JPH0731130B2 - Recognition device - Google Patents

Description

The present invention relates to a recognition device for recognizing characteristics of an object such as a soldering part inspection device and a printed board pattern inspection device, and in particular, reflected light and transmission of the object. The present invention relates to a recognition device suitable for reliable recognition by removing the influence of light variations.

[Conventional technology]

An example of a conventional recognition device is a soldered part inspection device. As described in JP-A-60-85363, this soldering portion inspection device vibrates the component leads by applying non-contact external force to the soldering portions of the component leads by a turbulent air jet or an AC magnet. At that time, changes such as vibration, movement, and deformation that occur in the floating leads are detected by observing speckles generated by irradiating the component leads with laser light, and if such changes are detected, there is a lead floating defect. There is a method using a judgment method. Detection of vibration, movement, deformation, etc. of an object by this laser speck is based on the following principle. Now, when irradiating laser light to the soldered part of the component lead and observing it with an optical sensor, spots with a strong contrast called a laser speck are observed. This laser speckle is generated by the fact that laser light irradiated on the surface of an object having minute irregularities that can be regarded as a random diffraction grating is diffracted by this diffraction grating and the diffracted lights interfere with each other. Since this speckle moves along with the movement of the object, it is possible to detect the vibration, movement or deformation of the object by observing the distribution and movement of the laser speckle with an optical sensor.

When the wiring pattern 2 on the substrate 1 and the component lead 4 of the flat package type component 3 are soldered to each other in the flat package type component soldering portion to be inspected as shown in FIG. The elastic property of the component lead 4 varies depending on the joint state. Therefore, for example, a turbulent air jet is ejected from the air nozzle to the soldered portion of the wiring pattern 2 and the component lead 4 to apply an external force, and the change such as vibration, movement, or deformation occurring in the component lead 4 at that time is detected. This makes it possible to detect an abnormality in the joining state of the soldered portion, that is, a defect. In this case, when observing a vibrating laser speck using an accumulating sensor that detects the time-integrated amount of incident light as an optical sensor, the accumulating time is equal to or longer than the vibration period when the position of the speck is vibrating. Therefore, the detected light quantity at any one point is a constant value that is almost independent of location. Therefore, the fourth
Regarding the speckle image of the floating lead before and after the jet of air jet shown in the figure, the distribution of the detected light quantity with respect to the non-vibrating speckle is that the speckle with strong contrast is observed as shown in FIG. As shown in FIG. 4 (b), a blurred image with no contrast is observed with respect to the present speckle. In addition, a different speckle image is detected before and after the moving speckle. By using such a method of detecting the contrast of the speckle image and the change of the speckle image, the defect of the joining state of the soldered portion is determined.

Another example of the conventional recognition device is a pattern inspection device for a printed board. A pattern detection device for a printed board using this reflected light irradiates the printed board with a light source such as a mercury lamp and detects the reflected light with a linear image sensor. In this case, a method of performing defect determination by scanning a table on which the printed board is mounted and detecting a two-dimensional image of the printed board to compare with design information and other patterns and to extract characteristics of defects is used. ing.

Further, as another example of the conventional recognition device, there is a case of recognizing a pattern, an outer shape, or the like on an object whose transmittance greatly varies.

[Problems to be solved by the invention]

The above-mentioned conventional technique is generally used when an optical sensor such as a linear image sensor detects reflected light due to light irradiation due to the difference in the normal direction of the surface of an object having a metallic luster such as a soldered part or a copper foil pattern. The amount of light incident on the sensor greatly varies, and even if the surface has the same normal direction, the surface condition may be due to flux residue when the soldered part is present, or due to clouding of the solder surface, etc. The amount of incident light on the sensor may vary due to the influence of, and the amount of incident light also varies in the case of an object having a significantly different transmittance, but the device can handle such variation in the amount of incident light. is not. For this reason, the variation in the incident light amount becomes the variation in the detected light amount as it is, which causes erroneous recognition. In order to prevent this, before the object is recognized by the recognition device, a step of applying a matting agent to reduce the variation in the amount of incident light is added, or the previous step is improved to eliminate the occurrence of pattern flaws. There was a problem such as the need to devise.

An object of the present invention is to provide a recognition device such as a soldering part inspection device or a printed board pattern inspection device that can reliably recognize the characteristics of an object having a large variation in the amount of incident light.

[Means for solving problems]

The above-mentioned object is, in a recognition device for recognizing the characteristics of an object, comprising a polarizing plate and a liquid crystal element having optical rotatory property in front of a sensor for detecting reflected light or transmitted light from the object or in a light projecting system A light amount control filter that can control the transmittance of each pixel by changing the effective voltage applied to each pixel is set, and based on the detected light amount of each part of the monitor sensor corresponding to each pixel of the liquid crystal element. This is achieved by a recognition device provided with a filter control unit that controls the effective voltage applied to each pixel of the liquid crystal element so that the amount of light incident on the sensor becomes appropriate at each unit.

[Action]

The filter control unit that controls the light amount control filter of the recognition device has an incident light amount bi (i corresponds to each pixel of the liquid crystal element) of each unit detected by a monitor sensor that monitors reflected light or transmitted light that illuminates the target unit. According to the index)
By determining the effective voltage ei applied to each pixel of the liquid crystal element by the relational expression obtained in advance, and applying the effective voltage ei to each pixel of the liquid crystal element, the transmittance of each pixel of the light quantity control filter is transmitted to a predetermined value. It is possible to obtain a proper amount of incident light on the sensor by controlling the rate of the light, so that it is possible to recognize the object with high reliability. Regarding the above relational expression, in order to make the detected light amount of the sensor uniform, the relation e (b) between the effective voltage e applied to the liquid crystal element of the light amount control filter and the transmittance b is used. Then, the effective voltage ei applied to each pixel of the liquid crystal element is determined by the following equation.

b = b ₀ × b ₁ / bi ei = e (b) where b ₁ is the target detected light amount, b ₀ is the transmittance of the light amount control filter where the detected light amount of the monitor sensor and the (detection) sensor are the same. is there. In addition, when removing the excessive light amount of the sensor, if the monitor light amount bi exceeds a certain value bth, the sensor may be saturated and blooming may occur.Therefore, the transmittance of the light amount control filter may be reduced to reduce the detected light amount. In other cases, the applied effective voltage ei is determined by the following equation so as to have a predetermined constant value.

When bi ≧ bth ei = ea When bi ≧ bth ei = eb where bth is a preset threshold value, ea is the effective voltage that gives the appropriate transmittance when the light amount is excessive, and eb is set when the light amount is appropriate. It is the effective voltage that is the transmittance.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of a soldering portion inspection device showing a first embodiment of a recognition device according to the present invention. This recognition device is a soldering part inspection device used to determine a floating defect in a soldering part between a wiring pattern 2 formed on a printed circuit board 1 and a plurality of component leads 4 provided on a flat package type component 3. Is.

This soldering part inspection device sprays a turbulent air jet onto the soldering parts of a plurality of component leads 4 which are inspection objects, and vibrates floating leads that are not joined together In order to observe the vibration system using the air pressure sensor 6 for detecting the temperature, the laser light irradiation optical system including the laser 7 for irradiating the soldered portion with the laser light, the lens system 8 and the half mirror 9, and the laser speckle. A condensing optical system 10 with an image plane set at the defocused position, a linear image sensor 11 for accumulation determination that is an optical sensor for observing the speckle, and a speckle waveform detected by this linear image sensor are scanned to form a two-dimensional speckle image. The galvano mirror 12 for determining the component lead position to be inspected based on this speckle image and the half mirror 13 for separating a part of the detection light are separated. A detection optical system including a light amount control filter 15 using a liquid crystal described later in detail for optimizing the detection light of the individual leads based on the detection light detected by the monitor sensor 14 and the monitor sensor that detects the detection light, An XY table 16 for positioning the inspection object, a jet control unit 17 for controlling the air jet and detecting the jet timing of the jet, a sensor drive circuit 18 for driving the determination linear image sensor and extracting the sensor signal, and a galvano mirror. Galvanometer mirror control unit for scanning and stopping at the lead position for detection
19, a monitor controller 20 that drives the monitor sensor, a filter controller 21 that controls the transmittance of each pixel of a light amount control filter 15 that can control the transmittance based on the amount of light detected by the monitor sensor 14, and a table. The control unit 22 and a defect determination unit 23 that determines a lead floating defect based on the spectrum waveform detected by the determination linear image sensor 11 and a control unit 25 including an overall control unit 24 are included.

The overall operation of the inspection with the above configuration will be described. First, prior to the inspection, the respective control units 17 to 23 are initialized by a command from the overall control unit 24 of the control unit 25, and then the following operation is repeated to perform the inspection. First, the table controller 23 drives the XY table 16 to position the component lead 4 on one side of the flat packaged component 3 to be inspected at the inspection position. At this time, as described later, the soldered portions of the plurality of leads 4 provided on one side of the flat package type component 3 can be inspected at the same time. Then, the galvano mirror 12 is scanned according to a command from the galvano mirror control unit 19, and the sum of the light amounts detected by the monitor sensor 14 driven by the monitor control unit 20 at each galvano scanning position y is calculated to obtain the maximum sum of light amounts. Position the galvanometer mirror 12 at the scan position ym. Next, based on the light amount detected by the monitor sensor 14, a light amount control filter will be described in detail later.
Determine and apply the effective voltage to each pixel of the 15 liquid crystal elements,
The transmittance of each pixel of the light quantity control filter 15 is individually controlled. Then, in response to a command from the jet control unit 17, the air nozzle 5
From the above, an air jet is jetted to the inspection object and the air pressure sensor 6 monitors the jet pressure, and when the jet pressure exceeds a predetermined threshold value and a predetermined time elapses, it is regarded as a detection timing. The speckle waveform detected by the determination linear image sensor 11 driven by the sensor drive circuit 18 is taken into the defect determination unit 23 from the sensor drive circuit 18 as a waveform after air injection, and this waveform and the previously detected speckle before air injection Defects are determined from the waveform and the method described later in detail.

FIG. 2 is a block diagram of the light amount control filter 15 using the liquid crystal of FIG. 1 and its control system. The light quantity control filter 15 installed in front of the determination linear image sensor 11 has a polarizing plate 26 for aligning the polarization planes of incident light and a plurality of strip-shaped pixels 27-1, 27-2 having optical rotatory power. , ..., 27-n is composed of a liquid crystal element 27 that can control the amount of optical rotation by changing the effective voltage to each electrode, and a polarizing plate 28 that transmits light other than the optical rotation component. One pixel of the judgment linear image sensor 11 or Corresponding to one pixel of the liquid crystal element 27 to several pixels, filter control unit
By changing the effective voltage applied to each pixel of the liquid crystal element 27 based on the detected light amount of each part of the monitor sensor 14 by 21 to change the transmitted light amount of each pixel, the determination linear image sensor 11 corresponding to each pixel is changed. The amount of incident light on each part can be controlled. Therefore, one monitor sensor 14 is installed at a position corresponding to the judgment linear image sensor 11 or the light control filter 15 or in the vicinity thereof, and a part of the incident light is separated by the half mirror 13 to pass through the light amount control filter 15. It is possible to know the outline of the detected light amount when there is no light.

A method of determining the applied effective voltage for controlling the transmittance of the light quantity control filter 15 having the above configuration will be described. Here, the incident light amount of the pixel corresponding to each pixel of the liquid crystal element 27 detected by the monitor sensor 14 is set as bi (i is an index corresponding to each pixel of the liquid crystal element 27), and is uniformized by the determination linear image sensor 11. The target amount of detected light is set to b ₁ , and the light amount control filter 15
The effective voltage ei applied to each pixel of the liquid crystal element 27 is determined by the following equation.

bi: b ₀ = b ₁ : b (ei) where b ₀ is the amount of light detected by the monitor sensor 14 that has been previously obtained for the standard sample, and b (e) is for the same standard sample as above. It is a function that represents the relationship between the effective voltage e applied to the liquid crystal element 27 of the light quantity control filter 15 and the detected light quantity b which is obtained in advance. The applied effective voltage e
The relationship between the detected light amount b and the detected light amount b varies depending on the temperature due to the temperature dependence of the liquid crystal element 27, and is therefore obtained in advance when the temperature reaches the device operating temperature at the time of device initialization after completion of warming up at device startup.

FIG. 3 is a perspective view of a soldering portion of a plurality of component leads 4 of the flat package type component 3 which is the inspection target of FIG. When the wiring pattern 2 on the printed board 1 and the component lead 4 are joined by soldering, the elastic properties of the component lead 4 differ depending on the joining state.
A turbulent air jet is jetted from the air nozzle 5 to the soldered portion of the wiring pattern 2 and the component lead 4 to apply an external force, and by detecting a change such as vibration, movement or deformation occurring in the component lead 4 at that time. It is possible to detect a defect due to an abnormal bonding state. In the inspection apparatus of this embodiment, in order to speed up the inspection, the soldered portions of the leads 4 provided on one side of the flat package type component 3 can be inspected at the same time.

FIGS. 4 (a) and 4 (b) are explanatory views of the speckle image of the floating lead before and after the air jet injection in FIG. 1, and FIG. 4 (a) is the specular image of the floating lead before the air jet injection. FIG. 4 (b) shows a speckle image of a floating lead during jetting of an air jet. The distribution of the detected light amount with respect to the speck of the lead 4 which is not vibrating before the air jet injection by the air nozzle 5 shown in FIG. 4 (a) shows a speck with high contrast, but it is shown in FIG. 4 (b). A blurred image with no contrast is observed in the distribution of the amount of detected light with respect to the speckle of the floating lead 4 which is vibrating during the jetting of the air jet by the air nozzle 5. Further, a different speckle image is detected before and after the movement of the floating lead 4 that is moving. From this, the defect of the soldered part of the component lead 4 can be determined by detecting the contrast of the speckle image and the change of the speckle image.

FIGS. 5 (a) and 5 (b) are explanatory diagrams of the detection speckle waveform before and after the air jet injection in FIG. 1, and FIG. 5 (a) is the speckle waveform before the air jet injection, and FIG. Is the waveform of the spectrum of the jet of air. Pixels of the judgment linear image sensor 11 are plotted on the horizontal axis of FIG. 5, and the detection light quantity of the judgment linear image sensor 11 in which the variation of the incident light quantity is eliminated by using the light quantity control filter 15 is plotted on the vertical axis. 5
FIG. 5A shows a speckle waveform f ₀ (x) of the component lead 4 (FIG. 3) before the air jet injection by the air nozzle 5, and FIG. 5B shows a component during the air jet injection by the air nozzle 5. The speckle waveform f ₁ (x) of the lead 4 is shown. Fifth
As shown in FIG. 3A, the speckle waveform f ₀ (x) of each component lead 4 (FIG. 3) before the air jet injection has almost the same severe uneven waveform, whereas As shown in Fig. 5 (b), the speckle waveform f ₁ during air jet injection
(X) shows a non-defective waveform 29 that retains the pre-ejection waveform for a non-defective lead, but a smooth floating defect waveform 30 with less unevenness due to vibration of the lead for the floating lead, or movement of the lead. The floating defect waveform 31 is significantly changed from the waveform before injection due to deformation.

The defect determination method based on the above-mentioned detected speckle waveform will be described. First, the two floating defect waveforms 31 and 30 in FIG.
A function H for detecting the movement represented by
(X), a function G (x) for detecting smoothness is obtained.

The values of these functions H (x) and G (x) are binarized with predetermined thresholds Hth and Gth, and the number of pixels exceeding the thresholds Hth and Gth for each read position given in the design data. And the sum exceeds the threshold value for defect determination, it is determined as a lead floating defect.

According to this embodiment, when inspecting floating defects of a plurality of component leads at the same time for high-speed inspection, the amount of transmitted light at each location corresponding to each lead is controlled by the light amount control filter,
Since it is possible to eliminate the variation in the detected light amount for each lead, highly reliable recognition can be performed.

Next, FIG. 6 is a block diagram of a printed board pattern inspection apparatus showing a second embodiment of the recognition apparatus according to the present invention. This recognition device is a pattern inspection device for a printed board used for inspecting a defect such as a pattern chip or a ridge of a copper pattern 33 formed on a base material 32 of the printed board 1.

This printed circuit board pattern inspection apparatus includes an illumination optical system including an illumination light source 34 and an optical fiber 35 for guiding the illumination light to an object, an imaging lens 36 for imaging the reflected light from the object, and the reflected light imaged. Linear image sensor for detection 37
And a half mirror 38 that separates a part of the reflected light and a linear image sensor 39 for a monitor that detects the amount of the separated reflected light
And a detection optical system including a light amount control filter 40 using a liquid crystal having a structure similar to that of FIG. 2 for controlling the amount of detected light incident on the linear image sensor 37 for detection, and an XY table 41 for scanning an object. , A sensor drive unit 42 that drives the detection linear image sensor 37 to extract the sensor signal, and a monitor control unit 43 that drives the monitoring linear image sensor 39 to extract the sensor signal and the monitor linear image sensor 39. Defect determination of the object is performed based on the two-dimensional image of the reflected light detected by the filter control unit 44, the table control unit 45, and the detection linear image sensor 37, which controls the transmittance of the light quantity control filter 40 based on the sensor signal. The control unit 48 is composed of a defect determination unit 46 to be executed and an overall control 47.

The overall operation of the inspection with the above configuration will be described. First, prior to the inspection, the control units 42 to 46 are initialized by a command from the overall control unit 47 of the control unit 48, and then the printed board 1 to be inspected is set on the XY table 41 by a command from the table control unit 45. Based on the light amount signal detected by the monitor linear image sensor 39 that is scanned and driven by the monitor control unit 43, the light amount control filter 40 is used by the filter control unit 44.
While performing the optimization of the light amount by controlling by the method described later in detail, the detection linear image sensor 37 driven by the sensor drive unit 42 detects the reflected light waveform of the object and scans the reflected light waveform. Defect determination is performed by the defect determination unit 46 based on the obtained two-dimensional image.

FIG. 7 is a perspective view of a pattern example of the printed board 1 which is the inspection object of FIG. The printed board 1 has a copper pattern 33 formed on a base material 32 such as polyimide or glass epoxy. The copper pattern 33 is inspected for defects such as pattern defects 33-1 and bridges 33-2.

FIG. 8 is an explanatory diagram of an arrangement showing the positional relationship between the linear image sensor 37 for detection and the linear image sensor 39 for monitoring shown in FIG. FIG. 8 shows the detection field of view of the detected two-dimensional image 51 of the copper pattern 33 of the inspection object at a certain time.
Here, the visual field for the monitor of the linear image sensor 39 for the monitor
49 is always set in front of the detection visual field 50 of the linear image sensor 37 for detection in the table scanning direction, and the light amount of the pattern to be detected is monitored in advance. Based on the monitored light amount, the transmittance of the light amount control filter 40 is controlled when the visual field is detected by the linear image sensor 37 for detection.

A method of controlling the transmittance for optimizing the light quantity of the light quantity control filter 15 with the above arrangement will be described. Here, the amount of light detected by the monitor linear image sensor 39 is bi, and the preset threshold of the amount of light is bth, and the effective voltage ei applied to the liquid crystal element (FIG. 2) of the light amount control filter 40 is expressed by the following equation. Determined by

When bi ≧ bth ei ＝ ea When bi <bth ei ＝ eb where ba and bb are preset applied voltages, ea is the effective voltage that gives proper transmittance when the light intensity is excessive, and eb is the light intensity. It is the effective voltage that is the transmittance set when appropriate. Note that i is an index corresponding to each pixel of the liquid crystal element.

According to the present embodiment, it is possible to prevent the problem that the detected light amount becomes excessively large due to the pattern flaws on the printed board, the linear image sensor for detection is saturated, blooming occurs, and the image at other places is also disturbed. There is.

Even when the transmitted light is detected, only the illumination method is different and the light quantity control method by the light quantity control filter is the same. Therefore, although the description is omitted, the detected light quantity of the image sensor can be optimized by the same method. .

〔The invention's effect〕

According to the present invention, since the transmittance of each pixel of the light quantity control filter using liquid crystal is controlled to optimize the detected light quantity of the image sensor, the light quantity control filter is reliable without being affected by the fluctuation of the detected light. There is an effect that it is possible to provide a recognition device that can recognize the characteristics of an object.

[Brief description of drawings]

FIG. 1 is a block diagram of a soldering portion inspection device showing a first embodiment of a recognition device according to the present invention, FIG. 2 is a block diagram of a light amount control filter of FIG. 1, and FIG. 3 is an inspection of FIG. FIG. 4 (a) and FIG. 4 (b) are perspective views of the soldering portion of the target flat package type component, and FIGS. 4 (a) and 4 (b) are explanatory views of the speckle image of the floating lead before and after the air jet injection, and FIG. , (B) are explanatory views of detection speckle waveforms before and after air jet injection in FIG. 1, and FIG. 6 is a configuration diagram of a pattern inspection device for a printed board showing a second embodiment of the recognition device according to the present invention, FIG. 7 is a perspective view of the pattern of the printed board to be inspected in FIG. 6, and FIG. 8 is an explanatory view of the arrangement of the linear image sensor for detection and the image sensor for monitor in FIG. 4 ... Component lead, 5 ... Air nozzle, 7 ... Laser,
11 …… Linear image sensor for judgment, 12 …… Galvano mirror, 14 …… Monitor sensor, 15 …… Light intensity control filter, 16 …… XY table, 25 …… Control unit, 27 …… Liquid crystal element, 33 …… Copper pattern, 34 …… Illumination light source, 37 …… Detection linear image sensor, 39 …… Monitor linear image sensor, 40 …… Light intensity control filter, 41 …… XY table,
48 ...... Control unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Nakagawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Hitachi, Ltd. Institute of Industrial Science (56) References JP 62-7198 (JP, A) Special features Kai 63-191949 (JP, A) JP 61-296243 (JP, A)

Claims (1)

[Claims] 1. A illuminating means for illuminating an object, a detecting means comprising an optical system and a sensor for detecting reflected light or transmitted light from the object irradiated by the illuminating means, and the detecting means. In a recognition device for recognizing the characteristics of an object, which comprises an analysis means for analyzing the characteristics of the object,
A light quantity control filter comprising a polarizing plate inserted in the detecting means and a liquid crystal element having optical rotatory power and capable of controlling the transmitted light quantity for each pixel by changing the effective voltage applied to each pixel arranged in a plurality of the liquid crystal elements. And a monitor unit composed of a monitor optical system and a sensor for detecting an approximate light amount of reflected light or transmitted light from the object, and based on the detected light amount of each unit of the monitor sensor corresponding to each pixel of the liquid crystal element. And a filter control unit that controls the effective voltage applied to each pixel of the liquid crystal element so that the amount of light incident on the sensor becomes appropriate at each unit.