JPS6352325B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a dimension measuring method that captures the wall thickness of a plate or pipe at multiple measurement points at one point, and measures the wall thickness, etc. using a line sensor camera using a photodiode array. The present invention provides a measuring device.

Configuration of conventional examples and their problems Conventional wall thickness measurement methods used contact-type micrometers and dial gauges, but because they are contact-type, it is difficult to accurately measure dimensions when the object to be measured is flexible like rubber. could not be measured. In addition, there is a risk of scratches or the like on objects with soft metal surfaces during measurement.

OBJECTS OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide an apparatus that accurately measures wall thickness, etc. without contact, without having to consider the material condition of the object to be measured.

Structure of the Invention In order to achieve the above object, the present invention attempts to measure dimensions using a line sensor camera, a telecentric aperture, and an optical system that forms an image of light in the vicinity of a measurement surface.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on FIGS. 1 and 2. In the figure, 1 is a lamp, 2 is a diffusion plate that creates a uniform diffusion surface, and 3 is a condensing lens, which projects the light from the diffusion surface of the diffusion plate 2 onto the measurement surface P. 4 is the object to be measured such as board-shaped or tubular shape, 5
6 is a light-receiving lens that receives the image of the measurement surface P, and 6 is a telecentric diaphragm for extracting only the parallel component of the light that enters the light-receiving lens 5. 7 is a photodiode array of a line sensor camera, which is a dimension measurement part.

Next, the operation of the above embodiment will be explained. The light emitted by the lamp 1 is made uniform by the diffuser plate 2, forming a brightness surface having a certain area. An image of the diffuser plate 2 is formed using the condenser lens 3 on the end face P of the object to be measured 4, that is, near the measurement surface. At this time, by creating an image sufficiently larger than the cross section of the object to be measured, the image formed on the measurement surface P is not only parallel to the object but also L ₁ ,
L Light components in _two directions are irradiated. Therefore, images of the diffuser plate 2 are formed on the measurement surface P in both the upper and lower directions with the object to be measured 4 at the center. This is imaged onto the photodiode array 7 by the light receiving lens 5, and the thickness dimension is measured. That is, photodiode array 7
The upper part of the object to be measured 4 is a dark part and the other part is a bright part, and the dimensions can be measured by counting the dark parts. A telecentric diaphragm 6 is placed on the focal plane of the light receiving lens 5, and only the parallel components of the light entering the light receiving lens 5 are imaged on the photodiode array 7, so the object to be measured 4 moves slightly in the optical axis direction from the focal position. Even if this happens, accurate dimensions can be measured without any problems. Furthermore, even if the object to be measured 4 is tilted in the direction perpendicular to the optical axis by an angle θ as shown in Fig. 2, there will be light of L ₁ and L ₂ components, so the X ₁ dimension in Fig. 3 A, which is measured using parallel rays, will be Instead, the _X2 dimension in Figure 3 (b) can be measured. The _X2 dimension is not the true wall thickness dimension, but even if the angle θ is 5 degrees, the _X2 dimension is about 0.966 times the true dimension, so it is within the error range of 1/100 to 1/1000th. . Therefore, there is no problem in measuring the wall thickness of general iron plates and steel pipes.

Effects of the Invention As is clear from the above embodiments, the present invention uses a diffuser plate and a condensing lens to create a light beam that is non-parallel to the optical axis, so even if the object to be measured is tilted, the measurement error is minimal. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a dimension measuring device according to an embodiment of the present invention, FIG. 2 is an enlarged configuration diagram of the same essential part, and FIGS. 3A and 3B are side views of the measurement dimension portion. 1... Lamp, 2... Diffusion plate, 3... Condensing lens, 4... Measured object, 5... Light receiving lens, 6...
Telecentric aperture, 7...photodiode array.

Claims (1)

[Claims] 1. A diffuser plate that creates a uniform diffusion surface from the light of the lamp, a condenser lens that projects the light from the diffuser surface of the diffuser plate onto the measurement surface, an object to be measured placed on the measurement surface, and the measurement surface A dimension measuring device equipped with a light receiving lens that receives an image of the light receiving lens, a telecentric diaphragm placed at the focal point of the light receiving lens, and a line sensor camera using a photodiode array that detects the light that passes through the telecentric diaphragm.