JP2002071571A - Projector for visual inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact and low-cost projector for visual inspection. SOLUTION: In the projector for visual inspection, the surface of a large substrate 3 is irradiated with illumination light, and a defect or the like is inspected. A Fresnel lens 20 is arranged in such a way that it is arranged near a mirror 11, that it regulates the illumination light to a parallel luminous flux so as to be guided to the mirror 11, that it regulates the parallel luminous flux reflected by the mirror 11 to a parallel luminous flux to be regulated to a convergence luminous flux, and that it regulates the luminous flux to the convergence luminous flux.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection inspection apparatus for inspecting the appearance of dust and foreign matter on the surface of a large substrate such as a glass substrate or a color filter of a flat panel display (FPD) or a semiconductor wafer. It relates to an optical device.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a light projecting device for visual inspection. This light-emitting device for visual inspection is a light-collecting Fresnel lens 1 that is arranged in an illumination light path and regulates incident light into a parallel light beam.
(Thickness: 5 mm) and a light projecting Fresnel lens configured to be able to be inserted into and removed from the parallel light beam guided through the light-collecting Fresnel lens 1, and to restrict the guided parallel light beam to a convergent light beam. 2 (thickness 5 mm) and a scattering plate 4 for illuminating an observation sample, for example, a large substrate 3 with a diagonal of 500 mm or more by giving optical characteristics to the convergent light beam guided through the light projecting Fresnel lens 2. And

The light-collecting Fresnel lens 1, the light-projecting Fresnel lens 2, and the scattering plate 4 each have a larger diameter (about 500 to 600 mm) than the large substrate 3. Thereby, the large-sized substrate 3 is illuminated without unevenness over the whole.

As the scattering plate 4, a transmission type liquid crystal plate to which a power supply 5 is connected via a transparent electrode (not shown) and to which a voltage can be applied (hereinafter, the scattering plate is described as a transmission type liquid crystal plate) is used. Used.

On the other hand, as the light source 6, for example, a metal halide lamp (150 to 250 W) is applied. The light source 6 is configured such that its light emitting point is located at the first focal point of the elliptical rotating mirror 7 and the second focal point of the elliptical rotating mirror 7 is the gate 8 provided with the scattering plate.
Further, the distance between the gate 8 and the light-collecting Fresnel lens 1 is equal to the focal length (f) of the light-collecting Fresnel lens 1.

A heat ray absorbing filter 9 is provided between the light source 6 and the gate 8. In addition, on the illumination optical path, a filter (green, yellow, polarizing plate, etc.) 10,
A mirror 11 is provided. The scattering plate disposed on the gate 8 has a size of 20 to 30 mm, and has a function of emitting uniform illumination light from the gate 8.

With such a configuration, the illumination light emitted from the light source 6 passes through the filter 10 via the elliptical rotating mirror 7, the heat ray absorbing filter 9 and the gate 8, and irradiates the mirror 11. The illumination light applied to the mirror 11 is reflected by the mirror 11 and is applied to the converging Fresnel lens 1 to be restricted to a parallel light flux.

Here, in the above-mentioned device, a convergent light beam is used as illumination light, so that a light-transmitting Fresnel lens 2 and a transparent liquid crystal plate 4 to which a voltage is applied and which is transparent are inserted in the illumination light path. ing. However, the convergent light beam from the light projecting Fresnel lens 2 passes through the transmissive liquid crystal plate 4 as it is, and is illuminated on the entire surface of the large substrate 3 without unevenness.

The reflected illumination light reflected from the large substrate 3 forms an image at a position S near the eye 12 of the observer. At this time, if a foreign substance 13 such as dust or a scratch is present on the surface of the large-sized substrate 3, scattered light is generated from the foreign substance 13 and no image is formed at the nearby position S. As a result, the observer can visually confirm the presence of the foreign matter 13 on the surface of the large-sized substrate 3 by visually observing the minute scattered light from outside the optical axis.

[0010]

However, in the above-mentioned light projecting device for visual inspection, after the illumination light is turned back by the mirror 11, the light-collecting Fresnel lens 1 and the light projecting light are located at a predetermined distance from the mirror 11. A convergent light beam is formed by using two Fresnel lenses with the Fresnel lens 2. Therefore, the size of the entire apparatus is increased. In particular, since a large substrate 3 having a diagonal size of 500 mm or more is inspected for appearance, the condensing Fresnel lens 1, the light projecting Fresnel lens 2 and the scattering plate 4 have a diameter (50) larger than the large substrate 3 as described above.
(About 0 to 600 mm).

An object of the present invention is to provide a compact and inexpensive light projecting device for visual inspection.

[0012]

According to a first aspect of the present invention, there is provided a light-emitting device for illuminating a surface of a large-sized substrate for inspecting a defect or the like for inspecting a defect or the like. A mirror for reflecting the illumination light emitted from the light source, and a mirror disposed close to the mirror for restricting the illumination light to a parallel light flux and guiding the light to the mirror, and converging the parallel light flux reflected by the mirror; A light projection device for visual inspection, comprising: a Fresnel lens that regulates a light beam.

According to a second aspect of the present invention, in the light emitting device for visual inspection according to the first aspect, light is guided through the Fresnel lens in a reflection optical path of the Fresnel lens which does not overlap with the light beam emitted from the light source. And a scattering means for giving predetermined optical characteristics to the convergent light beam and uniformly illuminating the large-sized substrate.

According to a third aspect of the present invention, in the light emitting device for visual inspection according to the second aspect, the scattering means is a transmissive liquid crystal plate which can be switched between a transparent state and an opaque state by voltage control. There is a feature.

According to a fourth aspect of the present invention, in the light projecting device for an appearance inspection according to the third aspect, the transmission type liquid crystal plate is provided with a convergent light beam or a surface light source by applying or blocking an applied voltage from a power supply. It can be arbitrarily selected.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The same parts as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a structural view of a light projecting device for visual inspection. The projection inspection light projecting device is disposed in proximity to the mirror 11 and controls the illumination light to a parallel light beam to guide the light to the mirror 11 and also controls the parallel light beam reflected by the mirror 11 to a convergent light beam. And a transmissive liquid crystal plate 21 as scattering means for illuminating the surface of the large-sized substrate 3 by giving predetermined optical characteristics to the convergent light flux guided from the Fresnel lens 20.

The Fresnel lens 20 is used for both restricting a parallel light beam and restricting a convergent light beam. The Fresnel lens 20 is disposed immediately before the mirror 11, and the smaller the distance between the Fresnel lens 20 and the mirror 11, the smaller the size of the entire apparatus.

The transmission type liquid crystal plate 21 is connected to the power supply 5 via a transparent electrode (not shown). The light control liquid crystal sheet (not shown) applied to the transmission type liquid crystal plate 21
Normally, the liquid crystal (not shown) is random in the liquid droplet, so that the incident light is scattered at the interface or inside and is in an opaque state. In order to prevent scattering of incident light and to change to transparent.

Each of the Fresnel lens 20 and the transmission type liquid crystal plate 21 has a diameter (500
程度 600 mm). Thus, the large substrate 3 is illuminated without unevenness over the entire surface.

Next, the operation of the device configured as described above will be described.

The illumination light emitted from the light source 6 passes through the filter 10 via the elliptical rotating mirror 7, the heat ray absorbing filter 9 and the gate 8, and is irradiated on the Fresnel lens 20.

The Fresnel lens 20 restricts the illumination light to a parallel light flux and guides the light to the mirror 11. The illumination light restricted to the parallel light flux is reflected by the mirror 11 and enters the Fresnel lens 20 again. This Fresnel lens 20
The illumination light of the parallel light flux reflected by the mirror 11 is restricted to a convergent light flux.

Here, the transmission type liquid crystal plate 21 is transparent when a voltage is applied from the power supply 5. Therefore, the convergent light beam from the Fresnel lens 20 is transmitted as it is to the transmission type liquid crystal plate 2.
1, the entire surface of the large substrate 3 is illuminated without unevenness.

The reflected illumination light reflected from the large substrate 3 forms an image at a position S near the eye 12 of the observer. At this time, if a foreign substance 13 such as dust or a scratch is present on the surface of the large-sized substrate 3, scattered light is generated from the foreign substance 13 and no image is formed at the nearby position S. As a result, the observer can confirm the presence of the foreign matter 13 on the surface of the large substrate 3 by visually observing the minute scattered light from outside the optical axis.

It is also preferable to arrange a light shielding plate (not shown) in the vicinity position S, for example, so that light reflected directly from the surface of the large-sized substrate 3 does not enter the eyes 12.

Such a convergent light beam is particularly generated by the large substrate 3
It is suitable for inspection of disorder or spots of a pattern printed on the surface of the large substrate 3 or dust or scratches on the surface of the large substrate 3.
Since the illuminance on the surface is extremely bright, not only the foreign matter 13 can be easily confirmed, but also since the light source image is not incident on the eye 12, it does not dazzle and does not hinder observation.

Next, when a surface light source is selected as the illumination light, as shown in FIG. 2, the voltage applied from the power supply 5 to the transmission type liquid crystal plate 21 is cut off to make the transmission type liquid crystal plate 21 opaque. As a result, the convergent light flux formed by passing through the Fresnel lens 20 becomes sharksten illumination light by the transmission type liquid crystal plate 21, and is illuminated on the entire surface of the large substrate 3 without unevenness.

Such a surface light source is particularly suitable for inspecting unevenness in thickness of a resist or the like on a large substrate 3 or pinholes on a transparent conductive film (ITO) or dust under the film. The illuminance becomes uniform over the entire surface of the substrate 3, and the interference pattern formed by the foreign matter 13 present on the surface of the substrate 3 is clearly seen by the observer.

As described above, in one embodiment,
A Fresnel lens, which is disposed close to the mirror 11 and regulates the illumination light to a parallel light flux and guides the light to the mirror 11, and also regulates the parallel light flux reflected by the mirror 11 to a convergent light flux. Since 20 were placed, 1
It is sufficient to use only one Fresnel lens 20, and the distance between the mirror 11 and the Fresnel lens 20 can be shortened, and the transmission type liquid crystal plate 21 can be brought close to the mirror 11, so that the entire apparatus can be made compact and The number of expensive Fresnel lenses 20 can be reduced by one compared with the conventional one, and the cost can be reduced. In particular, even when the appearance of a large substrate 3 having a diagonal of 500 mm or more is inspected, the appearance can be inspected by a downsized device. The smaller the distance between the Fresnel lens 20 and the mirror 11, the smaller the size of the entire device. Further, when the large substrate 3 becomes large, it is possible to divide the Fresnel lens 20 into a plurality of parts and arrange a plurality of light sources corresponding to the division. By dividing the Fresnel lens into a plurality of parts as described above, the focal length can be reduced, and the size of the apparatus can be easily reduced.

Further, by applying a transmission type liquid crystal plate 21 as a scattering plate and applying or blocking a voltage to the transmission type liquid crystal plate 21, a convergent light beam or a surface light source can be appropriately selected. This eliminates the need for insertion and removal, and can improve the efficiency of observation work.

Further, since the entire surface of the large-sized substrate 3 is configured to be illuminated without unevenness, the foreign-substance detection capability over the entire surface of the large-sized substrate 3 is excellent, and the appearance inspection of the large-sized substrate 3 can be efficiently performed. it can.

The present invention is not limited to the above embodiment, but may be modified as follows.

For example, the filter 10 in which a polarizing plate is inserted
By arranging a glass plate on which a film-shaped polarizing film is formed as an analyzer at a position where the illumination light guided from the substrate can be received, it is also possible to observe the polarization of the large substrate 3. The polarized light observation can also be performed by the observer wearing glasses or the like provided with a polarizing plate and placing the eye 12 at the light source image position.

Further, in the above-described embodiment, the visual inspection by the observer has been described. However, the configuration may be such that the substrate appearance inspection is performed via an image processing apparatus.

[0036]

As described above in detail, according to the present invention, it is possible to provide an inexpensive and compact light projector for visual inspection.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a light projecting device for visual inspection according to the present invention.

FIG. 2 is a view for explaining an operation when a surface light source is selected as the illumination light in the embodiment of the appearance inspection light projecting device according to the present invention.

FIG. 3 is a configuration diagram of a conventional light emitting device for visual inspection.

[Explanation of symbols]

 3: Large substrate 5: Power supply 6: Light source 7: Elliptical rotating surface mirror 8: Gate 9: Heat ray absorption filter 10: Filter 11: Mirror 20: Fresnel lens 21: Transmission type liquid crystal plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA49 BB02 BB29 CC19 FF04 HH02 JJ12 LL10 LL49 2G051 AA51 AA73 AA90 AB01 AB02 BA00 BB07 BB11 CA11 CB01 CB05 CC07 4M106 AA01 CA38 DB07 DB12 DB13 DB15 DB19 DB30

Claims (4)

[Claims] A light source for illuminating illumination light, and a mirror for reflecting the illuminating light emitted from the light source. And a Fresnel lens which is arranged close to the mirror, regulates the illumination light to a parallel light flux and guides the same to the mirror, and regulates the parallel light flux reflected by the mirror to a convergent light flux. Characteristic floodlight for visual inspection. 2. A scatterer which imparts predetermined optical characteristics to a convergent light beam guided through the Fresnel lens in a reflected light path of the Fresnel lens which does not overlap with an emitted light beam of a light source, and uniformly illuminates the large-sized substrate. 2. A light projecting device for visual inspection according to claim 1, wherein means are arranged. 3. The light projection device for visual inspection according to claim 2, wherein said scattering means is a transmissive liquid crystal plate which can be switched between a transparent state and an opaque state by voltage control. 4. The light projection device for visual inspection according to claim 3, wherein the transmission type liquid crystal plate can be arbitrarily selected as a convergent light beam or a surface light source by applying or interrupting an applied voltage from a power supply. .