JPH06307979A - Flaw inspection equipment for lens - Google Patents

Abstract

PURPOSE:To detect flaw of a lens by irradiating the lens with laser light or circular light and detecting the quantity or the area of the light leaked through the lens and reflected. CONSTITUTION:The flaw inspection equipment for leans comprises a light source 4 for projecting light 3 into a lens 2, a light source 10 for irradiating the edge of the lens with light, photodetectors 5, 11 for detecting the light 3 from the lens 2, bandpass filters 17, 18 transmitting the wavelengths corresponding to the light sources 4, 10, and a unit 6 for deciding presence of flaw on the lens 2 based on signals from the photodetectors 5, 11. This constitution allows detection of such flaw as sagging of the edge of lens or inner crack of lens in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens defect inspection apparatus for inspecting a transparent object such as a lens for defects such as cracks and cracks and blunt defects in which end faces are blunted.

[0002]

2. Description of the Related Art As a publicly known document describing the prior art according to the present invention, there is, for example, JP-A-5-18900. In this publication, the entire lens is irradiated with light from the side surface of the lens to be inspected after polishing, and scattered light generated in a defect existing in the lens is detected in the optical axis direction of the lens to determine whether there is a defect. It is a judgment. Generally, in the inspection of a transparent object such as a lens for defects, it has been conventionally performed by a human being.
The presence / absence of defects is visually determined one by one. Therefore, there is a problem in that the criteria for determining the presence or absence of defects are ambiguous, the criteria vary depending on the inspecting individual, and a large number of manpower is required for the inspection.

[0003]

In the conventional inspection of the presence or absence of a defect of a transparent object such as a lens by human visual inspection, the criterion for determining the presence or absence of a defect is ambiguous. There was a problem of requiring a lot of manpower. It is an object of the present invention to provide a lens defect inspection device that solves the above problems.

[0004]

SUMMARY OF THE INVENTION A lens defect inspection apparatus according to the present invention comprises a light source for radiating band-shaped light parallel to the optical axis of the lens toward the inside of the lens, and a light source leaking from the lens for output. And a photodetector for detecting light. Further, it is configured by a light source that irradiates the lens end surface from the upper side of the lens, and a photodetector that receives light and detects light reflected by the end surface of the lens. Further, the light is emitted from the light source toward the lens end surface on the side where the photodetector is arranged. Further, each photodetector is provided with a bandpass filter that transmits only light that matches the wavelength of the light source corresponding to each photodetector. Further, the respective light sources are alternately turned on, and the photodetector corresponding to each light source is operated only when the respective light sources are turned on.

[0005]

The lens defect inspection apparatus according to the present invention detects defects such as chips and cracks in the lens by detecting the light emitted toward the lens and leaking from the inside of the lens by the photodetector. To detect. For defects such as sagging of the lens end face, the defect from the lens is detected by detecting light from a light source arranged to illuminate the lens end face above the lens as light reflected by the lens end face. Further, by irradiating the lens end surface on the side where the photodetector is arranged with the light source, it is possible to prevent reflection from the opposite side of the lens and prevent erroneous determination. Further, by installing a bandpass filter on the photodetector corresponding to each light source, it is possible to perform a plurality of types of defect inspection processing on the same lens, such as cracks, chipping defects, and sagging defects.
Further, by alternately turning on each light source, it is possible to perform a plurality of types of defect inspection processing such as cracking, chipping defect, and sagging defect on the same lens. Also, by inputting the signal from each photodetector and installing a determiner for performing defect determination for each photodetector, a plurality of types of defect inspection processing such as cracks, chipping defects, and sagging defects can be performed on the same lens. Can be done.

[0006]

【Example】

Example 1. FIG. 1 is a configuration diagram showing an embodiment of a lens defect inspection apparatus according to the present invention, and FIG. 2 is an explanatory diagram showing light scattering in the lens, as viewed from the upper side of the lens. Figure 1
At the inside of the lens 2 to be inspected placed on the inspection stage 1, the band-shaped light 3 parallel to the central axis of the lens 2 is output from the light source 4 placed on the side orthogonal to the central axis of the lens 2. It If there is a defective portion 7 such as a crack or a chip inside the lens 2 to be inspected, the light 3 applied to the lens 2 diffuses and leaks from the defective portion 7 inside the lens 2 to the outside of the lens. The light leaking from the lens 2 is detected by a photodetector 5 arranged in the direction of the central axis of the lens 2, so that the determiner 6 determines whether or not there is a defective portion 7 such as a crack or a chip inside the lens 2. . In FIG. 2, the light 3 emitted from the incident portion 8 toward the inside of the lens 2 causes multiple reflection on the side surface inside the lens 2. A part of the reflected light leaks out from the side surface of the lens 2. Then, finally, the light applied to the inside of the lens 2 is attenuated. If there is a defective portion 7 such as a chip inside the lens 2, light that is multiply reflected inside the lens 2 causes irregular reflection at the defective portion 7, and a large amount of light leaks out from the defective portion 7. become. The light leaking from the lens 2 is detected by the photodetector 5 to determine whether the lens 2 is defective. In the incident portion 8 where the light 3 strikes the lens 2, reflection occurs on the lens surface, so the incident portion may be erroneously determined as a defect,
The photodetector 5 for detecting light leaking from the lens 2 needs to be arranged at a position off the center of the lens 2 so that the incident portion 8 of the lens 2 does not enter the visual field.

FIG. 3 shows the light 3 emitted to the lens 2 to be inspected.
5 is an explanatory diagram showing an example of an image detected by the photodetector 5 that is leaked and output by the defect portion 7. FIG. In FIGS. 1 and 3, the light 3 is incident on the inside of the lens 2 outside the field of view of the photodetector 5. If the lens has no defect 7 such as a crack or a chip in the field of view 9 of the photodetector 5, the photodetector 5 will not detect light leaking from the lens. However, if there is a defect such as a crack or a chip, light leaks out at the defect portion 7 and comes out, so the light is detected by the photodetector 5. An incident portion 8 for injecting light into the lens 2 to be inspected
Since a large amount of light is scattered, the incident portion 8 may be erroneously determined as a defect of the lens 2. Therefore, it is necessary to remove the light incident portion 8 from the visual field of the photodetector 5. Therefore, in order to perform the inspection over the entire circumference of the lens, it is necessary to rotate the lens 2 by the inspection stage 1. A camera is usually used as the photodetector 5, but a line sensor or a photo sensor may be used instead of the camera. A laser light source is usually used as the light source, but it is also effective to increase the beam spot of the laser light or spread it in a strip shape so that the irradiation light is uniformly reflected in the lens. In addition to the laser light source, an incandescent lamp or a fluorescent lamp may be used in a slit shape.

Example 2. FIG. 4 is a block diagram of another embodiment of the lens defect inspection apparatus according to the present invention, and FIG. 5 shows that the light 12 emitted to the end surface of the lens is reflected when the end surface of the lens has a defect. FIG. 6 is an explanatory diagram showing an example of an image in which the light reflected on the side surface of the lens is detected by the photodetector 11 arranged on the side surface of the lens. In FIG. 4, the light source 10 is arranged in the direction of the center axis of the lens 2 to be inspected placed on the inspection stage 1, and the photodetector is arranged on the side orthogonal to the center axis of the lens 2 to be inspected so as to face the side surface of the lens 2. 11 are arranged. As shown in FIG. 5, if there is a sagging defect portion 14 that is formed on the end surface of the lens 2 to be inspected, the amount of light reflected from the end surface is larger than that of a normal lens, and the range of reflection is generated. Becomes wider, the reflected light from the end face is detected by the photodetector 11, and the presence or absence of a defect is determined by the determiner 13. Therefore, when there is a defective portion 14 such as a droop on the end surface of the lens, a large amount of light is reflected by the defective portion 14 on the end surface of the lens 2 in the image 15 of the photodetector 11 as shown in FIG. Therefore, the light from the end face portion is detected, and eventually it is determined as a defect.

Embodiment 3. FIG. 7 is a block diagram showing another embodiment of the lens defect inspection apparatus according to the present invention. In FIG. 7, it is effective to use circular illumination for the light source 10 in order to clearly input the image of the end surface of the lens 2 to be inspected to the photodetector 11. However, when circular illumination is used for the light source 10, the light emitted from the illumination portion on the side opposite to the side where the photodetector 11 is arranged is reflected on the surface of the lens 2, and the reflected light on the lens surface is also changed. It will be detected by the photodetector 11. As described above, when circular illumination is used for the light source 10, the light 12 emitted from the illumination portion on the opposite side of the side where the photodetector 11 is arranged is reflected by the surface of the lens 2 and the light is detected by the photodetector 11. You need to prevent it from being detected. Therefore, the shielding plate 16 is installed in the illumination portion on the side opposite to the side where the photodetector 11 is arranged to shield the illumination on the side opposite to the photodetector 11. As a result, it is possible to prevent reflection due to illumination on the side opposite to the photodetector 11 and improve the defect inspection accuracy.

Embodiment 4. FIG. 8 is a block diagram showing another embodiment of the lens defect inspection apparatus according to the present invention. This is for detecting defects of different types such as defects such as chipping or cracking of the lens and sagging defects such as a blunted lens end face in the same inspection stage. In front of the photodetectors 5 and 11, bandpass filters 17 and 18 that transmit only the light of the wavelengths of the respective light sources are arranged. As a result, the photodetectors 5 and 11 detect only the light having the wavelength corresponding to the light sources 4 and 10 through the bandpass filters 17 and 18, and the light having the wavelength for detecting the other defect is not detected. Multiple types of defect detection processing can be performed in the same inspection stage.

If no bandpass filter is installed in each photodetector 5, 11, each photodetector 5, 11 will be used.
The light sources 4 and 10 are alternately turned on in synchronization with 11, and the photodetector 5 is operated when the light source 4 is turned on and the light source 10 is turned off. Conversely, the light source 10 is turned on and the light source 4 is turned off. By operating the photodetector 11 during the time, a plurality of types of defect detection processing can be performed on the lens 2 to be inspected at the same inspection stage. Further, in FIG. 8, the defect determiner 6 is a single unit and inputs signals from two photodetectors 5 and 11 to determine a defect. However, by adding a defect determiner to each photodetector, a plurality of defect detectors are simultaneously detected. It is possible to perform various types of defect detection processing.

Embodiment 5. FIG. 9 is a block diagram showing an embodiment of the defect determiner. In FIG. 9, the photodetector 5,
The optical signal detected by 11 is converted into a digital signal by the image input circuits 19 and 20 and input, and is stored in the image memory 22 by the CPU 21. The image data stored in the image memory 22 is processed by the CPU 21,
Determine the presence or absence of defects. FIG. 10 is a flowchart showing a defect presence / absence determination processing flow executed in the CPU 21. When the lens is illuminated with light,
An image of the upper surface of the lens is input by the camera placed on the upper surface of the lens (step 23). It is checked whether or not there is a point having a density equal to or higher than a certain level with respect to the entire input image data (step 25). In step 25,
It is judged whether or not there is a point having a density equal to or higher than a certain value (step 24), and if there is a point, it is judged that a lens has a defect and the inspection is ended (step 26). Next, while the circular light source placed on the upper surface of the lens is on, the side surface image of the lens is input by the camera placed on the side surface of the lens (step 27). It is checked whether or not there are density points of a certain level or more in the entire input image data (step 28) (step 2).
9) If it is above a certain value, it is judged that there is a defect in the lens (step 30), and if it is below a certain value, there is no defect and the inspection ends (step 31).

[0013]

According to the first aspect of the present invention, light is radiated from the side surface of the lens to be inspected, and the light leaking from the lens is detected by the photodetector arranged in the direction of the central axis of the lens. However, since the defect is determined when the detected light amount exceeds a predetermined amount, the defect inspection can be easily performed. Further, according to claim 2 or claim 3, the amount of light detected by the photodetector arranged on the side surface of the lens to be inspected is
Since the defective portion is detected by comparing with the amount of light reflected from a normal lens, it is possible to easily detect a defect such as a sag on the end surface of the lens. Further, according to the fourth aspect, since the side of the lens to be inspected on which the photodetector is arranged is illuminated, it is possible to prevent reflection from the opposite side of the lens and prevent erroneous determination. Further, according to claim 5, the lens is irradiated with the light of the first wavelength from the side orthogonal to the central axis of the lens, and the lens is irradiated with the light of the second wavelength from the direction of the central axis of the lens. It is detected as a defect when the amount of detected light exceeds a predetermined amount by detecting with a photodetector through each bandpass filter that transmits the wavelength, so it is judged as a defect of cracking or chipping for the same lens. Defects can be inspected. Further, according to claim 6, the light of the first wavelength emitted from the first light source and the light of the second wavelength emitted from the second light source are alternately turned on to deal with each. Since the amount of light leaking from the lens is detected by the photodetector to determine the defect, it is possible to inspect and process defects such as cracks or chips and sagging defects for the same lens.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a lens defect inspection apparatus according to the present invention.

FIG. 2 is an explanatory diagram illustrating light reflection inside the lens in FIG.

FIG. 3 is an explanatory diagram showing an example of an image input by a photodetector on the upper surface of the lens in FIG.

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

5 is an explanatory diagram of light reflected on the side surface of the lens in FIG.

6 is an explanatory diagram showing an example of an image input by a photodetector arranged on the side surface of the lens in FIG.

FIG. 7 is a configuration diagram showing another embodiment of the present invention.

FIG. 8 is a configuration diagram showing another embodiment of the present invention.

FIG. 9 is a block diagram showing an embodiment of a judging device which is a main part of the present invention.

10 is a flowchart showing a defect determination processing flow executed by the determiner of FIG.

[Explanation of symbols]

 2 Inspected lens 3 Light 4 Light source 5 Photodetector (camera) 6 Judgment device 7 Defect part 10 Light source 11 Photodetector (camera) 12 Light 13 Judgment device 14 Defect part 16 Shielding plate 17 Bandpass filter 18 Bandpass filter

Claims (6)

[Claims] 1. A light source for irradiating the lens with belt-shaped light parallel to the central axis of the lens from a side orthogonal to the central axis of the lens to be inspected, and arranged in the direction of the central axis of the lens, The photodetector for detecting the light leaking out from the lens, which is arranged so that the part excluding the part where the band-shaped light is irradiated to the lens is the field of view, and the amount of the light detected by the photodetector is By exceeding the prescribed amount,
A lens defect inspecting apparatus, comprising: a judging device for judging a defect. 2. A light source for irradiating the end face portion of the first lens from the direction of the central axis of the first lens to be inspected,
A photodetector arranged on the side orthogonal to the central axis of the first lens so as to face the side surface of the first lens, and the amount of light detected by the photodetector is reflected from a normal second lens. A lens defect inspection device including a determiner that detects a defective portion by comparing the amount of light that is generated. 3. A circular light source that irradiates the end surface portion of the first lens from the direction of the central axis of the first lens to be inspected, and the above-mentioned light source on the side orthogonal to the central axis of the first lens. A photodetector arranged to face the side surface of the first lens, and the amount of light detected by this photodetector is compared with the amount of light reflected from a normal second lens to detect a defective portion. A lens defect inspection apparatus including a judging device. 4. A photodetector arranged on the side orthogonal to the central axis of the first lens to be inspected so as to face the side surface of the first lens, and the photodetection from the center of the first lens. A lens provided with a light source that irradiates light to the container side, and a determiner that detects a defective portion by comparing the amount of light detected by the photodetector with the amount of light reflected from a normal second lens. Defect inspection equipment. 5. A first light source for irradiating the lens with light of a first wavelength from a side orthogonal to the central axis of the lens to be inspected, and a light source arranged in the direction of the central axis of the lens and leaking from the lens. A first photodetector for detecting light emitted by the first bandpass filter, and a first bandpass filter arranged between the first photodetector and the first light source and transmitting only the first wavelength. ,
A second light source that irradiates the end surface portion of the lens with light of a second wavelength from the direction of the central axis of the lens, and a second light source that is disposed on a side orthogonal to the central axis of the lens so as to face the side surface of the lens. A second photodetector and a second photodetector disposed between the second photodetector and the second light source, and transmitting only the second wavelength.
And a bandpass filter of (1) are arranged, and it is determined that the defect is caused when the amount of light detected by the first photodetector or the amount of light detected by the second photodetector exceeds a predetermined amount. And a lens defect inspection device. 6. A first light source that irradiates the lens with light from a side orthogonal to the center axis of the lens to be inspected and blinks at a predetermined interval, and an end surface of the lens from the direction of the center axis of the lens. A second light source that irradiates a part with light and alternately blinks with the first light source, and is arranged in the direction of the central axis of the lens, and leaks from the lens when the first light source is on. A first photodetector for detecting the emitted light and a side face of the lens which is arranged on the side orthogonal to the central axis of the lens so as to face the side face of the lens, and leaks from the lens when the second light source is turned on. A lens defect detection device comprising: a second photodetector for detecting emitted light; and a determiner for determining a defect when the amount of light detected by each of the photodetectors exceeds a predetermined amount.