is the width of the incident light.

In one embodiment, the step of rotating the mirror is performed before the glass is conveyed.

In one embodiment, the camera is installed so that the right end of the first region is located at the right end of the imaging region of the camera.

In one embodiment, the step of calculating the angle of incidence and the step of rotating the mirror are performed when at least one of the refractive index and the thickness of the glass changes.

Another aspect of the present disclosure provides a method of irradiating the upper surface of the glass with incident light to detect particles on the upper surface of the glass. The method is a step of arranging a rotatable mirror in the optical path of the light emitted from the light source so that the mirror reflects the light and irradiates the upper surface with the incident light, and the incident angle of the incident light is set to the glass. Based on the refractive index and thickness, the first region where the incident light intersects the top surface of the glass and the second region where the light passes through the glass and intersects the bottom surface of the glass are mutually exclusive when viewed from above. It includes a step of calculating so that they do not overlap and a step of rotating the mirror based on the calculated incident angle. The step of calculating the angle of incidence and the step of rotating the mirror are performed when at least one of the refractive index and the thickness of the glass changes.

In one embodiment, the angle of incidence is calculated based on the maximum value of the horizontal distance between the right edge of the first region and the left edge of the second region.

In one embodiment, the maximum value of the horizontal distance is calculated based on the following formula:

However,
L'is the horizontal distance,
d is the thickness of the glass,
n is the refractive index of glass,
θ is the incident angle of the incident light and
W is the width of the incident light.

Yet another aspect of the present disclosure provides a particle detector on the upper surface of the glass. The device includes a light source configured to emit light, a rotatable mirror placed on the optical path of the light and configured to adjust the angle of incidence of the incident light shining on the top surface, and a mirror. The rotation of the is controlled so that the first region where the incident light intersects the upper surface and the second region where the light passes through the glass and intersects the lower surface of the glass do not overlap each other when viewed from above. A control unit configured in the above and a camera configured to acquire an image of the first region are included. The control unit is configured to detect the particles by analyzing the acquired image, and considers the detected particles to be present on the upper surface.

In one embodiment, the control unit is configured to control rotation based on the refractive index and thickness of the glass.

In one embodiment, the control unit is configured to control rotation based on the maximum value of the horizontal distance between the right end of the first region and the left end of the second region.

In one embodiment, the maximum value of the horizontal distance is calculated based on the following formula:

However,
L'is the horizontal distance,
d is the thickness of the glass,
n is the refractive index of glass,
θ is the incident angle of the incident light and
W is the width of the incident light.

In one embodiment, the camera is configured such that the right end of the first region is located at the right end of the imaging region of the camera.

It is a side view which shows typically the particle detection apparatus on the upper surface of the glass by one Embodiment. It is a partially enlarged view of FIG. It is a partially enlarged view of FIG. It is a graph which shows the relationship between the incident angle and the horizontal distance when the apparatus of FIG. 1 is used. It is a flowchart which shows the particle detection method of the glass upper surface by one Embodiment. It is a flowchart which shows the incident light irradiation method by one Embodiment.

Hereinafter, embodiments of a particle detection method and an apparatus on the upper surface of the glass and an incident light irradiation method will be described with reference to the attached drawings.

In the attached drawings, FIGS. 1 to 3 use a two-dimensional Cartesian coordinate system (X-axis and Y-axis). In the following description, the positive X-axis direction and the positive Y-axis direction indicate the right direction and the upward direction, respectively. Further, the negative X-axis direction and the negative Y-axis direction indicate the left direction and the downward direction, respectively.

In the following description, terms such as "top", "bottom", "top", "bottom", "right", "left" are relatives shown in the attached drawings where the glass is considered to be transported horizontally. It is intended to refer to a specific spatial relationship, and is not intended to represent an absolute spatial relationship according to the transport direction of glass.

As shown in FIGS. 1 and 2, the particle detection device 100 (hereinafter, abbreviated as “particle detection device”) on the upper surface of the glass according to the embodiment includes a light source 110, a mirror 120, a control unit 130, and a camera 140. including.

In the particle detection device 100, the inspection target is the glass 10 conveyed in the horizontal direction (for example, to the right). In the particle detector according to another embodiment, the inspection target may be glass that is stationary without being conveyed. The glass 10 includes an upper surface 11 on which a microcircuit pattern is formed and a lower surface 12 on which no microcircuit pattern is formed. In other embodiments, the glass 10 may include flat glass, glass substrates, flat glass substrates, etc., which have a predetermined thickness and a predetermined width and stretch to the left or right. do. In order to explain the particle detection device 100 more clearly, in FIGS. 1 to 3, the glass 10 is made thicker than the actual thickness of the glass 10 (for example, about several millimeters to several micrometers), and is expanded. Shown as having.

The light source 110 is arranged above the glass 10 so that the light 31 is emitted in the direction perpendicular to the glass 10. Since the camera 140 is also arranged above the glass 10, the light source 110 can be manufactured integrally with the camera 140, thereby reducing the size of the particle detector 100. The light source 110 can cover concepts such as a light emitting device, a lighting device, a lamp, and a beam forming device. In another embodiment, the light source 110 may be arranged above the glass 10 so that the light 31 is emitted obliquely with respect to the glass 10. In one embodiment, the light 31 may include light rays, laser beams, and the like. In one embodiment, the light source 110 may include a focusing lens 111 that focuses the light 31 into a predetermined irradiation region. The focusing lens 111 can be configured to adjust the size of the irradiation region by the light emitted from the light source 110.

The mirror 120 is arranged on the optical path of the light 31 emitted from the light source 110 so that the incident light 32 irradiates the upper surface 11 of the glass 10. The incident angle θ of the incident light 32 is adjusted by the mirror 120 arranged in the optical path of the light 31. Therefore, the incident light 32 can be applied to the upper surface 11 of the glass 10 at an incident angle θ in a relatively large range as compared with the conventional device in which the light source is directly inclined with respect to the glass. The mirror 120 is electrically connected to the control unit 130 and rotates based on the control signal from the control unit 130. The mirror 120 is rotatable in the clockwise direction or the counterclockwise direction around the rotation shaft portion 121. For this purpose, the mirror 120 may include a drive mechanism and a power transmission mechanism. In one embodiment, the drive mechanism may include a drive motor, an electric motor, and the like. In one embodiment, the power transmission mechanism may include pulleys and belts, sprockets and chains, drive gears and driven gears, and the like. In one embodiment, the mirror 120 may cover concepts such as a reflective mirror, a reflector, a reflector, and the like. In the following description, the incident light 32 means the light that travels from the time when the light 31 is reflected by the mirror 120 to the time when the light 31 reaches the upper surface 11 of the glass 10.

The control unit 130 calculates the incident angle θ of the incident light 32, controls the rotation of the mirror 120 based on the calculated incident angle θ, and detects the particles by analyzing the image acquired by the camera 140. Further, it is determined that the detected particles are considered to be present on the upper surface 11 of the glass 10.

Specifically, the control unit 130 is configured to calculate the incident angle θ of the incident light 32 so that the first region 41 and the second region 42 do not overlap each other when viewed from above. .. In the present specification, the first region 41 is a region where the incident light 32 intersects the upper surface 11 of the glass 10, and in the second region 42, the transmitted light 33 transmitted through the glass 10 is the lower surface 12 of the glass 10. It is an area that intersects with. In other words, the control unit 130 calculates the incident angle θ of the incident light 32 so that the horizontal distance L'between the right end of the first region 41 and the left end of the second region 42 is greater than zero. It is configured to do so.

If the first region 41 and the second region 42 do not overlap each other when viewed from above, the camera 140 above the glass 10 is used without acquiring an image of the second region 42. It is possible to acquire an image of the first region 41. In this case, since the image of the irradiated region (that is, the second region 42) of the lower surface 12 of the glass 10 is not acquired by the camera 140, the image of the particles in the second region 42 is acquired by the camera 140. Can not. Further, since neither light reaches the particles existing in the unilluminated region (that is, the remaining region other than the second region 42) of the lower surface 12 of the glass 10, an image of those particles is acquired by the camera 140. Can not. Therefore, only the image of the upper particles 21 on the first region 41 can be acquired by the camera 140, and the image of the lower particles existing on the lower surface 12 of the glass 10 cannot be acquired by the camera 140.

In one embodiment, the control unit 130 may include a computer having a program storage unit. Any program related to the calculation of the incident angle θ, the rotation of the mirror 120, and the analysis of the image can be stored in the program storage unit. For example, the program storage unit may include a computer-readable hard disk, floppy disk, compact disk, magneto-optical disk, and memory card.

In one embodiment, the control unit 130, the rotation of the mirror 120, based on the refractive index and thickness of the glass 10, the first region 41 and the second region 42 do not overlap each other when viewed from above. It can be configured to be controlled in such a way.

For example, the horizontal distance L'can be calculated by the following formula:

However, L'is a horizontal distance,
d is the thickness of the glass 10.
n is the refractive index of the glass 10.
θ is the incident angle of the incident light 32.
W is the horizontal width of the incident light 32.

Equation 1 can be derived from Equations 2 to 6 below. First, the horizontal distance L'can be expressed by Equation 2 shown below:

However, referring to FIG.
W _A is the horizontal width of the first region 41,
W _B is the horizontal width of the second region 42,
L is a horizontal distance between the centers of W _A and the center of the W _B.

In Equation 2, the thickness of the glass 10, 4 mm and the like from 0.2 mm, so thin, the width _{W A} of the horizontal direction of the first region 41, the horizontal width _{W B} of the second region 42 Can be considered to be substantially equal to. Therefore, the horizontal distance L'can be expressed by Equation 3 shown below:

In Equation 3, L can be expressed using the trigonometric function according to Equation 4 with respect to the refraction angle α:

In Equation 4, the refraction angle α can be expressed using Snell's law according to Equation 5:

In Equation 3, the W _A, may represent by Equation 6 relates the incident angle theta:

Applying Equations 4 to 6 to Equation 3 leads to Equation 1. In Equation 1, since the refractive index n, the thickness d, and the width W are constants, the horizontal distance L'can be expressed by a function related to the incident angle θ.

Therefore, when a particular glass is determined for inspection, the index of refraction and thickness of that particular glass are also specified. In this case, the incident angle θ is set so that the horizontal distance L'is larger than zero based on Equation 1 (that is, the first region 41 and the second region 42 do not overlap each other when viewed from above). Can be calculated.

Moreover, Equation 1 is theoretical and, in reality, the index of refraction may not be uniform throughout the glass. Therefore, in order to ensure that the first region 41 and the second region 42 do not overlap each other, the incident angle θ is calculated based on Equation 1 so that the horizontal distance L'has the maximum value. Can be done. For example, when the glass 10 has a refractive index n of 1.5, a width of 100 μm, and a thickness of 500 μm, the relationship between the horizontal distance L'and the incident angle θ is shown in FIG. Referring to FIG. 4, the horizontal distance L'has a maximum value when the incident angle θ is 58.5 degrees. In this case, the maximum value of the horizontal distance L'is 154.1 μm.

The control unit 130 is configured to control the rotation (or tilt angle) of the mirror 120 based on the incident angle θ calculated by the above method by driving the drive mechanism of the mirror 120.

As described above, the incident angle θ at which the first region 41 and the second region 42 do not overlap each other depends on the refractive index and thickness of the glass 10. Therefore, when at least one of the refractive index and the thickness of the glass to be inspected changes, the control unit 130 calculates the incident angle θ of the incident light 32 based on the changed refractive index or the changed thickness. As a result, the rotation of the mirror 12 is controlled according to the calculated incident angle θ.

The camera 140 is placed above the glass 10 in a direction perpendicular to the glass 10. The camera 140 has an imaging region FOV (see dotted lines in FIGS. 1 and 2) that extends downward from the camera 140 perpendicular to the glass 10 and intersects the top surface 11 of the glass 10. The camera 140 is configured to acquire the image of the first region 41 without acquiring the image of the second region 42. That is, the camera 140 is installed so that the imaging region FOV of the camera 140 includes the first region 41 but does not include the second region 42. Since the upper particles 21 existing in the first region 41 of the upper surface 11 scatter the incident light 32 to form the scattered light 34, an image of the upper particles is acquired by the camera 140. The camera 140 is electrically connected to the control unit 130. The image acquired by the camera 140 is transmitted to the control unit 130 in the form of an electric signal. In this embodiment, the camera 140 may include a line CCD (charge coupled device) camera. In one embodiment, the camera 140 may cover concepts such as an imaging device, an imaging device, a detection device, and a detector.

In one embodiment, as shown in FIG. 2, the camera 140 is installed so that the right end of the first region 41 is located at the right end of the imaging region FOV, thereby causing the imaging region FOV to be the second. It can be located farthest from region 42. Therefore, it is possible to suppress the light scattered from the lower particles 22 existing in the second region 42 from generating noise in the image acquired by the camera 140.

By analyzing the image acquired by the camera 140, the control unit 130 is configured to regard a bright portion of the image as a particle. As described above, the image of the lower particles 22 existing on the lower surface 12 of the glass 10 is not acquired by the camera 140. Therefore, the control unit 130 is configured to consider that all the detected particles are present on the upper surface 11 of the glass 10.

As shown in FIG. 5, in the particle detection method 200 on the upper surface of the glass according to the embodiment (hereinafter, abbreviated as “particle detection method”), the step S201 for arranging the mirror and the incident angle of the incident light are calculated. A step S202, a step S203 of rotating a mirror, a step S204 of acquiring an image of a first region, and a step S205 of detecting particles are included.

In the step S201 of arranging the mirror, the mirror 120 is arranged in the optical path of the light emitted from the light source 110. The mirror 120 reflects the light 31 and irradiates the upper surface 11 of the glass 10 with the incident light 32.

In the step S202 of calculating the incident angle of the incident light, the incident angle θ of the incident light 32 is calculated so that the first region 41 and the second region 42 do not overlap each other when viewed from above. The incident angle θ of the incident light 32 can be calculated in the same manner as in the particle detection device 100 according to one embodiment. That is, the incident angle θ of the incident light 32 can be calculated based on the refractive index and the thickness of the glass 10. Further, the incident angle θ of the incident light 32 can be calculated based on the maximum value of the horizontal distance L'. Further, the maximum value of the horizontal distance L'can be calculated by Equation 1.

In the step S203 of rotating the mirror, the mirror 120 can be rotated based on the incident angle θ calculated in the step S202 of calculating the incident angle of the incident light. In one embodiment, the step S203 of rotating the mirror can be performed before the glass 10 is conveyed. Therefore, since the rotation of the mirror 120 is controlled in advance before starting the inspection of the glass, it is possible to reduce the time actually required for inspecting the glass 10.

In step S204 of acquiring an image of the first region, the camera 140 acquires an image of the first region 41 while the glass 10 is conveyed in the horizontal direction (for example, to the right). Since the position and function of the camera 140 have already been described in the particle detection device 100 according to the embodiment, the specific description of the above will be omitted.

In the step S205 for detecting the particles, the particles are detected by analyzing the image acquired in the step S202 for acquiring the image of the first region. Specifically, the particles are detected by finding the bright portion represented by the scattered light 34 from the image. The particles detected in the step S205 for detecting the particles are considered to be present on the upper surface 11 of the glass 10.

As shown in FIG. 6, the method of irradiating the incident light 300 according to the embodiment includes a step S301 of arranging the mirror, a step S302 of calculating the incident angle of the incident light, and a step S303 of rotating the mirror. In the present embodiment, the step S302 for calculating the incident angle of the incident light and the step S303 for rotating the mirror are performed when at least one of the refractive index and the thickness of the glass 10 changes.

The step S301 for arranging the mirror and the step S303 for rotating the mirror shown in FIG. 6 are the same as the step S201 for arranging the mirror and the step S203 for rotating the mirror shown in FIG. Description is omitted.

In step S302 of calculating the incident angle of the incident light, the incident angle θ of the incident light 32 was viewed from above by the first region 41 and the second region 42 based on the refractive index and the thickness of the glass 10. Calculate so that they do not overlap each other. The incident angle θ of the incident light 32 can be calculated in the same manner as in the particle detection device 100 according to one embodiment. That is, the incident angle θ of the incident light 32 can be calculated based on the maximum value of the horizontal distance L'. Further, the maximum value of the horizontal distance L'can be calculated by Equation 1.

The technical invention of the present disclosure is not limited to the above-described embodiment and the examples shown in the accompanying drawings. It will be apparent to those skilled in the art that various substitutions, modifications, and modifications are possible within the scope of the technical inventions of the present disclosure.

The particle detection method and apparatus on the upper surface of the glass according to one embodiment are configured to calculate the optimum incident angle of the incident light and control the rotation of the mirror based on the calculated optimum incident angle. Therefore, it is possible to accurately detect only the particles on the upper surface of the glass using only one camera. Further, according to the incident light irradiation method, it is possible to accurately irradiate the upper surface of the glass with incident light having an optimum incident angle.

Hereinafter, preferred embodiments of the present invention will be described in terms of terms.

Embodiment 1
In the particle detection method on the upper surface of glass
A step of arranging a rotatable mirror in an optical path of light emitted from a light source so that the mirror reflects the light and irradiates the upper surface with incident light.
The incident angle of the incident light is viewed from above with a first region where the incident light intersects the upper surface of the glass and a second region where the light passes through the glass and intersects the lower surface of the glass. And the process of calculating so that they do not overlap each other
The step of rotating the mirror based on the calculated incident angle, and
A step of acquiring an image of the first region with a camera arranged above the first region, and
A step of detecting particles by analyzing the acquired image, and
Including
A method in which the detected particles are considered to be present on the upper surface.

Embodiment 2
The method according to the first embodiment, wherein the incident angle is calculated based on the refractive index and the thickness of the glass.

Embodiment 3
The method according to the second embodiment, wherein the incident angle is calculated based on the maximum value of the horizontal distance between the right end portion of the first region and the left end portion of the second region.

Embodiment 4
The method according to the third embodiment, wherein the maximum value of the horizontal distance is calculated based on the following formula:

However,
L'is the horizontal distance,
d is the thickness of the glass,
n is the refractive index of the glass,
θ is the incident angle of the incident light and
W is the width of the incident light.

Embodiment 5
The method according to the first embodiment, wherein the step of rotating the mirror is performed before the glass is conveyed.

Embodiment 6
The method according to the first embodiment, wherein the camera is installed so that the right end portion of the first region is located at the right end portion of the imaging region of the camera.

Embodiment 7
The method according to the first embodiment, wherein the step of calculating the incident angle and the step of rotating the mirror are performed when at least one of the refractive index and the thickness of the glass changes.

8th Embodiment
In a method of irradiating the upper surface of glass with incident light to detect particles on the upper surface of the glass,
A step of arranging a rotatable mirror in an optical path of light emitted from a light source so that the mirror reflects the light and irradiates the upper surface with the incident light.
Based on the refractive index and thickness of the glass, the incident angle of the incident light is the first region where the incident light intersects the upper surface of the glass and the lower surface of the glass through which the light passes through the glass. The process of calculating so that the second regions intersecting with each other do not overlap each other when viewed from above.
The step of rotating the mirror based on the calculated incident angle, and
Including
The step of calculating the incident angle and the step of rotating the mirror are performed when at least one of the refractive index and the thickness of the glass changes.

Embodiment 9
The method according to embodiment 8, wherein the incident angle is calculated based on the maximum value of the horizontal distance between the right end of the first region and the left end of the second region.

Embodiment 10
The method according to embodiment 9, wherein the maximum value of the horizontal distance is calculated based on the following formula:

However,
L'is the horizontal distance,
d is the thickness of the glass,
n is the refractive index of the glass,
θ is the incident angle of the incident light and
W is the width of the incident light.

Embodiment 11
In the particle detector on the upper surface of the glass
With a light source configured to emit light,
A rotatable mirror arranged on the optical path of the light and configured to adjust the incident angle of the incident light applied to the upper surface.
The rotation of the mirror is such that the first region where the incident light intersects the upper surface and the second region where the light passes through the glass and intersects the lower surface of the glass overlap each other when viewed from above. A control unit configured to control so that it does not become
A camera configured to acquire an image of the first region, and
Including
The control unit is configured to detect particles by analyzing the acquired image, and considers the detected particles to be present on the upper surface.

Embodiment 12
The device according to embodiment 11, wherein the control unit is configured to control the rotation based on the refractive index and thickness of the glass.

Embodiment 13
The control unit is configured to control the rotation based on the maximum value of the horizontal distance between the right end portion of the first region and the left end portion of the second region. 12. The apparatus according to 12.

Embodiment 14
13. The apparatus according to embodiment 13, wherein the maximum value of the horizontal distance is calculated based on the following equation.

However,
L'is the horizontal distance,
d is the thickness of the glass,
n is the refractive index of the glass,
θ is the incident angle of the incident light and
W is the width of the incident light.

Embodiment 15
The apparatus according to the eleventh embodiment, wherein the camera is configured such that the right end portion of the first region is located at the right end portion of the imaging region of the camera.

10 Glass 11 Upper surface 12 Lower surface 21 Upper particle 22 Lower particle 31 Light 32 Incident light 33 Transmitted light 34 Scattered light 41 First region 42 Second region 100 Particle detector 110 Light source 111 Focusing lens 120 Mirror 121 Rotating axis Unit 130 Control unit 140 Camera FOV Imaging area 200 Particle detection method 300 Incident light irradiation method

Claims (12)

In the particle detection method on the upper surface of glass
A step of arranging a rotatable mirror in an optical path of light emitted from a light source so that the mirror reflects the light and irradiates the upper surface with incident light.
The incident angle of the incident light is viewed from above with a first region where the incident light intersects the upper surface of the glass and a second region where the light passes through the glass and intersects the lower surface of the glass. And the process of calculating so that they do not overlap each other
The step of rotating the mirror based on the calculated incident angle, and
A step of acquiring an image of the first region with a camera arranged above the first region, and
A step of detecting particles by analyzing the acquired image, and
Including
A method in which the detected particles are considered to be present on the upper surface. The method according to claim 1, wherein the incident angle is calculated based on the refractive index and the thickness of the glass. The method according to claim 2, wherein the incident angle is calculated based on the maximum value of the horizontal distance between the right end portion of the first region and the left end portion of the second region. The method according to claim 3, wherein the maximum value of the horizontal distance is calculated based on the following formula:

However,
L'is the horizontal distance,
d is the thickness of the glass,
n is the refractive index of the glass,
θ is the incident angle of the incident light and
W is the width of the incident light. The method according to any one of claims 1 to 4, wherein the step of rotating the mirror is performed before the glass is conveyed. The method according to any one of claims 1 to 5, wherein the camera is installed so that the right end portion of the first region is located at the right end portion of the imaging region of the camera. Any one of claims 1 to 6, wherein the step of calculating the incident angle and the step of rotating the mirror are performed when at least one of the refractive index and the thickness of the glass changes. The method described in. In the particle detector on the upper surface of the glass
With a light source configured to emit light,
A rotatable mirror arranged on the optical path of the light and configured to adjust the incident angle of the incident light applied to the upper surface.
The rotation of the mirror is such that the first region where the incident light intersects the upper surface and the second region where the light passes through the glass and intersects the lower surface of the glass overlap each other when viewed from above. A control unit configured to control so that it does not become
A camera configured to acquire an image of the first region, and
Including
The control unit is configured to detect particles by analyzing the acquired image, and considers the detected particles to be present on the upper surface. The device according to claim 8, wherein the control unit is configured to control the rotation based on the refractive index and the thickness of the glass. The control unit is configured to control the rotation based on the maximum value of the horizontal distance between the right end portion of the first region and the left end portion of the second region. 9. The apparatus according to 9. The device according to claim 10, wherein the maximum value of the horizontal distance is calculated based on the following formula.

However,
L'is the horizontal distance,
d is the thickness of the glass,
n is the refractive index of the glass,
θ is the incident angle of the incident light and
W is the width of the incident light. The device according to any one of claims 8 to 11, wherein the camera is configured such that the right end portion of the first region is located at the right end portion of the imaging region of the camera.

Images