JP6185539B2 - Optical connector ferrule end face inspection device and inspection program - Google Patents

Description

  The present invention relates to an inspection apparatus that photographs the end face of a ferrule of an optical connector provided at the end of an optical fiber, and quantitatively determines the quality of the end face state from the image data, and is particularly necessary for the end face quality determination. The present invention relates to a technique for accurately detecting the center position of a clad.

  At the end of the optical fiber used for various types of communication, an optical connector for relaying or connecting to other devices is provided. As shown in FIG. 13, the optical connector generally has a cladding 1 (including a core) on one end side of an optical fiber passed through the center of a ferrule 5 (core wire holder) made of synthetic resin or the like. Is held in a state where the end face of the ferrule 5 is substantially flush with the end face of the ferrule 5.

  If the end face of the clad 1 held by the ferrule 5 is soiled or scratched, light loss and reflection occur, and light cannot be efficiently propagated, resulting in a deterioration in communication quality. Further, if dust or the like adheres not only to the end face of the core wire 1 but also to the end face of the surrounding ferrule 5, a gap is generated inside the connector when the dust is connected to the optical connector. This causes problems such as obstructing the propagation of light.

  For this reason, when attaching an optical connector by performing an end treatment of the optical fiber at a site where the optical fiber is laid, etc., the quality of the end face of the ferrule 5 of the processed optical connector is quantitatively determined. An inspection apparatus 10 that can be used is required.

  The inspection apparatus 10 receives the ferrule 5 of the optical connector to be inspected, holds the ferrule 5 without rattling, and captures an end face image acquisition unit 11 that captures an image of the end face of the held ferrule 5, and the captured end face image. And an end face image analysis unit 12 that analyzes and determines the quality of the end face.

  The end face image acquisition unit 11 irradiates the ferrule end face with illumination light, and forms an image of the reflected light from the end face on an image sensor such as a CCD disposed at a predetermined focal position by a magnifying optical system including a lens. 14 is detected and output to the end face image analysis unit 12.

  As shown in FIG. 13, the end face image analysis unit 12 stores an image memory 13 for storing image data of the end face 5a of the ferrule 5, and a center position of the clad 1 in the end face 5a of the ferrule 5 based on the stored image data. Cladding center detecting means 14 for detecting (core center), elements such as dirt and dust within a predetermined radius (core radius, cladding radius, or surrounding radius beyond the cladding) with reference to the detected center position of the cladding Is included quantitatively, and a determination means 15 is provided for determining whether each radius is good or bad by comparing with a preset threshold value.

  In an actual apparatus, the end face image analysis unit 12 is configured by a computer, and sets various parameters necessary for inspection such as a diameter of a clad or the like serving as a determination region, a determination threshold value, and the progress of the inspection. And a display unit for displaying raw end face images before processing, end face images at the end of various processes, inspection results, and the like. These various setting operations, display processing, and the like are executed according to an inspection application program stored in advance in the apparatus. Here, processing, calculation processing, and determination processing that are sequentially performed on the acquired end face image are performed. The process will be described.

  As a clad center position detecting method by the clad center detecting means 14, a pattern matching method is generally used.

  As shown in FIG. 15, in the pattern matching method, a circular plate having a diameter corresponding to a known cladding diameter of an optical fiber on the image and having a constant luminance (for example, black) is set as a reference pattern Dr, and the position of the reference pattern Dr. Are sequentially shifted, and a correlation calculation is performed between the pixel of the reference pattern Dr and the pixel of the image data obtained by the end face image capturing unit 11, and the correlation calculation result becomes the maximum value, that is, on the reference pattern Dr and the image data. In this method, the center position of the reference pattern when the clad end face completely overlaps is detected as the center position of the cladding.

  In addition, although it does not quantitatively determine the quality of the ferrule end face of the optical connector, an example of an apparatus that enables observation by magnifying and photographing the ferrule end face of the optical connector is disclosed in Patent Document 1, The clad center detection process using the pattern matching method described above is performed on the image data obtained in this way, and the amount of dirt and scratches within a predetermined radius is examined with reference to the center position on the detected image. The quality of the end face can be determined by comparing the amount and the threshold value.

Japanese Patent Laid-Open No. 10-19728

  As described above, when the clad center position on the image is obtained by the pattern matching method, the position of the reference pattern Dr is shifted by one pixel, and the product-sum operation regarding the luminance is performed for all the pixels within the range of the reference pattern Dr. There is a problem that the processing takes a lot of time.

  In particular, it is necessary to inspect a large number of optical connectors at a time at the installation site of the optical fiber, and the above-described method results in extremely low inspection efficiency.

  An object of the present invention is to solve this problem and to provide an optical connector ferrule end face inspection apparatus and program capable of quickly detecting the center position of a clad on an image.

In order to achieve the above object, a ferrule end surface inspection device for an optical connector according to claim 1 of the present invention comprises:
An end face image acquisition unit (30) for acquiring image data of the ferrule end face of the optical connector to be inspected;
Cladding center detecting means (42, 42 ') for detecting the center position of the cladding of the optical fiber on the image based on the image data acquired by the end face image acquisition unit, and using the detected center position of the cladding as a reference position In the ferrule end face inspection device for an optical connector having an end face image analysis unit (40) for performing pass / fail judgment of the ferrule end face,
The clad center detection means includes
Pre-processing means (43, 43 ') for performing pre-processing including processing on luminance for the image data acquired by the end face image acquisition unit;
A reference circle that is centered on a specific pixel on the preprocessed image and is equal to the standard cladding diameter of the optical fiber on the image, an inner circle that is concentric with the reference circle and smaller in diameter than the reference circle, and the reference circle Assuming an outer circle that is concentric and larger in diameter than the reference circle, different circle luminance calculation means (44, 46, 48) for obtaining the total luminance of the pixels through which each circle passes while shifting the position of the specific pixel When,
Cladding center determining means (45, 47, 49) for determining the center position of the cladding on the image based on the sum of the brightness of each circle obtained by the different-diameter circular brightness calculating means. It is said.

An optical connector ferrule end surface inspection device according to claim 2 of the present invention is the optical connector ferrule end surface inspection device according to claim 1,
The cladding center determining means includes
The difference between the average luminance per circle obtained from the total luminance for the reference circle and the inner circle and the average luminance per circle obtained from the total luminance for the outer circle is the It is calculated for each specific pixel position, and the center position of the cladding is determined from the position of the specific pixel where the difference is maximum or within a predetermined range.

Moreover, the ferrule end surface inspection device for an optical connector according to claim 3 of the present invention is the ferrule end surface inspection device for an optical connector according to claim 1,
The preprocessing means includes a normalization process as the process for the luminance,
The pre-processing means includes
Means for performing edge detection processing for detecting the edge of the clad on the normalized image data;
Means for performing binarization processing on the image data subjected to the edge detection processing,
The different-diameter circular luminance calculating means includes
With respect to the binarized image data, the reference circle centered on the position of the specific pixel, a reference near outer circle concentric with the reference circle and passing near the outside, a concentric with the reference circle and the inside Assuming a reference inner circle that passes through a neighborhood, a center inner circle that is concentric with the reference circle and has a smaller radius than the reference neighborhood inner circle, the total luminance of the pixels that pass through each circle is shifted by the position of the specific pixel. While being shaped to seek each,
The cladding center determining means includes
The average value of luminance per circle obtained from the sum of luminance for the reference circle, the outer circle near the reference and the inner circle near the reference, and the per-circle obtained from the sum of luminance for the inner circle near the center. A difference from the average value of luminance is calculated for each position of the specific pixel, and the center position of the clad on the image is determined from the position of the specific pixel where the difference is maximum or within a predetermined range.

Moreover, the ferrule end surface inspection device of the optical connector according to claim 4 of the present invention is the ferrule end surface inspection device of the optical connector according to claim 1,
The preprocessing means includes a normalization process as the process for the luminance,
The pre-processing means includes
Means for performing edge detection processing for detecting the edge of the clad on the normalized image data;
Means for performing binarization processing on the image data subjected to the edge detection processing;
An image compression process for generating compressed image data having a small number of pixels from the binarized image data,
The clad center detection means includes
The reference circle centered on the position of a specific pixel on the compressed image, a reference vicinity outer circle concentric with the reference circle and passing near its outer periphery, a reference vicinity inner circle concentric with the reference circle and passing its inner vicinity, Assuming an inner circle near the center that is concentric with the reference circle and has a smaller radius than the inner circle near the reference, a first different-diameter circle that obtains the total luminance of the pixels through which each circle passes while shifting the position of the specific pixel. Luminance calculation means (46);
An average value of luminance per circle obtained from a sum of luminance values for the reference circle, the reference outer circle and the reference inner circle obtained by the first different-diameter luminance calculation means; and the vicinity of the center A difference from the average value of luminance per circle obtained from the total luminance of inner circles is calculated for each position of the specific pixel, and the compression is performed from the position of the specific pixel where the difference is maximum or within a predetermined range. First cladding center determining means (47) for determining the center position of the cladding on the image;
The reference circle centered on the position of a specific pixel on the image normalized by the preprocessing means, an inner circle concentric with the reference circle and smaller in diameter than the reference circle, concentric with the reference circle and from the reference circle Assuming a large-diameter outer circle, the second sum is obtained by shifting the specific pixel in the center position of the clad determined by the first clad center determining means and the range in the vicinity of the sum of the luminance of the pixels through which each circle passes. Different diameter circular luminance calculating means (48),
1 obtained from the average value of the luminance per circle obtained from the total luminance of the reference circle and the inner circle obtained by the second different diameter circular luminance calculating means, and 1 from the total luminance of the outer circle. The difference between the average value of the luminance per circle is calculated for each position of the specific pixel, and the center of the clad on the normalized image from the position of the specific pixel where the difference is maximum or within a predetermined range And a second clad center determining means (49) for determining the position.

A program for inspecting a ferrule end face of an optical connector according to claim 5 of the present invention,
Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
Means for performing preprocessing including luminance processing on the stored image data;
For the preprocessed image data, a reference circle centered on a specific pixel on the image and equal to the cladding diameter on the standard of the optical fiber on the image, an inner circle concentric with the reference circle and having a smaller diameter than the reference circle Supposing an outer circle that is concentric with the reference circle and larger in diameter than the reference circle, and obtains the sum of the luminance of the pixels through which each circle passes while shifting the position of the specific pixel,
Means for determining the center position of the clad on the image based on the total luminance of the obtained circles;
The center position of the determined clad is used as a reference position for inspection to function as a means for determining the quality of the ferrule end face.

The program for inspecting the ferrule end face of the optical connector according to claim 6 of the present invention,
Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
Means for performing preprocessing including normalization processing for luminance of the stored image data, edge detection processing for normalized image data, and binarization processing for edge detected image data;
For the binarized image data, a reference circle centered on a specific pixel on the image and equal to the cladding diameter on the standard of the optical fiber on the image, a reference that is concentric with the reference circle and passes near the outside Assuming a near-outer circle, a reference near-inner circle concentric with the reference circle and passing through its inner side, a center near-inner circle concentric with the reference circle and having a smaller radius than the reference near-inner circle, and pixels passing through each circle Means for obtaining the total sum of luminances while shifting the position of the specific pixel,
The average value of luminance per circle obtained from the sum of luminance for the reference circle, the outer circle near the reference and the inner circle near the reference, and the per-circle obtained from the sum of luminance for the inner circle near the center. Means for calculating a difference from an average value of luminance for each position of the specific pixel, and determining a center position of the clad from the position of the specific pixel where the difference is maximum or within a predetermined range;
The center position of the determined clad is used as a reference position for inspection to function as a means for determining the quality of the ferrule end face.

A program for inspecting a ferrule end face of an optical connector according to claim 7 of the present invention,
Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
A luminance normalization process for the stored image data, an edge detection process for the normalized image data, a binarization process for the edge-detected image data, and an image compression process for the binarized image data. Means for preprocessing,
A reference circle that is centered on a specific pixel on the compressed image with respect to the compressed image data and is equal to the cladding diameter on the standard of the optical fiber on the compressed image, concentric with the reference circle, and near the outside of the reference circle A reference near outer circle passing through the reference circle, a reference near inner circle concentric with the reference circle and passing through the inside of the reference circle, a center near inner circle concentric with the reference circle and having a smaller radius than the reference near inner circle, Means for obtaining the total sum of the luminances of passing pixels while shifting the position of the specific pixel,
The average value of luminance per circle obtained from the sum of luminance for the reference circle, the outer circle near the reference and the inner circle near the reference, and the per-circle obtained from the sum of luminance for the inner circle near the center. Means for calculating a difference with an average value of luminance for each position of the specific pixel, and determining a center position of a clad on the compressed image from the position of the specific pixel where the difference is maximum or within a predetermined range;
The reference circle centered on the position of a specific pixel on the normalized image, an inner circle that is concentric with the reference circle and smaller in diameter than the reference circle, and that is outside the diameter that is concentric with the reference circle and larger than the reference circle Means for assuming a circle and calculating the sum of the luminance of the pixels through which each circle passes while shifting a specific pixel in the center position of the clad determined on the compressed image and the vicinity thereof,
The average value of luminance per circle obtained from the sum of the luminance for the reference circle and the inner circle obtained on the normalized image, and the obtained on the normalized image A difference from the average value of luminance per circle obtained from the total luminance of the outer circle is calculated for each position of the specific pixel, and the normal value is calculated from the position of the specific pixel where the difference is maximum or within a predetermined range. Means for determining the center position of the cladding on the processed image;
The center position of the clad determined on the normalized image is used as a reference position for inspection to function as means for determining the quality of the ferrule end face.

  As described above, in the present invention, the image data acquired by the end face image acquisition unit is subjected to preprocessing including processing for luminance, centering on a specific pixel on the image, and on the optical fiber standard on the image. Assuming a reference circle equal to the cladding diameter, an inner circle inside it, and an outer circle outside it, the total luminance of the pixels through which each circle passes is obtained while shifting the position of the specific pixel, and the luminance of each obtained circle is calculated. Based on the sum, the center position of the cladding on the image is determined.

  This is because there is a difference in brightness on the image of a ferrule with high light-shielding properties on the outer side of the image of the cladding with high translucency, and when the reference circle and the center of the cladding coincide, This is based on the fact that the difference in luminance sum between the circle and the outer circle is maximized. However, if only the circle smaller than the clad diameter and the circle larger than the clad diameter have an error due to the difference in diameter, the center position of the clad cannot be specified, so a reference circle equal to the clad diameter is used. By including the sum, the center position of the clad can be obtained with high accuracy.

  Further, in claim 2 of the present invention, as a specific example, the average value of luminance per circle obtained from the sum of the luminance obtained for the reference circle and the inner circle, and the luminance obtained for the outer circle The center position of the clad on the image is obtained from the position of the specific pixel when the difference from the average value of luminance per circle obtained from the sum is maximized.

  According to a third aspect of the present invention, the edge of the clad is detected and binarized in the normalized image in the preprocessing, and the binarized image data is subjected to a reference circle. The average value of the luminance per circle obtained from the sum of the luminance values for the outer circle near the reference passing through the outer side of the reference circle and the inner circle near the reference passing through the inner side of the reference circle, and the inner side of the reference circle and near the reference The center position of the clad is determined from the position of a specific pixel in which the difference in the average value of brightness per circle obtained from the sum of the brightness of inner circles near the center whose radius is smaller than the inner circle is maximum or within a predetermined range. Yes.

  In this process, since the edge portion is detected and binarized, an image in which pixels near the edge portion of the clad are white, for example, the other is black, for example, and when the reference circle and the center of the clad coincide, And the difference between the average value of luminance per circle obtained from the sum of the luminance of the circles in the vicinity thereof and the average value of luminance per circle obtained from the sum of the luminances of the inner circles near the center inside The center position of the clad can be detected. In this case, since the calculation for the binarized image data is sufficient, the calculation for obtaining the sum of luminance can be performed at higher speed.

  Further, in the fourth aspect of the present invention, in the preprocessing, image data in which the edge is binarized is obtained in the same manner as described above, and after compressing the image data, the sum of luminance for each circle is obtained to obtain the center of the temporary cladding. The position is detected, and the sum of the luminance of each circle is obtained for the center position of the temporary clad and its vicinity with respect to the normalized image, and the final center position of the clad is detected.

  In this process, the center position of the temporary cladding can be obtained at a higher speed by the amount of image compression. For example, if 640 × 480 pixels of VGA are compressed to 320 × 240 pixels of QVGA, the number of pixels is reduced to ¼ so that the center position of the temporary cladding can be obtained at a very high speed, and the normalization processing is performed. The luminance calculation of each circle for the image need only be performed for the center position of the temporary cladding and the vicinity thereof, and the accurate center position of the cladding can be detected at a very high speed as the entire processing.

The figure which shows the structure of the 1st Embodiment of this invention. The figure which shows the structural example of the principal part of this invention. The flowchart which shows the procedure of the pre-processing of the 1st Embodiment of this invention. Diagram for explaining normalization processing The figure which shows the image before normalization processing, and the image after processing The figure for demonstrating the operation | movement of the principal part of 1st Embodiment. The figure which shows the structure of 2nd Embodiment. The flowchart which shows the procedure of the pre-processing of 2nd Embodiment. Image diagram explaining edge detection processing The figure which shows the image before a binarization process, and the image after a process The figure for demonstrating operation | movement of the principal part of 2nd Embodiment. The figure for demonstrating operation | movement of the principal part of 2nd Embodiment. Configuration diagram of end face inspection equipment The figure which shows an example of the acquisition picture The figure for demonstrating the process for detecting the center position of a clad

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration of an optical connector ferrule end surface inspection device (hereinafter simply referred to as an inspection device) 20 to which the present invention is applied.

  The inspection apparatus 20 includes an end face image acquisition unit 30, an end face image analysis unit 40, an operation unit 60, and a display unit 70.

  The end face image acquisition unit 30 is for receiving the ferrule 5 of the optical connector to be inspected and acquiring image data of the end face 5a, and has a shape corresponding to the optical connector to be inspected as shown in FIG. The ferrule 5 is received and held up to a predetermined depth without rattling, and the ferrule holding portion 31 that shields the ferrule 5 from being incident on the end face of the ferrule 5 and prevents the light from entering the end face 5a. An illuminating unit 32 that irradiates illumination light, a lens, and the like, and an optical system 33 that forms an image of the end face 5a by enlarging the image on the end face 5a to a position with a predetermined focal length, and outputs image data of the end face at the position of the focal length. An image sensor 34 such as a CCD, an image memory 35 for temporarily storing image data detected by the image sensor 34, and image data temporarily stored in the image memory 35. It includes an interface 36 for outputting the face image analysis unit 40.

  The end face image acquisition unit 30 enlarges the image of the end face 5a of the ferrule 5 by, for example, 200 times and outputs it as grayscale image data of, for example, 640 × 480 pixels (VGA).

  On the other hand, as shown in FIG. 1, the end surface image analysis unit 40 performs an image memory 41 that stores the image data acquired by the end surface image acquisition unit 30, performs predetermined processing on the stored image data, and Cladding center detecting means 42 for detecting the center position of the cladding appearing above (core center), and how much elements such as dirt and dust are contained within a predetermined radius with reference to the detected center position of the cladding. It includes determination means 50 for checking and determining the quality of the end face.

  The clad center detecting unit 42 includes a preprocessing unit 43, a different diameter circular luminance calculating unit 44, and a clad center determining unit 45.

  The pre-processing unit 43 performs pre-processing including luminance processing for image data stored in the image memory 41. FIG. 3 is a flowchart showing a specific example of the preprocessing procedure, and noise removal processing is performed on the image data acquired first (S1).

  There is a blurring process as one of the noise removal processes. In the blurring process, an average value (Br + B1 to Bn) / (n + 1) of the luminance Br of one target pixel in the image data and the luminances B1 to Bn of n pixels around the target pixel is obtained, and this is calculated as the luminance Br of the target pixel. This is done by substitution.

  After performing noise removal processing in this way, normalization processing (S2) for luminance is performed. In this normalization process, the luminance range of each pixel of the image data, for example, 0 to 255 in the case of 8 bits, as shown in FIG. As shown in FIG. 4B, the histogram is expanded so that the minimum luminance value is 0 and the maximum luminance value is 255. Accordingly, for example, image data in which contrast of light and dark is enhanced as shown in FIG. 5B can be obtained from the image shown in FIG. The normalization process is not limited to the expansion process, and includes all processes that are processed so as to conform to a preset reference.

  Next, it is examined whether or not a dark area exists in order to determine whether or not the clad image is included in the normalized image (S3). In this process, a histogram of image data that has been normalized as shown in FIG. 4B is obtained, and a predetermined number (for example, dark areas) of a predetermined luminance threshold R (for example, R = 90) or less is determined. It is determined whether or not there are more than 20000) pixels. If a predetermined number or more, it is assumed that there is a dark region due to the cladding, and the pre-processing is completed normally. As an image acquisition error.

  In this way, the processing by the different-diameter circular luminance calculation means 44 is performed on the image determined to include the contrast of light and dark and to include the image of the clad.

  The different-diameter circular luminance calculating unit 44 sets one pixel on the preprocessed image as a target pixel (specific pixel), sets the target pixel as a center, and sets the cladding diameter (converted value in the same manner as described above) in the optical fiber standard. Assuming an equal reference circle, an inner circle that is concentric and small in diameter, and an outer circle that is concentric with the reference circle and large in diameter, the sum of the brightness of each pixel that passes through the reference circle, and the brightness of each pixel that passes through the inner circle The sum of the luminance of each pixel through which the sum and the outer circle pass is obtained while shifting the position of the pixel of interest.

FIG. 6 shows an example of the processing.
The reference circle is Cr, the outer circle whose diameter is 5 pixels larger than the reference circle Cr, for example, Cout1, and the inner circle whose diameter is smaller than the reference circle Cr, for example, 1 pixel, is Cin1.

  Here, it is assumed that the total luminance of pixels passing through the outer circle Cout1 is Kout1, the total luminance of pixels passing through the reference circle Cr is Kr, and the total luminance of pixels passing through the inner circle Cin1 is Kin1.

Then, the clad center determination unit 45 obtains a determination value H for each pixel of interest by the following calculation using the total luminance of each circle obtained by the different-diameter circle luminance calculation unit 44.
H
= (Average value of luminance per circle obtained by dividing the sum of the luminances of the outer circles by the total number of outer circles)-(The sum of the luminances of the reference and inner circles is the sum of the luminances of the reference and inner circles) (Average value per circle calculated by dividing by the total number of)
= Kout1-{(Kr + Kin1) / 2}

Here, an example in which there is one outer circle and one inner circle is shown, but two or more outer circles and inner circles having different diameters may be set. For example, when there are N outer circles and M inner circles, the determination value H is expressed by a general formula:
H = {(Kout1 + Kout2 + ... + KoutN) / N}
-{(Kr + Kin1 + Kin2 + ... + KinM) / (M + 1)}
It becomes.

  The above processing pays attention to the fact that the brightness of the image of the end face of the clad is different from the brightness of the image of the end face outside the clad (the ferrule itself). That is, since the cladding and the core of the optical fiber are formed of a fiber material having high light transmittance, most of the illumination light irradiated to the end face enters the inside and the rest is reflected. On the other hand, since the ferrule is made of a material having a high light shielding property (low translucency), most of the illumination light is reflected. Therefore, in the image obtained by the image sensor 34, the clad portion is dark and the outer ferrule portion is brightly displayed.

  Therefore, when the reference circle and the center of the clad coincide, it is obtained from the average of the luminance per pixel obtained from the sum of the luminance of the pixels through which the reference circle and the inner circle pass and the sum of the luminance of the pixels through which the outer circle passes. It is predicted that the determination value H, which is the difference from the average luminance per circle, is maximized.

  That is, the above process is performed by changing the target pixel one by one, and the position of the target pixel when the determination value H becomes maximum can be determined as the center position of the cladding.

  However, a large luminance difference occurs at a position far from the clad position, and the determination value H becomes the maximum, or the determination value H is different for a plurality of different target pixels due to the influence of dirt on the end face or image focus shift. The case where the same maximum value is taken is considered.

  As a method for coping with this, the above-mentioned different-circle luminance calculation means 44 calculates the luminance for the inner circle Cin1 inside the reference circle, and the sum of the luminance values for the inner circle Cin1 is a predetermined threshold value. When A exceeds A (that is, the inside of the reference circle that should be dark is too bright), the luminance calculation process for this pixel of interest is skipped, and the process proceeds to the calculation of the next pixel of interest.

  Further, when there are a plurality of inner circles, even if the sum of the luminance values for the inner circle Cin1 does not exceed the threshold A, the luminance value of the pixels that pass through the inner circle Cin2 is lower. The number of pixels exceeding the threshold value A is counted, and when the number exceeds a specified number (for example, 120), the luminance calculation process for that pixel of interest is skipped and the process proceeds to the calculation of the next pixel of interest. .

  As shown in FIG. 4, the threshold A in this case is added in order from the number of pixels of the luminance value 255 in the histogram of the image whose luminance value is normalized, and the sum total is a predetermined number ( For example, the luminance value when exceeding 120,000 pixels is used.

  By this processing, it is not necessary to perform a calculation process for a large luminance difference generated at a position far from the position of the clad, and erroneous clad center position detection is eliminated. In addition, since unnecessary calculations are skipped, the processing time can be shortened.

  Also, the same maximum determination value H may be obtained for a plurality of neighboring pixels of interest due to the influence of dirt on the end face, image focus shift, and the like. In this case, the clad center determining means 45 examines the distribution of target pixels that give the same determination value H, and determines the target pixel closest to the center of gravity position as the center position of the cladding, thereby accurately determining the center position of the cladding. Can be requested.

  In this process, the range that the target pixel can take is limited to a range in which the outermost circle Cout1 having the maximum diameter does not protrude from the edge of the image.

  After the center position of the clad on the image is detected in this way, the determination means 50 includes, to the original image data, how much elements such as dirt and dust are included within a predetermined radius with respect to the center position of the clad. Whether the clad and ferrule end faces are good or bad is determined, and the determination result and the like are displayed on the display unit 70.

  This determination process will be briefly described. For detection of dust, a pixel having a luminance equal to or lower than a certain threshold is detected as a dirty pixel in a grayscale end face image, and checked in eight directions around the dirty pixel. , And make other adjacent dirty pixels the same group (one dust).

And
Area per pixel x number of pixels in group = dust area (μm ² )
And calculate the area of all garbage groups. here,
Area per pixel = [clad diameter (μm) ÷ number of pixels in the diameter of the reference circle] ²
Calculate from However, the clad diameter is 125 μm, for example.

  Next, a plurality of concentric circles having a predetermined diameter (core diameter, clad diameter, etc.) are set around the center of the clad detected on the end face image, and are set in advance from the number and area of dust contained in each circle. Pass / fail is determined according to the determination criteria (International Electrotechnical Commission IEC61300, etc.).

  The various parameters necessary for the inspection can be set in advance by operating the operation unit 60, and the operation mode for proceeding with the inspection is only the mode in which the above-described series of processing is performed automatically and continuously. In addition, a mode in which the processing result is displayed for each step and the inspector moves to the next step by operating the operation unit 60 is also possible.

  Although not described in detail, the end face image analysis unit 40 sequentially displays information necessary for the inspection on the display unit 70, such as the obtained raw end face image, the processed image from the preprocessing to the clad center detection, and the determination result. Or a list display function. The display form is arbitrary, and description thereof is omitted here.

  In the inspection apparatus 20 configured as described above, the reference pattern correlation calculation process is not performed on the acquired image data, and the reference circle centering on the pixel of interest and the inner and outer circles are assumed, and the luminance of the pixels passing through those circles is assumed. Since the center position of the clad on the image is detected based on the sum of the above, it is possible to detect the center position of the clad at a high speed with a remarkably small amount of computation compared with the method using the conventional correlation calculation processing. Thus, many optical connectors can be efficiently inspected at the site of optical fiber installation.

(Second Embodiment)
In the first embodiment described above, the average brightness of the inner and outer sides of the cladding is examined based on the luminance of the pixels through which the reference circle and the outer and inner circles pass, and the center of the cladding is detected. If there is a lot of dirt in the vicinity of the outside and the average luminance value is low, the detection accuracy of the center position of the clad may be lowered. In addition, although it is faster than the method of performing the correlation calculation with the reference pattern, it cannot cope with further increase in speed.

  As a method for improving this, it is possible to detect the edge of the outer periphery of the clad, binarize the image of the edge, and then detect the center position of the clad based on the brightness of a different diameter circle around the edge.

  FIG. 7 shows an example of the configuration. As shown in FIG. 8, the preprocessing means 43 'of the clad center detection means 42' of the inspection apparatus 20 'first performs noise removal processing S11, and then performs luminance normalization processing S12. . The noise removal processing S11 uses, for example, a median filter or a Gaussian filter.

  In the same manner as described above, normalization processing S12 is performed on the image data subjected to such noise removal processing. This normalization process also has the purpose of eliminating the unevenness of the brightness distribution that occurs when the filter process that compresses the change in brightness is performed in the noise removal process S11. Similarly to the above, the image subjected to the noise removal process The data is expanded so that the minimum value of the luminance is 0 and the maximum value is 255.

  In the first embodiment, dark area determination processing is performed on the normalized image, but in this embodiment, circle determination is performed using a binarized edge image as described later. Here, the dark area determination process is not performed, and the process proceeds to the edge detection process S13. However, the dark area determination may be performed in advance to notify an image acquisition error.

  In edge detection processing S13, the edge of the clad is detected, a threshold value is set between the brightness of the pixel detected as the edge portion and a pixel darker than that, and binarization processing S14 is performed. Set to maximum brightness (white).

  For this edge detection, for example, Sobel filter processing is used. In this process, the following q × q horizontal and vertical coefficient convolution operations are performed on luminance data of q × q (q is an odd number, eg, 3) pixels centered on the target pixel. Do.

Then, the sum Sum square root of the result SumX of the horizontal coefficient and the result SumY of the convolution result of the vertical coefficient,
√ (SumX ² + SumY ² )
By performing the process of substituting with the luminance of the target pixel, an edge image in which only the luminance of the pixel at the edge portion of the cladding is high and the luminance of the other pixels is low can be obtained.

  FIG. 9 shows an example of an image obtained by this edge detection process. 9A is used as the original image, the horizontal edge is detected as shown in FIG. 9B by the horizontal convolution operation, and the vertical convolution operation is performed as shown in FIG. 9C. An edge in the vertical direction is detected, and the edge of the entire circumference is finally detected as shown in FIG.

  For this edge detected image, the brightness of the pixel detected as the edge portion and a predetermined threshold value between the darker pixels are set and the binarization process S14 is performed. Set to maximum brightness (white).

  This binarization is performed using a threshold value that is a predetermined ratio from the top of the luminance value to the histogram of the image whose edge is detected. For example, for the original image in FIG. 10 (a), when the upper 25th luminance value is the threshold value, the image in FIG. 10 (b) is obtained, and the upper 10th luminance value is the threshold value. Is an image of (c) of FIG. Comparing both, it can be seen that the edge portion is clearly displayed in the image of the top 10 percent.

  Then, edge emphasis processing S15 for expanding the white pixel portion including the edge portion is performed on the binarized image. This edge enhancement process S15 is a process for preventing lack of continuity of the edge portion by the next image compression process S16.

  In the edge enhancement process, if one or more pixels have a luminance value of 255 (white) among v × v pixels (v is an odd number, for example, v = 3) centered on the target pixel, the luminance of the target pixel is determined. If the value is 255 (white) and there is no value, the luminance value of the pixel of interest is 0 (black).

In addition to the purpose of preventing the lack of continuity of the edge portion by the next image compression processing S16 as described above, this edge enhancement processing is as follows.
The more the focus of the image on the end face is, the thinner the edge,
The size of the clad end face on the image data may change due to individual differences of each member constituting the end face image acquisition unit 30,
It is used for the purpose of eliminating the point where an edge may be formed along the dirt adhering to the periphery of the clad.

At the end of the preprocessing, an image compression process S16 is performed on the image subjected to the edge enhancement process.
For example, if the number of pixels M × N of the original image is 640 × 480 pixels of VGA, it is compressed to QVGA 320 × 240 of ¼ size. In this compression processing, four VGA 2 × 2 pixels are set as one QVGA pixel, and 0 (black) or 256 (white) is assigned to this pixel.

  For example, if the luminance of 3 or more of 4 pixels of 2 × 2 of VGA is 0, the luminance of 1 pixel of QVGA corresponding to it is 0 (black), otherwise 1 of QVGA The luminance of the pixel is 256 (white). This processing is shifted so that 2 × 2 pixels of VGA do not overlap, and the luminance of each pixel of QVGA is assigned.

  In this processing, if 3 or more white pixels are not present among 2 × 2 pixels of the VGA, one pixel of the QVGA does not become white, so that the edge portion is likely to be thinned and broken. Since the above-described enhancement processing is performed at a stage, the possibility that the edge portion is interrupted even when the image is compressed is reduced.

  The compressed image obtained by such pre-processing is subjected to arithmetic processing by the first different-diameter circular luminance calculating means 46 of the cladding center detecting means 42 ', and the first cladding center determining means 47 for the calculation result is subjected to arithmetic processing. The provisional clad center on the compressed image is obtained by the determination process. The first different-diameter circular luminance calculating means 46 performs luminance calculation around the edge portion and inside thereof.

FIG. 11 shows an example of the processing.
Similarly to the above, Cr is the reference circle, Cout1 is the outer circle near the reference that is one pixel larger than the reference circle Cr, Cin1 is the inner circle near the reference that is one pixel smaller than the reference circle Cr, and 5 is larger than the reference circle Cr. The inner circle near the center that is smaller by the pixel is Cin2, the inner circle near the center that is 15 pixels smaller than the reference circle Cr is Cin3, and the inner circle near the center that is 25 pixels smaller in diameter than the reference circle Cr is Cin4. Here, compared to the size of the reference circle Cr, the three inner circles Cin2 to Cin4 near the center are set to be considerably small because it is unclear how wide the edge portion subjected to image processing is. This is to provide a sufficient margin.

  The reference circle, the reference vicinity outer circle, and the reference vicinity inner circle are circles for passing a pixel displayed in white as an edge portion of the cladding when the pixel of interest coincides with the cladding center. Is a circle for passing pixels displayed in black near the center of the clad. Also, here, the reference neighborhood circle is set inside and outside the reference circle, but only one of them may be set, and the center neighborhood circle is not only three, but also four or more or Two or less may be sufficient.

  The first different-diameter circular luminance calculating means 46 then calculates the total luminance Kout1 of the pixels passing through the reference neighboring outer circle Cout1, the total luminance Kr of the pixels passing through the reference circle Cr, and the luminance of the pixels passing through the reference neighboring inner circle Cin1. , The total luminance Kin2 of the pixels passing through the center vicinity inner circle Cin2, the total luminance Kin3 of the pixels passing through the center vicinity inner circle Cin3, and the total luminance Kin4 of the pixels passing through the center vicinity inner circle Cin4. However, although the binarized luminance is two types, 0 (black) and 255 (white), here, the luminance of the pixel through which each circle passes by replacing black luminance with 0 and white luminance with 1. Is obtained as the sum of the number of white pixels.

  In addition, the first different-diameter circular luminance calculating means 46 has a predetermined ratio (for example, 1) of the number of pixels having a luminance of 0 (black) out of the total number of pixels through which the reference circle Cr passes (a value that is uniquely determined when the radius is determined). / 4) Check whether or not there is more than a predetermined ratio, and if it is a predetermined ratio or more, it is determined that the pixel of interest at that time is not a candidate for the center of the clad, and the calculation of each circle is skipped. Move on to computation.

  FIG. 12 shows an example in which the number of pixels with brightness 0 (black) out of the total number of pixels through which the reference circle Cr passes is 1/4 or more of the total, and the target pixel at this time is a candidate for the center position of the cladding. If not, the process proceeds to the calculation of each circle for the next pixel of interest.

The first clad center determining means 47 sequentially obtains a determination value H for each pixel of interest (excluding the skipped pixel) using the total luminance (total number of white pixels) of each circle by the following calculation.
H = {(Kout1 + Kr + Kin1) / 3} − {(Kin2 + Kin3 + Kin4) / 3}

  Then, the target pixel when the obtained determination value H is the maximum or the upper-side predetermined percentage with respect to the maximum value is determined as the temporary cladding center.

  In other words, if the thickness of the white pixel forming the edge on the compressed image is uniform over the entire circumference, the center of the reference circle passing through the center of the thickness becomes the center position of the cladding, but the white pixel actually obtained The thickness of the film becomes non-uniform and uneven. Therefore, when the determination value H is maximized, the position of the target pixel is also shifted from the actual center of the clad according to the deviation. Further, when the white pixel becomes thicker due to edge enhancement, the maximum determination value H is obtained with a plurality of different target pixels, and it may not be possible to specify one.

  In order to deal with this, in the present embodiment, the first cladding center determination unit 47 performs a labeling process in which a set of continuous white pixels is set as one group and a unique label number is assigned to each of the plurality of groups.

  In this labeling process, for example, the compressed image is moved one pixel at a time in the horizontal direction from the upper left corner, and when reaching the right end, the white pixel is found while repeating the scanning operation that moves to the lower stage and moves in the horizontal direction. A unique label number is assigned as a group of consecutive sets and assigned to each white pixel belonging to the group.

  That is, as shown in FIG. 11, when white pixels are continuous in a ring shape, the same label number (for example, 1) is assigned to all the white pixels.

Then, the following processing is performed on a set of pixels assigned with a specific label number for the target pixel having the maximum determination value H.
Calculate the maximum / minimum of the judgment value H.
Find the maximum and minimum values of the x and y coordinates of the area to which the same label number is assigned (area identification).
The center (center of gravity) of a plurality of pixels of interest that fall within the upper 10% of the range from the maximum value to the minimum value of the determination value H in the set of white pixels assigned the same label number The center.

  By doing so, even if the white pixels forming the edges are unevenly distributed, or the white pixels forming the edges are thick, and there are a plurality of target pixels that give the maximum determination value H Even so, the center position of the cladding can be accurately obtained.

  The above processing is based on the fact that the image representing the edge portion of the clad is binarized, and the average brightness of the pixels around the edge is larger than the average brightness of the pixels sufficiently inside the edge portion. Is.

  When obtaining the provisional cladding center, the number of pixels of interest is reduced by the amount corresponding to the compression of the original image (in the above example, 1/4), and the conditional expressions and calculations described above are reduced. Higher speed than compression ratio can be expected.

  However, since the accuracy of the center position of the detected clad is reduced by the amount of image compression, the center position of the detected clad is set as the temporary clad center position, and the second different circular luminance calculation means 48 Then, with respect to the image that has been normalized in the preprocessing (image that has not been subjected to edge detection and binarization), the center position of the temporary cladding and its vicinity are used as the target pixel, and a different circle luminance calculation process is performed. Find the center position more accurately.

  The calculation processing by the second different-diameter circle luminance calculation means 48 is the same as in the first embodiment, and the reference circle on the normalized image is Cr ′, and the diameter is larger than that of the reference circle Cr ′. For example, an outer circle larger by 5 pixels is Cout1 ′, and an inner circle whose diameter is smaller by one pixel than the reference circle Cr ′ is Cin1 ′. Here, an example in which one outer circle and one inner circle are assumed will be described. However, as described above, a plurality of both may be assumed.

  Similarly to the above, the total luminance Kout1 ′ of the pixels through which the outer circle Cout1 ′ passes, the total luminance Kr ′ of the pixels through which the reference circle Cr ′ passes, and the total luminance Kin1 ′ of the pixels through which the inner circle Cin1 ′ passes. This calculation uses the luminance of a grayscale image that has not been binarized, but can be executed in a very short time because the area of the pixel of interest to be calculated is very narrow.

The second clad center determining means 49 obtains a judgment value H by the following calculation with respect to the total luminance of the obtained circles, and sets the target pixel that gives the maximum value as the final clad center position. .
H = Kout1 ′ − (Kr ′ + Kin1 ′) / 2

  Since this process is only performed on 2 × 2 pixels of the original VGA image corresponding to one pixel detected as the center position of the temporary cladding in the compressed image and the surrounding pixels, the processing time is extremely short. In other words, the center position of the clad can be accurately detected in a short time. However, in this case as well, there may be a case where a plurality of target pixels having the maximum determination value H is obtained. In this case, for example, at the center of gravity of the distribution of the plurality of target pixels from which the same determination value H is obtained. The closest target pixel is set as the final center position of the cladding, or as described above, the center position of the distribution of the target pixel that falls within the range of 10% from the maximum value of the determination value H is the final center position of the cladding. do it.

  As described above, in the second embodiment, preprocessing including normalization processing, edge detection processing, binarization processing, edge enhancement processing, and image compression processing is performed on the acquired end face image, and the compressed image is processed. The center position of the temporary cladding on the compressed image is obtained by the first different diameter circular luminance calculating means 46 and the first cladding center determining means 47, and the second different diameter is obtained with respect to the normalized image. An accurate center position of the clad is detected from the vicinity of the center position of the temporary clad by the circular luminance calculating means 48 and the second clad center determining means 49.

  For this reason, the center position of the clad can be obtained more quickly and accurately, and the end face state can be inspected at high speed and accurately.

  In the above embodiment, the radius of the circle in the vicinity of the reference circle assumed when detecting the temporary cladding center in the compressed edge image is increased or decreased by one pixel from the reference circle. However, depending on the state of the end face to be inspected, a pixel that is increased or decreased by two pixels or three pixels can be used as the reference neighborhood circle.

  In the second embodiment, the binarized image is subjected to compression processing as preprocessing, the provisional cladding center position detection processing is performed on the compressed image, and the pre-compression image is provisionally processed. The center position of the clad and its neighboring range are detected again as the target pixel, but the center position of the clad is detected again. However, as indicated by the dotted line in FIG. With respect to the binarized edge image that has not been processed, the sum of the luminances of the reference circle, the reference vicinity outer circle, the reference vicinity inner circle, and the center vicinity inner circle by the first different-diameter circular luminance calculation means 46 is obtained. The final center position of the clad may be detected by performing a computation and determination calculation processing by the first clad center determining means 47. In this case, as indicated by a dotted line in FIG. 8, the second different diameter circular luminance calculating means 48 and the second cladding center determining means 49 are omitted, and the cladding obtained by the first cladding center determining means 47 is omitted. The determination unit 50 may be provided with the center position.

  The inspection devices 20 and 20 'of each of the above embodiments are generally configured by an end surface image acquisition unit 30, an end surface image analysis unit 40, an operation unit 60, and a display unit 70. However, as an actual hardware configuration, the end surface The image acquisition unit 30 is configured as a probe type that can be connected to the connector of the optical fiber to be inspected, and its output interface is an interface such as a USB that can be connected to a personal computer. It can be set as the structure which performs the said process with respect to the image data which the acquisition part 30 acquired according to the program stored beforehand.

In this case, when performing the processing of the first embodiment,
Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
Means for performing preprocessing including luminance processing on the stored image data;
For the preprocessed image data, a reference circle centered on a specific pixel on the image and equal to the cladding diameter on the standard of the optical fiber on the image, an inner circle concentric with the reference circle and having a smaller diameter than the reference circle Supposing an outer circle that is concentric with the reference circle and larger in diameter than the reference circle, and obtains the sum of the luminance of the pixels through which each circle passes while shifting the position of the specific pixel,
Means for determining the center position of the cladding on the image based on the total luminance of the obtained circles;
This can be realized by using a program that functions as means for determining the quality of the ferrule end face using the determined center position of the clad as a reference position for inspection.

When performing the processing of the second embodiment,
Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
A luminance normalization process for the stored image data, an edge detection process for the normalized image data, a binarization process for the edge-detected image data, and an image compression process for the binarized image data. Means for preprocessing,
A reference circle that is centered on a specific pixel on the compressed image with respect to the compressed image data and is equal to the cladding diameter on the standard of the optical fiber on the compressed image, concentric with the reference circle, and near the outside of the reference circle A reference near outer circle passing through the reference circle, a reference near inner circle concentric with the reference circle and passing through the inside of the reference circle, a center near inner circle concentric with the reference circle and having a smaller radius than the reference near inner circle, Means for obtaining the total sum of the luminances of passing pixels while shifting the position of the specific pixel,
The average value of luminance per circle obtained from the sum of luminance for the reference circle, the outer circle near the reference and the inner circle near the reference, and the per-circle obtained from the sum of luminance for the inner circle near the center. Means for calculating a difference with an average value of luminance for each position of the specific pixel, and determining a center position of a clad on the compressed image from the position of the specific pixel where the difference is maximum or within a predetermined range;
The reference circle centered on the position of a specific pixel on the normalized image, an inner circle that is concentric with the reference circle and smaller in diameter than the reference circle, and that is outside the diameter that is concentric with the reference circle and larger than the reference circle Means for assuming a circle and calculating the sum of the luminance of the pixels through which each circle passes while shifting a specific pixel in the center position of the clad determined on the compressed image and the vicinity thereof,
The average value of luminance per circle obtained from the sum of the luminance for the reference circle and the inner circle obtained on the normalized image, and the obtained on the normalized image A difference from the average value of luminance per circle obtained from the total luminance of the outer circle is calculated for each position of the specific pixel, and the normal value is calculated from the position of the specific pixel where the difference is maximum or within a predetermined range. Means for determining the center position of the cladding on the processed image;
This can be realized by using a program that functions as means for determining the quality of the ferrule end face by using the center position of the clad determined on the normalized image as a reference position for inspection.

Further, as described above, the preprocessing is up to binarization processing, and for the binarized edge image, the first different circle luminance calculation means 46 calculates the sum of the luminance of each circle and the first In the case of realizing an embodiment in which the final clad center position is detected by performing arithmetic processing by the clad center determining means 47,
Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
Means for performing preprocessing including normalization processing for luminance of the stored image data, edge detection processing for normalized image data, and binarization processing for edge detected image data;
For the binarized image data, a reference circle centered on a specific pixel on the image and equal to the cladding diameter on the standard of the optical fiber on the image, a reference that is concentric with the reference circle and passes near the outside Assuming a near-outer circle, a reference near-inner circle concentric with the reference circle and passing through its inner side, a center near-inner circle concentric with the reference circle and having a smaller radius than the reference near-inner circle, and pixels passing through each circle Means for obtaining the total sum of luminances while shifting the position of the specific pixel,
The average value of luminance per circle obtained from the sum of luminance for the reference circle, the outer circle near the reference and the inner circle near the reference, and the per-circle obtained from the sum of luminance for the inner circle near the center. Means for calculating a difference from an average value of luminance for each position of the specific pixel, and determining a center position of the clad from the position of the specific pixel where the difference is maximum or within a predetermined range;
This can be realized by using a program that functions as means for determining the quality of the ferrule end face using the determined center position of the clad as a reference position for inspection.

  DESCRIPTION OF SYMBOLS 1 ... Optical fiber core wire, 5 ... Ferrule, 20, 20 '... Ferrule end surface inspection apparatus, 30 ... End surface image acquisition part, 31 ... Ferrule holding part, 32 ... Illumination part, 33 ... Optical system, 34 …… Image sensor, 35 …… Image memory, 36 …… Interface, 40 …… End face image analysis unit, 41 …… Image memory, 42, 42 ′ …… Cladding center detection means, 43, 43 ′ …… Pre-processing Means 44... Different diameter circular luminance calculating means 45... Cladding center determining means 46... First different diameter circular luminance calculating means 47. 47. First cladding center determining means 48. Different diameter circular luminance calculating means, 49... Second clad center determining means, 60.

Claims (7)

An end face image acquisition unit (30) for acquiring image data of the ferrule end face of the optical connector to be inspected;
Cladding center detecting means (42, 42 ') for detecting the center position of the cladding of the optical fiber on the image based on the image data acquired by the end face image acquisition unit, and using the detected center position of the cladding as a reference position In the ferrule end face inspection device for an optical connector having an end face image analysis unit (40) for performing pass / fail judgment of the ferrule end face,
The clad center detection means includes
Pre-processing means (43, 43 ') for performing pre-processing including processing on luminance for the image data acquired by the end face image acquisition unit;
A reference circle that is centered on a specific pixel on the preprocessed image and is equal to the standard cladding diameter of the optical fiber on the image, an inner circle that is concentric with the reference circle and smaller in diameter than the reference circle, and the reference circle Assuming an outer circle that is concentric and larger in diameter than the reference circle, different circle luminance calculation means (44, 46, 48) for obtaining the total luminance of the pixels through which each circle passes while shifting the position of the specific pixel When,
Cladding center determining means (45, 47, 49) for determining the center position of the cladding on the image based on the sum of the brightness of each circle obtained by the different-diameter circular brightness calculating means. An optical connector ferrule end face inspection device. The cladding center determining means includes
The difference between the average luminance per circle obtained from the total luminance for the reference circle and the inner circle and the average luminance per circle obtained from the total luminance for the outer circle is the 2. The ferrule end face inspection device for an optical connector according to claim 1, wherein the center position of the clad is calculated from the position of the specific pixel which is calculated for each position of the specific pixel and the difference is maximum or within a predetermined range. The preprocessing means includes a normalization process as the process for the luminance,
The pre-processing means includes
Means for performing edge detection processing for detecting the edge of the clad on the normalized image data;
Means for performing binarization processing on the image data subjected to the edge detection processing,
The different-diameter circular luminance calculating means includes
With respect to the binarized image data, the reference circle centered on the position of the specific pixel, a reference near outer circle concentric with the reference circle and passing near the outside, a concentric with the reference circle and the inside Assuming a reference inner circle that passes through a neighborhood, a center inner circle that is concentric with the reference circle and has a smaller radius than the reference neighborhood inner circle, the total luminance of the pixels that pass through each circle is shifted by the position of the specific pixel. While being shaped to seek each,
The cladding center determining means includes
The average value of luminance per circle obtained from the sum of luminance for the reference circle, the outer circle near the reference and the inner circle near the reference, and the per-circle obtained from the sum of luminance for the inner circle near the center. The difference from the average value of luminance is calculated for each position of the specific pixel, and the center position of the clad on the image is determined from the position of the specific pixel where the difference is maximum or within a predetermined range. Item 3. A ferrule end face inspection device for an optical connector according to Item 1. The preprocessing means includes a normalization process as the process for the luminance,
The pre-processing means includes
Means for performing edge detection processing for detecting the edge of the clad on the normalized image data;
Means for performing binarization processing on the image data subjected to the edge detection processing;
An image compression process for generating compressed image data having a small number of pixels from the binarized image data,
The clad center detection means includes
The reference circle centered on the position of a specific pixel on the compressed image, a reference vicinity outer circle concentric with the reference circle and passing near its outer periphery, a reference vicinity inner circle concentric with the reference circle and passing its inner vicinity, Assuming an inner circle near the center that is concentric with the reference circle and has a smaller radius than the inner circle near the reference, a first different-diameter circle that obtains the total luminance of the pixels through which each circle passes while shifting the position of the specific pixel. Luminance calculation means (46);
An average value of luminance per circle obtained from a sum of luminance values for the reference circle, the reference outer circle and the reference inner circle obtained by the first different-diameter luminance calculation means; and the vicinity of the center A difference from the average value of luminance per circle obtained from the total luminance of inner circles is calculated for each position of the specific pixel, and the compression is performed from the position of the specific pixel where the difference is maximum or within a predetermined range. First cladding center determining means (47) for determining the center position of the cladding on the image;
The reference circle centered on the position of a specific pixel on the image normalized by the preprocessing means, an inner circle concentric with the reference circle and smaller in diameter than the reference circle, concentric with the reference circle and from the reference circle Assuming a large-diameter outer circle, the second sum is obtained by shifting the specific pixel in the center position of the clad determined by the first clad center determining means and the range in the vicinity of the sum of the luminance of the pixels through which each circle passes. Different diameter circular luminance calculating means (48),
1 obtained from the average value of the luminance per circle obtained from the total luminance of the reference circle and the inner circle obtained by the second different diameter circular luminance calculating means, and 1 from the total luminance of the outer circle. The difference between the average value of the luminance per circle is calculated for each position of the specific pixel, and the center of the clad on the normalized image from the position of the specific pixel where the difference is maximum or within a predetermined range 2. The ferrule end face inspection device for an optical connector according to claim 1, further comprising second clad center determining means (49) for determining a position. Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
Means for performing preprocessing including luminance processing on the stored image data;
For the preprocessed image data, a reference circle centered on a specific pixel on the image and equal to the cladding diameter on the standard of the optical fiber on the image, an inner circle concentric with the reference circle and having a smaller diameter than the reference circle Supposing an outer circle that is concentric with the reference circle and larger in diameter than the reference circle, and obtains the sum of the luminance of the pixels through which each circle passes while shifting the position of the specific pixel,
Means for determining the center position of the clad on the image based on the total luminance of the obtained circles;
A program for inspecting a ferrule end face of an optical connector for causing the determined center position of the clad as a reference position for inspection to function as a means for determining the quality of the ferrule end face. Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
Means for performing preprocessing including normalization processing for luminance of the stored image data, edge detection processing for normalized image data, and binarization processing for edge detected image data;
For the binarized image data, a reference circle centered on a specific pixel on the image and equal to the cladding diameter on the standard of the optical fiber on the image, a reference that is concentric with the reference circle and passes near the outside Assuming a near-outer circle, a reference near-inner circle concentric with the reference circle and passing through its inner side, a center near-inner circle concentric with the reference circle and having a smaller radius than the reference near-inner circle, and pixels passing through each circle Means for obtaining the total sum of luminances while shifting the position of the specific pixel,
The average value of luminance per circle obtained from the sum of luminance for the reference circle, the outer circle near the reference and the inner circle near the reference, and the per-circle obtained from the sum of luminance for the inner circle near the center. Means for calculating a difference from an average value of luminance for each position of the specific pixel, and determining a center position of the clad from the position of the specific pixel where the difference is maximum or within a predetermined range;
A program for inspecting a ferrule end face of an optical connector for causing the determined center position of the clad as a reference position for inspection to function as a means for determining the quality of the ferrule end face. Computer
Means for storing image data of the ferrule end face of the optical fiber to be inspected;
A luminance normalization process for the stored image data, an edge detection process for the normalized image data, a binarization process for the edge-detected image data, and an image compression process for the binarized image data. Means for preprocessing,
A reference circle that is centered on a specific pixel on the compressed image with respect to the compressed image data and is equal to the cladding diameter on the standard of the optical fiber on the compressed image, concentric with the reference circle, and near the outside of the reference circle A reference near outer circle passing through the reference circle, a reference near inner circle concentric with the reference circle and passing through the inside of the reference circle, a center near inner circle concentric with the reference circle and having a smaller radius than the reference near inner circle, Means for obtaining the total sum of the luminances of passing pixels while shifting the position of the specific pixel,
The average value of luminance per circle obtained from the sum of luminance for the reference circle, the outer circle near the reference and the inner circle near the reference, and the per-circle obtained from the sum of luminance for the inner circle near the center. Means for calculating a difference with an average value of luminance for each position of the specific pixel, and determining a center position of a clad on the compressed image from the position of the specific pixel where the difference is maximum or within a predetermined range;
The reference circle centered on the position of a specific pixel on the normalized image, an inner circle that is concentric with the reference circle and smaller in diameter than the reference circle, and that is outside the diameter that is concentric with the reference circle and larger than the reference circle Means for assuming a circle and calculating the sum of the luminance of the pixels through which each circle passes while shifting a specific pixel in the center position of the clad determined on the compressed image and the vicinity thereof,
The average value of luminance per circle obtained from the sum of the luminance for the reference circle and the inner circle obtained on the normalized image, and the obtained on the normalized image A difference from the average value of luminance per circle obtained from the total luminance of the outer circle is calculated for each position of the specific pixel, and the normal value is calculated from the position of the specific pixel where the difference is maximum or within a predetermined range. Means for determining the center position of the cladding on the processed image;
A program for inspecting a ferrule end face of an optical connector for causing the center position of a clad determined on the normalized image as a reference position for inspection to function as a means for judging the quality of the ferrule end face.

Images