KR0155800B1 - Centering control method of camera for chip mounter - Google Patents

Abstract

The present invention relates to a method for correcting the position of a camera for a chip mounter used for image recognition of parts.

According to the position correction method of the camera for a chip mounter of the present invention, since the position of the camera can be corrected even without the test piece processed with high precision, the camera becomes easy to work, and the camera that picks up the parts adsorbed to the nozzle is a nozzle. It is possible to check whether the camera is rotated with respect to the nozzle about its optical axis and whether the camera is rotated with respect to the optical axis and correcting the position of the camera accordingly, so that more accurate camera position correction is possible.

Description

Position correction method of camera for chip mounter

1 is a schematic diagram of a chip mounter.

FIG. 2 shows a pixel coordinate system recognized by the camera shown in FIG.

3 is a schematic structural diagram of a state where a nozzle is located on an upper portion of a camera.

4 is a schematic front view of a test piece taken by a camera in the state shown in FIG. 3 and displayed on a screen.

5 is a schematic structural diagram of a state in which a nozzle is located on the top of a camera in the process of performing the method according to the present invention.

FIG. 6 is a schematic front view of the nozzle captured by the camera in the state shown in FIG. 5 and shown on the screen; FIG.

7 is a schematic front view of a nozzle which is transferred to a plurality of coordinate values in the course of performing a method according to the present invention and is captured and displayed on a screen;

8 is a schematic structural diagram showing a field of view in a state where the optical axis of the camera forms a predetermined angle with the central axis of the nozzle.

* Explanation of symbols for main parts of the drawings

1: robot 2: head

3: nozzle 5: conveyor

10 camera 11 optical axis

20: control unit 30: image processing unit

31: central axis of the nozzle

The present invention relates to a method for correcting the position of a camera used for image recognition of a component, and in particular, the position correction method of an improved chip mounter camera for accurately recognizing the adsorption state of a component adsorbed to a nozzle for a chip mounter. It is about.

A chip mounter for automatically mounting various chip components on a printed circuit board is generally driven and controlled by a control unit 20 having a first coordinate system, such as an XY coordinate system, as schematically shown in FIG. XY robot (1), a conveyor (5) driven by the control unit 20, and a nozzle (3) for sucking the chip parts to be mounted on the printed circuit board (6) transported by the conveyor (5) Doing. The nozzle 3 is provided so that the head 2 fixed to the X-Y robot 1 can be lifted and lowered so as to be position controlled by the control unit 20. The nozzle 3 is attached with a reflecting plate 4 so that a chip component to be sucked is picked up by a camera to be described later and its suction state can be easily confirmed.

The chip mounter further includes a camera 10 fixedly installed at an appropriate position and connected to the camera 10 in order to recognize a component adsorption state such as the size or position of the chip component adsorbed by the nozzle 3. The image processing unit 30 is provided. The image processing unit 30 is a portion that calculates position coordinates or the like based on the image information transmitted from the camera 10 and has a coordinate system that is different from the first coordinate system of the control unit 20, that is, a pixel coordinate system. . This pixel coordinate system is a coordinate system according to the arrangement of pixels (pixels 10b) formed in the imaging device 10a of the camera 10 as shown in FIG. The X'-Y 'coordinate system in which the horizontal direction of (10a) is the X' axis and the vertical direction is the Y '. Therefore, even if the position of the camera 10 is changed on the first coordinate system of the controller 20 so that the coordinate value according to the first coordinate system of each pixel 10b is changed, each pixel on the pixel coordinate system of the image processor 30 is changed. The coordinates do not change.

On the other hand, in order to achieve accurate image recognition for the components adsorbed on the nozzle 3, it is necessary to set the field of view of the camera and the relative size of the pixel to be described later, that is to initialize the pixel coordinate system, Conventionally, the following method was used.

First, a test piece (refer to Fig. 3) of a predetermined size and shape standard is placed in a part supplying part where a chip part to be mounted on the printed circuit board 6 is placed. Then, the X-Y robot 1 is driven through the control unit 20 to move the nozzle 3 onto the test piece P, and the test piece P is sucked by the nozzle 3. When the test piece P is attracted to the nozzle 3 in this manner, the nozzle 3 is transferred to the camera installation position on the first coordinate system previously input to the control unit 20, and then lowered, as shown in FIG. The nozzle 3 is positioned on the focal length of the camera 10. Then, the test piece P adsorbed by the nozzle 3 is imaged by the camera 10, and the image information is sent to the image processing part 30. FIG. Accordingly, the image processing unit 30 performs the recognition processing operation based on the image information to calculate the relative size of the pixels and the field of view of the camera.

Here, the relative size of the pixel is the actual size of the test piece P, as shown in Fig. 4, the test piece P captured by the camera 10 and formed on the imaging device 10a of the camera 10. ) Is the size divided by the number of pixels occupied. The field of view of the camera may be divided into a horizontal field of view and a vertical field of view. The horizontal field of view is a value obtained by multiplying the relative size of the pixels by the number of horizontal pixels among the pixels constituting the screen. Similarly, the longitudinal field of view is the product of the relative size of pixels multiplied by the number of vertical pixels.

The relative sizes of the pixels and the field of view of the camera obtained in this way are stored in the memory of the image processing unit 30 to form a predetermined pixel coordinate system, and based on these, the size of the component adsorbed on the nozzle 3 is calculated. have.

However, according to this conventional method, since the size requires a test piece that is input to the control unit in advance, there is a problem that the test piece must be processed with high precision. In addition, it is not possible to determine whether the camera is inclined with respect to the nozzle, that is, whether the optical axis of the camera and the central axis of the nozzle are at a predetermined angle without forming a parallel state. Since the relative size and the field of view of the camera vary depending on the angle formed between the optical axis of the camera and the central axis of the nozzle, the values for the relative size of the pixel and the field of view of the camera obtained by the above-described conventional methods are substantially correct. There was a problem that it was difficult to confirm. In addition, the rotation angle of the camera rotated with respect to the nozzle about its optical axis also affects the relative size of the pixel and the field of view of the camera. According to the above-described method, there is a problem that the values are inaccurate.

The present invention has been made in order to solve such a problem, it is possible to correct the position of the camera without using a test piece, such as a separate ultra-precision processing, and to check whether the camera is inclined with respect to the nozzle and Accordingly, an object of the present invention is to provide a method of correcting a position of a camera for a chip mounter, which enables the camera to be corrected in position, thereby enabling easier and accurate position correction of the camera.

Another object of the present invention is to correct the position of the camera without using a separate test piece, and whether the camera is inclined with respect to the nozzle and whether the camera is rotated by a predetermined angle with respect to the nozzle about its optical axis. The present invention provides a method for correcting the position of a camera for a chip mounter, which can not only determine whether or not, but also correct the position of the camera accordingly, so that the camera can be easily and accurately corrected.

In order to achieve the above object, the method of positioning a camera for a chip mounter according to the present invention is a method for positioning a camera for activating an adsorption state of a component adsorbed to a chip mounter nozzle. A position control is performed by a control unit having a coordinate system, and the camera is connected to an image processing unit having a pixel coordinate system and performing image recognition operation based on the image information picked up by the camera, wherein the nozzle is previously inputted to the control unit. A nozzle transfer step of transferring the camera to the center coordinates of the camera and positioning it on the focal length of the camera; and imaging the nozzle transferred through the nozzle transfer step with the camera, and the image processing unit coordinates the position of the imaged nozzle with the coordinates of the pixel coordinate system. After performing the first memory step of storing the value as the value, and the first memory step, the nozzle to the control unit A second memory step of photographing with a camera while transferring to a plurality of previously input positions, and storing the positions of nozzles photographed at each position as coordinate values of a pixel coordinate system, the first memory step, and the second memory step; An interaxial angle calculating step of calculating an interaxial angle between the optical axis of the camera and the central axis of the nozzle on the basis of the coordinate values of the nozzles stored in the image processing unit and the positions of the nozzles previously input to the controller in the storage step; And a position correction step of correcting the position of the camera based on the value obtained in the calculation step.

In order to achieve the latter object, a method of positioning a camera for a chip mounter according to the present invention is a method for positioning a camera for photographing an adsorption state of a component adsorbed to a chip mounter nozzle. A position control is performed by a control unit having a coordinate system, and the camera is connected to an image processing unit having a pixel coordinate system and performing image recognition operation based on the image information picked up by the camera, wherein the nozzle is previously inputted to the control unit. A nozzle transfer step of transferring the camera to the center coordinates of the camera and positioning it on the focal length of the camera; and imaging the nozzle transferred through the nozzle transfer step with the camera, and the image processing unit coordinates the position of the imaged nozzle with the coordinates of the pixel coordinate system. After performing the first memory step of storing the value as the value, and the first memory step, the nozzle to the control unit A second memory step of photographing with a camera while transferring to a plurality of previously input positions and storing the positions of nozzles photographed at each position as coordinate values of a pixel coordinate system; and the first memory step and the second memory. Calculating an interaxial angle between the optical axis of the camera and the central axis of the nozzle on the basis of the coordinate values of the nozzle stored in the image processing unit and the positions of the nozzles previously input to the control unit, and the first memory A rotation angle calculation step of calculating an angle at which the camera is rotated with respect to the optical axis based on the coordinate values of the nozzles stored in the image processing unit in the step and the second memory step and the positions of the nozzles previously input to the control unit; And a position correction step of correcting the position of the camera based on the values obtained in the angle calculation step and the rotation angle calculation step.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a schematic structural diagram of a state where a nozzle is located on a focal length of a camera, and FIG. 6 is a schematic front view showing a nozzle captured by a camera and displayed on a screen in the state shown in FIG. FIG. 7 is a schematic front view illustrating a nozzle captured on a plurality of positions spaced a predetermined distance from the center position of the camera input to the controller and displayed on the screen. 8 is a schematic side view showing a state in which the optical axis of the camera and the central axis of the nozzle form a predetermined angle.

The position correction method of the chip mounter camera according to the present invention will be described with reference to FIGS. 5 to 8 and FIG. 1 as follows.

First, as shown in FIGS. 5 and 6, the nozzle 3, in which the parts are not adsorbed, is input in advance to the control unit 20 as a coordinate value of the XY coordinate system by the program. It moves to the center position (X0, Y0) of the camera, and performs the nozzle conveyance step of lowering the nozzle 3 to the height input to the control part 20 so that it may be located on the focal length of the camera 10 previously.

After that, the camera 10 picks up the nozzle 3 positioned on the focal length and sends the picked-up image information to the image processing unit 30. On the basis of this image information, the image processing unit 30 is attached to the imaging device 10a of the camera 10 as shown in FIG. 6, that is, the center of gravity of the nozzle 3 shown on the screen. After the calculation, the first storage step of storing the coordinate values X0 'and Y0' on the pixel coordinate system is performed.

After performing the first storage step, the camera 30 captures images while transferring the nozzles 3 to a plurality of positions on the XY coordinate system previously input to the controller 20, and describes the center positions of the nozzles captured at each position. Similarly, a second storage step is performed which is obtained by a method and stored on the pixel coordinate system of the image processing unit 30. In this embodiment, in order to facilitate the image recognition operation, a plurality of positions input to the controller 20 and the nozzle 3 is transferred, as shown in FIG. 7, the camera on the XY coordinate system of the controller 20. The first position (X1, Y1), which is located on the same distance from the center coordinates (X0, Y0), that is, the values a, b, c, and d are the same in FIG. The second position (X2, Y2), the third position (X3, Y3) and the fourth position (X4, Y4), and the four positions are located on the X-axis and Y on the XY coordinate system of the control unit 20 It was.

Accordingly, the image processing unit 30 sets each of the nozzle center positions to four coordinate values ((X1, Y1 '), (X2', Y2 '), (X3', Y3 '), (X4', Y4) on the pixel coordinate system. ')).

Then, the coordinate values ((X0 ', Y0'), (X1 ', Y1'), (X2 ', Y2'), (X3) stored in the image processing unit in the first storage step and the second storage step. ', Y3'), (X4 ', Y4') and the positions of nozzles previously inputted to the controller 20 ((X0, Y0), (X1, X1), (X2, Y2), (X3, Y3), (X4, Y4) is performed to calculate the angle between the axis to calculate the angle formed by the optical axis of the camera 10 and the central axis of the nozzle (3).

To do this, first, in the coordinate system of the control unit, the relative size of the pixel in the + Y direction, the relative size of the pixel in the -Y direction, the relative size of the pixel in the + X direction, and the relative size of the pixel in the -X direction are respectively expressed by the following equation. Obtain

The field of view of the camera in each direction is obtained based on the values obtained in the above formulas (1) to (4). For example, the values obtained in the above formulas (1) to (4) are referred to as LX1, LX2, LY1, and LY2, and the screen is composed of 640x480 pixels, that is, X 'constituting the horizontal direction of the screen. If the number of pixels in the direction is 640 and the number of pixels in the Y 'direction forming the horizontal direction of the screen is 480,

Becomes

The values obtained in the above Equations 5 and 6 are referred to as A and B, respectively, and are shown in FIG. Referring to FIG. 8, the camera 10 is provided such that the optical axis 11 and the central axis 31 of the nozzle 3 are arranged side by side as shown by the solid line at the time of design. Therefore, when the central axis 31 of the nozzle 3 coincides with the optical axis 11 of the camera 10, the field of view of the camera is the same as the field of view in the + X direction and the field of view in the -X direction from the optical axis 11. It will have a value. However, when the camera 10 is installed, the camera 10 is inclined with respect to the central axis 31 of the nozzle 3 so that the optical axis 11 of the camera 10 and the central axis of the nozzle 3 ( When 31) forms a predetermined angle, the field of view of the camera is changed from the optical axis 11 to the field of view in the + X direction and the field of view in the -X direction.

Therefore, when A and B have different values, the camera 10 is installed with the camera 10 inclined with respect to the central axis 31 of the nozzle 3, as shown by a dotted line in FIG. This means that the central axis 31 of 3) and the optical axis 11 of the camera 10 form a predetermined angle θ1 with respect to the X-axis direction. At this time, the interaxial angle θ1 with respect to the X-axis direction formed by the central axis 31 of the nozzle 3 and the optical axis 11 of the camera 10 is + X and − from the optical axis 11 of the camera 10. Based on the wide angle θ in the X direction, the distance D between the camera 10 lens and the nozzle 3, and the values A obtained from the above expression (5) and the values B obtained from the equation (6). It is obtained by the depreciation method.

Similarly, the field of view in the + Y direction and the field of view in the -Y direction are obtained by the following equations (7) and (8).

On the basis of the values obtained in (7) and (8), the central axis of the nozzle in the Y-axis direction and the optical axis of the camera in the Y-axis direction are similar to the above-described method of calculating the interaxial angle in the X-axis direction. Find the angle between the axes in the Y-axis direction.

The camera is arranged such that the central axis 31 of the nozzle 3 and the optical axis 11 of the camera 10 are in parallel with each other based on the angle between the axes in the X-axis direction and the axes in the Y-axis direction thus obtained. A position correction step of correcting the position of (10) is performed.

When the position of the camera 10 is corrected according to the above-described method, it is not necessary to use the test piece P processed with high precision, which is used in the conventional method. Since the optical axis 11 of (10) is in parallel with the central axis 31 of the nozzle 3, the adsorption state of the chip component adsorbed by the nozzle 3 and imaged by the camera 10 is more accurate. It can be recognized as a value.

On the other hand, after performing the second memory step, as shown in FIG. 7, when the pixel coordinate system of the camera 10 appears to be rotated with respect to the XY coordinate system of the control unit (X'-Y 'coordinate system) This means that the camera 10 is rotated with respect to the optical axis and at the same time, the position of the camera 10 needs to be corrected for more accurate component recognition. Therefore, it is necessary to perform the rotation angle calculation step of calculating the rotation angle of the camera 10 with respect to the optical axis, and the position correction step of correcting the position of the camera 10 based on the value obtained in this conversion angle calculation step. .

To this end, first, the rotation angle of the camera 10 is calculated by the following equation (9).

(Here, α is the angle of rotation of the camera, α1 is the angle formed by the Y axis of the controller coordinate system and the Y 'axis of the pixel coordinate system, α2 is an angle formed by the X axis of the controller coordinate system and the X' axis of the pixel coordinate system.)

Then, the camera is rotated by the rotation angle α of the camera obtained in Equation 9 to correct the position.

As described above, according to the position correction method of the camera for a chip mounter of the present invention, since the position correction of the camera can be performed even without the ultra-precise test piece, the operation is easy and the image picked up by the nozzle is picked up. Whether the camera is inclined with respect to the nozzle can be checked, and the position of the camera can be corrected so that the center axis of the nozzle and the optical axis of the camera are parallel, so that the camera can be accurately positioned.

In addition, it is possible to check whether the camera is rotated with respect to the nozzle about its optical axis and to correct the position of the camera accordingly, thus enabling more accurate position correction of the camera.

Claims (5)

A method for positioning a camera for imaging a suction state of a component adsorbed on a chip mounter nozzle, the nozzle being positioned controlled by a control unit having an XY coordinate system, the camera having a pixel coordinate system and being picked up by the camera. A method of correcting a position of a chip mounter camera to which an image processing unit for performing image recognition operation based on the received image information, the method comprising: transferring the nozzle to a camera center coordinate previously input to the control unit and positioning the camera on a focal length of the camera; A first memory step of imaging a nozzle transferred through the nozzle transferring step with the camera and storing the position of the nozzle photographed by the image processing unit as a coordinate value of the pixel coordinate system; After performing the step, the nozzle is transferred to a plurality of positions previously input to the controller, and the image is captured by the camera. A second storage step of storing the positions of the nozzles photographed at each position as coordinate values of the pixel coordinate system, and coordinate values of the nozzles stored in the image processing unit in the first and second memory steps; And an interaxial angle calculating step of calculating an interaxial angle between the optical axis of the camera and the central axis of the nozzle based on the positions of the nozzles previously input to the controller, and correcting the position of the camera based on the values obtained in the interaxial angle calculating step. Position correction method for a chip mounter camera, characterized in that it comprises a position correction step. The method of claim 1, wherein the plurality of positions of the nozzles transferred in the second memory step are located at the same distance from the camera center coordinates previously input to the controller. The method of claim 1, wherein the plurality of positions of the nozzles transferred in the second memory step are four locations. 4. The method of claim 3, wherein the four positions are located on the X-axis and the Y-axis on the coordinate system of the control unit, respectively. A method for positioning a camera for imaging a suction state of a component adsorbed on a chip mounter nozzle, the nozzle being positioned controlled by a control unit having an XY coordinate system, the camera having a pixel coordinate system and being picked up by the camera. A method of correcting a position of a chip mounter camera to which an image processing unit which performs image recognition operation based on the received image information, the method comprising: transferring the nozzle to a camera central coordinate previously input to the control unit and positioning the nozzle on a focal length of the camera; A first memory step of capturing a nozzle transferred through the nozzle transferring step with the camera and storing the position of the imaged nozzle as a coordinate value of the pixel coordinate system; and the first memory step After performing the above operation, the nozzle is transferred to a plurality of positions previously input to the controller, and the image is captured by the camera. A second storage step in which the image processing unit stores the positions of the nozzles photographed at each position as coordinate values of the pixel coordinate system, and coordinate values of the nozzles stored in the image processing unit in the first and second memory steps. And an interaxial angle calculating step of calculating an interaxial angle between the optical axis of the camera and the central axis of the nozzle based on the positions of the nozzles previously input to the controller, and the nozzles stored in the image processing unit in the first and second memory steps. A rotation angle calculation step of calculating an angle at which the camera is rotated with respect to the optical axis based on coordinate values of the controller and positions of the nozzles previously input to the controller, and based on values obtained in the shaft-to-axis angle calculation step and the rotation angle calculation step. And a position correction step of correcting the position of the camera.