1. An inspection apparatus of a transmission optical system, comprising:

a light source that irradiates light to a subject;

a condensing lens that forms a focal point of the light on the subject;

a light shielding portion that partially shields the light concentrated by the condensing lens; and

an imaging unit for receiving the light passing through the subject to acquire an image,

the ratio of the width of the light source to the width of the light shielding portion is 1: 1-1: 8.

2. the inspection apparatus of a transmission optical system according to claim 1,

the light source, the condenser lens, and the imaging unit are arranged in a line.

3. The inspection apparatus of a transmission optical system according to claim 2,

the light shielding portion is arranged on a straight line with the light source, the condenser lens, and the imaging portion.

4. The inspection apparatus of a transmission optical system according to claim 1,

the light source and the light shielding portion have a strip shape.

5. The inspection apparatus of a transmission optical system according to claim 1,

a ratio of a distance between the light source and the subject to a distance between the light source and the light shielding portion is 1: 3-1: 17.5.

6. the inspection apparatus of a transmission optical system according to claim 1,

the width of the shading part is 5-10 mm.

7. The inspection apparatus of a transmission optical system according to claim 1,

the width of the light source is 6-40 mm.

8. The inspection apparatus of a transmission optical system according to claim 1,

the distance between the light source and the shading part is 4-10 mm.

9. The inspection apparatus of a transmission optical system according to claim 1,

the distance between the light source and the subject is 30-70 mm.

10. The inspection apparatus of a transmission optical system according to claim 1,

the light shielding portion shields light entering the subject perpendicularly from the light passing through the condenser lens.

11. The inspection apparatus of a transmission optical system according to claim 1,

the light shielding portion is arranged obliquely at an angle of 45 degrees or more and less than 90 degrees with respect to a conveying direction of the subject on a plane.

12. The inspection apparatus of a transmission optical system according to claim 1,

the subject includes a defective portion on a surface thereof, and light refracted, diffracted, or scattered by the defective portion among light not blocked by the light blocking portion is collected by the imaging portion.

Background

Conventionally, an inspection method based on visual observation is automatically performed by a mechanical device using an automated apparatus. An inspection apparatus as a transmission optical system of an automated inspection apparatus is used for finding surface defects of a substance having a flat surface.

For example, in order to improve the image output quality of an image display device, glass and various optical films included as a member of the image display device are required to have smooth and flat surfaces.

In particular, in the case of optical films used for image display devices, such as retardation films, polarizing plates, and retardation films, the surface thereof needs to be very flat.

However, defects such as scratches, foreign matter, bubbles, irregularities, cracks, twists, or breaks often occur on the surface of glass or optical films during the production or handling thereof.

In order to improve the image quality of the image display device, it is necessary to detect these defects with high sensitivity. For example, an inspection apparatus for an optical film is disclosed in korean patent laid-open publication No. 10-2017-0010675, but there is a limit in detecting a finer defect.

Prior art documents

Patent document

Patent document 1: korean patent laid-open publication No. 10-2017-0010675

Disclosure of Invention

Summary of the invention

Problems to be solved by the invention

The invention provides an inspection device for an optical system with excellent detection resolution.

[ MEANS FOR solving PROBLEMS ] A method for solving the problems

1. An inspection apparatus of a transmission optical system, comprising: a light source that irradiates light to a subject; a condensing lens that forms a focal point of the light on the subject; a light shielding portion that partially shields the light concentrated by the condensing lens; and an imaging unit that receives light that has passed through the subject and acquires an image, wherein a ratio of a width of the light source to a width of the light shielding unit is 1: 1-1: 8.

2. in the item 1, the inspection apparatus for a transmission optical system is such that the light source, the condenser lens, and the imaging unit are arranged in a line.

3. In the inspection apparatus of item 2, the light shielding portion is arranged on a straight line with the light source, the condenser lens, and the imaging portion.

4. In the item 1, the inspection device of a transmission optical system is such that the light source and the light shielding portion have a bar (bar) shape.

5. In the item 1, in the inspection apparatus of a transmission optical system, a ratio of a distance between the light source and the object to a distance between the light source and the light shielding portion is 1: 3-1: 17.5.

6. in the item 1, the inspection apparatus for a transmission optical system is such that the width of the light shielding portion is 5 to 10 mm.

7. In the item 1, the inspection apparatus for a transmission optical system is such that the width of the light source is 6 to 40 mm.

8. In the item 1, the inspection apparatus for a transmission optical system is such that a distance between the light source and the light shielding portion is 4 to 10 mm.

9. In the item 1, the inspection apparatus for a transmission optical system is such that a distance between the light source and the subject is 30 to 70 mm.

10. In the item 1, the inspection apparatus of the transmission optical system is configured such that the light shielding portion shields light that enters the object perpendicularly from among the light that has passed through the condenser lens.

11. In the inspection device of item 1, the light blocking section is disposed so as to be inclined at an angle of 45 degrees (°) or more and less than 90 degrees on a plane with respect to a transport direction of the subject.

12. In the inspection apparatus of item 1, the object includes a defect portion on a surface thereof, and light refracted, diffracted, or scattered by the defect portion among light not blocked by the light blocking portion is collected by the imaging portion.

[ Effect of the invention ]

In the inspection device for an optical system according to the embodiment of the present invention, the light that travels straight from the light source to the imaging unit is blocked by the light blocking unit, and the image acquired by the imaging unit is displayed in a dimmed manner as a whole.

In a defective portion of a subject, light reaching the defect changes its path of travel by diffraction, scattering, or refraction, and the light is collected by an imaging unit.

This makes it possible to obtain an image in which a portion having no defect is displayed in a dark state and only a portion having a defect is displayed in a bright state, and to easily detect a defect having a fine size.

Further, by condensing light using the condenser lens, the amount of light reaching the defect without being blocked by the light blocking portion can be increased, and the detection sensitivity of the defect can be improved.

Further, by arranging the light shielding portion and the light source at a specific angle with respect to the transport direction of the subject, defects of various sizes and shapes formed on the subject in various directions can be detected with substantially uniform sensitivity.

Drawings

Fig. 1 and 2 are schematic diagrams showing an inspection apparatus of a transmission optical system according to an exemplary embodiment.

Fig. 3 and 4 are diagrams showing an inspection apparatus of a transmission optical system of a comparative example and an image obtained therefrom.

Fig. 5 to 7 are diagrams showing inspection apparatuses of a transmission optical system according to some embodiments and images obtained therefrom.

Fig. 8 to 10 are diagrams showing inspection apparatuses of a transmission optical system and images obtained therefrom according to some embodiments.

Description of the symbols:

100: an inspection device of the optical system; 110. 210: a light source; 130. 230: a condenser lens; 150: a light shielding portion; 170. 270: a subject; 190. 290: an imaging unit.

Detailed Description

An exemplary embodiment of the present invention provides an inspection apparatus for a transmission optical system, including a condenser lens that forms a focal point of light on a subject, a light shielding portion that partially shields the light concentrated by the condenser lens, and an imaging portion that receives the light having passed through the subject and acquires an image, wherein a ratio of a width of the light shielding portion to a width of a light source is 1: 1-1: 8. this enables detection of defects in the subject with high sensitivity.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. However, the drawings attached to the present specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention, serve to further understand the technical ideas of the present invention, and therefore, the present invention is not to be construed as being limited to the matters described in the drawings.

The term "conveying direction of the subject" used in the present specification refers to a longitudinal direction of the subject on a plane of the subject.

Fig. 1 and 2 are schematic diagrams showing an inspection apparatus of a transmission optical system according to an exemplary embodiment.

Referring to fig. 1 and 2, an inspection apparatus 100 of a transmission optical system (hereinafter, simply referred to as an "inspection apparatus") may include a light source 110, a light shielding portion 150, and an imaging portion 190. According to an exemplary embodiment, the subject 170 can be positioned between the imaging section 190 and the light shielding section 150.

The light source 110 can irradiate light to the object 170. Non-limiting examples of the light source 110 include an LED, a metal halide lamp, a fluorescent lamp, a halogen lamp, and the like. For example, the light source 110 may have a bar shape or a rod shape.

The subject 170 can be disposed between the light source 110 and the imaging unit 190, and can be irradiated with light from the light source 110. Among the light emitted from the light source 110, light that is not blocked by the light blocking portion 150 can be received by the imaging portion 190 through the subject 170.

The object 170 may be, for example, a plate-like, film-like, or sheet-like material, and may be conveyed while being placed on a transparent conveyor belt or wound around a roller, for example.

The object 170 can include glass or an optical film. The optical film or the glass may be inserted into an OLED device, an LCD device, or the like. The optical film can include, for example, a polarizing plate, a retardation film, an encapsulation film, a window film, a protective film, and a touch sensor film.

The object 170 can include a defect 172. The defect 172 may include, for example, a flaw, scratch, crack, dent, foreign matter, fracture, or the like, and may refer to an uneven or inhomogeneous portion of the surface of the object 170. The light reaching the defect 172 may change the traveling path by, for example, refraction, diffraction, or scattering.

The object 170 may be a transparent or transmissive substance, or may be a substance having at least translucency. The light may be opaque because the light may travel to the imaging unit 190 by changing the travel path of the light through diffraction or scattering.

The light shielding portion 150 is disposed between the subject 170 and the light source 110, and can partially shield the light. For example, the light shielding portion 150 may be arranged in parallel with the object 170. For example, light traveling substantially straight toward the imaging section 190 among light emitted from the light source 110 can be blocked by the light blocking section 150.

The light shielding portion 150 may be formed of a material that shields light. By "block light" is meant substantially no light passes through. For example, the light shielding portion 150 can be formed of a substance having a light transmittance of less than 10%.

The light shielding portion 150 may be formed of a material that absorbs or reflects light, for example. Non-limiting examples of the light shielding portion 150 include a metal plate and an opaque plastic.

The "partially blocking light" means not completely blocking the light, and may mean, for example, blocking 50% to 90% of the light.

If the shielding ratio is within the above range, the light amount does not become excessive, and therefore the background of the image acquired by the imaging unit 190 can be maintained dark, and the light amount does not become too small, and therefore the defect can be detected brightly, and the detection capability of the inspection apparatus 100 can be ensured.

The imaging unit 190 can acquire light passing through the subject 170 to acquire an image. For example, an image can be acquired by light passing through the subject 170 without being blocked by the light blocking portion 150. The imaging unit 190 includes, for example, a CCD Camera, and may include, for example, a Line-scan Camera (Line-scan Camera) and an Area Camera (Area Camera).

For example, when the imaging unit 190 receives light, the image acquired by the imaging unit 190 is brightly displayed, and when the light is not received, the image acquired by the imaging unit 190 is dimly displayed.

More specifically, fig. 1 is a schematic diagram showing a case where light is irradiated to a portion of the subject 170 having no defect in some embodiments, and fig. 2 is a schematic diagram showing a case where light is irradiated to a defective portion 172 of the subject 170 in some embodiments.

As shown in fig. 1, when light is irradiated to a portion of the subject 170 having no defect, light traveling substantially straight toward the imaging unit 190 among the light is blocked by the light blocking unit 150, and light traveling while avoiding the light blocking unit 150 can reach the subject 170. The light can go straight through the subject 170. The "straight forward" refers to a case where the traveling path of light is not changed but substantially maintained, and can include a case where light is refracted in a range of about 10 degrees, for example.

In this case, the light may not be collected by the image pickup unit 190. Therefore, the image acquired by the photographing section 190 may be displayed dimly.

On the other hand, as shown in fig. 2, when light is irradiated to the defect 172 of the object 170, the light reaches the defect (e.g., scratch) and is diffracted, scattered, or refracted, and the travel path of the light can be changed.

In this case, a part of the diffracted, scattered, or refracted light is received by the imaging unit 190, and an image obtained by the imaging unit 190 can be brightly displayed.

Therefore, the image is displayed dimly in the case where the subject 170 has no defect, and is displayed brightly in the case where there is a defect. Therefore, since only the portion corresponding to the defect 172 is brightly displayed on a dark background, a minute defect of the object 170 can be easily detected by the inspection apparatus 100.

In an exemplary embodiment, the ratio of the width (w2) of the light source 110 to the width (w1) of the light shielding portion 150 is 1: 1-1: 8, may preferably be 1: 1-1: 3.5.

in an exemplary embodiment, the width (w1) of the light shielding portion 150 may be 5 to 10 mm. If the width (w1) of the light shielding portion 150 is within the above range, the detection performance can be improved. The width (w1) of the light shielding portion 150 may preferably be 5 to 9mm, 6 to 10mm, 5 to 8mm, or 6 to 8 mm.

In an exemplary embodiment, the width (w2) of the light source 110 may be 6-40 mm. If the width (w2) of the light source 110 is within the range, the detection performance can be improved. The width (w2) of the light source 110 may preferably be 6 to 30mm or 6 to 21 mm.

In an exemplary embodiment, the ratio of the distance (d2) between the light source 110 and the object 170 to the distance (d1) between the light source 110 and the light shielding portion 150 may be 1: 3-1: 17.5, may preferably be 1: 3.75-1: 15.

in an exemplary embodiment, the distance (d1) between the light source 110 and the light shielding part 150 may be 4 to 10 mm. If the distance (d1) between the light source 110 and the light shielding portion 150 is within the range, the detection performance can be improved. The distance (d1) between the light source 110 and the light shielding part 150 may preferably be 4 to 9mm or 4 to 8 mm.

In an exemplary embodiment, the distance (d2) between the light source 110 and the subject 170 may be 30-70 mm. If the distance (d2) between the light source 110 and the subject 170 is within the range, the detection performance can be improved. The distance (d2) between the light source 110 and the subject 170 may preferably be 30 to 65mm, 35 to 65mm, or 30 to 60 mm.

In an exemplary embodiment, "w 1", "w 2", "d 1", and "d 2" can satisfy the following formula 1.

[ equation 1]

In some embodiments, the light source 110 can emit light having a wavelength of 400 to 700nm or 500 to 600 nm. In this case, when the light source 110 and the light shielding portion 150 have the above-described dimensions and positions, the defect detection capability can be improved.

In some embodiments, the width of the defect 172 may be 0.2 to 20 μm. The width of the defective portion 172 is a distance between both end portions of the defective portion 172 in a direction parallel to the moving direction of the object 170.

In several embodiments, the ratio of the distance between the light shielding portion 150 and the object 170 to the width (w1) of the light shielding portion 150 may be 1: 5-1: 10. if within the range, the defect detection capability can be improved. The ratio of the distance between the light shielding portion 150 and the object 170 to the width (w1) of the light shielding portion 150 may preferably be 1: 6-1: 9.

fig. 3 and 4 are diagrams showing an inspection apparatus of a transmission optical system of a comparative example and an image obtained therefrom.

Referring to fig. 3, the inspection apparatus 200 of the transmission optical system of the comparative example includes a light source 210 and an imaging unit 290, and does not include the light shielding film 150 included in the inspection apparatus 100 of the embodiment. The configuration and/or structure substantially the same as those of fig. 1 and 2 will not be described.

When the light shielding portion 150 is omitted, light substantially straight from the light source 210 toward the imaging portion 290 is received by the imaging portion 290 without being shielded. In this case, unlike the inspection apparatus 100 of the embodiment, the amount of light received by the imaging unit 290 is too large, and the entire acquired image is brightly displayed.

In a defective portion in the object 270, there is a possibility that refraction, diffraction, or scattering of light reaching the defect is caused. In this case, the traveling path of the light changes, and the light may travel while avoiding the imaging unit 290. Therefore, the defective portion is displayed more dimly in the image.

In fig. 4, the dark portion crossing the center in the longitudinal direction corresponds to the defect existing in the subject 270, and is displayed more faintly than the portion having no defect.

Therefore, in the case where the light shielding portion 150 is not provided, as shown in fig. 4, the difference in color and brightness between the portion having no defect and the defective portion is not large, and thus the defect detection capability may be lowered.

In several embodiments, the inspection apparatus 100 can further include a condenser lens 130 disposed between the light source 110 and the light blocking portion 150. The condenser lens 130 functions to condense the straight light while passing through it, and may include a concave lens or the like, for example.

The condenser lens 130 may be integrated with the light source 110 and included as one component in the light source 110. Further, the light source 110 may be integrated with the condensing lens and the light source 110 up to the light shielding portion 150, and included as one component in the light source 110.

According to an embodiment, the condenser lens 130 can be configured to form a focal point on the surface of the subject 170.

In the case where the focal point is formed on the surface of the object 170, the amount of light reaching the defective portion 172 can be increased. This increases the amount of light that changes its path due to diffraction, scattering, or refraction in the defect portion 172, and also increases the amount of light that is received by the imaging unit 190, thereby increasing the defect detectability.

In several embodiments, the light shielding part 150 can have a bar (bar) shape partially overlapping the light source 110 or the condensing lens 130 on a plane.

For example, the light source 110 or the condenser lens 130 may have the strip shape, and the light source 110 or the condenser lens 130 may uniformly block the light emitted from the light source 110 and condensed by the condenser lens 130 in the longitudinal direction of the strip shape by the light blocking portion 150 having the strip shape. This reduces the amount of light received by the imaging unit 190, and the acquired image maintains a dark background, thereby improving the defect detection capability.

In one embodiment, the light shielding portion 150 can shield light incident perpendicularly to the subject 170 from among the light having passed through the condenser lens 130.

The "vertically incident light" refers to light that is substantially vertically incident, and may include light that is refracted by the condenser lens 130 and is incident at an angle in a range of approximately 60 degrees to 90 degrees, for example.

By blocking the vertically incident light, the amount of light received by the imaging unit 190 can be adjusted so as not to become excessive, and the background of the acquired image can be maintained dark.

According to one embodiment, the light source 110, the condenser lens 130, the light shielding portion 150, and the imaging portion 190 may be arranged in a line in a direction perpendicular to the subject 170.

As shown in fig. 1 and 2, when the light source 110, the condenser lens 130, the light shielding portion 150, and the imaging portion 190 are arranged as described above, a focal point can be easily formed on the surface of the object 170, and light can be incident symmetrically to the focal point, whereby the capability of detecting defects formed in various directions can be increased.

Fig. 5 to 7 are diagrams showing inspection apparatuses of a transmission optical system according to some embodiments and images obtained therefrom.

In some embodiments, as shown in fig. 5, the light shielding portion 150 may be disposed perpendicular to the conveying direction of the subject 170 on a plane. The term "perpendicular" refers to an angle that can be recognized at substantially 90 degrees, and may include, for example, an angle of 80 to 100 degrees.

For example, the light source 110 may be arranged in the same direction as the light shielding portion 150. This increases the amount of light applied to the defect formed in the width direction of the object 170, and improves the defect detection capability.

Therefore, as shown in fig. 6 and 7, a defect such as a linear scratch formed to have a small thickness can be easily recognized on the acquired image, and the defect detection resolution can be improved.

Fig. 8 to 10 are diagrams showing inspection apparatuses of a transmission optical system according to some embodiments and images obtained therefrom.

In some embodiments, as shown in fig. 8, the light shielding portion 150 may be arranged obliquely at an angle of 45 degrees or more and less than 90 degrees with respect to the transport direction of the subject 170 on a plane. In fig. 8, an angle formed by the light shielding portion 150 and the transport direction of the subject 170 is represented by θ.

The defective portion 172 may be formed in each direction and shape in the object 170. For example, when the direction in which the defect 172 extends is substantially perpendicular to the direction in which the light shielding film 150 and the light source 110 are arranged, the amount of light reaching the defect 172 may be small, and the defect detection capability may be degraded.

For example, when the arrangement angle of the light shielding portions 150 is an angle in the above range, both a defect formed in the conveyance direction of the object 170 and a defect formed perpendicular to the conveyance direction can be detected with high sensitivity. This makes it possible to detect defects formed in various directions and shapes in a versatile manner (with substantially uniform sensitivity).

Fig. 9 is an image taken from the same portion of the same subject as the subject of fig. 6. Fig. 10 is an image taken from the same portion of the same subject as the subject of fig. 7. Fig. 10 and 7 are images obtained from scratches formed in a direction parallel to the conveying direction of the subject.

According to these, in the case of the scratch formed at a specific angle with respect to the transport direction of the subject 170, as shown in fig. 9, the detection sensitivity can be further improved (compared with fig. 6).

In addition, in the case of the scratch formed in parallel to the transport direction of the subject 170, as shown in fig. 10, the detection sensitivity can be further improved as compared with the image shown in fig. 7.

According to some embodiments, the object 170 includes a scratch inside, and light diffracted by the scratch among light not blocked by the light blocking part 150 is collected by the photographing part 190. Accordingly, the scratch having a small thickness can be detected by the inspection apparatus 100 by the diffraction, and the detection resolution can be improved.

In several embodiments, a subject containing a defect may be prepared, and light is irradiated after a light shielding portion is disposed below the subject so that vertical light with respect to the subject is filtered by the light shielding portion. Then, the light diffracted by the defect is collected to acquire an image, whereby the defect of the object can be inspected.

Hereinafter, preferred embodiments are described to help understanding of the present invention, but these embodiments are merely illustrative of the present invention and do not limit the scope of the appended claims. It will be apparent to those skilled in the art that various changes and modifications can be made to the embodiments within the scope of the present invention and the technical spirit, and these changes and modifications naturally fall within the scope of the appended claims.

Examples

The illumination, light shielding portion, polarizing film (subject), and camera are arranged as shown in fig. 1.

The polarizing film includes a scratch having a line width of about 50 μm, and an inspection image is obtained from light obtained by a camera by irradiating a region where the scratch is located with light having a wavelength of about 550 nm.

The difference between the brightness (gradation; 0-255 units) of the region where the scratch is formed on the inspection image and the brightness of the peripheral region (dark portion) is calculated and expressed by the detection intensity.

Experimental example 1: evaluation of detection Performance based on Width of light-blocking portion (w1)

At w 2: 21mm, d 1: 6mm, d 2: the examination image and the detection intensity were obtained while changing w1 under the condition of 50 mm.

[ TABLE 1]

Experimental example 2: evaluation of detection Performance based on Width (w2) of light Source

At w 1: 6mm, d 1: 6mm, d 2: the examination image and the detection intensity were obtained while changing w2 under the condition of 50 mm.

[ TABLE 2 ]

Experimental example 3: evaluation of detection Performance based on distance (d1) between light source and light-shielding part

At w 1: 6mm, w 2: 21mm, d 2: the inspection image and the detection intensity were obtained under the condition of 50mm while changing d 1.

[ TABLE 3 ]

Experimental example 4: evaluation of detection Performance based on distance (d2) between light Source and subject

At w 1: 6mm, w 2: 21mm, d 1: the inspection image and the detection intensity were obtained under the condition of 6mm while changing d 2.

[ TABLE 4 ]