JPH09273996A - Projector for inspecting appearance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector for inspecting appearance which can carry out uniform illumination of even a large substrate entirely to allow highly reliable inspection of appearance and moreover, achieves a smaller size of the apparatus. SOLUTION: Fresnel lenses 321 and 322 for split condensing are arranged corresponding to light sources 21 and 25 for illumination are so arranged that the axes thereof deviate from the axis of the illumination light of the light sources 21 and 25 to regulate the illumination light from the light sources 21 and 25 to a parallel luminous flux. The parallel luminous fluxes are regulated to the focused luminous flux through the Fresnel lenses 331 and 332. Moreover, a scattering plate 34 is arranged in the focused luminous flux by the Fresnel lenses 331 and 332 for split projection to generate viewing screen illumination light. The surface of a glass substrate 35 is irradiated with the illumination light and fine scattered light on the glass substrate 35 attributed to a defect part 36 is observed by visual recognition of an observing person 37.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light projecting device for visual inspection used for visual inspection of large liquid crystal glass substrates and the like.

[0002]

2. Description of the Related Art Conventionally, in order to keep the quality of a glass substrate of a liquid crystal display stable, it has been printed on a substrate such as a visual inspection for unevenness of the film thickness of a resist or the like on a substrate or a pinhole on an IOT film. It is extremely important to inspect appearances such as pattern irregularities and irregularities, and dust and scratches adhering to the substrate surface.

Conventionally, an appearance inspection light projecting device is used for such an appearance inspection. Among such appearance inspection light projecting devices, the unevenness of the film thickness of the resist or the like on the substrate and the IOT film are used. As shown in FIG. 3, an elliptical rotating mirror 2 is arranged on the back of the light source 1 so that the elliptic rotating mirror 2 reflects the illuminating light from the light source 1 to absorb the heat rays. Gate 4 through filter 3
Of the glass substrate 7 as a member to be inspected at a predetermined angle in the parallel luminous flux regulated by the converging Fresnel lens 6 through the filter 5. A film such as a resist on the substrate is provided by arranging it so that the surface of the glass substrate 7 is evenly illuminated and the minute scattered light generated from the surface of the glass substrate 7 is visually observed by an observer 9. There is a device which detects a defective portion 8 such as uneven thickness or a pinhole on the IOT film.

Further, as suitable for the visual inspection of the irregularity or unevenness of the pattern printed on the substrate, or the dust and scratches adhering to the substrate surface, the same parts as those in FIG. As shown in FIG. 3, a light projecting Fresnel lens 10 is further arranged in the parallel light beam regulated by the light collecting Fresnel lens 6, and the light beam is projected in the optical path before the convergence position A of the light beam by the light projecting Fresnel lens 10. A glass substrate 7 as an inspection member is arranged at a predetermined angle to uniformly illuminate the surface of the glass substrate 7, and the glass substrate 7
By observing the minute scattered light generated from the surface of the glass substrate 7 from the vicinity of the convergence position S of the reflected light from the viewer 9, the disorder or unevenness of the pattern printed on the substrate, or the substrate There is a device that detects a defective portion 11 such as dust or scratches attached to the surface. By the way, recently, liquid crystal displays have been increasing in size, and with this trend, glass substrates used therein are also increasing in size.

[0005]

However, when the glass substrate is enlarged in any of the above-mentioned configurations, the converging Fresnel lens 6 and the condensing Fresnel lens 6 having the same size as the glass substrate at this time are used. Since the Fresnel lens 10 for projecting light is required, the converging Fresnel lens 6 and the Fresnel lens 10 for projecting light tend to become larger and larger, but with the current technology, the lens diameter is larger than necessary. However, it is difficult to manufacture the lens in order to keep the lens performance constant, and it is difficult to illuminate the glass substrate 7 evenly. Therefore, there is a problem that the reliability of the visual inspection is deteriorated. When the larger condensing Fresnel lens 6 and the projecting Fresnel lens 10 are used, the focal length also becomes large. Therefore, in the vertical type as shown in the figure, the dimension in the height direction is Properly increases, there is a problem that also inevitable size of the apparatus.

The present invention has been made in view of the above circumstances, and it is possible to uniformly illuminate a large substrate even for a large substrate.
It is an object of the present invention to provide an appearance inspection light projecting device capable of performing highly reliable appearance inspection and capable of downsizing the device.

[0007]

According to the first aspect of the present invention,
A first optical unit that has an illumination light source and a Fresnel lens that is divided into at least two, and that limits the illumination light from the illumination light source to a light beam in a predetermined direction, and a light beam by the first optical unit. While being placed inside,
It is composed of a second optical means for giving a predetermined optical characteristic to the light flux, and a member to be inspected which is illuminated by the light flux of the second optical means and whose appearance is inspected from this illumination state.

According to a second aspect of the present invention, there is provided a first optical system which has an illuminating light source and a Fresnel lens which is divided into at least two, and which regulates the illuminating light from the illuminating light source into a luminous flux in a predetermined direction. And a member to be inspected, which is illuminated by the light flux of the first optical means and whose appearance is inspected from the vicinity of the converging position of the reflected light.

The invention described in claim 3 is the first or second invention.
In the description, the illumination light source is provided corresponding to each of the at least two Fresnel lenses, and is arranged so as to be displaced from the illumination optical axis of each light source.

As a result, according to the present invention, it is easy to keep the lens performance constant by using a plurality of small Fresnel lenses for the illumination light source as the first optical means. The lens can be made simple,
Moreover, since the respective optical axes of the divided Fresnel lenses are arranged so as to be offset from the illumination optical axis of the illumination light source, it is possible to uniformly illuminate the large member to be inspected. From this illumination state, it is possible to realize a highly reliable visual inspection for the inspected member.
By using a small Fresnel lens having a small focal length, the device can be downsized.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a schematic structure of a light-projection apparatus for appearance inspection to which a first embodiment of the present invention is applied. The light projecting device for appearance inspection in this case is applied to the appearance inspection under the film such as the unevenness of the film thickness of the resist on the substrate, the pinhole on the IOT film, or the under film.

In the figure, 21 is a light source, and this light source 21
An elliptical rotating mirror 22 is arranged on the back of the. The elliptical rotation mirror 22 reflects the illumination light from the light source 21 and collects it at the gate 24 via the heat ray absorption filter 23.

Similarly, 25 is a light source, and an elliptical rotation mirror 26 is arranged at the back of the light source 25. The elliptical rotation mirror 26 reflects the illumination light from the light source 25 and passes through a heat ray absorption filter 28. I'm trying to collect at gate 29. The illumination light passing through these gates 24 and 29 is filtered (green, yellow, polarizing plate, etc.) 3
0 and 31 are separately passed to irradiate the converging Fresnel lens 32.

In this case, the condenser Fresnel lens 32 is
Two split converging Fresnel lenses 32 having the same focal length
1 and 322. The split condensing Fresnel lens 321 is irradiated with the illumination light from the light source 21, and the split condensing Fresnel lens 322 is irradiated with the illumination light from the light source 25. The light is regulated to a parallel light flux. At this time, the respective optical axes 321a and 32a of the Fresnel lenses 321 and 322 for splitting and condensing the illumination light axes 21a and 25a of the light sources 21 and 25, respectively.
2a are arranged at a predetermined angle.

Further, two divided converging Fresnel lenses 3 are provided.
The condensing Fresnel lens 32 composed of 21, 322 is, for example, prepared by forming a lens mold, and by pouring the lens material into this mold, the condensing Fresnel lenses 321 and 322 having the same focal length are integrally formed. And two Fresnel lenses 321 and 32 for condensing light having the same focal length
2 is prepared, and these Fresnel lenses 321 for split light collection are provided.
322 are fused together to form an integrated structure, or a predetermined frame body is prepared.
It is conceivable that one is configured such that the individual Fresnel lenses 321 and 322 for divided light collection are fitted.

Fresnel lenses 321 and 322 for condensing light.
Further, a Fresnel lens 33 for projecting light is arranged in the parallel light flux regulated by. The light projecting Fresnel lens 33 is also composed of two divided light projecting Fresnel lenses 331 and 332 having the same focal length. The parallel light beams from the split converging Fresnel lenses 321 and 322 are restricted to convergent light beams by arranging the light beams 321 and 322 in correspondence with each other.

Incidentally, such a Fresnel lens 3 for projecting light is used.
Similarly to the condensing Fresnel lens 32 described above, the optical axes of the light sources 3 and 3 are the illumination optical axes 21a and 2a of the light sources 21 and 25, respectively.
It is arranged so as to deviate from 5a, and is manufactured in the same manner as the converging Fresnel lens 32.

Then, the scattering plate 34 is arranged in the convergent light flux formed by the Fresnel lenses 331 and 332 for split light projection. The scattering plate 34 transmits the light fluxes emitted from the light-projecting Fresnel lenses 331 and 332, thereby giving a predetermined optical characteristic to generate the Scherkasten illumination light.

A glass substrate 35 as a member to be inspected is arranged at a predetermined angle corresponding to the scattering plate 34. The glass substrate 35 is arranged so that the Schaukasten illumination light from the scattering plate 34 is uniformly illuminated,
The unevenness of the film thickness of the resist or the like on the glass substrate 35 or I
The minute scattered light on the surface of the glass substrate 35 caused by the defective portion 36 such as a pinhole on the OT film is visually detected by the observer 37.

With such a configuration, the illumination light from the light source 21 is reflected by the elliptical rotary mirror 22, passes through the heat ray absorption filter 23, the gate 24, and the filter 30, and then the one of the condenser Fresnel lenses 32. The split condensing Fresnel lens 321 is irradiated, and similarly, the illumination light from the light source 25 is reflected by the elliptical rotation mirror 26, passes through the heat ray absorption filter 28, the gate 29, the filter 31, and the condensing light. The other split condensing Fresnel lens 322 of the Fresnel lens 32 is irradiated. Then, the parallel light fluxes regulated by the divided converging Fresnel lenses 321 and 322 are emitted, and the divided converging Fresnel lenses 3 are emitted.
The parallel luminous fluxes from the light emitting elements 21, 322 are further divided by the Fresnel lens 331 for projecting light.
Is irradiated onto the scattering plate 34 as a convergent light beam.

Then, the scattering plate 34 produces a schaukasten illumination light, which illuminates the surface of the glass substrate 35. Then, from this state, the minute scattered light generated on the surface of the glass substrate 35 is observed by the observer 37.
By visually observing, the unevenness of the film thickness of the resist or the like on the glass substrate 35 and the defective portion 36 such as the pinhole on the IOT film can be detected.

Therefore, in this way, the illumination light source 2
The split converging Fresnel lenses 321 and 322 having the same focal length corresponding to Nos.
1 and 25 are arranged so as to deviate from the illumination optical axis, and the split converging Fresnel lenses 321 and 322 regulate the illumination light from the light sources 21 and 25 into parallel light fluxes. And 322, the parallel light fluxes from the light sources 322 and 322 are arranged so as to face the split light-collecting Fresnel lenses 321 and 322.
2 to regulate the convergent light flux, and further dispose the scattering plate 34 in the convergent light flux by the split light projecting Fresnel lenses 331 and 332 to generate the Scherkasten illumination light,
By irradiating the surface of the glass substrate 35, which is the member to be inspected, with this illuminating light, and observing the minute scattered light on the surface of the glass substrate 35 caused by the defect portion 36 by the observer 37, the glass substrate 35 is observed. It is possible to perform a pinhole on the IOT film and a visual inspection under the film for unevenness of the film thickness of the upper resist or the like.

In this case, the light collecting Fresnel lens 32 and the light projecting Fresnel lens 33 are respectively composed of two light collecting Fresnel lenses 321 and 322 and a light projecting Fresnel lens 331 and 332. Since a small size lens can be used, the lens performance is kept constant compared to the conventional one that prepares a converging Fresnel lens for condensing and a Fresnel lens for projecting light, which is almost the same size as the glass substrate of the member to be inspected. It is easy and the lens can be made easily.

Further, these divided converging Fresnel lenses 3
21, 322 and the Fresnel lens 331 for split light projection,
332 are arranged such that their optical axes are displaced from the illumination optical axes of the light sources 21 and 25, and the light flux formed through these is uniformly irradiated on the surface of the scattering plate 34, so that the entire surface of the scattering plate 34 is evenly distributed. Since it is possible to generate a simple schaukasten illumination light, it is possible to realize a highly reliable visual inspection even for a large glass substrate 35.

Further, the split light collecting Fresnel lens 32 and the light projecting Fresnel lens 33 are constituted by the light collecting Fresnel lenses 321 and 322 and the light projecting Fresnel lenses 331 and 332, respectively. Since the focal length of each of the split condensing Fresnel lenses 321, 322 and the split projecting Fresnel lenses 331, 332 can be reduced as compared with the one requiring a large Fresnel lens having a large focal length as the size of the substrate increases. The height of the entire device can be reduced, and the device can be downsized. (Second Embodiment) FIG. 2 shows a schematic structure of a light projecting apparatus for appearance inspection to which a second embodiment of the present invention is applied. The same parts as those in FIG. ing.

In the second embodiment, the one applied to the visual inspection for the irregularity or unevenness of the pattern printed on the substrate, or the dust and scratches adhering to the substrate surface is shown.

In this case, the scattering plate 34 described in the first embodiment is removed from the optical path, and the Fresnel lens 33 for projecting light is emitted.
The glass substrate 35 as the member to be inspected is arranged at a predetermined angle in the convergent light flux regulated by the respective Fresnel lenses 331 and 332 for divided light projection, and the glass substrate 3
The five surfaces are uniformly illuminated by the convergent light fluxes from the respective Fresnel lenses 331 and 332 for split light projection, and the defective portion 36 on the glass substrate 35 is caused from the vicinity of the convergence position S of the reflected light from the glass substrate 35. The minute scattered light is detected visually by the observer 37. Also in this case, the illumination optical axes 21a, 2a of the light sources 21, 25, respectively.
Fresnel lenses 321 and 322 for condensing light for 5a
By arranging the respective optical axes 321a, 322a of the light sources by shifting them by a predetermined angle, the light source image positions of the respective light sources 21, 25 are made to coincide with the converging position A of the light flux by the split projection Fresnel lenses 331, 332. .

If, for example, a light shielding plate is arranged at the convergence position S of the reflected light from the glass substrate 35, the glass substrate 35
It is also possible to adopt a configuration in which the light reflected by the light does not directly enter the eyes of the observer 37.

Even in this case, however, the illumination light from the light source 21 is reflected by the elliptical rotation mirror 22, passes through the heat ray absorbing filter 23, and is passed from the gate 24 to the filter 30.
One of the divided converging Fresnel lenses 321 of the condensing Fresnel lens 32 is irradiated therethrough, and similarly, the light source 2
The illumination light from 5 is reflected by the elliptical rotation mirror 26, passes through the heat ray absorption filter 28, the gate 29, the filter 31 and the other split condensing Fresnel lens 322 of the condensing Fresnel lens 32. It Then, the parallel light fluxes regulated by the split converging Fresnel lenses 321 and 322 are emitted, and the parallel light fluxes from the split light converging Fresnel lenses 321 and 322 are further divided by the light projecting Fresnel lens 33. Fresnel lens 331,
It is irradiated to 332, and it is irradiated to the glass substrate 35 surface as a convergent light flux.

From this state, the observer 37 visually observes minute scattered light caused by the defective portion 36 on the glass substrate 35 from the vicinity of the convergence position S of the reflected light from the glass substrate 35. The defect or irregularity of the pattern printed on the substrate, or the defective portion 36 such as dust or scratches attached to the substrate surface can be detected.

Therefore, even in this way, the above-mentioned first
The effect similar to that of the embodiment can be expected, and further, the optical axes of the split condensing Fresnel lenses 321 and 322 and the split projecting Fresnel lenses 331 and 332 are displaced from the illumination optical axes of the light sources 21 and 25. By arranging as described above, the convergent light flux formed through them can be uniformly illuminated on the surface of the glass substrate 35. Therefore, the observation of the reflected light from the surface of the glass substrate 35 in the vicinity of the convergence position S is A highly reliable appearance inspection can be realized even for a large glass substrate 35.

In the above embodiment, the light source for illumination is the two light sources 21 and 25, and the converging Fresnel lens 32 and the light projecting Fresnel lens 33 are each divided into two. The number of illumination light sources may be two or more, and the light-collecting Fresnel lens 32 and the light-projecting Fresnel lens 33 may also be divided into two or more. Further, in the above description, the number of light sources and the number of Fresnel lenses are the same, but if the light source is capable of illuminating a wide range, a plurality of Fresnel lenses can be arranged in the illumination range of this light source. Further, in the above description, the scattering plate 34 is fixed, but if the scattering plate 34 is detachable, the first embodiment and the second embodiment are selectively executed. be able to.

[0033]

As described above, according to the present invention, by using a plurality of small Fresnel lenses as the first optical means, it is easy to keep the lens performance constant, and the lens performance can be kept constant. It can be made simple. Further, by arranging the respective optical axes of the divided Fresnel lenses so as to be displaced from the illumination optical axis of the light source for illumination, it is possible to illuminate the entire substrate evenly for a large substrate. A highly reliable visual inspection can be realized. Further, by using a small Fresnel lens having a small focal length, the device can be downsized.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a second embodiment of the present invention.

FIG. 3 is a view showing an example of a conventional appearance inspection light projecting device.

FIG. 4 is a diagram showing another example of a conventional light emitting device for appearance inspection.

[Explanation of symbols]

 21, 25 ... Light source, 22, 26 ... Elliptical rotation mirror, 23, 28 ... Heat ray absorption filter, 24, 29 ... Gate, 30, 31 ... Filter, 32 ... Converging Fresnel lens, 321, 322 ... Divided condensing Fresnel lens, 33 ... Fresnel lens for projecting light, 331, 332 ... Fresnel lens for split projecting light, 34 ... Scattering plate, 35 ... Glass substrate, 36 ... Defect part, 37 ... Observer.

Claims (3)

[Claims] 1. A first optical means having an illuminating light source, a Fresnel lens arranged in at least two divisions, and regulating the illuminating light from the illuminating light source into a luminous flux in a predetermined direction, and the first optical means. The second optical means which is arranged in the light flux by the optical means and which gives a predetermined optical characteristic to the light flux, and the light flux of the second optical means are illuminated, and an appearance inspection is performed from this illumination state. A projecting device for visual inspection, comprising: a member to be inspected. 2. A light source for illumination, a first optical means which has a Fresnel lens arranged in at least two divisions, and which regulates the illumination light from the light source for illumination to a luminous flux in a predetermined direction, and the first optical means. And a member to be inspected, which is illuminated by the luminous flux of the optical means and whose appearance is inspected from the vicinity of the converged position of the reflected light. 3. The illumination light source is provided so as to correspond to at least a Fresnel lens divided into at least two, and is arranged so as to be displaced from an illumination optical axis of each light source. Light projector for visual inspection.