JP2004205308A - Displacement measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement measuring instrument for sharply reducing assembly/adjustment manpower since a lighting system for irradiating a measuring object and an imaging optical system for measuring reflected light from the measuring object are downsized/integrated, performing clear guide mark projection on the measuring object, and performing irradiation with brightness enough for measurement. <P>SOLUTION: This displacement measuring instrument for optically measuring displacement of the measuring object, is characterized at least in that the lighting system and the imaging optical system are mounted on a common base. The lighting system includes a light guide for transmitting output light of a light source and a condensing lens for condensing the output light of the light guide to irradiate the measuring object. The optical system forms an image of reflected light of the measuring object on the surface of a light receiving sensor. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a displacement measuring device that optically measures vibration, position change, speed, and the like of various devices, and more particularly, to improvement of an illumination system.
[0002]
[Prior art]
The applicant has filed, for example, Japanese Patent Application Laid-Open No. 2001-241919 as a displacement measuring device capable of performing high-speed and high-accuracy measurement in a non-contact manner without limiting the measurement object.
[0003]
FIG. 6 is a block diagram showing a configuration example of such a conventional apparatus. The measurement object 1 is irradiated with measurement light from the illumination system 2. The reflected light from the measurement target 1 is incident on the image sensor unit 4 via the imaging optical system 3.
[0004]
Here, the positional relationship between the measurement target 1, the imaging optical system 3, and the image sensor unit 4 is such that the measurement target 1 moves and displaces along the arrangement direction of the elements of the image sensor unit 4 (X-axis direction) as shown in FIG. It shall be.
[0005]
The illumination system 2 narrows the wavelength of the illumination light using infrared light or the like to eliminate the influence of external light, and provides a filter on the front surface of the image sensor unit 4 for passing only the wavelength.
[0006]
As the imaging optical system 3, a telecentric optical system in which the imaging magnification does not change depending on the distance from the measurement target 1 is used.
[0007]
The image sensor unit 4 is an image sensor for reading a real image formed by the image forming optical system 3, and uses a CCD linear image sensor in which pixels are arranged in a line and has a function of retaining image data by one exposure. Note that the image sensor unit 4 has a mechanical or electrical shutter function.
[0008]
The image data captured by the image sensor unit 4 is sequentially read out to the A / D converter 6 according to the clock applied from the clock generation unit 5 and is converted into digital data. Output data of the A / D converter 6 is taken into the signal processing unit 7.
[0009]
The signal processing unit 7 calculates the displacement of the measurement target 1 based on the image data converted and output from the A / D converter 6, and uses, for example, a DSP (digital signal processor).
[0010]
The reference image storage unit 8 stores reference state image data for calculating the displacement amount of the measurement target 1, and the measurement image storage unit 9 stores the displacement state image data for calculating the displacement amount of the measurement target 1. Is stored.
[0011]
The calculation result of the signal processing unit 7 is converted to an analog signal by the D / A converter 10 and output to the outside, and is displayed on the display 11 digitally or as an analog image.
[0012]
In such a configuration, a light amount distribution corresponding to the measurement target 1 appears on the image sensor unit 4, and an analog voltage signal proportional to the light amount of each pixel is sequentially output from the output terminal of the image sensor unit 4 as shown in FIG. Is output. The analog voltage signal is sequentially converted into digital data by the A / D converter 6, the image data So of the measurement target 1 in the reference state is stored in the reference image storage unit 8, and the measurement target image S in the measurement state is measured. It is stored in the image storage unit 9.
[0013]
Thereafter, the signal processing unit 7 compares the image data So of the measurement target 1 and the image data of the measurement target image S in the reference state as shown in FIG. The actual displacement of the measuring object 1 is determined by multiplying the displacement x by the optical magnification.
[0014]
By the way, as shown in FIG. 10, the conventional illumination system includes a light source 12 such as halogen and a plurality of light guides 14 composed of an optical fiber bundle for guiding the output light of the light source 12 to the condenser lens unit 13. Have been. As shown in FIG. 11, the condensing lens unit 13 includes a lens barrel 13b having one end into which an end of a light guide 14 is inserted and fixed, and the other end having a lens 13a mounted thereon.
[0015]
12A and 12B are enlarged views of the periphery of the condensing lens unit 13, where FIG. 12A is a configuration diagram viewed from above, FIG. 12B is a cross-sectional view taken along line AA of FIG. FIG. 4 is an explanatory view of irradiation on a measurement object 1 as viewed from above.
[0016]
Each condenser lens unit 13 is attached to the holder 15 at a predetermined angle so that each output light 13c irradiates the same location of the measurement target 1 (see (C)) (see (A)). ). Here, the number of sets of the condenser lens unit 13 and the light guide 14 can be increased or decreased according to the amount of light required for the measurement of the measurement target 1. In the example of FIG. 12, a total of four sets are arranged at each corner forming a square. ing. An imaging lens 16 for detecting an image irradiated on the measurement target 1 is provided at an intersection position connecting these four sets in a diagonal direction.
[0017]
In addition, a shield plate 13e having a rectangular slit 13d for projecting the guide mark GM onto the measurement target 1 is provided near the ends of two sets of the light guides 14 among these four sets. These guide marks GM are used for positioning and focusing between the measuring object 1 and the displacement measuring device MA as shown in FIG.
[0018]
FIG. 12C shows a state in which the two sets of guide marks GM overlap as one pattern, the measurement object 1 and the displacement measuring device are arranged in parallel, and the focus is accurately adjusted. ing. On the other hand, when the focus is out of focus, two guide marks GM are projected as shown in FIG. 14A, and when the measurement object 1 and the displacement measurement device are not arranged in parallel, as shown in FIG. As shown in (B), the inclined guide mark GM is projected.
[0019]
[Patent Document 1]
JP 2001-241919 A
[0020]
Patent Literature 1 discloses an invention relating to a displacement measurement device capable of performing high-speed, high-precision measurement without contact without limiting the measurement target.
[0021]
[Problems to be solved by the invention]
However, in the illumination system of such a conventional displacement measuring device, since the condenser lens unit 13 is attached at a predetermined angle to the holder 15, the number of components increases and the size of the entire device is reduced by this angle. However, there is a problem that it is difficult to reduce the size because the size becomes large.
[0022]
In addition, each condenser lens unit 13 attached to the holder 15 needs to be positioned so that the same place of the measurement target 1 is illuminated in the same area in the same range. It is inevitable that the number of steps will be increased.
[0023]
If the illumination light of the measurement target 1 needs brightness, the number of sets of the condenser lens unit 13 and the light guide 14 to be irradiated is increased. However, since the light guide 14 is in a cable shape, When the number of sets increases, the light guides 14 become entangled with each other, and the operability decreases. Then, the weight increases in proportion to the number of sets of the condenser lens unit 13 and the light guide 14.
[0024]
As a method of increasing the number of sets of the condenser lens unit 13 and the light guides 14, it is conceivable to increase the number and the number of the light guides 14. In order to increase the number of the light guides 14, the number of the light sources 12 must be increased.
[0025]
Since the condenser lens portion 13 has a structure in which the tip of the light guide 14 is inserted into the lens barrel 13b, it is difficult to provide a shutter mechanism for shielding light as necessary. Even if a shutter mechanism can be provided in the lens barrel 13b, it is even more difficult to control the opening and closing of the lights of the plurality of condenser lenses 13 at the same time.
[0026]
In the case of irradiating the guide mark GM as shown in FIG. 12, the mounting position of the light guide 14 with respect to the condenser lens is different for the guide mark and the illumination. When the guide mark GM is illuminated, the light guide tip position is the in-focus position, but in the case of illumination, the light guide tip position is the position at which the maximum illuminance is obtained, and adjustment must be performed according to the application.
[0027]
Further, according to the configuration of FIG. 12, the light guide 14 attached to the holder 15 includes a light guide 14 having a shielding plate 13e at the tip and a light guide having no shielding plate 13e. As a result, since the light of the light guide 14 without the shielding plate is also irradiated to the same irradiation position as the guide mark GM, the contrast of the guide mark GM is reduced, and the visibility of the guide mark GM is reduced.
[0028]
Further, when the position of the measurement object 1 and the displacement measuring device MA are adjusted as shown in FIG. 13 using the guide mark GM, the guide for the focusing along the Z-axis direction and the angle adjustment about the Z-axis as the center of rotation. The mark GM sufficiently functions as a guide, but the guide mark GM hardly functions as a guide for angle adjustment about the X-axis and the Y-axis as a rotation center. This is because the shield plate 13e is provided on the same side with respect to the imaging lens 16, and the attitude change between the guide marks GM is small, and the guide mark GM itself is not clear enough to discriminate the small change. It depends.
[0029]
The present invention focuses on these problems, and its object is to reduce the number of assembling adjustment steps by integrating the illumination system for irradiating the object to be measured and the imaging optical system for measuring the reflected light of the object to be measured. An object of the present invention is to provide a displacement measuring device that can reduce the number of projections, can project a clear guide mark on a measurement target, and can irradiate with sufficient brightness for measurement.
[0030]
[Means for Solving the Problems]
The invention of claim 1, which achieves such an object,
A displacement measurement device that optically measures a displacement amount of a measurement target,
at least,
An illumination system including a condensing lens for condensing the output light of the light source and irradiating the measurement target,
An imaging optical system that forms reflected light of the measurement target on the light receiving sensor surface,
It is characterized by being attached to a common base.
[0031]
According to a second aspect of the present invention, in the displacement measuring device according to the first aspect,
A light guide for transmitting output light of the light source to the condenser lens is included.
[0032]
According to a third aspect of the present invention, in the displacement measuring device according to the first or second aspect,
The condensing lens is characterized in that a plurality of single lenses are two-dimensionally arranged around the imaging optical system.
[0033]
According to a fourth aspect of the present invention, in the displacement measuring device according to the second or third aspect, an end position of the light guide and a center of each single lens are adjusted and arranged so as to illuminate the same position of the measurement target. It is characterized by having.
[0034]
As a result, the illumination system for irradiating the object to be measured and the imaging optical system for measuring the reflected light of the object to be measured are mounted and integrated on a common base, so that the size can be reduced, and the number of assembling and adjusting steps can be greatly reduced.
[0035]
According to a fifth aspect of the present invention, in the displacement measuring device according to the first or second aspect,
The illumination system includes a guide mark irradiation system that irradiates a plurality of guide marks to the same position of the measurement target.
[0036]
According to a sixth aspect of the present invention, in the displacement measuring device according to the fifth aspect,
The illumination system includes a shutter that selectively opens and closes output light of an illumination system other than the guide mark.
[0037]
According to a seventh aspect of the present invention, in the displacement measuring device according to the fifth or sixth aspect,
The guide mark irradiation system has an aperture stop.
[0038]
The invention according to claim 8 is the displacement measuring device according to any one of claims 5 to 7,
The distance between the end of the light guide and the condenser lens in the guide mark irradiation system and another irradiation system is different.
[0039]
As a result, a clear guide mark can be projected on the measurement object, and the measurement target can be irradiated with sufficient brightness.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an example of an embodiment of the present invention, in which (A) is a side view and (B) is a front view of a block 18. Output light from a light source (not shown) such as halogen, metal halide, xenon, or a light emitting diode is guided to a light block 18 via a light guide 17 in which a number of optical fibers are bundled. The light block 18 is attached to a base (not shown).
[0041]
When a light emitting diode is used as a light source, the light guide 17 can be omitted by directly attaching the light emitting diode to the light block 18.
[0042]
The light block 18 is, for example, an aluminum block formed in a predetermined shape, and has a stepped concave portion 19 in the vertical direction at the center of the front surface. Near the upper and lower ends of the stepped concave portion 19, an irradiation port 20 for irradiating the measurement target 1 with the output light of the light source guided by the light guide 17 is provided. A shielding plate 21 is provided on the front surface of these irradiation ports 20, and the shielding plate 21 is provided with an opening 22 for projecting a guide mark GM (rectangular in FIG. 1) having a predetermined shape.
[0043]
Irradiation ports 23 for irradiating the measurement target 1 with the output light of the light source guided by the light guide 17 are also provided near the upper and lower ends of both sides of the front surface of the light block 18 and at the center. The distal end portion of the light guide 17 is branched and inserted and fixed to the irradiation port 20 and the irradiation port 23. In the center of the stepped concave portion 19, an imaging optical system 24 for imaging the reflected light of the measurement target 1 on a light receiving sensor surface (not shown) is provided.
[0044]
The difference in the position of the irradiation port 20 in the stepped concave portion 19 of the light block 18 and the position of the irradiation port 23 on both sides of the front surface causes a difference in the distance from the condenser lens 28, and the irradiation light on the measurement target 1 is The guide mark GM output from the irradiation port 20 can be sharply formed at the focal position, and the output light from the other irradiation ports 23 can be set and adjusted to have the maximum brightness.
[0045]
Further, on the front surface of the light block 18, a shutter 25 is movable vertically along a guide pin (not shown) as shown in FIGS. 2A and 2B. It is semi-fixed so as to sandwich both sides. The shutter 25 has a plurality of holes 26 corresponding to the irradiation port 23 and a plurality of oval holes 27 corresponding to the opening 22 of the shielding plate 21.
[0046]
When the shutter 25 is raised as shown in FIG. 2A, the plurality of holes 26 corresponding to the irradiation port 23 completely expose the irradiation port 23, and as shown in FIG. The irradiation port 23 is provided so as to be completely hidden when lowered.
[0047]
The plurality of oval holes 27 corresponding to the openings 22 of the shield plate 21 are provided so as to always expose the openings 22 of the shield plate 21 regardless of the vertical movement of the shutter 25. Further, the shutter 25 is provided with a hole for penetrating the imaging optical system 24 so as not to hinder the movement in the vertical direction, but is not shown. That is, FIG. 2A shows a state where the shutter 25 is opened, and FIG. 2B shows a state where the shutter 25 is closed. Not only the oval hole 27 but also a notch or a large hole may be provided.
[0048]
The shutter 25 functions to irradiate the measurement target 1 with the guide mark GM more clearly. By closing the shutter 25 as shown in FIG. 2B at the time of adjusting the alignment between the measurement object 1 and the displacement measuring device MA, the output light of the irradiation port 23 that does not irradiate the guide mark GM is blocked and the measurement object 1 is blocked. Since only the guide mark GM is emitted from the opening 22 of the plate 21, a clearer guide mark GM can be obtained as compared with the related art.
[0049]
After the alignment adjustment, by opening the shutter 25 as shown in FIG. 2A, the guide mark GM is radiated from the opening 22 of the shielding plate 21 and the output light of the irradiation port 23 is also radiated to the measurement target 1, and the measurement is performed. The brightness required for measuring the displacement of the object 1 is obtained.
[0050]
A condensing lens 28 is provided on the front surface of the light block 18 including the shutter 25 so as to maintain a predetermined distance necessary for irradiating the measurement target 1. Specifically, the upper portion is attached to the light block 18 via an attachment member (not shown), and the lower portion is fixed to a base (not shown).
[0051]
Thus, the light block 18 is fixed to the base, the imaging optical system 24 is fixed to the light block 18, the shutter 25 is semi-movably fixed to the light block 18, and the condenser lens 28 is fixed to the light block 18 and the base. Since the aperture stop 32 is fixed to the surface facing the irradiation port 20, the size can be reduced, the number of components can be reduced, and the number of man-hours for assembling and adjusting can be significantly reduced.
[0052]
In addition, a camera for measurement may be fixed to the base as necessary. Since the light source irradiation system and the measurement system can be housed and integrated in a common case, work operability during measurement is improved. Can be enhanced.
[0053]
FIG. 3 is a configuration diagram showing a specific example of the condenser lens 28. (A) shows a state in which a square lens 30 is formed by processing a round lens 29 shown by a two-dot chain line as shown by a solid line, and (B) shows a state in which eight square lenses are formed around an imaging optical system 24. This shows a state in which the two surfaces are two-dimensionally arranged and the opposing surfaces are bonded together. (C) shows the positional relationship between the irradiation ports 20 and 23 provided in the light block 18 and the center P of the square lens 30. That is, each square lens 30 is attached such that its center P is located at a point offset in the direction of the imaging optical system 24 with respect to the irradiation ports 20 and 23 provided in the light block 18.
[0054]
As described above, since the center P of the square lens 30 is mounted so as to be located at a point offset in the direction of the imaging optical system 24 with respect to the irradiation ports 20 and 23 provided in the light block 18, The output light of the condenser lens 28 irradiates the same position of the measurement target 1. If the tip positions of the light guides are different, light can be collected at the same position by shifting the lens optical axis position of the square lens 30.
[0055]
In the above embodiment, square lenses are arranged in a grid pattern around the imaging lens, but condensing lenses may be arranged radially around the imaging lens.
[0056]
Further, the shape of one lens may be hexagonal, and the condensing lens may be arranged in a honeycomb shape around the imaging lens.
[0057]
Further, as shown in FIG. 4, the lenses may be arranged at an angle so as to face the irradiation position. According to such a configuration, the same position can be irradiated without offsetting the lens center and the light guide tip. In the present invention, it is assumed that a plurality of lenses are two-dimensionally arranged when viewed from the front also in the condenser lens of FIG.
[0058]
As the condenser lens 28, the same type of lens having the same focal length may be combined, or a plurality of types of lenses having different focal lengths may be combined.
[0059]
The material of the condenser lens 28 may be optical glass or plastic.
[0060]
The manufacture of the condenser lens 28 is not limited to the bonding of a single lens, and for example, an integral molding is also possible.
[0061]
FIG. 5 is an explanatory diagram of a guide mark irradiation system. (A) is an aperture stop 32 having an aperture 31 for limiting peripheral light having a large aberration, and is opposed to the irradiation port 20 forming the guide mark irradiation system among the square lenses 30 forming the condenser lens 28. It is provided on the facing surface of the square lens 30. The aperture stop 32 functions to project a clear guide mark on the measurement target 1. The guide mark irradiation system is provided so as to have a symmetrical positional relationship (vertical direction in the present embodiment) with respect to the imaging optical system 24.
[0062]
(B), (C) is a projection example figure of the guide mark GM. (B) shows the positional relationship between the measurement object 1 around the Y-axis in FIG. 13 and the displacement measuring device MA. If the positional relationship between the two is shifted, the projection pattern of the two guide marks GM becomes “C”. Character. (C) shows the positional relationship between the measurement object 1 around the X-axis in FIG. 13 and the displacement measuring device MA. If the positional relationship between them is shifted, the size of the projected pattern of the two guide marks GM is changed. Will be different.
[0063]
By referring to the projection patterns of these two guide marks GM, the positional relationship between the measuring object 1 and the displacement measuring device MA can be quickly adjusted to an optimum state suitable for measurement.
[0064]
【The invention's effect】
As described above, according to the present invention, the illumination system for irradiating the object to be measured and the imaging optical system for measuring the reflected light of the object to be measured can be integrated in a small size, and the number of man-hours for assembling and adjusting can be greatly reduced. This makes it possible to realize a displacement measuring device which can project a clear guide mark and irradiate with sufficient brightness for the measurement, and is suitable for various displacement measurements such as a recording paper feed amount measurement in a printer.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a shutter 25 in FIG.
FIG. 3 is a configuration diagram showing a specific example of a condenser lens 28 in FIG.
FIG. 4 is a configuration diagram showing another example of the condenser lens 28.
FIG. 5 is an explanatory diagram of a guide mark irradiation system of FIG. 1;
FIG. 6 is a block diagram illustrating a configuration example of a conventional device.
FIG. 7 is an operation explanatory diagram of FIG. 6;
FIG. 8 is an explanatory diagram of the image calculation processing of FIG. 6;
FIG. 9 is an explanatory diagram of the image calculation processing of FIG. 6;
FIG. 10 is a configuration diagram of a conventional illumination system.
11 is a configuration diagram of the condenser lens unit 13 of FIG.
FIG. 12 is an enlarged view around the condenser lens unit 13 of FIG.
FIG. 13 is an explanatory diagram of positioning and focusing between the measurement object 1 and the displacement measuring device MA.
FIG. 14 is an explanatory diagram of a conventional guide mark.
[Explanation of symbols]
17 Light guide 18 Block 19 Stepped recesses 20, 23 Irradiation port 21 Shielding plate 22 Opening 24 Imaging optical system 25 Shutter 26 Hole 27 Oval hole 28 Condensing lens 29 Round lens 30 Square lens 31 Opening 32 Aperture stop

Claims (8)

A displacement measurement device that optically measures a displacement amount of a measurement target,
at least,
An illumination system including a condensing lens for condensing the output light of the light source and irradiating the measurement target,
An imaging optical system that forms reflected light of the measurement target on the light receiving sensor surface,
Displacement measuring device mounted on a common base. The displacement measurement apparatus according to claim 1, wherein the illumination system includes a light guide that transmits output light of the light source to a condenser lens. The displacement measuring apparatus according to claim 1, wherein the condenser lens includes a plurality of single lenses arranged two-dimensionally around the imaging optical system. 4. The displacement measuring device according to claim 2, wherein an end position of the light guide and a center of each single lens are adjusted and arranged so as to irradiate the same position of the measurement target. The displacement measuring apparatus according to claim 1, wherein the illumination system includes a guide mark irradiation system that irradiates a plurality of guide marks to the same position of the measurement target. The displacement measurement apparatus according to claim 5, wherein the illumination system includes a shutter that selectively opens and closes output light of an illumination system other than the guide mark. 7. The displacement measuring apparatus according to claim 5, wherein the guide mark irradiation system has an aperture stop. 8. The displacement measuring apparatus according to claim 5, wherein a distance between an end portion of the light guide and a condenser lens in the guide mark irradiation system and another irradiation system is different.

Images