JP2954817B2 - Optical extensometer camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera for an optical extensometer.

[0002]

2. Description of the Related Art In order to optically measure the physical elongation of a measuring object, images of a plurality of indices marked on the measuring object are formed on a position detector by an imaging optical system. The amount of elongation is calculated by measuring the amount of displacement of the image of the index before and after elongation, and forming and reading the image of the index of the measurement object on the position detector. An "optical extensometer camera" is used.

An optical extensometer camera basically includes an image forming optical system for forming an image of a plurality of indices integrated on a measuring object, and a position of the index image by the image forming optical system. And a position detector.

The number and interval of a plurality of indices marked on the object to be measured are set in accordance with the physical properties of the object to be measured. It is desirable that the tolerance for the change of the maximum interval between indices is as large as possible.

For example, as a position detector, the number of light receiving elements is one.
When using a 0000 line sensor having a total length of 70 mm and measuring the elongation at a resolution of 3.5 μm or more,
The imaging magnification of the imaging optical system needs to be 2 times or more. Then, in this case, if the maximum interval between the indices marked on the measurement object is 35 mm or more, elongation measurement is impossible in principle.

As a camera for an optical extensometer capable of measuring the amount of elongation even if the maximum interval between indices is large, Japanese Patent Laid-Open No.
JP-A-204106 and JP-A-63-61106 are well known.

The optical extensometer camera disclosed in Japanese Patent Laid-Open Publication No. Hei 4-20416 forms individual images of indices marked on an object to be measured on a position detector by a separate imaging optical system. Since imaging is required, an imaging optical system is required according to the number of indices, which increases the cost of the camera, and accurate measurement cannot be performed unless the imaging performance and magnification of each imaging optical system are accurately adjusted. There is a problem.

In the invention described in JP-A-63-61106, a pair of line sensors is used, and the position of the index image is detected for each line sensor. However, in practice, this may not be enough.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has a novel optical system which has a large tolerance for a change in the maximum interval of a plurality of indices integrated with an object to be measured. The purpose is to provide an extensometer camera.

[0010]

The camera for an optical extensometer according to the present invention is a "camera for measuring the physical elongation of an object to be measured".

[0011] The camera for an optical extensometer according to claim 1 is
It has an imaging optical system, three or more position detectors, and a case. The “imaging optical system” forms an image of a plurality of indices integrated with a measurement object whose elongation is to be measured on a predetermined plane at a predetermined magnification. The fact that the index is “integrated with the measurement target” means that the index may be marked on the measurement target, or that the LED or the like may be integrally added to the measurement target as an index. .

The "three or more position detectors" are arranged so that the light receiving surface is aligned with a predetermined plane on which the target image is formed by the image forming optical system, and the light receiving surfaces correspond to the direction of extension of the object to be measured. Then, they are closely arranged so as to be continuous. That is, three or more position detectors are provided on the same plane. "Case"
Holds an imaging optical system and three or more position detectors, and is immovable with respect to a measurement target at the time of measurement.

According to a second aspect of the present invention, there is provided an optical extensometer camera.
It has an imaging optical system, two or more position detectors, adjusting means, and a case. The “imaging optical system” forms an image of a plurality of indices integrated with a measurement object whose elongation is to be measured on a predetermined plane at a predetermined magnification. The “two or more position detectors” are provided such that the light receiving surface is aligned with the predetermined plane and the distance between the light receiving surfaces can be adjusted in the direction in which the measurement object extends.

The "adjustment mechanism" is a mechanism for adjusting the distance between the two or more position detectors. The adjustment by the adjustment mechanism may be performed manually, or may be automatically controlled from the outside.

The "case" holds the imaging optical system, two or more position detectors, and adjustment means, and is immovable with respect to the object to be measured during measurement.

The "position detector" used in the optical extensometer camera according to claim 1 or 2 includes:
The semiconductor position detector (PSD) disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 4-204106 may be used, or a line sensor may be used. "Line sensor" as position detector
Is used, the imaging magnification of the imaging optical system can be set according to "the desired resolution and the arrangement pitch of the light receiving elements of the line sensor".

The optical extensometer camera of the present invention may be integrally provided with a dedicated light source (various lamps, LEDs, LDs, etc.) for illuminating the object to be measured.

[0018]

In the present invention, since a plurality of position detectors are provided on the same plane which is the image plane of the imaging optical system, three or more position detectors can be provided continuously. Alternatively, it is possible to adjust the distance between two or more position detectors on the same plane.

[0019]

EXAMPLES Specific examples will be described below. FIG. 1 is a schematic illustration of an embodiment of an optical extensometer camera according to the first and third aspects of the present invention.

Reference numeral 1 denotes an imaging lens as an “imaging optical system”. Three line sensors indicated by reference numerals 2A, 2B, and 2C are used as “position detectors”. Reference numeral 3 indicates a case. Further, reference numeral 5 indicates an object to be measured. A "tensile force" is applied to the measurement object 5 in the vertical direction in the figure, and the elongation due to the tensile force is measured. Case 3
Indicates an end surface of a cross section of a plane parallel to the optical axis and the elongation measurement direction of the imaging lens 1.

The imaging lens 1 is a fixed focus lens in this embodiment, and has an imaging surface 4 (predetermined plane) indicated by a chain line.
An image of a predetermined magnification is formed on the image. That is, at the time of measurement, the position of the case 3 is kept stationary with respect to the measurement object 5 so that such an image formation relationship is established. The three line sensors 3A, 3B, 3C are arranged such that the arrangement lines of the light receiving elements are arranged in the vertical direction in the figure (corresponding to the direction in which the measurement object 5 extends).
The light receiving surfaces of the line sensors are arranged close to each other, and coincide with the imaging plane 4.

Although two indices A and B are marked on the measurement object 5, light from the index A is not formed in a state where no tensile force is applied, that is, in a natural state of the measurement object 5. The position A ₁ on the light receiving surface of the line sensor 2A by the image lens ₁
Image. Similarly, in the natural state of the measuring object 5, the light from the index B forms an image at the position B ₁ on the light receiving surface of the line sensor 2 C by the imaging lens 1. The output of each of the line sensors 2A, 2B, 2C is sent as a "camera output" to a not-shown arithmetic system (computer or the like).

When one end (upper end in the figure) of the measuring object 5 is fixed and a tensile force is applied to the other end, the measuring object 5 is stretched downward in the figure, and the indices A and B are denoted by reference numerals, respectively. A 'and B' are displaced to the positions indicated by A 'and B', respectively.
Displaced on A, 2C to position: A ₂ , B ₂ .

Therefore, from the outputs of the line sensors 2A and 2C before and after the action of the tensile force, the displacement amounts ΔA and ΔB of the index image accompanying the elongation of the measuring object 5 can be detected. Generally, ΔA <ΔB, and the “elongation amount: Δ between the indices A and B”
L ”is the imaging magnification of the imaging lens 1: M and the displacement amount: Δ
For example, it can be obtained by calculating the quantity: (ΔB−ΔA) / M using A and ΔB. Further, ΔL
And the interval L between the indices A and B in the natural state, the elongation can be calculated as ΔL / L, and the Young's modulus and the like can be calculated from these and the tensile force.

In the example described, the line sensor 2B
Is not used for the calculation, the line sensor 2B may be turned off if necessary. Conversely, when the interval between the indices on the measurement target is small, the elongation measurement may be performed only with the line sensor 2B. In such a case, the line sensor 2B may be used as necessary.
The measurement may be performed with A and 2C turned off. Depending on the positional relationship between the indices A and B, the line sensors 2A and 2A
Needless to say, the measurement can be performed by B or the line sensors 2B and 2C.

As the line sensors 2A, 2B, and 2C, the aforementioned "number of light receiving elements: 10000, total length 70 mm" is used, and if the imaging magnification of the imaging lens 1 is set to 2, the indices A and B are obtained. The elongation between them can be measured at a resolution of 3.5 μm. At this time, since the length of the light receiving surface of the position detector in the “direction of extension of the measurement object 5” is 210 mm, the maximum length of the index interval that can be imaged in this range is 10 mm.
It is 5 mm, and even if there is a margin, the elongation of the object to be measured can be measured up to the index interval: 90 mm, and the lower limit of the index interval is not limited. If necessary, the maximum number of measurable index intervals can be further increased by increasing the number of arrayed position detectors.

FIG. 2A shows an embodiment of an optical extensometer camera according to the second and third aspects. Reference numeral 10 denotes an imaging lens as an imaging optical system; reference numerals 21 and 22 denote line sensors as position detectors; reference numeral 30 denotes a case;
0 indicates an adjusting mechanism.

The imaging lens 10 is held by the case 30 so that the image of the index of the object to be measured (not shown in FIG. 2) is formed on the image plane 40 during measurement. Line sensor 2
Reference numerals 1 and 22 denote a light-receiving surface coincident with the image-forming surface 40, the arrangement line of the light-receiving elements is set in the direction of the extension of the object to be measured (vertical direction in the drawing), and the distance between the light-receiving surfaces is set to the extension of the object. And held by the adjustment mechanism 60.

The adjusting mechanism 60 in this embodiment is similar to that of FIG.
This will be described with reference to FIG. The line sensor 21 is fixedly held by the holder 200, and the line sensor 22 is fixedly held by the holder 300. Holders 200, 30
Numeral 0 is supported by a support mechanism (not shown) and is slidable in the left-right direction in the figure (corresponding to the up-down direction in FIG. 2A), and racks are formed at end portions close to each other. The pinion 62 is engaged.

The pinion 62 is an adjustment knob 61 shown in FIG.
, So that the line sensors 21 and 22 can be manually turned by the adjustment knob 61.
Can be adjusted in the “direction of elongation of the object to be measured”. Thus, the line sensors 21 and
Since the distance between the two light receiving surfaces can be adjusted, the positions of the light receiving surfaces of the line sensors 21 and 22 can be set to the positions most suitable for measurement in accordance with the distance between the indices on the measurement object. Assuming that the maximum width of the distance adjustment is X, the light receiving surface length of the line sensors 21 and 22 is Y, and the imaging magnification of the imaging lens 10 is M, the maximum index width that can be received by the line sensors 21 and 22 is (X + 2Y) / M, and it is possible to measure a very large index interval. There is no limit to the lower limit of the index interval that can be measured.

In the above description, the case where the number of displaceable position detectors is two has been described. However, three or more position detectors may be displaceable, or three or more position detectors may be used as in the embodiment of FIG. When using the line sensors 2A, 2B, and 2C, the line sensor 2B may be fixed, and the line sensors 2A and 2C may be displaceable in the vertical direction in the drawing with respect to the line sensor 2B.

As the image forming optical system, a variable focus lens or a lens whose focal length can be switched can be used in place of the above-mentioned fixed focus lens. In this case, measurement can be performed according to the measurement object or the index interval. Resolution and imaging magnification suitable for measurement can be set.

[0033]

As described above, according to the present invention, a novel optical extensometer camera can be provided. Since the optical extensometer camera of the present invention has the above-described configuration, it is possible to measure the elongation of a wide range of measurement objects having different index intervals. In the optical extensometer camera according to the second aspect, a small number of position detectors can cope with a large range of the index interval.

The optical extensometer camera of the present invention has a simple structure and can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of the invention described in claims 1 and 3;

FIG. 2 is a diagram for explaining one embodiment of the invention described in claims 2 and 3;

[Explanation of symbols]

 Reference Signs List 1 imaging lens (imaging optical system) 2A, 2B, 2C line sensor (position detector) 3 case 4 imaging surface (predetermined plane) 5 measurement object A, B index

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuya Sasaki 1-31 Kurobeoka, Hiratsuka-shi, Kanagawa, Japan Tobacco Inc. Production Technology Development Center (72) Inventor Shigemi Masuno Kurobe, Hiratsuka-shi, Kanagawa Hill 1-31, Japan Tobacco Inc., Production Technology Development Center (72) Inventor Masaya Yabe 639 Horiuchi, Hayama-cho, Miura-gun, Kanagawa Prefecture (72) Inventor Toshiyuki Inoue 4,600 Nakasu, Oaza, Suwa-shi, Nagano Prefecture・ Nisshin Koki Co., Ltd. (72) Inventor Toshihiro Ikukuma, Nagano Prefecture, Suwa City, Oaza 4600 Nakasu ・ Nisshin Machine Co., Ltd. Inside Machine Co., Ltd. (72) Inventor Tsutomu Iida 4600, Nakasu, Suwa-shi, Nagano, Nissin Machine Co., Ltd. Inside Machine Co., Ltd. (72) Yasuo Komatsu Shimosu, Suwa-gun, Nagano Prefecture 5329-cho, Sankyo Seiki Seisakusho Co., Ltd. (56) References JP-A-4-204106 (JP, A) JP-A-63-61106 (JP, A) JP-A-4-301710 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 11/00-11/30 102 G01N 3/00-3/62 G03B 15/00

Claims (3)

(57) [Claims] An image forming optical system for forming an image of a plurality of indices integral with a measurement object whose elongation is to be measured on a predetermined plane at a predetermined magnification; And three or more position detectors which are closely arranged so that their light receiving surfaces correspond to each other in the direction of extension of the object to be measured, and the imaging optical system and three or more position detectors. An optical extensometer camera having a case that holds and is immovable with respect to an object to be measured during measurement. 2. An image forming optical system for forming images of a plurality of indices integral with a measurement object whose elongation is to be measured on a predetermined plane at a predetermined magnification, and a light receiving surface corresponding to the predetermined plane. And two or more position detectors arranged so that the distance between the light receiving surfaces can be adjusted in the direction of extension of the measurement object; an adjustment mechanism for adjusting the distance between the two or more position detectors; and the imaging optics An optical extensometer camera having a system, two or more position detectors, and an adjusting mechanism, and having a case that is immovable with respect to an object to be measured during measurement. 3. A camera for an optical extensometer according to claim 1, wherein the position detector is a line sensor, the imaging magnification of the image forming optical system is a desired resolution, and the arrangement of light receiving elements of the line sensor. An optical extensometer camera, wherein the camera is set according to a pitch.