JPH05249048A - Inspecting apparatus - Google Patents

Abstract

PURPOSE:To provide an inspecting apparatus by using parallel beams of light for taking a clear image of an object in a single step even if the object has a three-dimensional structure. CONSTITUTION:Parallel beams are applied from a source of light 12 to the fore end of a coaxial cable 17, and a CCD camera 11 receives the parallel beams through the fore end of the coaxial cable 17 and forms an image of the fore end of the coaxial cable 17. Based on the image obtained by this image pickup, the fore end of the coaxial cable 17 is inspected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection device for inspecting an image of an object to be inspected, and particularly to an object to be inspected suitable for inspecting a minute object to be inspected having a three-dimensional spread. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, in this type of inspection apparatus, an object to be inspected is irradiated with diffused light, the object to be inspected is picked up by an image pickup means to obtain an image, and an arithmetic processing is performed on this image. The object to be inspected has been inspected by applying.

For example, in the "processing terminal device for optical fiber cable" disclosed in Japanese Patent Laid-Open No. 62-213569,
The optical fiber cable that is the object to be inspected is irradiated with diffused light, the optical fiber cable is imaged by a CCD camera, and the image representing the optical fiber cable is arithmetically processed by a processor to determine the length and damage of the optical fiber cable. I was trying to inspect.

[0004]

However, in the inspection apparatus as described above, the object to be inspected is irradiated with diffused light and the object to be inspected is imaged from a close position. The inspectable range, that is, the range between the minimum distance and the maximum distance at which the object to be inspected can be clearly imaged in the optical axis direction of the lens of the image pickup means is narrow. It was limited within the depth of field based on the wavelength of the irradiation light on the inspection object. Here, when the depth of field is ε, this depth of field ε is expressed by the following equation (1).

[0005]

[Equation 1]

Here, n is the refractive index, NA is the aperture value (= the reciprocal of the diaphragm of the lens), and λ is the wavelength of the light emitted from the light source.

According to the above equation (1), it is clear that one method is to reduce the aperture value NA in order to increase the depth of field. Therefore, the aperture of the lens of the image pickup means is normally narrowed down to some extent so that the aperture value NA becomes small. However, if the aperture of the lens is excessively narrowed down, the resolution is lowered and the light quantity is insufficient. Therefore, there is a limit to how narrow the lens diaphragm can be, and it is not possible to sufficiently expand the depth of field with this alone.

For example, when the wavelength λ of light is 550 (nm) and the refractive index n is 1, and the aperture value NA is 1/32 (the aperture of the lens is 32), the depth of field ε = 0. .3
(Mm). In this case, the imaging means can clearly image the inspected object only within the range of 0.3 (mm) in the optical axis direction of the lens.

When the depth of field is narrow as described above, a problem particularly occurs when inspecting an inspection object having a three-dimensional spread. For example, when an outer skin of a very thin coaxial cable is peeled off, the shielded wire is exposed and spreads. When the shielded wire having this spread is used as an object to be inspected, the entire shielded wire has a depth of field ε = 0. It can be said that it is impossible to image clearly and at once in the range of 3 (mm), and the process of inspecting the shield line becomes difficult.

Therefore, an object of the present invention is to improve this type of inspection device for an object to be inspected in order to solve the above-mentioned inconvenience.

[0011]

In order to solve the above-mentioned problems, the present invention provides an object to be inspected by imaging an object to be inspected by an image pickup means and inspecting the object to be inspected based on this image. In the inspection device for an object, a parallel light beam irradiating means for irradiating the inspected object with a parallel light beam is provided, and the imaging means transmits the parallel light beam emitted from the parallel light beam irradiating means through the object to be inspected. Incident on the object to be imaged.

[0012]

In the inspection apparatus configured as described above, the parallel light rays are emitted from the parallel light ray irradiation means to the object to be inspected, and the image pickup means makes the parallel light rays incident through the object to be inspected. The object to be inspected is imaged. By using parallel rays in this way, the aperture value NA in the above equation (1) depends not only on the diaphragm of the lens of the image pickup means but also on the parallelism of the parallel rays. Therefore, in order to reduce the aperture value NA and expand the depth of field ε, it is sufficient to improve the parallelism of parallel rays. Therefore, the depth of field ε can be increased by improving the parallelism of the parallel rays without narrowing the aperture of the lens of the image pickup means to sacrifice the light amount and the resolution.

[0013]

Embodiments will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of an inspection apparatus according to the present invention. In the figure, the Y-axis stage 1
A vertical movement mechanism 2 is connected to the lower side surface of the Y-axis stage 1. The vertical movement mechanism 2 moves the Y-axis stage 1 in the y direction, that is, in the vertical direction. A first rail 3 and a second rail 4 are provided on the upper side surface of the Y-axis stage 1, and grooves are formed on both sides of each of these rails.

A pair of guide portions 6 and 6 and a pair of other guide portions 7 and 7 project from the lower side surface of the X-axis stage 5, and each one guide portion 6 and 6 is located on both sides of the first rail 3. , And the other guide portions 7, 7 are fitted in the grooves on both sides of the second rail 4. Thereby, the X-axis stage 5 can move in the x direction, that is, the horizontal direction along the first rail 3 and the second rail 4. Furthermore, a screw hole is formed in the convex portion 8 on the lower side surface of the X-axis stage 5 along the x direction, and a screw rod 9 is screwed into this screw hole. A rotating shaft of a motor 10 is connected to the screw rod 9, and the screw rod 9 is rotated by the rotating shaft of the motor 10. With the rotation of the screw rod 9, the X-axis stage 5 is moved in the x direction.

Therefore, by moving the Y-axis stage 1 in the y-direction and moving the X-axis stage 5 in the x-direction, the X-axis stage 5 can be moved in the xy-direction.

On the upper side surface of the X-axis stage 5, a CCD camera 11 and a parallel beam irradiator 12 are arranged so as to face each other in a direction orthogonal to the x direction. The CCD camera 11 has a signal line 14 for transmitting an image signal showing an image obtained by imaging. Parallel light irradiator 12
Emits parallel rays toward the CCD camera 11, and has a power cord 15 for a light source.

The chuck mechanism 16 is for sandwiching and holding an object to be inspected, and here, an ultrafine coaxial cable 17 is held as the object to be inspected along the x direction.

In such a configuration, the coaxial cable 1
A work process before inspecting No. 7 and up to setting the cable will be described below.

First, the vertical movement mechanism 2 is actuated to pull down the Y-axis stage 1 and the X-axis stage 5 to form a sufficient space around the chuck mechanism 16. In this state, the chuck mechanism 16 holds the coaxial cable 17, and the tip of the cable is projected forward.

Next, the vertical movement mechanism 2 is operated to pull up the Y-axis stage 1 and the X-axis stage 5 to return them to their original positions in the y direction. Subsequently, the vertical movement mechanism 2 and the motor 10 are appropriately operated so that the tip of the coaxial cable 17 enters the field of view of the CCD camera 11.

Through the above-described work process, the coaxial cable 17 is moved to the CCD camera 11 and the parallel light irradiator 12.
It is possible to prevent the tip end of the coaxial cable 17 from being entangled in the same, and to surely guide the tip of the coaxial cable 17 into the visual field of the CCD camera 11.

FIG. 2 schematically shows the structures of the CCD camera 11 and the parallel light irradiator 12. In the figure,
The parallel light irradiator 12 includes a white light source (for example, a halogen lamp of 50 (W)) 21, a condenser lens 22 that condenses the light emitted from the white light source 21, and light condensed by the condenser lens 22. There is built in a pinhole plate 24 having a pinhole 23 that allows light to pass through, and a parallel light lens 25 that receives light from the pinhole 23 of the pinhole plate 24 and emits parallel light. The lens 25 for parallel rays is
It is arranged so that the focal point of the lens and the position of the pinhole 23 of the pinhole plate 24 coincide with each other. By matching the focal point of this lens and the position of the pinhole 23, the parallel light ray lens 25 can emit a parallel light ray.

The CCD camera 11 has a lens hood 26, and a lens 27 is incorporated therein. An image sensor (for example, a CCD image sensor) 28 is arranged at the focal point of the lens 27, and an image is displayed on the image sensor 28.

The CCD camera 11 and the parallel light irradiator 12 are arranged so that the optical axis of the lens 27 of the CCD camera 11 and the parallel light emitted from the parallel light irradiator 12 are parallel to each other.

Here, the tip end of the coaxial cable 17 which is the object to be inspected is the CCD camera 11 and the parallel light irradiator 12.
The image representing the tip of the coaxial cable 17 is displayed on the image pickup device 28 of the CCD camera 11 because it is interposed between the two. The image sensor 28 sends out an image signal showing this image to the signal line 14. This image signal is stored in the image memory 3
1 and the image representing the tip of the coaxial cable 17 is stored therein. The computer 32 has an image memory 3
The image in 1 is read out, and a predetermined arithmetic processing is performed on the image, whereby the tip of the coaxial cable 17 is inspected.

As described above, the aperture value NA in the above equation (1) is not limited to the diaphragm of the lens of the image pickup means,
It depends on the parallelism of parallel rays. If the parallelism of the parallel rays is improved, the aperture value NA becomes smaller and the depth of field ε
Can be expanded.

Therefore, in the parallel light irradiator 12, the pinhole 23 of the pinhole plate 24 has a diameter of 400 (μm).
And a single lens having a focal length of 75 (mm) is applied as the parallel light ray lens 25, and a parallel light ray emitted from the parallel light ray lens 25 has a parallelism of 5 (mrad) or less. obtain.

When the parallel rays having the parallelism of 5 (mrad) thus obtained are used, the parallelism of 5 is set as the aperture value NA.
By substituting (mrad) into the above equation (1), the depth of field ε can be approximately calculated as shown below.

[0030]

[Equation 2]

However, it is assumed that the refractive index n = 1 and the wavelength λ of parallel rays is 550 (nm).

According to the depth of field ε obtained here,
The CCD camera 11 has a lens 11 in the optical axis direction.
The object to be inspected can be clearly imaged in the range of (mm).

In the state where the parallel rays of parallelism of 5 (mrad) are emitted from the parallel ray irradiator 12, CC
As the lens 27 of the D camera 11, the focal length f = 25
A combination of a (mm) shooting lens and a cylinder length 20 (mm) close-up ring is used, which results in 8
An image of the tip of the coaxial cable 17 is captured by the CCD camera 11 that can obtain a (mm) four-sided visual field.

FIG. 3 illustrates the tip of the coaxial cable 17 to be imaged. As is clear from this figure, the coaxial cable 17 is constructed by covering the core wire 33 with an inner skin 34, covering the inner skin 34 with a shield wire 35, and covering the shield wire 35 with an outer skin 36. The outer skin 36 has a diameter of 120 (μm) and the core wire 33.
Has a diameter of 30 (μm).

At the tip of the coaxial cable 17, the inner skin 34 and the outer skin 36 are peeled off, and the core wire 33 and the shield wire 35 are exposed. The exposed shield wire 35 has a three-dimensional spread, and spreads about 5 (mm) along the optical axis direction of the lens 27 of the CCD camera 11.

When the tip of such a coaxial cable 17 is imaged, an image as shown in FIG. 4 is obtained. As is clear from this figure, the tip of the coaxial cable 17 is clearly imaged although it extends about 5 (mm) along the optical axis.

That is, the depth of field ε obtained earlier
According to the above, 11 (mm) in the optical axis direction of the lens 27
The object to be inspected can be clearly imaged within the range.
For this reason, if the shielded wire 35 that extends about 5 (mm) along the optical axis direction is moved within the range of 11 (mm), it is possible to clearly image even the expanded shielded wire 35. it can.

The image showing the tip of the coaxial cable 17 is stored in the image memory 31 as described above,
It is processed by the computer 32. As a result, the tip of the coaxial cable 17 is automatically inspected, and the contents of this inspection include the peeling length of the inner skin 34 and the outer skin 36, the presence or absence of uncut portions of the shield wire 35, and the like.

As described above, in this embodiment, the parallel light beam irradiator 12 irradiates the object to be inspected with a parallel light beam, and the CCD camera 11 makes the parallel light beam enter through the object to be inspected to inspect the object to be inspected. The object is imaged. For this reason,
The depth of field ε is widened, and even a three-dimensionally spread object to be inspected can be clearly imaged. Further, by increasing the depth of field ε, it becomes unnecessary to strictly focus the CCD camera 11, so that the inspection efficiency can be improved when a large number of objects to be inspected are inspected.

In this embodiment, the object to be inspected is inspected from only one direction, but if the inspection is performed from a plurality of directions, it is possible to perform an inspection without a blind spot. In this case, a mechanism for rotating the facing image pickup means and parallel light beam irradiation means around the inspection object may be used, or a plurality of sets of image pickup means and parallel light irradiation means may be used for the inspection object. You may arrange around.

Further, by separating the light source of the parallel light irradiator from the pinhole and the lens for parallel light rays and connecting both with an optical fiber, the irradiator can be miniaturized and used in a narrow place. ..

Further, the object to be inspected is not limited to the coaxial cable, and the present invention is sufficiently effective also for the inspection of the uncut portion of the optical fiber Kepler, the inspection of minute foreign substances contained in glass, and the like.

By the way, an experiment was conducted to compare the inspection apparatus of this embodiment with the conventional inspection apparatus, and the results are shown in FIG.
And it shows in FIG.

FIG. 5 shows an image obtained by picking up an image of a test pattern by the inspection apparatus of this embodiment.

In FIG. 5A, the test pattern is C
An image obtained by capturing a test pattern when the CD camera 11 is on the focus is shown.

In FIGS. 5B and 5C, when the test pattern is deviated from the focus of the CCD camera 11 to the respective positions of -5 (mm) and -20 (mm),
The respective images obtained by imaging the test pattern are shown.

In FIGS. 5D and 5E, when the test pattern is deviated from the focus of the CCD camera 11 to the respective positions of +5 (mm) and +20 (mm),
The respective images obtained by imaging the test pattern are shown.

FIG. 6 shows an image obtained by capturing an image of a test pattern by a conventional inspection apparatus.

FIG. 6A shows an image obtained by imaging the test pattern when the test pattern is on the focal point of the imaging means.

In FIGS. 6B and 6C, the test pattern is -2 (mm) and -5 from the focus of the image pickup means.
The respective images obtained by imaging the test pattern when displaced to respective positions of (mm) are shown.

As is clear from comparison between FIG. 5 and FIG. 6, according to the inspection apparatus of this embodiment, the test pattern is C
While a clear image can be obtained when it is within ± 5 (mm) from the focus of the CD camera 11, according to the conventional inspection apparatus, the test pattern is -2 (mm) from the focus of the image pickup means. ) I can't get a clear image even if it just deviates. Therefore, the inspection apparatus of this embodiment is far more suitable for inspecting an object to be inspected having a three-dimensional spread.

The depth of field ε = 11 (mm) obtained in this embodiment is “the test pattern is ± 5 from the focus of the CCD camera 11” as the experimental result shown in FIG.
A clear image can be obtained when it is within the range of (mm). "

[0053]

As described above, in the inspection device for an object to be inspected according to the present invention, the parallel light rays are emitted to the object to be inspected from the parallel light beam irradiating means, and the imaging means emits the parallel light beam to the object to be inspected. It is incident through and is imaging this inspected object. Therefore, the depth of field ε can be expanded by improving the parallelism of parallel rays without narrowing the aperture of the lens of the image pickup means to sacrifice the resolution. Accordingly, even if the inspection target has a three-dimensional spread, the inspection target can be clearly imaged and inspected.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an inspection apparatus according to the present invention.

2 is a diagram schematically showing the configuration of a CCD camera and a parallel light irradiator in the apparatus of the embodiment shown in FIG.

FIG. 3 is a perspective view showing a tip end of a coaxial cable which is an object to be inspected in the apparatus of the embodiment shown in FIG.

FIG. 4 is a diagram showing an image obtained by imaging the tip of the coaxial cable shown in FIG.

5 is a diagram showing an experimental result when a test pattern is imaged by the apparatus of the embodiment shown in FIG.

FIG. 6 is a diagram showing an experimental result when a test pattern is imaged by a conventional inspection device.

[Explanation of sign]

 1 Y-axis stage 2 Vertical movement mechanism 3 First rail 4 Second rail 5 X-axis stage 6, 7 Guide part 8 Convex part 9 Screw rod 10 Motor 11 CCD camera 12 Parallel light irradiator 14 Signal line 15 Power cord 16 Chuck mechanism 17 Coaxial cable 21 White light source 22 Condensing lens 23 Pinhole 24 Pinhole plate 25 Lens for parallel rays 26 Lens hood 27 Lens 28 Image sensor 31 Image memory 32 Computer

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[Procedure amendment]

[Submission date] August 25, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Patent application title: Imaging inspection device using parallel rays

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup inspection apparatus using parallel rays suitable for inspecting a minute object having a three-dimensional spread.

[0002]

2. Description of the Related Art Conventionally, in this type of inspection apparatus, an object is irradiated with diffused light, the object is imaged by an imaging means to obtain an image, and an arithmetic process is performed on the image. I was trying to inspect the object.

For example, in the "processing terminal device for optical fiber cable" disclosed in Japanese Patent Laid-Open No. 62-213569,
The optical fiber cable that is the object is irradiated with diffused light, the optical fiber cable is imaged by the CCD camera, the image representing the optical fiber cable is processed by the processor, and the length and damage of the optical fiber cable are inspected. I was trying to do it.

[0004]

However, in the above inspection apparatus, the object is irradiated with diffused light,
Since this object is imaged from a close position, the inspectable range by the imaging means, that is, the range between the minimum distance and the maximum distance at which the object can be clearly imaged in the optical axis direction of the lens of the imaging means is narrow. The inspectable range is limited to the depth of field based on the diaphragm of the lens of the image pickup means and the wavelength of the irradiation light to the object. Here, when the depth of field is ε, this depth of field ε is expressed by the following equation (1).

[0005]

[Equation 1]

Here, n is the refractive index, NA is the aperture value (= the reciprocal of the diaphragm of the lens), and λ is the wavelength of the light emitted from the light source.

According to the above equation (1), it is clear that one method is to reduce the aperture value NA in order to increase the depth of field. Therefore, the aperture of the lens of the image pickup means is normally narrowed down to some extent so that the aperture value NA becomes small. However, if the aperture of the lens is excessively narrowed down, the resolution is lowered and the light quantity is insufficient. Therefore, there is a limit to how narrow the lens diaphragm can be, and it is not possible to sufficiently expand the depth of field with this alone.

For example, when the wavelength λ of light is 550 (nm) and the refractive index n is 1, and the aperture value NA is 1/32 (the aperture of the lens is 32), the depth of field ε = 0. .3
(Mm). In this case, the imaging means can clearly image the object only within the range of 0.3 (mm) in the optical axis direction of the lens.

Such a narrow depth of field causes a particular problem when inspecting an object having a three-dimensional spread. For example, when the outer skin of a very thin coaxial cable is peeled off, the shielded wire is exposed and spreads. When the shielded wire having this spread is the object, the entire shielded wire has a depth of field ε = 0.3 ( It can be said that it is impossible to take an image clearly and at once in the range of (mm), and the process of inspecting the shield line becomes difficult.

Therefore, an object of the present invention is to obtain an imaging inspection apparatus using parallel rays suitable for inspecting an object having a three-dimensional spread.

[0011]

In order to solve the above-mentioned problems, in the present invention, a parallel light beam irradiating means for irradiating a parallel light beam and a parallel light beam irradiating means are disposed so as to face each other, and the parallel light beam irradiating means irradiates the light beam. And an image signal processing unit for inputting and processing the image signal from the image pickup unit. The image pickup unit includes the image pickup unit and the parallel light beam. An image of an object located between the irradiation means is imaged, and the image processing means,
The object is inspected based on the image signal from the image pickup means.

Further, according to the present invention, the parallel light beam irradiation means and the stage on which the image pickup means is mounted,
It further comprises a moving means for moving the stage and a holding means for holding the object.

Further, in the present invention, an object having a three-dimensional spread is inspected.

[0014]

According to the present invention, the object is positioned between the parallel light irradiating means and the image pickup means, and the image pickup means makes the parallel light beam incident through the object and picks up the image of the object. The image processing means receives the image signal from the image pickup means and inspects the object indicated by the image signal. By using parallel rays in this way, the aperture value NA in the above equation (1) depends not only on the diaphragm of the lens of the image pickup means but also on the parallelism of the parallel rays. Therefore, in order to reduce the aperture value NA and expand the depth of field ε, it is sufficient to improve the parallelism of parallel rays. Therefore, the depth of field ε can be increased by improving the parallelism of the parallel rays without narrowing the aperture of the lens of the image pickup means to sacrifice the light amount and the resolution. Thus the depth of field ε
When the object is expanded, if the object is positioned within the range of the expanded depth of field ε, the object is clearly imaged by the imaging means, so that the inspection of the object becomes easy.

Further, according to the present invention, the object is clamped by the clamping means and the stage is moved by the moving means, so that the object can be positioned between the parallel light irradiating means and the imaging means on the stage. Therefore, it is easy to position the object within the range of the previously expanded depth of field ε.

Further, according to the present invention, since the object can be clearly imaged within the previously expanded depth of field ε, it is suitable for inspecting an object having a three-dimensional spread. is there.

[0017]

Embodiments will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of an inspection apparatus according to the present invention. In the figure, the Y-axis stage 1
A vertical movement mechanism 2 is connected to the lower side surface of the Y-axis stage 1. The vertical movement mechanism 2 moves the Y-axis stage 1 in the y direction, that is, in the vertical direction. A first rail 3 and a second rail 4 are provided on the upper side surface of the Y-axis stage 1, and grooves are formed on both sides of each of these rails.

A pair of guide portions 6, 6 and a pair of other guide portions 7, 7 project from the lower side surface of the X-axis stage 5, and one guide portion 6, 6 is located on both sides of the first rail 3. , And the other guide portions 7, 7 are fitted in the grooves on both sides of the second rail 4. Thereby, the X-axis stage 5 can move in the x direction, that is, the horizontal direction along the first rail 3 and the second rail 4. Furthermore, a screw hole is formed in the convex portion 8 on the lower side surface of the X-axis stage 5 along the x direction, and a screw rod 9 is screwed into this screw hole. A rotating shaft of a motor 10 is connected to the screw rod 9, and the screw rod 9 is rotated by the rotating shaft of the motor 10. With the rotation of the screw rod 9, the X-axis stage 5 is moved in the x direction.

Therefore, the X-axis stage 5 can be moved in the xy directions by moving the Y-axis stage 1 in the y-direction and the X-axis stage 5 in the x-direction.

On the upper side surface of the X-axis stage 5, a CCD camera 11 and a parallel light irradiator 12 are arranged so as to face each other in a direction orthogonal to the x direction. The CCD camera 11 has a signal line 14 for transmitting an image signal showing an image obtained by imaging. Parallel light irradiator 12
Emits parallel rays toward the CCD camera 11, and has a power cord 15 for a light source.

The chuck mechanism 16 is for sandwiching and holding an object, and here, an extremely fine coaxial cable 17 is held as the object along the x direction.

In such a structure, the coaxial cable 1
A work process before inspecting No. 7 and up to setting the cable will be described below.

First, the vertical movement mechanism 2 is operated to pull down the Y-axis stage 1 and the X-axis stage 5 to form a sufficient space around the chuck mechanism 16. In this state, the chuck mechanism 16 holds the coaxial cable 17, and the tip of the cable is projected forward.

Next, the vertical movement mechanism 2 is operated to pull up the Y-axis stage 1 and the X-axis stage 5 to return them to their original positions in the y direction. Subsequently, the vertical movement mechanism 2 and the motor 10 are appropriately operated so that the tip of the coaxial cable 17 enters the field of view of the CCD camera 11.

Through the above work process, the coaxial cable 17 is moved to the CCD camera 11 and the parallel light irradiator 12.
It is possible to prevent the tip end of the coaxial cable 17 from being entangled in the same, and to surely guide the tip of the coaxial cable 17 into the visual field of the CCD camera 11.

FIG. 2 schematically shows the structures of the CCD camera 11 and the parallel light irradiator 12. In the figure,
The parallel light irradiator 12 includes a white light source (for example, a halogen lamp of 50 (W)) 21, a condenser lens 22 that condenses the light emitted from the white light source 21, and light condensed by the condenser lens 22. There is built in a pinhole plate 24 having a pinhole 23 that allows light to pass through, and a parallel light lens 25 that receives light from the pinhole 23 of the pinhole plate 24 and emits parallel light. The lens 25 for parallel rays is
It is arranged so that the focal point of the lens and the position of the pinhole 23 of the pinhole plate 24 coincide with each other. By matching the focal point of this lens and the position of the pinhole 23, the parallel light ray lens 25 can emit a parallel light ray.

The CCD camera 11 has a lens hood 26, and a lens 27 is incorporated therein. An image sensor (for example, a CCD image sensor) 28 is arranged at the focal point of the lens 27, and an image is displayed on the image sensor 28.

The CCD camera 11 and the parallel light irradiator 12 are arranged so that the optical axis of the lens 27 of the CCD camera 11 and the parallel light emitted from the parallel light irradiator 12 are parallel to each other.

Since the tip of the coaxial cable 17 which is the object is interposed between the CCD camera 11 and the parallel light irradiator 12, the tip of the coaxial cable 17 is placed on the image pickup device 28 of the CCD camera 11. An image representing is displayed. The image sensor 28 sends out an image signal showing this image to the signal line 14. This image signal is input to the image memory 31, and the image representing the tip of the coaxial cable 17 is stored therein. The computer 32 reads the image in the image memory 31 and performs a predetermined arithmetic processing on the image, thereby inspecting the tip of the coaxial cable 17.

As described above, the aperture value NA in the above equation (1) is not limited to the diaphragm of the lens of the image pickup means,
It depends on the parallelism of parallel rays. If the parallelism of the parallel rays is improved, the aperture value NA becomes smaller and the depth of field ε
Can be expanded.

Therefore, in the parallel light irradiator 12, the pinhole 23 of the pinhole plate 24 has a diameter of 400 (μm).
And a single lens having a focal length of 75 (mm) is applied as the parallel light ray lens 25, and a parallel light ray emitted from the parallel light ray lens 25 has a parallelism of 5 (mrad) or less. obtain. When using the parallel rays of parallelism 5 (mrad) thus obtained,
The parallelism of 5 (mrad) as the numerical aperture NA is given by the above formula (1).
, The depth of field ε can be approximately calculated as follows.

[0033]

[Equation 2]

However, it is assumed that the refractive index n = 1 and the wavelength of parallel rays λ = 550 (nm).

According to the depth of field ε obtained here,
The CCD camera 11 has a lens 11 in the optical axis direction.
The object can be clearly imaged in the range of (mm).

In the state where the parallel rays of parallelism 5 (mrad) are emitted from the parallel ray irradiator 12, CC
As the lens 27 of the D camera 11, the focal length f = 25
A combination of a (mm) shooting lens and a cylinder length 20 (mm) close-up ring is used, which results in 8
An image of the tip of the coaxial cable 17 is captured by the CCD camera 11 that can obtain a (mm) four-sided visual field.

FIG. 3 illustrates the tip of the coaxial cable 17 to be imaged. As is clear from this figure, the coaxial cable 17 is constructed by covering the core wire 33 with an inner skin 34, covering the inner skin 34 with a shield wire 35, and covering the shield wire 35 with an outer skin 36. The outer skin 36 has a diameter of 120 (μm) and the core wire 33.
Has a diameter of 30 (μm).

At the tip of the coaxial cable 17, the inner skin 34 and the outer skin 36 are peeled off, and the core wire 33 and the shield wire 35 are exposed. The exposed shield wire 35 has a three-dimensional spread, and spreads about 5 (mm) along the optical axis direction of the lens 27 of the CCD camera 11.

When the tip of such a coaxial cable 17 is imaged, an image as shown in FIG. 4 is obtained. As is clear from this figure, the tip of the coaxial cable 17 is clearly imaged although it extends about 5 (mm) along the optical axis.

That is, the depth of field ε obtained earlier
According to the above, 11 (mm) in the optical axis direction of the lens 27
The object can be clearly imaged in the range. For this reason, if the shielded wire 35 that extends about 5 (mm) along the optical axis direction is moved within the range of 11 (mm), it is possible to clearly image even the expanded shielded wire 35. it can.

The image showing the tip of the coaxial cable 17 is stored in the image memory 31 as described above,
It is processed by the computer 32. As a result, the tip of the coaxial cable 17 is automatically inspected, and the contents of this inspection include the peeling length of the inner skin 34 and the outer skin 36, the presence or absence of uncut portions of the shield wire 35, and the like.

As described above, in this embodiment, the parallel light beam is applied from the parallel light beam irradiator 12 to the object, and the CCD camera 1
Reference numeral 1 is for injecting parallel light rays through an object to image the object. For this reason, the depth of field ε is expanded, and even a three-dimensionally expanded object can be clearly imaged. Further, by expanding the depth of field ε, the strict positioning of the object and the CCD camera 1
Since the strict focus adjustment of 1 is not required, the processing from the movement of the Y-axis stage 1 and the X-axis stage 5 to the imaging of the object becomes extremely easy, which is effective in realizing automatic inspection of many objects. Play.

In this embodiment, the object is inspected from only one direction, but if the inspection is performed from a plurality of directions, it is possible to perform an inspection without a blind spot. In this case, a mechanism for rotating the facing image pickup means and parallel light beam irradiation means around the object may be used, or a plurality of sets of image pickup means and parallel light beam irradiation means may be arranged around the object. You may.

Further, by separating the light source of the parallel light irradiator from the pinhole and the lens for parallel light rays and connecting both with an optical fiber, the irradiator can be miniaturized and used in a narrow place. ..

Further, the object is not limited to the coaxial cable, and the present invention is sufficiently effective also for the inspection of the uncut portion of the Kepler of the optical fiber, the inspection of minute foreign matter contained in thick glass, and the like.

By the way, an experiment was conducted to compare the inspection apparatus of this embodiment with the conventional inspection apparatus, and the results are shown in FIG.
And it shows in FIG.

FIG. 5 shows an image obtained by picking up an image of a test pattern by the inspection apparatus of this embodiment.

In FIG. 5A, the test pattern is C
An image obtained by capturing a test pattern when the CD camera 11 is on the focus is shown.

5B and 5C, when the test pattern is deviated from the focus of the CCD camera 11 to the respective positions of -5 (mm) and -20 (mm),
The respective images obtained by imaging the test pattern are shown.

5D and 5E, when the test pattern is deviated from the focus of the CCD camera 11 to the positions of +5 (mm) and +20 (mm), respectively,
The respective images obtained by imaging the test pattern are shown.

FIG. 6 shows an image obtained by capturing an image of a test pattern by a conventional inspection apparatus.

FIG. 6A shows an image obtained by imaging the test pattern when the test pattern is on the focal point of the imaging means.

In FIGS. 6B and 6C, the test pattern is -2 (mm) and -5 from the focus of the image pickup means.
The respective images obtained by imaging the test pattern when displaced to respective positions of (mm) are shown.

As is clear from comparison between FIG. 5 and FIG. 6, according to the inspection apparatus of this embodiment, the test pattern is C
While a clear image can be obtained when it is within ± 5 (mm) from the focus of the CD camera 11, according to the conventional inspection apparatus, the test pattern is -2 (mm) from the focus of the image pickup means. ) I can't get a clear image even if it just deviates. Therefore, the inspection apparatus of this embodiment is much more suitable for inspecting an object having a three-dimensional spread.

The depth of field ε = 11 (mm) obtained in this embodiment is “the test pattern is ± 5 from the focus of the CCD camera 11” as the experimental result shown in FIG.
A clear image can be obtained when it is within the range of (mm). "

[0056]

As described above, in the inspection apparatus according to the present invention, the depth of field ε can be expanded without narrowing the aperture of the lens of the image pickup means to sacrifice the resolution, so that the three-dimensional expansion can be achieved. It is possible to clearly inspect and inspect the target object. Also, the expanded depth of field ε
Since the object can be clearly imaged by locating the object within the range of, the processing from the positioning of the object to the imaging becomes extremely easy, and it is possible to realize automatic inspection of many objects. To work.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of an inspection apparatus according to the present invention.

2 is a diagram schematically showing the configuration of a CCD camera and a parallel light irradiator in the apparatus of the embodiment shown in FIG.

FIG. 3 is a perspective view showing a tip end of a coaxial cable which is an object in the apparatus of the embodiment shown in FIG.

FIG. 4 is a diagram showing an image obtained by imaging the tip of the coaxial cable shown in FIG.

5 is a diagram showing an experimental result when a test pattern is imaged by the apparatus of the embodiment shown in FIG.

FIG. 6 is a diagram showing an experimental result when a test pattern is imaged by a conventional inspection device.

[Explanation of reference signs] 1 Y-axis stage 2 Vertical movement mechanism 3 First rail 4 Second rail 5 X-axis stage 6, 7 Guide part 8 Convex part 9 Screw rod 10 Motor 11 CCD camera 12 Parallel beam irradiator 14 Signal Line 15 Power cord 16 Chuck mechanism 17 Coaxial cable 21 White light source 22 Condenser lens 23 Pinhole 24 Pinhole plate 25 Parallel light lens 26 Lens hood 27 Lens 28 Image sensor 31 Image memory 32 Computer

Claims (1)

[Claims] 1. An inspection object inspection device for inspecting an object to be inspected on the basis of the image by picking up an image of the object to be inspected by an image pickup means, wherein: Parallel light irradiating means for irradiating parallel light rays is provided, and the imaging means makes parallel light rays emitted from the parallel light ray irradiating means enter through the inspection object, and images the inspection object. The inspection device for the inspection object.