JPH0650715A - Optical displacement cage - Google Patents

Abstract

PURPOSE:To obtain an optical displacement gage suitably employed in the measurement of profile of a planar member including flatness thereof in which highly accurate measurement is realized through simple signal processing while fixing the optical displacement gage body even when the surface to be measured varies significantly. CONSTITUTION:When a surface 16 to be inspected is located on the outside of displacement measurable range, an optical beam is projected toward a cross point P between a passage of reference reflection light at a time when an optical beam is projected onto a predetermined reference surface located in the displacement measurable range and a set reference surface 15 for the surface 16 to be inspected located on the outside of the displacement measurable range. Fixing angles theta1, theta2 of first and second reflectors 9, 10 and fixing positions X, Y are regulated, respectively, by means of first and second drive mechanisms 11, 12 such that the light reflected on the cross point P1 impinges on a same position A0 as that of the reference reflection light on a detector 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical displacement meter suitable for use in measuring the flatness or other shape of a plate-shaped test material.

[0002]

2. Description of the Related Art FIG. 2 shows a typical means for performing distance measurement by a triangulation method using an optical displacement meter. In FIG. 2, reference numeral 1 is a light source such as a semiconductor laser, 2 is a light projecting lens that collects light emitted from the light source 1 and irradiates it onto a surface 7 or 8 of a material 3 to be inspected, and 5 is a light source 1 A light receiving lens for receiving reflected light from the surface 7 or 8 to be inspected from the surface 7 or 8 to be inspected through the light projecting lens 2.
Reference numeral 6 denotes a detector formed of a PSD (position detecting element) which receives reflected light from the surface 7 or 8 to be detected through the light receiving lens 5 and detects the incident position thereof.

When measuring the position of the surface 7 to be inspected using such an optical displacement meter, a light beam is emitted from the light source 1 through the projection lens 2 toward a point O ₀ on the surface 7 to be inspected. , The reflected light from the surface 7 to be inspected passes through the light receiving lens to the point a on the detector 6.
_It is incident on ₀ and is imaged.

If the position of the point a ₀ from the center of the light receiving lens 5 is read, the distance d between the light receiving lens 5 and the detector 6 is known, and therefore the line segment connecting the point O ₀ and the point a _0. Vertical line
The azimuth angle (line perpendicular to the surfaces 7 and 8 to be inspected) can be easily calculated. Since the irradiation angle of the irradiation light beam and the distance D between the light projecting lens 2 and the light receiving lens 5 are initial setting values, based on the above-mentioned azimuth angle obtained by the detector 6, the inspection is performed by the principle of triangulation. The distance L to the point O ₀ on the surface 7 can be obtained.

When the position of the material 3 to be inspected is changed and the irradiation point of the light from the light source 1 becomes the point O ₁ on the surface 8 to be inspected, the reflected light image forming position on the detector 6 is changed. becomes a _1, it is possible to determine the distance to the point O ₁ on the test surface 8 in the same manner as described above.

As described above, conventionally, in the shape measurement of the plate-shaped test material using the optical displacement meter, the light is directly projected onto the test material from the optical displacement meter projecting section (the light source 1, the projecting lens 2). The light reflected by the surface of the material to be inspected is received by the optical displacement meter light receiving portion (light receiving lens 5,
The light is received by the detector 6) and the reflection position on the test material is measured. This method is non-contact and does not require a special sensor copying device or the like for measurement, and is characterized by high-speed and highly-accurate measurement.

[0007]

By the way, in a general optical displacement meter, when the resolution is several μm to several tens μm, the measurable displacement range of the test material is several mm to several tens mm. The flatness of a plate-shaped material is measured by measuring the position of the corresponding point on the surface of the material (inspected surface) and using the plane of the surface plate, pass line, etc. as a reference, the difference between the position of that measurement point and the reference position. Is calculated, and the front, rear, left, and right of these displacement amounts are related to each other.

In the continuous measurement of the flatness of a series of materials conveyed on a roller table or the like, when the change in thickness between the materials exceeds the measurable range of this optical displacement meter, it is inspected. The measurement is performed from the back surface side of the test material so that the position of the measurement point on the material surface is not affected by the thickness.

However, in this case, the measured displacement includes not only the original displacement but also the displacement due to the strain of the material to be inspected due to gravity, so these are separated and only the original displacement is extracted. Therefore, the signal processing function must be enhanced and complex signal processing must be performed. As a result, not only is the device cost increased, but
There is a problem that the reliability of the measurement result is impaired due to the inadequacy and incompleteness of the signal processing algorithm.

Therefore, it is conceivable to dispose an optical displacement meter on the surface side of the material to be measured and measure the displacement immediately above the roll. In this case, the measurable displacement range is wide,
Use an optical displacement meter that is inferior in measurement accuracy, or
Since it is not possible to cover the fluctuation amount of the thickness of the test material of a hundred and several tens of mm within the measurable displacement range of the optical displacement meter, the mounting position of the optical displacement meter corresponds to the thickness of the test material. There is a need for a structure that attaches an optical displacement meter to a robust and precise moving device that can move accurately and quickly. In the case of the former, there is a problem that high measurement accuracy cannot be obtained, and in the case of the latter, the characteristic that a simple device configuration can be configured by using an optical displacement meter is impaired because of a precise moving device. There are problems such as being lost.

The present invention is intended to solve such a problem. Even when it is necessary to greatly change the measurement range due to the change in the thickness of the material to be inspected, the mounting position of the optical displacement meter main body can be changed. It is an object of the present invention to provide an optical displacement meter that realizes highly accurate measurement with a simple configuration and simple signal processing without modification.

[0012]

In order to achieve the above object, an optical displacement meter of the present invention comprises a light source and a light beam emitted from the light source, which is focused and irradiated on a surface to be inspected at a predetermined incident angle. A light projecting lens, a light receiving lens that receives the reflected light reflected from the surface to be inspected, and a detector that forms an image of the reflected light by the light receiving lens and detects an incident / image forming position of the reflected light. In the device for detecting the displacement of the surface to be inspected by the principle of triangulation based on the detection result of the detector, a first reflecting mirror arranged immediately after the light beam emitting side of the light projecting lens; A second reflecting mirror arranged between the light beam and the reflected light so as to face the first reflecting mirror;
A first drive mechanism that adjusts and drives the mounting angle of the reflecting mirror and a second drive mechanism that adjusts and drives the mounting angle and the mounting position of the second reflecting mirror, and the surface to be inspected has a predetermined displacement by the detector. If it is out of the measurable range, the path of the reference reflected light to the detector when the light beam is applied to the predetermined reference surface when the surface to be inspected is in the predetermined displacement measurable range, and The light beam is irradiated toward an intersection position of the surface to be inspected, which is outside the predetermined displacement measurable range, with the set reference surface, and reflected light from the intersection position is on the detector. A mounting angle of the first reflecting mirror so that the reference reflected light is incident on the same position as the incident position;
The mounting angle and the mounting position of the second reflecting mirror are adjusted by the first driving mechanism and the second driving mechanism, respectively, and the light beam is reflected by the first reflecting mirror and the second reflecting mirror. Irradiation is performed on the surface to be inspected.

[0013]

In the above-mentioned optical displacement meter of the present invention, when the surface to be inspected is outside the displacement measurable range by the detector, the predetermined reference plane is irradiated when the surface to be inspected is within the displacement measurable range. The light beam is directed toward the intersection of the path of the reference reflected light and the reference surface that is set outside the displacement measurable range, and the light reflected from the intersection is detected by the detector. The mounting angle of the first reflecting mirror, the mounting angle of the second reflecting mirror, and the mounting position are adjusted by the first drive mechanism and the second drive mechanism, respectively, so that the reference reflection light is incident on the same position as the incident position. However, by controlling the path of the light beam, the main body of the optical displacement meter can be fixed above the surface to be inspected, and it is possible to cope with a large change in the measurement surface while maintaining the high resolution of the optical displacement meter.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical displacement meter as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining its configuration and its operation. As shown in FIG. The optical displacement meter of the embodiment is basically similar to the conventional one, and the light source 1 such as a semiconductor laser and the light beam emitted from the light source 1 are projected on the surface 16 to be inspected of the plate material (inspection material) 13. A light projecting lens 2 that collects and irradiates the light at a predetermined incident angle, and a light receiving lens 5 that receives the reflected light reflected from the surface 13 to be tested.
And a detector 6 which forms an image of reflected light by the light receiving lens 5 and detects the incident / image forming position of the reflected light, and based on the detection result of the detector 6, the displacement of the surface 16 to be detected (described later) by the principle of triangulation. The displacement relative to the predetermined reference plane 14 or the nominal plate thickness plane 15) is detected.

In the optical displacement meter of this embodiment, the positions of the above-mentioned components (optical displacement meter main body) indicated by reference numerals 1, 2, 5 and 6 are not changed, and the first reflecting mirror 9 is newly added. ，
Second reflecting mirror 10, first driving mechanism 11, second driving mechanism 12
Has been added.

The first reflecting mirror 9 is arranged immediately after the light beam exit side of the light projecting lens 2, and the second reflecting mirror 10 is provided between the light beam and the reflected light so as to face the first reflecting mirror 9. It is located in. The first drive mechanism 11 adjusts and drives the mounting angle θ ₁ of the first reflecting mirror 9, and the second driving mechanism 12 controls the mounting angle θ ₂ of the second reflecting mirror 10 and the mounting positions X and Y. (Coordinate system with the center M ₁ of the first reflecting mirror 9 as the origin) is adjusted and driven.

However, when the surface 16 to be measured of the displacement measured by the optical displacement meter of this embodiment is within a predetermined displacement measurable range by the detector 6, the first reflecting mirror 9 emits light. Arranged parallel to the direction of the light beam from the lens 2,
The light beam from the light projecting lens 2 is irradiated onto the surface to be inspected without being reflected by the first reflecting mirror 9.

It should be noted that a predetermined reference surface (the surface to be detected 16 is the detector 6
The angle of incidence of the light beam with respect to the reflection point P ₀ on the surface 14 serving as the displacement reference of the surface 16 to be inspected when it is within the predetermined displacement measurable range (angle with respect to a line perpendicular to the predetermined reference plane 14) α Setting reference plane for the plate material 13 (test surface 1
When 6 is out of the predetermined displacement measurable range by the detector 6, a reflection point on a surface 15 which is a displacement reference of the surface 16 to be inspected and which is located above the predetermined reference surface 14 by T). The incident angle of the light beam with respect to P ₁ (angle with respect to the line perpendicular to the set reference plane 15) γ, and the detection angle of the reflected light at the reflection point P ₀ at the detector 6 (angle with respect to the line perpendicular to the predetermined reference plane 14) )
β is a value that is preset to be optimal in consideration of the surface properties of the plate material 13, the reflection / scattering state of the light beam, the intensity of the light beam, and the required measurement accuracy.

Further, the reflection direction Δα of the light beam at the first reflecting mirror 9 (the angle formed by the reflected light with the predetermined reference surface 14) and the distance from the predetermined reference surface 14 to the center point M ₁ of the first reflecting mirror 9. S is a value selected depending on the mounting space of the displacement gauge main body, the plate thickness range of the plate member 13, and the like.

Further, from the predetermined reference plane 14, the projection lens 2
The distance L to the line connecting the light receiving lens 5 with the light receiving lens 5, the horizontal distance D between the light projecting lens 2 and the light receiving lens 5, and the distance d between the light receiving lens 5 and the detector 6 can be measured by an optical displacement meter. It is a value peculiar to the optical displacement meter determined by the displacement range of 13 and the measurement accuracy.

With the above-described structure, in the optical displacement meter of this embodiment, first, the first reflecting mirror 9 is arranged in parallel with the light beam from the light projecting lens 2, so that the light beam is directed to the predetermined reference plane 14. The upper reflection point P ₀ is directly projected and irradiated, and the incident / imaged position A ₀ of the reflected light on the detector 6 at that time is obtained, and this position A ₀ is used as a reference for subsequent displacement measurement. At this time, the light beam passes through the light projecting lens 2 from the light source 1 and is irradiated at an incident angle α with respect to the reflection point P ₀ on the predetermined reference surface 14, and the reflected light at the reflection point P ₀ has an azimuth angle β. With light-receiving lens 5
And enters the detector 6.

The surface 16 to be detected of the plate member 13 is the detector 6
If it is within the predetermined displacement measurable range by
When the conventional displacement measurement is performed while the reflecting mirror 9 is arranged parallel to the light beam from the light projecting lens 2, and the surface 16 to be detected is outside the predetermined displacement measurable range by the detector 6. Is provided with a set reference surface 15 serving as a displacement reference of the new optical displacement meter above the predetermined reference surface 14 by T based on the nominal plate thickness of the plate member 13. Setting reference plane 15
May be the same as the nominal plate thickness surface of the plate member 13 (the surface to be inspected when the plate member 13 has a plate thickness equal to the nominal plate thickness), or the total nominal plate thickness of the plate member measured by the optical displacement meter. It may be provided as a surface that divides the covered range at appropriate intervals.

The case where the set reference surface is the same as the nominal plate thickness surface will be described. The intersection of the path of the reference reflected light and the nominal plate thickness surface 15 when the light beam is applied to the reflection point P ₀ of the predetermined reference surface 14. with light beams toward the position P ₁ is irradiated, as reflected light from the intersection P ₁ is incident on the same position as the incident-imaging position a ₀ of the reference light reflected on the detector 6,
A mounting angle theta ₁ of the first reflecting mirror 9, the mounting angle theta ₂ of the second reflecting mirror 10, the mounting position X, the first drive mechanism and a Y respectively 1
It is adjusted by the first and second drive mechanisms 12.

[0024] The mounting angle theta ₁ of satisfying the first reflecting mirror 9 as described above, the mounting angle theta ₂ of the second reflecting mirror 10, the mounting position X, and Y, are determined as follows. The center M ₁ of the first reflecting mirror 9 is arranged at a distance S above the predetermined reference plane 14 on the line connecting the center of the light projecting lens 2 and the reflection point P ₀ on the predetermined reference plane 14, and the predetermined reference The mounting angle θ _{1 with} respect to the surface 14 is set so that the light beam from the light projecting lens 2 is reflected by the center M ₁ of the first reflecting mirror 9 in the direction forming an angle Δα with the predetermined reference surface 14 according to the following equation (1). The first reflecting mirror 9 is set and adjusted by the first driving mechanism 11 at the mounting angle θ ₁ .

Θ ₁ = (90 ° −α−Δα) / 2 (1) where Δα is the light beam reflected by the first reflecting mirror 9 and the center M ₁ of the first reflecting mirror 9 as described above. Is an angle formed by a line drawn in parallel with the predetermined reference surface 14 and is "+" when the parallel line is reflected toward the projection lens 2 side, and "-" when the parallel line is reflected toward the predetermined reference surface 14 side. And

On the other hand, the second reflecting mirror 10 has the second driving mechanism 1
The 2, it is possible to adjust the mounting angle theta ₂ with respect to a predetermined reference surface 14 around the center M _2, the mounting position X of the center M ₂ with respect to the center M ₁ of the first reflection mirror 9 is disposed so as to be able to adjust the Y In order for the reflected light of the light beam from the second reflecting mirror 10 to enter the reflection point P ₁ on the nominal plate thickness surface 15 at a predetermined incident angle γ, and to pass through the path satisfying the above condition,
The mounting angle θ ₂ and the mounting positions X and Y are set by the following equations (2) to (4).

[0027]

[Equation 1]

However, the incident angle γ of the reflected light at the second reflecting mirror 10 with respect to the nominal plate thickness surface 15 of the plate member 13 located at a distance T above the predetermined reference surface 14 is the nominal value of the plate member 13 from the predetermined reference surface 14. The angle θ ₂ of the second reflecting mirror 10 can be fixed if it is not necessary to change it according to the distance T from the plate thickness surface 15.

By the way, in the case of continuously measuring the flatness of the plate member 13 whose nominal plate thickness surface 15 conveyed by a roller table or the like is above the predetermined reference surface 14 by T,
Mounting angle theta ₂ and the mounting position X of the mounting angle theta ₁ and the second reflecting mirror 10 of the first reflecting mirror 9 as described above, in a state of setting the Y, continuously at a predetermined sampling period while conveying the sheet material 13 The incident / imaged position A ₁ of the reflected light from the surface 16 to be detected on the detector 6 is detected, and the distance Δa (= A ₀ −A ₁ ) is sequentially calculated and fetched. Based on this distance Δa, the plate material 13
The displacement ΔT of the surface 16 to be measured with respect to the nominal thickness surface 15 can be obtained by using the following equation (5).

[0030]

[Equation 2]

Here, Δa is, as described above, the detector 6 at the reflection point P ₁ of the light beam on the nominal thickness surface 15 of the plate member 13.
Incident / imaging point A ₀ on top (reflection point P ₀ on the predetermined reference plane 14
Is also the point of incidence and image formation of reflected light from the plate material 13
Of the distance to the entrance-imaging point A ₁ of the reflected light from the reflection point P ₂ in the above test surface 16, the image forming point A ₁ of the reflection point P ₂ on the test surface 16 of the plate 13 When the reflection point P _{1 on} the nominal plate thickness surface 15 of the plate member 13 is on the right of the image formation point A ₀ , it is “+”, and when it is on the left, it is “−”.

Then, with respect to the displacement ΔT continuously obtained at a predetermined sampling period, the maximum adjacent ΔTmax and
The minimum ΔTmin is extracted, and the distance R of the plate material 13 from the position where the maximum value ΔTmax is obtained to the position where the next maximum value ΔTmax including the minimum value ΔTmin is obtained from the transport speed.
By (6), the flatness (steepness) λ of the test surface 16 of the plate material 13
To calculate.

Λ = (ΔTmax−ΔTmin) / R (6) As described above, according to the optical displacement meter of this embodiment, two reflecting mirrors 9 and 10 having a simple structure are added to a general optical displacement meter. By adjusting the mounting angles θ ₁ and θ ₂ and the mounting positions X and Y, the plate material can be used even when the optical displacement meter is used to greatly change the surface 16 to be measured while the optical displacement meter main body is fixed. It becomes possible to measure the intra-material variation of No. 13 with high accuracy. As a result, it is possible to easily install the optical displacement meter above the plate member 13 by selecting a measurement point that has the least influence of disturbance factors related to the displacement of the plate member 13 such as the displacement of the plate member 13 due to gravity or the vibration accompanying conveyance. In addition, since the correction of the measurement value by the detector 6 may be geometrically performed, an accurate measurement result can be obtained by simple signal processing.

Therefore, by using the optical displacement meter of the present embodiment, the flatness and other shapes of the plate material 13 to be inspected, which is conveyed by the roller table or the like, can be measured with a simple apparatus configuration and high measurement accuracy. There are advantages.

[0035]

As described above in detail, according to the optical displacement meter of the present invention, two reflecting mirrors having a simple structure are added to a general optical displacement meter and the mounting angle and the mounting position thereof are adjusted. As a result, even if the measurement range needs to be changed significantly due to changes in the thickness of the material to be tested, etc., it is possible to achieve high accuracy with a simple configuration and simple signal processing without changing the mounting position of the optical displacement meter main body. There is an effect that the measurement can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a configuration and an operation of an optical displacement meter as an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining the configuration and operation of a conventional optical displacement meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 2 light emitting lens 5 light receiving lens 6 detector 9 first reflecting mirror 10 second reflecting mirror 11 first driving mechanism 12 second driving mechanism 13 plate material (test material) 14 predetermined reference surface 15 nominal plate thickness surface (setting) Reference surface) 16 Test surface

Claims (1)

[Claims] 1. A light source, a light projecting lens for collecting and irradiating a light beam emitted from the light source onto a surface to be inspected at a predetermined incident angle, and receiving reflected light reflected from the surface to be inspected. The light receiving lens and a detector that forms an image of the reflected light by the light receiving lens and detects an incident / image forming position of the reflected light. Based on the detection result of the detector, the surface to be inspected is based on the principle of triangulation. An optical displacement meter for detecting the displacement of the first
A reflecting mirror, a second reflecting mirror arranged between the light beam and the reflected light so as to be opposed to the first reflecting mirror, and a first drive for adjusting and driving an attachment angle of the first reflecting mirror. A mechanism and a second drive mechanism for adjusting and driving the mounting angle and the mounting position of the second reflecting mirror, and when the surface to be detected is outside a predetermined displacement measurable range by the detector, The path of the reference reflected light to the detector when the predetermined reference surface is irradiated with the light beam when the surface to be inspected is within the predetermined displacement measurable range, and is outside the predetermined displacement measurable range The light beam is irradiated toward an intersection position of the surface to be inspected with the set reference surface, and reflected light from the intersection position is incident on the detector at the same position as the incident position of the reference reflected light. To do
The mounting angle of the first reflecting mirror and the mounting angle and mounting position of the second reflecting mirror are adjusted by the first driving mechanism and the second driving mechanism, respectively, and the light beam is adjusted to the first reflecting mechanism. An optical displacement meter which is reflected by a mirror and a second reflecting mirror and is irradiated onto the surface to be inspected.