JP2005188955A - Shape measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive device which measures the outside dimension of an article with sufficient accuracy. <P>SOLUTION: The shape measuring device which measures the outside dimension of an article 10 is provided with: a lighting transparent plate 20 for laying the article; an irradiation means 30 for irradiating the article via the lighting transparent plate; an imaging means 40 which picturizes the projection image of the article which the irradiation light of the irradiation means forms; and an image pick-up polarizing plate 50 which intercepts lights other than the direct light from a lighting means, located between the article and the imaging means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for measuring a shape of a machine part or the like, and more particularly to an apparatus for measuring the shape of an article using a projection image by transmitted illumination.

  Conventionally, as a device for measuring the shape of a machine part or the like, light is irradiated from behind the object to be measured, the projected image is captured by a high-resolution industrial camera, and the captured image is processed and processed as desired. There has been known an apparatus for calculating a dimension of a location (see, for example, Patent Document 1).

JP 2003-194529 A

  However, in the shape measuring apparatus using the conventional projection image, the light irradiated from behind the object to be measured is refracted at the angle of the object to be measured or irradiated at a slight angle to the object to be measured. Light is reflected from the surface of the object to be measured. As a result, the projected image is projected smaller than the actual measurement object, which hinders accurate shape measurement of the measurement object. In addition, it is also considered that a divergence between a projected image and a real image is suppressed by using a parallel optical system illumination device that irradiates parallel light rays as a light source of an illuminating unit that irradiates the measurement object. The cost was high, and the practical application was hindered in terms of cost effectiveness.

  Therefore, an object of the present invention is to provide an inexpensive apparatus that accurately measures the external dimensions of an article.

  The shape measuring device according to claim 1 is a shape measuring device for measuring an outer dimension of an article, an illumination transmission plate on which the article is placed, an irradiation means for irradiating the article through the illumination transmission plate, An image pickup means for picking up a projected image of an article formed by irradiation light, and an image pickup polarizing plate that is positioned between the article and the image pickup means and blocks light other than direct light from the illumination means. This solves the above-mentioned problem.

  In addition to the configuration of the shape measuring device according to claim 1, the shape measuring device according to claim 2 further includes an irradiation polarizing plate having the same deflection characteristics as the imaging polarizing plate between the article and the irradiation means. By having the configuration, the above-described problems are further solved.

  In addition to the configuration of the shape measuring device according to claim 1 or 2, the shape measuring device according to claim 3 includes an optical filter that transmits light from the irradiation unit between the imaging unit and the article. By adopting a configuration, the above-described problems are further solved.

  Here, the optical filter means a low-pass filter that transmits light having a wavelength equal to or greater than the wavelength of the light of the irradiating means, or a band-pass filter that transmits only near the wavelength of the light of the irradiating means (near the frequency). ing.

  In addition to the configuration of the shape measuring device according to any one of claims 1 to 3, the shape measuring device according to claim 4 is a light shield in which the illumination transmission plate has a window frame slightly larger than the outer shape of the article. By adopting a configuration having a mask, the above-described problems are further solved.

  According to a fifth aspect of the present invention, in addition to the configuration of the shape measuring device according to any one of the first to fourth aspects, the imaging unit is a camera using a telecentric lens. The present invention aims to further solve the above problems.

  Here, the telecentric lens is an imaging lens having a parallel beam path. The depth of the subject is deep, a constant magnification is obtained within the range, and an image captured even if the distance to the object to be measured changes. It has a characteristic that does not change.

  According to the shape measuring apparatus according to claim 1, an illumination transmission plate for placing the article, an irradiation unit for irradiating the article through the illumination transmission plate, and a projection image of the article formed by the irradiation light of the irradiation unit Reflecting light reflected on the surface of the article is configured by including an imaging means for imaging, and an imaging polarizing plate that is positioned between the article and the imaging means and blocks light other than direct light from the illumination means. Since it is blocked by the imaging polarizing plate, accurate dimension measurement is possible.

  According to the shape measuring apparatus according to claim 2, in addition to the configuration of the shape measuring apparatus according to claim 1, an irradiation polarizing plate having the same deflection characteristics as the imaging polarizing plate is further provided between the article and the irradiation means. By having the configuration, it is possible to form a projected image using only light in a specific polarization direction, so the influence of reflected light reflected on the surface of the article or the influence of refracted light refracted at the corner of the article Can be cut off more reliably, and more accurate dimension measurement becomes possible.

  According to the shape measuring apparatus of claim 3, in addition to the configuration of the shape measuring apparatus of claim 1 or 2, an optical filter that transmits light from the irradiation means between the imaging means and the article. Since the projection image can be formed without being affected by ambient light other than the light from the irradiation unit, more accurate dimension measurement can be performed.

  According to the shape measuring apparatus according to claim 4, in addition to the configuration of the shape measuring apparatus according to any one of claims 1 to 3, the illumination transmission plate has a window frame slightly larger than the outer shape of the article. By adopting the configuration having the light shielding mask, it is possible to block the influence of the light emitted from the irradiation means that is irradiated on the article at a large irradiation angle, thereby enabling more accurate dimension measurement. .

  According to the shape measuring apparatus according to claim 5, in addition to the configuration of the shape measuring apparatus according to any one of claims 1 to 4, the imaging means is a camera using a telecentric lens. As a result, the projected image of the article can be taken without distortion, so that more accurate dimension measurement can be performed.

  An embodiment of the shape measuring apparatus of the present invention will be described with reference to FIGS. As shown in FIG. 1, the shape measuring apparatus of the present invention includes an illumination transmission plate 20 on which an article 10 for shape measurement is placed, an irradiation unit 30 that irradiates the article 10 through the illumination transmission plate 20, and An imaging unit 40 that captures a projection image of the article 10 formed by the irradiation light of the irradiation unit 30, and an imaging that is positioned between the article 10 and the imaging unit 40 and blocks light other than direct light from the illumination unit 30. And a polarizing plate 50. Further, by installing a light shielding mask 25 having a window frame slightly larger than the outer shape of the article on the illumination transmission plate 20, it is possible to block the inclined light irradiated on the side wall or the like of the article 10.

  The irradiation means 30 is not particularly limited as long as it is a light source that can uniformly irradiate the article 10. For example, incandescent bulbs, halogen bulbs, fluorescent lamps, metal halide lamps, xenon lamps, light-emitting diodes, etc. are used as light sources, and a light diffusing plate such as a milky white acrylic plate is used to randomly illuminate the target object. A diffuse transmission illumination type illumination device that irradiates from behind the object and observes the shadow of the object is preferably used.

  The imaging means 40 is not particularly limited as long as it can capture images with high resolution and no distortion. However, from the viewpoint of simplicity of image data processing, cost, and the like, a commercially available industrial camera such as a CCD camera is available. A camera is preferably used. When extremely high measurement accuracy is required, an imaging lens having a parallel beam path, that is, a CCD camera using a telecentric lens in an optical system is used. Since this telecentric lens has a deep subject depth and a constant magnification within that range, it has a characteristic that the image to be captured does not change even if the distance to the object to be measured changes.

  Further, an imaging polarizing plate 50 is installed between the imaging means 40 and the article 10. In general, a polarizing plate has a property of transmitting only light in one vibration direction (for example, the T direction in FIG. 2). Light also has the property of changing its vibration direction when reflected or refracted on an object. Therefore, by installing the imaging polarizing plate 50 between the imaging means 40 and the article 10, as shown in FIG. 2, the light L1 refracted at the corner of the object to be measured or the vicinity of the corner of the object to be measured. It is possible to prevent the light L <b> 2 reflected in step S <b> 2 from reaching the imaging unit 40, and to reduce an error between the shadow size of the measurement object and the actual size.

  Furthermore, by placing the irradiation polarizing plate 60 having the same polarization characteristics as the imaging polarizing plate 50 between the article 10 and the irradiation means 30, the vibration direction of the light irradiated on the article 10 can be aligned, and the projection The error between the image and the actual size can be further reduced.

  In this embodiment, an optical filter 70 that transmits light from the irradiation unit 30 is provided between the imaging unit 40 and the article 10. Here, a low-pass filter that transmits light having a wavelength equal to or greater than the wavelength of the light of the irradiation unit (frequency or less) is used, but a band-pass filter that transmits only near the wavelength of light of the irradiation unit (near the frequency) can also be used. . By installing such an optical filter 70, it is possible to avoid the influence of light from other than the illumination unit 30 and to perform more accurate measurement.

  The present invention enables high-precision measurement of an article with an inexpensive configuration, and can be applied in any industrial field where shape measurement of the article is required, and its industrial applicability is extremely large.

It is explanatory drawing explaining the apparatus structure of the shape measuring apparatus of this invention. It is explanatory drawing explaining the principle of the high precision measurement of the shape measuring apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Article 20 ... Illumination transmission plate 25 ... Light shielding mask 30 ... Irradiation means 40 ... Imaging means 50 ... Imaging polarizing plate 60 ... Irradiation polarizing plate 70 ... Optical filter

Claims (5)

In a shape measuring device that measures the external dimensions of an article,
An illumination transmission plate on which the article is placed;
Irradiating means for irradiating the article through the illumination transmission plate;
Imaging means for capturing a projected image of the article formed by the irradiation light of the irradiation means;
A shape measuring apparatus, comprising: an imaging polarizing plate that is positioned between the article and the imaging unit and blocks light other than direct light from the illumination unit.   The shape measuring apparatus according to claim 1, further comprising an irradiation polarizing plate having the same deflection characteristics as the imaging polarizing plate between the article and the irradiation unit.   The shape measuring apparatus according to claim 1, further comprising an optical filter that transmits light from the irradiation unit between the imaging unit and the article.   The shape measuring apparatus according to claim 1, wherein the illumination transmitting plate has a light shielding mask having a window frame slightly larger than an outer shape of the article. The shape measuring apparatus according to claim 1, wherein the imaging unit is a camera using a telecentric lens.

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