JP2013213778A - Camera movement-type two-dimensional coordinate measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an imaging-type two-dimensional coordinate measurement device with a movable camera mounted on an actuator to capture an image with a boundary of a tabular workpiece made clear in its entire measurement area and perform a highly accurate coordinate measurement.SOLUTION: A measurement workpiece (5) is mounted on a transparent plane table (4). A clearance between the measurement workpiece (5) and a camera (6) is supported by a height adjustment mechanism (3) so as to be kept constant in an entire range where the camera (6) is movable by a Y-axis actuator (7) and an X-axis actuator (8). A plane illumination (2) placed below the plane table (4) is larger than a movement range of the camera (6). Vertical parallel-transmitted light is supplied to the plane table (4) and the measurement workpiece (5), thereby allowing illumination light without refraction to capture a shadowless image, and a highly accurate two-dimensional measurement device is achieved by a precise camera imaging.

Description

  The present invention relates to an apparatus for capturing an outline, a pattern, or the like of a measurement workpiece having a two-dimensional shape with an image, performing image processing, and automatically measuring the coordinates and geometric shape.

  Work products processed into a predetermined two-dimensional shape by die cutting or cutting from paper, optical sheets, films, and other plate-like materials such as metal and glass are used in industrial products and the like. In order to inspect and assure that the shape satisfies the required accuracy, a workpiece is captured as an image by a camera, and coordinates, dimensions, and geometric shapes are measured.

  At this time, in order to obtain numerical data such as coordinates from a pattern in which the workpiece is captured as an image, an edge which is a portion having a large contrast difference is extracted as a line by a so-called image processing technique. An edge has a predetermined thickness, but it is important to make the edge line as narrow as possible and extract it uniformly within the measurement surface in order to increase the accuracy of the measurement. A device incorporating such a system The challenge is to provide

  The workpiece is captured as an image, and the position data of the edge that becomes the boundary of the pattern is used to obtain the coordinate and dimension data. In order to obtain accurate data, it is necessary to grasp the width of the edge appearing in the image narrowly. For this purpose, a clear contrast difference is necessary at the edge portion of the workpiece (hereinafter referred to as a measurement workpiece), and it largely depends on illumination.

  When the measurement workpiece does not fit in the field of view of the camera, a measuring machine that moves the camera with an actuator is used. However, the size of the surface plate on which the measurement workpiece is placed needs to be larger than the measurement workpiece. In the case of such a measuring apparatus, in the case of an illuminating apparatus that expands point-emitting illumination such as a light bulb with a lens or the like, the local illumination light beam is radial with respect to the measurement surface. In the case of a measuring work having a certain thickness, a shadow is generated at the edge of the pattern depending on the radiation angle of the light beam. As a result, the thickness of the edge changes depending on the position of the pattern, making it difficult to accurately define the position. The present invention has been devised based on these points.

  In order to solve the above problem, a description will be given with reference to FIGS. The measurement workpiece (5) is placed on a surface plate (4) made of a glass plate or the like having a high light transmittance, which is installed on the two-dimensional coordinate measuring device frame (1). The surface plate (4) has three or more height adjustment mechanisms (3) that support the surface plate (4) so that the focal position of the CCD camera (6) set on any measurement surface can be applied to all measurement surfaces. It is supported and fixed by.

  The surface illumination (2) is placed under the surface plate (4). The surface illumination (2) is composed of a light guide plate (10), a light emitting LED (9) provided on the end face thereof, a reflection plate (12) for reflecting light in the surface direction, and a diffusion plate (11) for uniformizing light. Has been. The light guide plate (10) is made of a transparent acrylic resin plate or the like, and the light incident from the LED (9) on the end surface is a dot pattern and a reflection plate subjected to printing processing for irregularly reflecting light (not shown) on the back surface of the light guide plate (10). Radiated to the surface by (12).

  The surface illumination (2) emits illumination light (13) vertically on the entire surface of the light emitting surface. The illumination light (13) is transmitted without being refracted by vertically entering the surface plate (4), and the illumination light (13) is also not refracted in the same manner when the measurement work (5) has light transmittance. Go through and go straight to the camera. This realizes a highly accurate non-contact type two-dimensional measuring device that detects an edge position from an image without creating an unnecessary image such as a shadow on the edge portion of the measurement work (5).

  The two-dimensional coordinate measuring apparatus according to claim 1 and claim 2 is a high-accuracy geometrical data such as the shape of a plate-like measurement workpiece and the coordinates, dimensions, and shape of a printed pattern on the entire surface of the surface plate (4). It is possible to perform measurement with extremely small repetition error.

It is a side view which shows embodiment of this invention. It is a top view which shows embodiment of this invention. It is a side view of the surface illumination in this invention.

DESCRIPTION OF SYMBOLS 1 Two-dimensional coordinate measuring device frame 2 Surface illumination 3 Height adjustment mechanism 4 Surface plate 5 Measurement workpiece 6 Camera 7 Y-axis actuator 8 X-axis actuator 9 LED illumination 10 Light guide plate 11 Diffusion plate 12 Reflection plate 13 Illumination light

  The camera (6) that captures the image of the measurement work (5) is the size of a field of view that captures a portion of the measurement work (5) as an image, and Y is placed at a predetermined position of the edge or shape for measuring the center of the camera (6). The coordinates are measured by reading the position data of an encoder (not shown) provided in the Y-axis actuator (7) and the X-axis actuator (8) by moving the axis actuator (7) and the X-axis actuator (8). As a result, a measurement workpiece (5) larger than the camera's field of view can be measured, and high accuracy can be obtained by completely canceling the distortion of the image captured by the camera.

  In order to set the center of the camera (6) to the predetermined position of the edge or shape to be measured, it is necessary to position the measurement object in advance at the position where the measurement object is captured as the image of the camera (6) with the XY both actuators. is there. This positioning is performed by handing over the approximate coordinate data of the movement destination to both XY actuators and instructing automatic movement, or by manual operation while looking at the screen.

  A predetermined edge position of the image photographed by the camera (6) is obtained as two-dimensional coordinate data in the image. The difference between the two-dimensional image coordinate data at the center of the camera (6) is obtained in the X-axis and Y-axis directions, and the camera (6) is instructed to move the alignment to the Y-axis actuator (7) and the X-axis actuator (8). Is close to the target position. It is necessary to repeat several times until the difference becomes zero. As a result, position data of encoders (not shown) provided in both actuators become measurement coordinates.

  In addition to the method of using the measurement coordinate position as the position data of the encoder, a method of determining the coordinates by adding / subtracting the difference data of the camera and the encoder data of the Y-axis actuator (7) and the X-axis actuator (8) may be performed. good. In this case, the measurement accuracy is sacrificed somewhat, but the measurement can be completed in a short time.

  A pattern of a size that fits all of the target pattern within the field of view of the camera (6), and the shape such as a circle or rectangle can be obtained by performing geometric image processing on the target geometric data to obtain data such as dimensions and angles. You can also.

  A surface plate (4) made of a glass plate or the like having a high light transmittance is placed on the two-dimensional coordinate measuring device frame (1). The surface plate (4) has three or more height adjustment mechanisms (3) that support the surface plate (4) so that the focus of the CCD camera (6) set on any measurement surface can be applied to all measurement surfaces. It is fixed.

  The surface illumination (2) is placed under the surface plate (4). The surface illumination (2) emits illumination light (13) vertically on the entire surface of the light emitting surface. The illumination light (13) passes through the surface plate (4) and the light-transmitting measurement workpiece vertically without being refracted and goes straight to the camera. As a result, a useless image such as a shadow is not formed on the edge portion of the measurement work (5), and the edge position is detected in a non-contact manner with high accuracy.

Claims (2)

In a two-dimensional coordinate measuring device installed on the moving part of an actuator that moves a measurement workpiece in an image in two dimensions parallel to the measurement surface, a surface plate that faces the camera and places the measurement workpiece on its upper surface The surface plate and the surface illumination are larger than the movable range of the actuator. The surface plate has a surface illumination that emits parallel light on its lower surface. A two-dimensional coordinate measuring device characterized in that it can be set uniformly within the movable part of the actuator. 2. A two-dimensional coordinate measuring apparatus according to claim 1, wherein the material of the surface plate is a so-called plastic such as polycarbonate or acrylic.

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