JPH0755443A - Defect inspection system - Google Patents

Abstract

PURPOSE:To facilitate arrangement of signal transmission cables connecting between a large number of sensor cameras and a signal processing section and to enhance reliability in the detection of defect by suppressing the influence of disturbance on the cable. CONSTITUTION:Image information of a specimen 12 is obtained by means of a large number of sensor cameras 15, each having a light receiving section 14 comprising a one-dimensional CCD image sensor, and the information is subjected to pattern matching at a signal processing section 21 thus detecting a defect of the specimen 12. In such defect inspection system, image information from each camera 15 is converted through an A/D converter 19 into a multilevel digital data which is subjected to high frequency compression by a signal transmission means 20 to produce a serial multiplex signal. The serial multiplex signal is transmitted on an optical fiber and subjected to parallel conversion to produce a digital data. Frequency of the digital data is returned back to the driving frequency of the camera 15 and fed to the signal processing section 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection device for determining the quality of a pattern to be inspected such as a print pattern obtained by imaging a printed matter with a large number of sensor cameras by pattern matching.

[0002]

2. Description of the Related Art A defect inspection apparatus for determining defects by pattern matching is, for example, a one-dimensional CCD (charge c
oupled device = Electrification coupling device) A number of sensor cameras with image sensors as light receiving parts are arranged side by side, these cameras are arranged facing the subject, and the image sensors are scanned in the width direction of the moved subject. The image information for inspection is obtained by.

A large number of sensor cameras, which are arranged in parallel with each other to form one visual unit, respectively image a predetermined area in the width direction of the subject to obtain a required resolution. When the defect inspection apparatus performs a print defect inspection on, for example, a newspaper surface printed by a rotary printing machine, since there are many printed paper surfaces, it is necessary to install a large number of the visual units corresponding to the number of paper surfaces.

In the prior art, as shown in FIG. 4, signal transmission between the signal processing unit 1 for pattern matching and each sensor camera 3 of the visual unit 2 is directly connected to each sensor camera 3. It was performed using the coaxial cable 4.

[0005]

As described above, in the parallel signal transmission method in which signal transmission is performed using the coaxial cable 4 directly connected to each sensor camera 3, when the total number of sensor cameras 3 is small. There is no particular problem, but when a large number of visual units are used as typified by the printing defect inspection on the newspaper, that is, when the total number of sensor cameras 3 to be used is large, the coaxial cable 4 is accordingly changed. The number of uses of is greatly increased.

Since the coaxial cable 4 is easily affected by disturbance, there is a problem that noise is superimposed on the transmitted video signal and the reliability of defect detection is lowered. Particularly, the thinner the coaxial cable 4 is and the longer the coaxial cable 4 is, the more easily it is affected by disturbance.

As a measure for preventing this noise superposition, the electromagnetic shield performance of the coaxial cable 4 may be improved. However, if this is done, the diameter of the coaxial cable 4 becomes thicker, and in combination with the increase in the number of the coaxial cables 4 used as the number of the visual units 2 is increased, the coaxial cable 4 has a large routing space for the group of coaxial cables 4 and the weight of the coaxial cable 4 increases. This causes a problem in cable arrangement that requires special consideration for supporting the group.

The object of the present invention is to facilitate the disposition of a signal transmission cable for connecting a large number of sensor cameras and signal processing units, and to reduce the influence of disturbance on this cable to improve the reliability of defect detection. To get an inspection device.

[0009]

In order to achieve the above-mentioned object, the defect inspection apparatus of the present invention has a light receiving portion composed of a CCD image sensor which scans a moving object in its width direction. A large number of sensor cameras, an A / D converter for converting video signals output from these sensor cameras into multivalued digital data, and a master memory are provided, and master pattern data stored in this memory and the light receiving unit are stored. A signal that connects the A / D converter and the signal processing unit with the signal processing unit for comparing and collating the inspected pattern data of the sample according to the amount of received light to determine the defect of the sample. And a transmission means.

The signal transmitting means is connected to the A / D.
A serial multiplex converter for compressing the digital data obtained by the converter into a high frequency and converting it into serial digital data arranged in series, an optical transmission module for converting the serial digital data into an optical signal, and an optical fiber cable for this module. An optical receiving module that is connected via an optical signal to photoelectrically convert the optical signal to return to the serial digital data, and serially arranges each digital data of the serial digital data processed by the optical receiving module, A parallel converter for returning the transmission frequency to the driving frequency of the sensor camera and supplying the signal to the signal processing unit.

[0011]

In the above structure, the sensor camera scans the CCD image sensor, which is the light receiving portion thereof, in the width direction of the moving object at a predetermined frequency (driving frequency of the sensor camera) to obtain an image of the object. Get information (video signal). The A / D converter converts the video signal into multivalued digital data. The signal transmission means transmits the digital data to the signal processing unit. The signal processing unit performs pattern matching between the master pattern data that has already been stored and the received pattern data to be inspected, and detects the quality of the object, that is, the defect.

The signal transmission means for transmitting the digital data first compresses the digital data into a high frequency by a serial multiplex converter to convert the digital data into serial digital data arranged in series, and then converts this data. It is converted into an optical signal by the optical conversion module and transmitted to the optical receiving module through the optical fiber cable. The optical receiving module photoelectrically converts the received optical signal of the high-frequency serial digital data into the high-frequency serial digital data. Each digital data of the high-frequency serial digital data obtained in this way is arranged in parallel by the processing by the parallel converter,
The transmission frequency of each of these digital data is returned to the original frequency, that is, the drive frequency of the sensor camera, and is supplied to the signal processing unit.

By adopting the signal transmission means for performing such a serial signal transmission system, the transmission means can be a shared component for a large number of sensor cameras, and accordingly, the signals arranged between the sensor cameras and the signal processing section can be provided. The number of transmission cables can be reduced. Moreover, since an optical fiber cable is used for this cable, it is less affected by disturbance regardless of its length or thickness, and it is possible to prevent noise from being superimposed on transmitted digital data.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a block diagram showing the configuration of a printing defect inspection apparatus for newspapers according to an embodiment of the present invention. In FIG. 2, 11 is a master such as a block copy (original), and 1
Reference numeral 2 denotes a printed newspaper, that is, a subject, and an arrow A in FIG. 2 indicates a moving direction of the master 11 and the subject 12.

A visual unit 13 is arranged so as to separately face the respective conveyance paths of the subject 12 forming each sheet. Each visual unit 13 includes a large number (e.g., 8) of sensor cameras 15 each having a one-dimensional CCD image sensor and a light receiving section 14, and an illuminating device 16 that illuminates a conveyance path. Light receiving unit 14 is usually 10 MHz
Scanning frequency, that is, the driving frequency of the sensor camera 15 is scanned.

Each visual unit 13 as shown in FIG.
The sensor cameras 15 are arranged side by side at predetermined intervals in the width direction of the transport path, in other words, in the width direction of the moving master 11 and the subject 12, and the areas of the predetermined width predetermined in the master 11 and the like. Is imaged, and each sensor camera 15 images the entire width of the master 11 and the like. The illumination device 16 is also provided so as to extend in the width direction of the transport path.
The illuminating device 16 shown in FIG. 2 is of a reflective type, but a transmissive type of illuminating device arranged on the opposite side of the sensor camera 15 with the conveyance path interposed may be used. In some cases, both of the lighting devices 16 of FIG.

The video signal (analog signal) output from each sensor camera 15 is AGC (automatic gain control).
ler) 17 and gain / shading correction processing is performed in this AGC 17. The electric signal output from the AGC 17 is input to, for example, an 8-bit A / D (analogue / digital) converter 19 via an amplifier 18, and the A / D converter 1 is supplied in accordance with the voltage level of the signal.
In 9, it is converted into multivalued digital data.

The multivalued digital data is supplied to the signal processing section 21 via the signal transmission means 20 described later.
The processing unit 21 includes a master memory, and compares the master pattern data stored in the memory with the pattern data to be inspected for the sample 12 according to the amount of light received by the light receiving unit 14 to check the sample 12. To detect the printing defect of.

More specifically, as shown in FIG. 2, the signal processing section 21 includes an object pattern extraction circuit 22, a first defect recognition section 23, a first defect determination circuit 24, and a second defect recognition section 25. , A second defect determination circuit 26 and a control circuit 27. The subject pattern extraction circuit 22 is a circuit for extracting contour pattern data from the image information of the master 11 and the subject 12 by digital processing. Control circuit 2
Reference numeral 7 is in charge of overall control of each circuit and memory of the signal processing unit 21.

The first defect recognizing unit 23 receives the contour pattern data extracted with respect to the image information of the subject 12, and absorbs the variation such as the moving speed error of the subject 12 in the inputted pattern data. A first pattern enlargement processing circuit 28 that obtains the first pattern data to be inspected by performing an enlargement process (masking process) with an allowable value, and the contour pattern data extracted with respect to the image information of the master 11 are input. A first master memory 29 for storing as one master pattern data, and the first inspected pattern data and the first master pattern data which are synchronously input from the first pattern enlargement processing circuit 28 and the first master memory 29, respectively. And a first pattern comparison circuit 30 for comparing and collating. The output of the comparison circuit 30 (defect information) is input to the first defect determination circuit 24, and it is determined whether the defect information recognized by the first defect recognition unit 23 in this circuit 24 is a defect having a predetermined size or more. judge.

The second defect recognizing unit 25 receives the contour pattern data extracted by the object pattern extracting circuit 22 with respect to the image information of the master 11, and the allowable value for absorbing the variation in the inputted pattern data. A second pattern enlargement processing circuit 31 that performs enlargement processing (masking processing) with a mark, and the master 1 that is enlarged by this circuit 31.
The contour pattern data regarding the image information of No. 1 is input, the second master memory 32 that stores the contour pattern data as second master pattern data, and the object pattern extraction circuit 22 synchronizes with the reading of the data from the memory 32. It is formed by the second pattern comparison circuit 33 which takes in the extracted pattern data extracted with respect to the image information of the subject 12 as the second inspected pattern data and compares and collates these two pattern data. The output (defect information) of the comparison circuit 33 is input to the second defect judgment circuit 26, and it is determined whether the defect information recognized by the second defect recognition section 25 in this circuit 26 is a defect having a predetermined size or more. judge.

In this signal processing unit 21, the master 11
When the image information from each sensor camera 15 is converted into a digital signal and input, the object pattern extraction circuit 22 extracts the contour pattern of the image information of the master 11, and the pattern data is the first and the first pattern data. 2 is input to the defect recognition units 23 and 25. The first defect recognizing unit 23 stores the contour pattern data in the first master memory 29 as first master pattern data. At the same time, in the second defect recognition section 25, in the second master memory 32,
A second pattern enlargement processing circuit 3 is added to the contour pattern data.
The second master pattern data that has been subjected to the enlargement processing by 1 is stored.

After storing the master pattern data in this way, the scanning of the subject 12 is performed by each sensor camera 15
The image information is converted into a digital signal and is input to the defect recognizing units 23 and 25 through the object pattern extracting circuit 22 of the signal processing unit 21.

As a result, in the first defect recognizing section 23, the first master pattern data stored in the first master memory 29 and the first pattern to be inspected which has been subjected to the enlargement processing by the first pattern enlargement processing circuit 28. The data is compared and collated by the first pattern comparison circuit 30. By this pattern matching processing, when the subject 12 has a defect of so-called chipping property such as a part of the print being missing or being blurred, a part of the first master pattern data is enlarged. Since the data is squeezed out from the first pattern data to be inspected, the data of the squeezed-out portion is recognized as defect information of chipping property. The defect information is judged by the first defect judgment circuit 24 whether it is a defect or not, and is inputted to the control circuit 27. This control circuit 27 outputs it to a notifying device (not shown) such as a display device such as a monitor television. It

In the second defect recognizing section 25, the contour pattern data about the subject 12 inputted thereto is directly used as the second inspected pattern data without being enlarged, and this is used as the second pattern comparison circuit. At 33, the second master pattern data stored in the second master memory 32 is compared and collated. By this pattern matching process,
When the subject 12 has a defect such as scattered ink or stains, a part of the second inspection pattern data is eroded with respect to the second master pattern data. Recognize as information. The defect information is judged by the second defect judgment circuit 26 whether it is a defect or not, and is input to the control circuit 27.
Is output to a notification device (not shown) such as a display device such as a monitor television.

The signal transmission means 20 connecting the signal processing unit 21 and the A / D converter 19 has a serial multiplexing converter 34 and an optical transmission module 35 as shown in FIG.
And an optical fiber cable 36 as a signal transmission cable
And a light receiving module 37 and a parallel converter 38.

The serial multiple converter 34 connected to the output terminal of the A / D converter 19 compresses the digital data converted by the A / D converter 19 into a high frequency and converts it into serial digital data arranged in series. . In this example, high frequency compression is performed on serial digital data having a frequency of 125 MHz as shown in FIG. The optical transmission module 35 connected to the output terminal of the converter 34 converts the high frequency compressed serial digital data into an optical signal.
One end of an optical fiber cable 36 for guiding an optical signal is connected to the output end of this module 35.

The other end of the optical fiber cable 36 is guided into the signal control board and connected to the input end of the optical receiving module 37. The optical receiving module 37 photoelectrically converts the optical signal guided by the optical fiber cable 36 into the high frequency serial digital data. This module 37
The parallel converter 38 connected to the output end of the parallel aligns each digital data of the high frequency serial digital data processed by the optical receiving module 37 in parallel, and sets the frequency of these digital data to the drive frequency of the sensor camera ( (For example, 10 MHz), the output end of which is the inspected pattern extraction circuit 22 of the signal processing unit 21.
It is connected to the.

The signal transmission means 21 having such a configuration scans the CCD image sensor 14 forming the light receiving portion 14 of each sensor camera 15 at a driving frequency of, for example, 10 HMz, and obtains image information about the subject 12 and the like ( E1 in Fig. 3
To En) transmit the multivalued digital data converted by the A / D converter 19 to the signal processing unit 21 by optical communication.

In this transmission, first, the serial data is converted by the serial multiple converter 34 (image information E1).
~ En) is compressed and converted to a high frequency of 125 HMz to be converted into serial digital data (shown by F in FIG. 3) arranged in series, and this data is converted into an optical signal by the optical conversion module 35, and the optical fiber cable 36 Through the optical receiving module 37.

Then, the optical receiving module 37 photoelectrically converts the received serial digital data F into the high frequency serial digital data (indicated by G in FIG. 3).
Then, the digital data g1 to gn of the high-frequency serial digital data G thus obtained are arranged in parallel by the processing in the parallel converter 38, and the digital data g1 to gn are obtained. Is returned to the original frequency, that is, the drive frequency (10 HMz) of the sensor camera 15. As a result, the image information E1 to En are obtained again, and these data are supplied to the signal processing section 21.

Therefore, such signal transmission means 20
By adopting, the transmission means 20 can be a common component for many sensor cameras 15. By the way, at the transmission frequency (125 HMz) of this embodiment, the image information output from about 10 sensor cameras 15 is transmitted by one signal transmission means 20.
You can send it at. Therefore, it is possible to reduce the number of signal transmission cables, that is, the optical fiber cables 36, arranged between the large number of sensor cameras 15 and the signal processing unit 21.
Along with this, the weight and installation space of the signal transmission means 20 are reduced, so that it is easy to arrange a signal transmission cable that connects the many sensor cameras 14 and the signal processing unit 21.

In addition, since the signal transmission mode is optical communication, the transmission data is less likely to be affected by disturbance regardless of the length or thickness of the optical fiber cable 36. Therefore, noise can be less likely to be superimposed on the transmitted digital data, and the reliability of the defect detection in the signal processing unit 21 can be improved.

The present invention is not limited to the above-mentioned embodiment. The drive frequency of the sensor camera and the transmission frequency of the optical signal can be set arbitrarily, and the present invention is not limited to the defect detection of newspaper printing. It can be applied to other printed matter and other defect detection.

[0035]

As described in detail above, in the defect inspection apparatus of the present invention, the image signals of a large number of sensor cameras are converted into A /
Since it is configured to be D-converted and supplied to the signal processing unit via the signal transmission means for transmitting as a serial multiplex signal by optical communication, this signal transmission means can be a shared component for many sensor cameras. Therefore, irrespective of the number of sensor cameras used, the number of signal transmission cables arranged between these sensor cameras and the signal processing unit is small, and the weight and installation space of the signal transmission cables can be reduced. It is possible to easily arrange the signal transmission cable that connects the camera and the signal processing unit. Moreover, since the signal transmission means adopts the configuration adopting optical communication, noise is less likely to be superimposed on the transmitted digital data, and therefore the reliability of defect detection can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a signal transmission means included in a defect inspection device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of the entire defect inspection apparatus according to the embodiment.

FIG. 3 is a diagram showing a signal waveform of the signal transmission means according to the embodiment.

FIG. 4 is a block diagram showing a configuration of a defect inspection device according to a conventional example.

[Explanation of symbols]

13 ... Visual unit, 14 ... Light receiving part. 1
5 ... Sensor camera, 19 ... A / D converter, 20 ... Signal transmission means, 21 ... Signal processing part, 22 ... Subject pattern extraction circuit, 28 ... First
Pattern enlargement processing circuit, 29 ... First master memory,
30 ... 1st pattern comparison circuit, 31 ... 2nd pattern expansion processing circuit, 32 ... 2nd master memory, 33 ... 2nd pattern comparison circuit, 34 ... Serial multiplex converter, 35 ... Optical transmission module, 36 ... Optical Fiber cable (signal transmission cable), 37 ... Optical receiving module,
38 ... Parallel converter.

Claims (1)

[Claims] 1. A large number of sensor cameras each having a light receiving portion composed of a CCD image sensor which scans a moving object in its width direction, and a multivalue digital image signal output from these sensor cameras. An A / D converter for converting into data and a master memory are provided, and the master pattern data stored in this memory is compared and collated with the inspected pattern data of the sample according to the amount of light received by the light receiving unit. A signal processing unit that determines a defect of the sample, and a signal transmission unit that connects the A / D converter and the signal processing unit, wherein the signal transmission unit is configured by the A / D converter. A serial multiplex converter that converts the obtained digital data into high-frequency signals that are serially arranged serially, and an optical transmitter that converts the serial digital data into an optical signal. A module, an optical receiving module connected to the module via an optical fiber cable, for photoelectrically converting the optical signal into the serial digital data, and each digital data of the serial digital data processed by the optical receiving module. A parallel inspection device, which is arranged in parallel with each other, and has a parallel converter for returning the transmission frequency of these digital data to the driving frequency of the sensor camera and supplying the same to the signal processing unit.