JPH0484705A - Optical size measuring apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for optically measuring dimensions such as the outer diameter of a round bar or the width of a tape.

(Prior art) As this type of device, for example, Japanese Patent Application Laid-open No. 6O-80703
r optical outer diameter measuring device" is well known.

In FIG. 5 showing its structure, a light projecting body 10 includes a light source 11, such as a red light emitting diode (LED), and a light projecting lens 12 that converts the light beam emitted from the light source 11 into parallel light beams.

30 is, for example, a charge coupled device (COD)
The light receiving body 30 is made of a line sensor, and the light receiving body 30 is disposed opposite to the light projecting lens 12 of the light projecting body with a space for interposing the object to be measured 60 therebetween.

In this case, when the object to be measured 60 is inserted at an arbitrary position in space, among the parallel rays emitted from the projection lens 12, the part of the rays facing the object 60 is blocked by the object 60, but the other rays are not received. It reaches the body 30, and the output of the CCD of the unreached part changes. Therefore, this photoreceptor 3
The length of the output changing portion, that is, the outer diameter of the object 60 to be measured, can be determined by scanning the CCD 0 and determining the scanning time of the output changing portion, for example.

(Problems to be Solved by the Invention) By the way, the above-mentioned effect is based on the assumption that the light source 11 is a point with no area, and the light source actually has a certain area. Therefore, the parallel light rays formed through the light projecting lens 12 inevitably have a certain divergence angle, and as a result, the boundary portion of the object 60 on the photoreceptor 30 is diffracted.

The image becomes blurred due to scattering, and the determination of the size of the image area becomes unclear.

Note that this blurring becomes more noticeable as the gap between the photoreceptor 30 and the object to be measured 60 becomes larger, so keeping them close to each other at a constant 1 wA is considered to prevent blurring, but the gap itself It has been difficult to eliminate measurement instability because it depends on the diameter of the intervening object to be measured 60.

(118 & Means for Solving) In order to solve the above problem, the present invention uses an optical dimension measuring device as an optical system with a telescopic link on the object side, so that the size of the image is independent of the intervention position of the object. In addition, the relationship between the object through the light-receiving lens and the position of the light-receiving body is used as an imaging relationship to obtain a clear image.

That is, the present invention includes a light projecting body that emits scattered light or parallel light, a light receiving lens disposed opposite to the light projecting body through a space for intervening an object to be measured, and a light receiving lens that emits scattered light or parallel light. an aperture stop disposed at an image-side focal position; and a photoreceptor disposed at a substantially conjugate position sandwiching the light-receiving lens between the object-to-be-measured intervention position in the space and having at least a row of light-receiving elements aligned in the measurement dimension direction. Become.

As mentioned above, in this optical system, the size of the image of the object formed on the photoreceptor is the same as when the object to be measured is placed at a conjugate position, even if it is not placed at a strictly conjugate point. 6. Therefore, the above-mentioned substantially conjugate position means a position that includes that range.

(Function) As mentioned above, in this optical system, the object and the photoreceptor position are in an image-forming relationship through the light-receiving lens, and the parallel rays emitted from the projector (the case of scattered rays will be described later)
An image corresponding to the outer dimensions of the object to be measured is formed on the photoreceptor via the light receiving lens and the aperture diaphragm, and the output of the light receiving element corresponding to the imaged area changes, and based on that change, the same as above is performed. The external dimensions of the object to be measured can be determined by

In this case, the parallel rays actually have a certain divergence angle because the light source is not infinitesimal, but the aperture stop placed at the image-side focal point of the light receiving lens prevents rays other than strictly parallel rays from forming. Since the light is cut off here, the outline of the image will not be blurred.

The above explanation was about parallel rays, but even when the rays emitted from the projector are scattered lights, 2. The rays other than the parallel rays are blocked by the aperture diaphragm. 4. The result is the same as in the case of parallel rays above. , no blurring occurs in the outline of the image.

(Example) Hereinafter, the present invention will be described in detail based on an example in which the present invention is implemented in an apparatus for measuring the outer diameter dimension of a round bar.

FIG. 1 shows an embodiment of an optical system of the present invention, FIG. 2 shows an external appearance of a device incorporating the optical system, and FIGS. 3 and 4 show embodiments of an aperture stop.

In FIG. 1, a light source 11 with the same reference numerals as in FIG.
, a light emitter 10 consisting of a light emitter lens 12 and a light receiver 30
is the same as that shown in FIG. 5, and its explanation will be omitted.

A light-receiving lens 40 is arranged between the light-emitting lens 12 and the light-receiving body 30 with an appropriate space between the light-emitting lens 12 and the light-receiving lens 40 . As shown in FIG. 3, this is made by punching a pinhole 51 in a thin light shielding plate.

With the above, an optical system that is a telescopic link is constructed on the object side.

The object to be measured 60 is inserted at an arbitrary position in the space between the light projecting lens 12 and the light receiving lens 40 of the optical system,
The photoreceptor 30 is placed at a conjugate position between the center point of the space and the photoreceptor lens 40, and the relationship between the object 60 at an arbitrary position and the position of the photoreceptor 30 in the space maintains a substantially imaging relationship. .

The light source 11 and the light projection lens 12 are housed in the light projection section 1 of the case having a concave cross section as shown in FIG.
A light-receiving lens 40. Aperture 50. A photoreceptor 30 is housed.

In the above, when the round rod 60, which is the object to be measured, is inserted into the space 3 in a state perpendicular to the optical axis, an image corresponding to the outer diameter of the object 60 is formed on the photoreceptor 30 by parallel light rays. . As a result, the output of the light receiving element row in that part changes,
Based on this output change, the outer diameter of the round bar 60 is determined in the same manner as described above.

Note that the description of the above embodiment is based on the light projecting body 1 that emits parallel light rays.
0 is used, but the same applies to a device that emits scattered light.

Furthermore, although the above embodiment has been described in the case where the aperture of the aperture diaphragm 50 is a pinhole, if a large resolution is required, the aperture may be a slit perpendicular to the optical axis of the optical system (invention Effects of this invention) This invention uses an optical system with a telescopic link on the object side, and the relationship between the object through the light receiving lens and the position of the light receiving body is an imaging relationship, so the size of the image is determined by the size of the object. It is independent of the intervention position, the image is clear, and external dimensions can be measured easily and accurately.

[Brief explanation of the drawing]

FIG. 1 is an optical system diagram showing an embodiment of the present invention, and FIG. 2 is an optical system diagram showing an embodiment of the present invention. FIG. 2 is a perspective view showing the appearance of an apparatus incorporating the optical system shown in FIG. 1; 3 and 4 are perspective views showing embodiments of the aperture stop of the present invention. FIG. 5 is an optical system diagram of the prior art. 10: Emitter 30: Receiver 40: Receiver lens 5
0: Aperture diaphragm

Claims (1)

[Claims] 1. A light projecting body that emits scattered light or parallel light, a light receiving lens disposed opposite to the light projecting body through a space for intervening the object to be measured, and an image-side focal position of the light receiving lens. an aperture diaphragm disposed in the space, and a photoreceptor disposed at a position substantially conjugate with the intervening position of the object to be measured in the space and the light-receiving lens, and having a light-receiving element array at least in the measurement dimension direction. Device