JP2011247690A - Connector pin inspection device and its inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for capturing an object to be measured from two different directions with two cameras and acquiring a three-dimensional shape of the object to be measured using parallax between the cameras.
[Solution]
A light source that emits line-shaped illumination light, means for gripping and moving the connector so that the pin tip of the connector pin passes within a predetermined position of the line illumination, and two units that image the pin tip that passes through the line illumination A connector pin comprising means for imaging the pin tip from the front and rear of the line illumination with respect to the direction of movement of the connector by a camera, and measuring the three-dimensional position of the pin tip from the two captured images It relates to an inspection device.
[Selection] Figure 1

Description

  The present invention relates to a connector pin inspection technique.

  In a manufacturing process of a computer apparatus or the like, when inserting a connector into a board, if some of the pin tip positions are misaligned, the misaligned pins are not correctly inserted, which causes a malfunction of the apparatus. Therefore, the position of the pin tip of such a connector is required to be measured and inspected as a three-dimensional position including the height.

  On the other hand, a parallax measurement method has been proposed as a three-dimensional measurement method for measuring the height of an object surface. The parallax measurement method includes a method of scanning the object surface with a laser and measuring the reflected light, or irradiating the object with line-shaped light and changing the object measured according to the line light from an oblique direction. There is a method for identifying the height of an object based on the above.

  For example, with respect to the lead shape measuring apparatus, the height of an object is determined from an outline image or a plurality of parallel line lights at the intersection of virtual lines existing on the line of the object.

  In addition, for example, a set of line sensors and a matching unit arranged orthogonal to the moving direction of the object to be measured are provided, the object to be measured on the belt conveyor is imaged, and the parallax between the two cameras is calculated, The three-dimensional shape of the cross section of the measurement object is acquired.

Japanese Patent Laid-Open No. 05-26640 JP 2004-117186 A

  However, the conventional three-dimensional measurement method based on visual field measurement enables high-speed data acquisition. However, the parallax cannot be obtained sufficiently, so measurement accuracy does not come out, and it cannot be used for targets for which corresponding point search is difficult. In measuring the area with high accuracy, it has the following problems.

  In the parallax measurement method that measures the displacement of the object from the difference between the images of the two cameras, the difference in the image becomes more remarkable when there is a large parallax, and high measurement accuracy can be expected. However, as shown in FIG. 10, in order to capture a focused image over a wide area in the field of view, the two cameras need to be at an angle substantially perpendicular to the target surface, and the parallax is sufficient. Can't take on. If the entire field of view is not in focus, the image captured by the camera will be blurred, and if the parallax is increased further, it will be difficult to focus on the entire field of view.

  In addition, in the parallax measurement method, when the same part (corresponding point) is shown between the images of two cameras, the position in the depth direction of this point can be calculated, but the feature is poor like the pin tip of the connector When many objects appear in the field of view, it is difficult to find corresponding points.

  In view of this, the present invention provides an inspection technique capable of enlarging parallax and facilitating the search for corresponding points in the parallax measurement method.

  One aspect of the invention is that illumination means for irradiating a connector pin tip with linear illumination light, and the pin tip of the connector passes through a predetermined position within the range where the illumination light is illuminated by the illumination means. Moving means for gripping and moving the connector, imaging means for taking an image of the pin tip with two cameras arranged obliquely forward and obliquely behind the line illumination with respect to the movement direction of the connector, and the camera And a position calculating means for calculating a three-dimensional position of the pin tip of the connector from two images taken by the connector.

  According to the present invention, it is possible to obtain a sufficient parallax without affecting the depth of field by the parallax given to the two cameras with the pin tip of the connector pin as a three-dimensional position. A device can be provided.

It is a figure explaining the principle of the parallax measuring method using the line sensor which becomes embodiment of this invention. It is a figure which shows the structural example of the connector pin measurement by the parallax measuring method which becomes embodiment of this invention. It is a figure which shows the pin position and height which are observed according to the movement of a connector. It is a figure which shows the relationship between the alignment state of the pin in a connector, and the output image of a sensor. It is a figure which shows the corresponding point search of the neighboring pin by a sensor image. It is a figure which shows the example of a detection of the corresponding point by the line illumination colored in the width direction. It is a figure which shows the rule of a corresponding point search by colored line illumination. It is a figure which shows the structural example of the connector pin test | inspection apparatus which becomes embodiment of this invention. It is a flowchart which shows the test | inspection procedure of the connector pin which becomes embodiment of this invention. It is a figure which shows the inspection method by the conventional parallax measurement.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating the principle of a parallax measurement method using a line sensor. In the parallax measurement of the present invention, a linear illumination light is vertically irradiated by a line illumination 4 to a measurement object 5 that can move linearly, and the measurement object 5 in the irradiation area is imaged by two line sensor cameras 1. It has a configuration. In the present invention, in order to obtain a large parallax between the two line sensor cameras 1, the measurement object 5 is moved so as to cross the vertically illuminated line illumination 4, and this state is sequentially captured by the two cameras. It is a feature.

Each of the two line sensor cameras 1 has a line sensor 2 composed of a charge coupled device (CCD) and a lens 3 that collects the reflected light from the measurement object 5, and the line sensor 4 is parallel to the line illumination 4. The illumination 4 is tilted across the front and back to focus on the irradiation point (pin tip) of the measurement target (connector pin) 5.
Moreover, the line illumination 4 irradiates the measurement object (connector pin) 5 which moves the linear illumination light containing the illumination mechanism by the color light source and LED (Light Emitting Diode; light emitting element) juxtaposed in the width direction. is there.

  Here, in the following description, the two line sensor cameras 1 are expressed as cameras A and B, and the line sensors 2 provided in the cameras A and B are expressed as sensors A and B, respectively.

  As shown in FIG. 1, with the line illumination 4 at the illumination position, one camera B images the measurement object 5 from the front in the moving direction of the measurement object 5 and the other camera A from the rear. In addition, the cell arrangement in the line sensor 2 mounted on the cameras A and B is orthogonal to the moving direction. And each cell of the line sensor 2 images the surface of the measuring object 5 inside the line illumination on the optical axis at each time.

  With the configuration of the present invention described above, the range that needs to be focused at a time can be set to about the width of the line light, and the parallax by the two line sensor cameras 1 eliminates the influence of the depth of field. It is possible to achieve a parallax sufficient for this.

  FIG. 2 shows a configuration example of connector pin measurement by the parallax measurement method of the present invention.

  As shown in FIG. 2, the line illumination 4 illuminates the pins from above so that the width of the connector 6 is a line-shaped light that is narrower than the interval of the pins, and the connector 6 moves across the line illumination 4. It is possible. Of the two line sensors 2, the sensor B is disposed in front of the moving direction of the connector 6, and the sensor A is disposed behind the moving direction of the connector 6.

  The optical axes A and B of the respective line sensors 2 intersect with each other at the center of the line illumination 4 and are adjusted so that they are in focus at this intersection. The intersection point is the origin of the coordinate system, and when a pin with a standard height passes under the line illumination 4, the tip of the pin passes this intersection point. In addition, the cell arrangement of the line sensor 2 is made to coincide with the longitudinal direction of the line illumination 4, the arrangement direction of the line sensor 2 is taken as the X axis, and the moving direction of the connector 6 is taken as the Y axis.

  As described above, in the measurement configuration described above, the line tip 2 that crosses the line illumination 4 can be imaged by each line sensor 2 by taking horizontal synchronization with the line sensor 2 at a sufficiently high speed with respect to the moving speed of the connector 6. .

  FIG. 3 shows the relationship between the pin position and the height observed as the connector moves. The figure explains a state in which the surface of the measuring object 5 inside the line illumination 4 is imaged on each optical axis at each time by each cell of the line sensor. FIG. 3A shows an example of detection by the sensor A arranged behind the line illumination, and FIG. 3B shows an example of detection by the sensor B arranged in front of the line illumination.

  Here, if the heights of the pins are the same, the image is picked up at an earlier time in order from both pins A and B in front of the moving direction. On the other hand, when the in-plane positions of the pins are the same, the sensor A placed rearward with respect to the moving direction takes an image of the high pin A at an earlier time, and the sensor B placed forward has a height of The low pin D is imaged at an early time.

  FIG. 4 shows the relationship between the pin alignment state in the connector and the output image of the sensor. FIG. 4 (a) shows the state of pins that have the same height and are aligned in the line direction, and FIG. 4 (b) shows the state of pins that have the same height but are not aligned in the line direction. c) shows the state of pins that are aligned in the line direction but have irregular heights.

  If the height of the pin is at the focus position of the sensor as shown in (a) and (b), the sensor images taken by sensors A and B are picked up at the same time by both sensors A and B. The position of the pin in the Y direction can be known at the time when the image is picked up.

  As shown in FIG. 4A, with the pins aligned in the longitudinal direction of the line illumination, all the pins are imaged at the same time. When the positions of the pins are different as in (b), the time at which the image is captured differs according to the position of the pins. On the other hand, when the heights of the pins are different as shown in (c), even when the pins are aligned, the time taken by the sensor is different.

  In the case of a pin whose height coincides with the intersection of the optical axes of the two sensors, the times appearing in the images of the two sensors coincide, and a pin lower than this appears earlier in the sensor B than in the sensor A. Conversely, a high pin appears early on sensor A. In this way, if the correspondence between the images of the pins appearing in the images of the sensor A and the sensor B is attached, the height of the pin can be specified.

  FIG. 5 is a diagram for explaining the corresponding point search for neighboring pins from the sensor image. The figure shows how to find the corresponding pins in the two sensor images.

  When the pin interval in the Y-axis direction is separated, the X-axis position matches in both images, and the correspondence can be taken by searching for the closest pin image. However, if the pin spacing becomes dense, it is difficult to know the correspondence with this method. FIG. 5 shows that the correspondence between the two sensor images cannot be taken with a simple method.

  When searching for a pin shown in the sensor image A with the sensor image B, a pin having the same X coordinate and having a Y coordinate in the vicinity is searched, but the pin in the nearest vicinity is not necessarily the corresponding pin. In the partial image as shown in FIG. 5, it cannot be determined which of the two pins reflected on the sensor B corresponds to the pin of the sensor A.

  Here, the corresponding points are points where images of the same object appear at the same position in the images of the two sensors, and in pin measurement, the point where the apex of the same pin appears in each sensor image. It becomes a corresponding point.

  In contrast to the pin tip image that appears in the center of the sensor image A in FIG. 5A, the sensor image B has the same X coordinate as the sensor image A and two pin tip images that are substantially equidistant. Appears. In this case, there are two possibilities shown in FIGS. (B) is a case where the two pins in sensor B are both higher than the standard. The image of the sensor B corresponding to the image of the pin of the sensor A is (1), and the image of the sensor A appears before the image of the sensor B. On the other hand, in FIG. 5C, conversely, when the two pins are lower than the standard, the image of sensor B corresponding to the image of sensor A is (2).

  Therefore, in order to easily find the corresponding pins by the two line sensors 2, it is preferable to change the line illumination 4 in the plane as follows.

  FIG. 6 shows an example of detection of corresponding points by line illumination colored in the width direction.

  FIG. 6A shows a configuration example of colored line illumination in which the color of the line illumination 4 is sequentially changed in accordance with the movement of the measurement object 5 in the line width direction, and FIG. 6B shows the colored line illumination. The sensor image example imaged when using is shown.

  The color of the light source of the line illumination 4 having the same thickness as the change range of the pin height to be measured is changed in the width direction. The half-value width of each color is adjusted to the measurement range (for example, about 500 μm) as the peak interval of the two-color light arranged in the line width direction of the line illumination 4. In the embodiment, a red light source is disposed on the left side of the line illumination 4 and a blue light source is disposed on the right side, and the measurement surface 4 changes from red to blue as the measurement object 4 moves. If each sensor is a color line sensor under the line illumination 4, the pin higher than the reference plane is imaged red by the sensor A and blue by the sensor B. In this case, the corresponding image is captured with the sensor B being delayed from the sensor A. On the contrary, the pin lower than the reference plane is imaged blue by the sensor A and red by the sensor B, and the sensor B is imaged more advanced than the sensor A.

  Thus, by coloring the line illumination 4, it becomes possible to know the approximate height of the pins and the order in which they appear in the sensors A and B, and the corresponding pin images can be obtained from the images of the respective sensors. It becomes possible.

  FIG. 7 shows a rule for searching for corresponding points by colored line illumination. The figure shows the position and color combinations between corresponding pins between the images of sensor A and sensor B under line illumination.

  (A) When the pin height exceeds the reference plane, the pin image captured by the sensor A appears in red, the pin image captured by the sensor B appears in blue, and is earlier than the sensor B. Appears on sensor A. Also, (b) when the pin height is at the same level as the reference plane, both the images of sensors A and B appear at the same time in red and blue intermediate colors. (C) When the pin height is lower than the reference plane, the pin image captured by the sensor A appears in blue, the pin image captured by the sensor B appears in red, and is earlier than the sensor A. Appears at sensor B at time.

  Corresponding points are determined based on the above rules.

  FIG. 8 shows a configuration example of the connector pin inspection apparatus of the present invention.

  The connector pin inspection apparatus includes a lighting unit including a line illumination 4 for irradiating the measurement target 5 with two-color line-shaped illumination light and an illumination control unit 11 for controlling the illumination, and within a predetermined position of the line illumination vertically irradiated. And a moving stage 7 for holding and moving the connector 6 so that the pin tip portion which is the measurement object 5 of the connector 6 passes, and a moving means 13 for controlling the moving amount thereof.

  In addition, the connector pin inspection device images the pin tip of the moving connector 6, the camera A disposed obliquely rearward of the line illumination 4 with respect to the moving direction of the connector 6, the camera B disposed obliquely forward, and the imaging timing. And an imaging control unit 12 for controlling the imaging. Each camera includes a line sensor 2 using a color CCD image sensor.

  Further, the connector pin inspection device includes a control device 10 that controls the entire device, stores an image acquired from the imaging control unit 12 in the storage device 100, and creates a two-dimensional sensor image from the image; Position calculating means for calculating the three-dimensional position of the pin tip of the connector 6 from two sensor images captured by two cameras.

  Below, operation | movement of the connector pin test | inspection apparatus of this invention is demonstrated.

  The illumination light source has a line shape that crosses the connector 6 of the measurement object 5 and is set to change in order of colors from red to blue in the width direction on the measurement object 5 in the width direction on the reference surface having a standard height. Line light sources with different colors are in close proximity. For this purpose, it is assumed that a light source in which LEDs are arranged in a line shape is formed on a reference surface by using a lens 3, but a laser light source such as an LD (Laser Diode) is passed through a slit to form a linear illumination. May be made. The width of the line is equal to or less than the pin interval and the same as the range of change in the height of the pin to be measured.

  A connector 6 to be inspected is held below the line illumination 4 with a pin tip facing upward, and a movable stage 7 is provided. At the time of inspection, the connector 6 is moved so as to cross the line illumination 4. At this time, the center of the line illumination 4 on the reference plane is set as the origin, the longitudinal direction of the line illumination 4 is defined as the X axis, and the moving direction of the connector is defined as the Y axis.

  The two line sensors 2 are arranged so that one can image the line illumination 4 on the reference plane from the front and the other from the rear. The cell array is parallel to the longitudinal direction of the line illumination, and the line illumination on the reference plane is focused. The sensor behind the illumination is referred to as sensor A, and the sensor ahead is referred to as sensor B. Further, the angles θa and θb formed by the incident direction of the line illumination 4 and the optical axis of the sensor A are set to be the same. The line sensor 2 applies a color sensor so that brightness and color can be imaged.

  One line imaged by each sensor is an image projected in the line illumination 4 toward the reference plane along the optical axis of the camera. Line images captured while moving the connector 6 are two-dimensionally arranged at regular time intervals so that the scales (lengths per pixel) in the X and Y directions match, and the images are used as sensor images. . The scale in the X direction of the image is a value obtained by dividing the cell size of the sensor by the optical magnification of the camera lens, and the scale in the Y direction is a value obtained by multiplying the moving speed of the connector 6 by the horizontal synchronization interval of the sensor.

Each sensor image is imaged brightly with the illumination color at that position when the pin tip appears on the sensor optical axis in the line illumination 4, and is imaged darkly at other times.
<Calculation of pin tip position>
A corresponding pin tip image obtained by imaging the same pin is obtained from each sensor image, and the pin tip position is calculated.

  First, a pin tip image in the sensor B image corresponding to each pin tip image appearing in the sensor A image is found. In the image of each sensor, there is the following rule between the corresponding pin images (see FIG. 7).

  The sensor cell alignment direction (X-axis) in each sensor image always matches. However, this is based on the premise that the camera configuration in FIG. 2 has no distortion or misalignment in the image as designed. If there is distortion or misalignment between the cameras, it is recommended to use a chessboard image or the like and correct the distortion and misalignment by a general camera calibration method.

  Next, the image that appears red in the sensor A image is a pin that is higher than the height of the reference surface (reference height), and the sensor B appears blue with a delay. Conversely, an image that appears blue with sensor A is a pin that is lower than the reference height, and sensor B will appear to move forward. An image that appears to be an intermediate color between red and blue on sensor A appears on sensor B in the same color with no delay or advance.

  If the above rule is applied to the pin tips whose coordinates are close in the two images, the corresponding pin tips can be determined as a pair.

  If the corresponding pin tip can be found in both sensor images, the three-dimensional position of the pin tip can be obtained from the coordinates in each image by the following calculation. If the coordinates of the pin tip appearing in the sensor A image are (Xa, Ya) and the coordinates of the pin tip in the corresponding sensor B image are (Xb, Yb), the three-dimensional position (x, y) of the pin tip , Z) is expressed by the following equations (1) to (3).

However, the angle θ formed by the line illumination 4 and the optical axis of each sensor is θ = θ _a = θ _b .

  Also, the horizontal and vertical synchronization of each sensor and the moving speed of the connector are adjusted so that the same distance in the X-axis direction and the Y-axis direction is captured as the same pixel difference in the image, and Xa in the equation , Ya and Xb, Yb are positions in the plane calculated by multiplying the pixel in which the pin tip appears in each sensor image by the length per pixel.

  As described above, if the image of the pin tip can be associated with both sensor images using the configuration of FIG. 2, the three-dimensional position of the pin tip can be obtained.

  FIG. 9 is a flowchart showing a procedure for inspecting a connector pin of the present invention.

  First, the pin tip of the connector 6 to be measured 5 is set on the moving stage 7 so as to face the top surface, alignment of the line illumination 4 that irradiates the pin tip perpendicularly from the top surface, and the optical axis and reference of the two cameras. The focal position on the measurement target 5 on the surface is adjusted (steps S11 to S13).

  When the adjustment is completed, in step S14, the movement control unit 13 moves the moving stage 7 in the Y-axis direction. In step S15, the imaging control unit 12 uses the sensors A and B as the connector pins move. The control device 10 acquires the captured line image of the pin and stores it in the storage device 100.

  In step S16, it is determined whether or not the imaging of all the pins has been completed. If it has not been completed, steps S14 to S15 are repeated until completion.

  When the imaging of all the pins is completed, in step S17, the control device 10 creates a two-dimensional image arranged in the Y-axis direction in time series from the imaging line video as a sensor image.

  Next, in step S18, the three-dimensional position of the corresponding pin is calculated from the two sensor images based on the equations (1) to (3).

  In step S19, the calculation result is output to the output device.

  The present invention is applied to the field of connector pin automatic inspection technology.

DESCRIPTION OF SYMBOLS 1 Camera 2 Line sensor 3 Lens 4 Line illumination 5 Measuring object 6 Connector 7 Movement stage 10 Control apparatus 11 Illumination control part 12 Imaging control part 13 Movement control part 100 Storage device

Claims (5)

Illumination means for irradiating the pin tip of the connector with linear illumination light;
A moving means for gripping and moving the connector so that a pin tip of the connector passes through a predetermined position within a range where the linear illumination light is irradiated by the illumination means;
Imaging means for imaging the pin tip with two cameras arranged obliquely forward and obliquely behind the line illumination with respect to the movement direction of the connector;
Position calculating means for calculating a three-dimensional position of the pin tip of the connector from two images captured by the camera;
A connector pin inspection device characterized by comprising:   The connector pin inspection apparatus according to claim 1, wherein the camera includes a line sensor, and a cell arrangement direction in the line sensor is arranged in parallel with the line illumination.   The connector pin inspection apparatus according to claim 1, wherein the line illumination includes two or more line illuminations having different illumination colors and arranged in parallel.   The position calculation means estimates the color and position of the pinpoint of the other camera image from the color of the pinpoint in the image captured by either camera and the position in the image, and the image closest to the estimated position 4. The connector pin inspection device according to claim 3, wherein a pin tip in the inside is determined as a corresponding pin tip. An inspection method applied to a connector pin inspection apparatus having two or more line illuminations arranged in parallel and different in illumination color from two cameras by line sensors,
An illumination process for irradiating line-shaped illumination light;
A moving step of gripping and moving the connector so that a pin tip of the connector passes through a predetermined position of the line illumination;
An imaging step of imaging the pin tip with two cameras arranged diagonally forward and diagonally behind the line illumination with respect to the moving direction of the connector;
A position calculating step for calculating a three-dimensional position of the pin tip of the connector from two images captured by the camera;
A method for inspecting a connector pin, comprising: