JP2010019836A - Displacement tilt sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement tilt sensor which can measure a position displacement and an angle displacement of an object to be detected at the same time even when a light source is used both as a light source of an optical system for measuring a displacement and a light source of an optical system for measuring an angle, namely even when one light source is used as the light source of the displacement tilt sensor. <P>SOLUTION: The displacement tilt sensor includes an optical system including a projecting part for outputting measuring lights to an area to be detected and a light receiving part for receiving the measuring lights reflected from the area to be detected. The projecting part includes a projecting element such as a light emitting diode, a projecting lens and means for thinning the measuring lights outputted from the projecting element. The displacement tilt sensor further includes an angle detecting part and a displacement detecting part. The angle detecting part includes an angle measuring light receiving lens and an angle measuring light receiving element. The displacement detecting part includes a displacement measuring light receiving lens and the displacement measuring light receiving lens. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a displacement tilt sensor, and more particularly to a displacement tilt sensor for measuring the displacement and angle of a detection object having a substantially mirror-reflecting surface such as a specular object, a glossy material object, or a metal object.

  2. Description of the Related Art Conventionally, a displacement sensor that includes a displacement measurement light projecting unit and a displacement measurement light receiving unit and detects the displacement of a detection object is known.

  However, the detected object may not only be displaced, but also the detected object may be tilted. At that time, the light receiving spot of the light receiving element changes not only when the detected object is displaced but also when the angle is inclined. That is, the light receiving spot of the light receiving element changes not only by the amount of displacement of the detected object but also by the amount of inclination of the detected object, and even if the amount of movement of the light receiving spot on the light receiving element is the same, the light receiving spot is tilted to the detected object. The actual amount of displacement of the detected object differs depending on whether there is no tilt, when there is a tilt, and depending on the amount of tilt. For this reason, when detecting the displacement of a detection object that may be tilted, a measurement error occurs in the displacement amount due to the inclination of the detection object, which causes a decrease in measurement accuracy of the displacement sensor.

  Therefore, for example, as shown in Patent Document 1 and as shown in FIG. 6, as shown in FIG. 6, a displacement measurement light source unit 82 that emits displacement measurement light 81 toward the detection region, and a displacement measurement light 81 reflected by the detection region. A displacement measurement optical system including a displacement measurement light receiving unit 83, an inclination measurement light source unit 92 that emits inclination measurement light 91 toward the detection region, and an inclination measurement light reflected by the detection region. And a tilt measuring optical system for detecting the tilt of the object, which measures the displacement and the tilt of the detected object at the same time, and independently determines the displacement and the tilt amount. A displacement tilt sensor for detection has been proposed.

  However, since such a displacement tilt sensor has two optical systems, a displacement measurement optical system and a tilt (angle) measurement optical system, the number of components constituting the displacement tilt sensor increases. Since the light source unit for displacement measurement and the light source unit for inclination measurement were provided, there was a problem that the apparatus was increased in size.

JP-A-8-240408

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to use both the light source of the displacement measuring optical system and the angle measuring optical system, that is, one light source of the displacement tilt sensor. Even so, an object of the present invention is to provide a displacement tilt sensor capable of simultaneously measuring the positional displacement and the angular displacement of a detection object.

  The above object of the present invention includes an optical system including a light projecting unit that emits measurement light toward the detection region and a light receiving unit that receives the measurement light reflected from the detection region, A light projecting element such as a light emitting diode, a light projecting lens, and means for narrowing the measurement light emitted from the light projecting element, and the light receiving unit includes an angle detection unit and a displacement detection unit. The angle detection unit includes an angle measurement light-receiving lens and an angle measurement light-receiving element, and the displacement detection unit includes a displacement measurement light-receiving lens and a displacement measurement light-receiving lens. This is achieved by providing a displacement tilt sensor.

  Further, the object of the present invention is to effectively provide a displacement tilt sensor characterized in that the means for narrowing the measuring light is a pinhole, a beam expander, or a small diameter lens. Achieved.

  Furthermore, the above object of the present invention is more effective by providing a displacement tilt sensor characterized in that the light receiving lens for angle measurement and the light receiving lens for displacement measurement are combined with a single light receiving lens. To be achieved.

  The displacement tilt sensor according to the present invention includes an optical system including a light projecting unit that emits measurement light toward the detection region and a light receiving unit that receives the measurement light reflected from the detection region. The light unit includes a light projecting element such as a light emitting diode, a light projecting lens, and means for thinning the measurement light emitted from the light projecting element, and the light receiving unit includes an angle detection unit and a displacement detection unit. The angle detection unit includes an angle measurement light-receiving lens and an angle measurement light-receiving element, and the displacement detection unit includes a displacement measurement light-receiving lens and a displacement measurement light-receiving lens. As described above, since the means for narrowing the measurement light is provided in the light projecting unit, the diameter of the measurement light can be narrowed. Therefore, the displacement tilt sensor can be further miniaturized and the cost can be reduced because it is sufficient to use both the light source for the displacement measurement and the light projection unit for the angle measurement and to provide one light source and one light projection lens. Can also be suppressed. Further, since the diameter of the measurement light can be reduced to be a point light source, the measurement light 11 can be measured at any location, and even a small detection object can be displaced and tilted. Can be detected with high accuracy.

  Further, since the displacement measuring optical system and the angle measuring optical system can be integrated as a displacement tilt sensor, the displacement tilt sensor can be reduced in size and weight.

  Further, since the number of components constituting the displacement tilt sensor can be reduced by combining the angle measuring light receiving lens and the displacement measuring light receiving lens with a single light receiving lens, the weight of the displacement tilt sensor can be reduced. In addition, the manufacturing cost of the displacement tilt sensor can be reduced. In addition, since the displacement measuring light receiving element and the angle measuring light receiving element can be configured to be close to each other, the weight of the displacement tilt sensor can be reduced.

It is a figure which shows the structure of the optical system of the displacement tilt sensor based on one Example of this invention. It is a block diagram for demonstrating the angle detection principle of the displacement tilt sensor shown in FIG. It is a block diagram for demonstrating the displacement detection principle of the displacement tilt sensor shown in FIG. It is a figure which shows the structure of the optical system of the displacement tilt sensor which concerns on the other Example of this invention. It is a figure which shows the outline of the optical system of the displacement tilt sensor which concerns on the other Example of this invention. It is a figure which shows the structure of the optical system of the conventional displacement tilt sensor.

  FIG. 1 is a diagram showing a configuration of an optical system of a displacement tilt sensor A (hereinafter, referred to as “main displacement tilt sensor A”) according to an embodiment of the present invention, in which an inclination amount β and a displacement of a detection object 1 are illustrated. The amount γ is measured. That is, the displacement tilt sensor A according to the present invention includes an optical system including a light projecting unit 2 that emits measurement light toward the detection region and a light receiving unit 3 that receives the measurement light reflected from the detection region. I have.

  The light projecting unit 2 includes a light projecting element 21 such as a light emitting diode (LED), a light projecting lens 22, and means 23 for narrowing the measurement light 11 emitted from the light projecting element 21. The optical element 21 and the light projection lens 22 are configured so that their optical axes coincide with each other. Then, the measurement light 11 emitted from the light projecting element 21 is collimated by the light projection lens 22, then is thinned by the thinning means 23, and is irradiated to the detection object 1 as measurement light that is parallel light. It has become.

  As the light projecting element 21, laser light can be used in addition to the light emitting diode. Examples of the laser light projecting element 21 include a laser oscillator such as a helium-neon (He-Ne) laser and a semiconductor laser element (LD), an optical fiber for guiding laser light output from the laser oscillator, and the like. For example, an optical conduit can be used.

  Thus, by providing the light projecting unit 2 with the means 23 for narrowing the measurement light 11, the measurement light 11 can be turned into a point light source, improving collimation, Since the blur of the light receiving spot for displacement measurement can be reduced, the displacement tilt sensor A can have one light projecting element 21 as a light source, and the displacement tilt sensor A can be reduced in size and weight. . Further, by providing the means 23 for thinning in this way, the measurement light 11 becomes a parallel light that is converted into a point light source, so that the measurement light 11 reaches far. Therefore, more measurable locations can be obtained than diffused light. As the means 23 for narrowing the measurement light 11 in this way, a pinhole, a beam expander, or a small diameter lens can be used.

  The light receiving unit 3 receives the measurement light 11 and detects an inclination amount β that is the inclination angle of the detection object 1. The light reception unit 3 receives the measurement light 11 and detects the displacement γ of the detection object 1. And a translucent mirror 6 for separating the measurement light 11 reflected from the surface of the detection object 1 into angle measurement light and displacement measurement light. Has been. The angle detection unit 4 that receives angle measurement light includes an angle measurement light receiving element 41 such as a position detection element (PSD) or a charge coupled device (CCD), and an angle measurement light receiving lens 42. The displacement detector 5 includes a displacement measurement light receiving element 51 such as a position detection element (PSD) or a charge coupled device (CCD), and a displacement measurement light receiving lens 52.

  The light projecting unit 2 and the light receiving unit 3 are arranged symmetrically on both sides of the standard line SL, and the optical axis 24 of the light projecting unit 2 and the optical axis 31 of the light receiving unit 3 are both standard lines SL. Are equal to α. Here, the standard line SL indicates a reference position for measuring the displacement amount γ of the detection object 1, and the displacement amount γ of the detection object 1 is the displacement distance on the standard line SL. Is defined as Further, the optical axis 24 of the light projecting unit 2 and the optical axis 31 of the light receiving unit 3 intersect at one point on the standard line SL, and the point on the standard axis SL at which the optical axes 24 and 31 intersect. Is referred to as a standard point SP, and a plane passing through the standard point SP and perpendicular to the standard line SL is referred to as a standard plane SF.

  In addition, on the standard surface SF, the distance between the light projecting element 21 and the light projecting lens 22 is adjusted so that the optical axis 24 of the light projecting element 21 and the light projecting lens 22 is condensed at the standard point SP. The optical unit 2 is configured. Further, the angle measuring light receiving lens 42 and the angle measuring light 11 that are collimated light reflected at the standard point SP are condensed by the angle measuring light receiving lens 42 and are condensed on the angle measuring light receiving element 41. The angle detector 4 is configured by adjusting the distance to the measurement light receiving element 41, and the measurement light 11 reflected by the standard point SP and passing through the semitransparent mirror is collected by the displacement measurement light receiving lens 52. The displacement detector 5 is configured by adjusting the distance between the displacement measuring light receiving lens 52 and the displacement measuring light receiving element 51 so that the light is irradiated and imaged on the displacement measuring light receiving element 51.

  Thereby, as shown by a solid line in FIG. 1, when the detection object 1 is located on the standard surface SF, the measurement light 11 emitted from the light projecting element 21 is irradiated on the surface of the detection object 1. Then, the measurement light 11 is condensed at one point at the standard point SP, and the measurement light 11 specularly reflected by the surface of the detection object 1 is measured through the angle measurement light receiving lens 42 and the displacement measurement light reception lens 52. An image is formed on the light receiving element 41 for displacement and the light receiving element 51 for displacement measurement, and an angle measuring light receiving spot 43 and a displacement measuring light receiving spot 53 are formed at points on the optical axis, respectively. Hereinafter, the position of the light receiving spot 43 for angle measurement that occurs when the tilt amount β = 0 is referred to as an origin position 44 for angle measurement, and the position of the light receiving spot 53 for displacement measurement that occurs when the displacement amount γ = 0 is displaced. It is called the origin position 54 for measurement.

  Next, as shown by a detection object 1 (B) in FIG. 1, when the detection object 1 is inclined by β with respect to the standard line SL, the tilt amount β of the detection object 1 is measured by the displacement tilt sensor A. The principle to do is explained. Of the displacement tilt sensor A, only the angle measuring optical system for measuring and detecting the tilt amount β is taken out and shown in FIG. 2 (however, a translucent mirror is omitted).

  As shown in FIG. 2, the measurement light 11 emitted from the light projecting element 21 passes through a light projecting lens 22 to become collimated light, and is narrowed through a means 23 for narrowing light such as a pinhole, and is detected. The surface of the object 1 is irradiated. At this time, if the detection object 1 is inclined by β with respect to the standard line SL, the measurement light 11 reflected by the surface of the detection object 1 (B) is also inclined with respect to the optical axis 24. As shown in FIG. 4, the angle measurement light receiving spot 43 generated by the measurement light 11 reflected by the detection region being condensed on the angle measurement light receiving element 41 through the angle measurement light receiving lens 42 is an angle measurement origin position 44. Move from. The amount of movement of the angle measurement light receiving spot 43 from the origin position 44 (the distance from the origin position 44 to the gravity center position of the received light intensity) is defined as an angle movement amount D.

Therefore, the inclination z of the detected object 1 can be calculated by detecting the angular movement amount D of the light receiving spot 43 for angle measurement. That is, if the distance between the standard point SP and the angle measurement light receiving lens 42 is f ₁ and the angle movement amount (position displacement) of the angle measurement light reception spot 44 is D, the detected object with reference to the standard line SL is used. The inclination z is expressed by the following (Equation 1).
(Equation 1)
2f ₁ z = D
By obtaining this inclination z, the inclination amount β of the detected object 1 can be determined.

  Next, as shown by a detection object 1 (C) in FIG. 1, when the detection object 1 is displaced by γ from the standard surface SF, the displacement amount γ of the detection object 1 is measured by the displacement tilt sensor A. Will be explained. Of this displacement tilt sensor A, only the displacement measuring optical system for measuring and detecting the displacement amount γ is taken out and shown in FIG. 3 (however, the translucent mirror is omitted).

  As shown in FIG. 3, when the detection object 1 is displaced by γ with respect to the standard surface SF, the standard point SP becomes the position of the standard point SP ′. Accordingly, as indicated by a two-dot chain line in FIGS. 1 and 3, the measurement light 11 is reflected by the measurement measurement light 11 reflected by the standard point SP ′ of the detection region through the displacement measurement light receiving lens 52. The displacement measurement light receiving spot 53 generated by being condensed on the element 51 moves from the origin position 54 for displacement measurement. The amount of movement of the displacement measurement light receiving spot 53 from the origin position 54 (the distance from the origin position 54 to the center of gravity of the received light intensity) is defined as a displacement movement amount d.

Accordingly, by detecting the displacement d of the displacement measuring light receiving spot 53, the displacement γ of the detection object 1 can be calculated from the relationship of image formation. That is, when the displacement amount of the detection object 1 is γ, the displacement movement amount of the light receiving spot 53 for displacement measurement is d, and the distance between the standard point SP and the standard point SP ′ is x, x is the following (Equation 2). It is represented by
(Equation 2)
x = γ / cos α
The displacement movement amount d is expressed by the following (Equation 3) when x is used.
(Equation 3)
d = x · sin2α
Therefore, from the above (Equation 2) and (Equation 3), the displacement movement amount d is expressed by the following (Equation 4).
(Equation 4)
d = γ · 2 sin α
Therefore, in this displacement tilt sensor A, the distance between the standard point SP ′ and the angle measuring light receiving lens 42 is f ₂ , and the distance between the displacement measuring light receiving lens 52 and the displacement measuring light receiving element 51 is f _3. If the displacement movement amount of the light receiving spot 53 for displacement measurement is d, the displacement amount γ of the detection object 1 is expressed by the following (Equation 5).
(Equation 5)
_{d = 2γ (f 3 / f} 2) sinα
Thus, according to the present displacement tilt sensor A, the tilt amount β and the displacement amount γ can be detected simultaneously and independently.

  FIG. 4 is a schematic diagram showing a displacement tilt sensor B according to a modification of the present invention. In this displacement tilt sensor B, instead of the angle measurement light receiving lens 42 in the angle detection unit 4 and the displacement measurement light reception lens 52 in the displacement detection unit 5, the angle measurement light reception lens 42 and the displacement measurement light reception light are used. A light receiving lens 7 that also serves as the lens 52 is provided. As described above, the angle measuring optical system and the displacement measuring optical system are optically configured by using the angle measuring light receiving lens 42 and the displacement measuring light receiving lens 52 as one light receiving lens 7. Are separated and independent from each other, but are structurally integrated and have a small number of parts, so that the displacement tilt sensor according to the present invention can be made smaller and lighter.

  Note that the method of detecting the tilt amount β of the detection object 1 in the case of the displacement tilt sensor B is the same as that of the displacement tilt sensor A described above and is omitted, but the method of detecting the displacement amount γ is as follows.

  That is, assuming that the distance between the light receiving lens 7 and the standard point SP is a, the distance (optical path length) between the light receiving lens 7 and the displacement measuring light receiving element 51 is b, and the focal length of the light receiving lens 7 is f. There is a relationship of (1 / a) + (1 / b) = (1 / f) according to the lens formula.

  Therefore, in the displacement tilt sensor B, the displacement amount γ is represented by γ = (b / a) · d cos α sin 2α.

  As described in detail above, according to the displacement tilt sensor of the present invention, the number of components can be reduced, so that the displacement tilt sensor can be further reduced in size and weight.

  Next, a method of correcting the tilt amount β of the detected object 1 that is displaced from the reference surface SF and is tilted with respect to a line different from the standard line SL will be described. FIG. 5 is a schematic diagram showing a displacement tilt sensor C according to another modification of the present invention. As shown in FIG. 5, this displacement tilt when the detection object 1 is displaced from the standard plane SF by γ and is inclined by β with respect to a reference line SL ′ that is a line different from the standard line SL. The principle of correcting the displacement amount γ ′ by measuring the tilt amount β and the displacement amount γ ′ of the detection object 1 by the sensor C will be described. Here, the reference line SL ′ is perpendicular to the standard surface SF, where O is the intersection of the detection object 1 whose inclination amount is β and the measurement light 11 emitted from the light projecting element 21, and the intersection O It is a line that intersects.

  Since the configuration of the displacement tilt sensor C is the same as that of the displacement tilt sensors A and B described above, the same components are denoted by the same reference numerals, the description thereof is omitted, and for ease of understanding. FIG. 5 shows only an outline of the optical path and the like, and most of the components are omitted. The method of detecting the tilt amount β of the detection object 1 of the displacement tilt sensor C is the same as that of the displacement tilt sensor A described above, and therefore the description thereof is also omitted. In the following, the detection object 1 is the reference line SL ′. A method for measuring and correcting the actual displacement amount when β is inclined with respect to FIG.

  As shown in FIG. 5, when the detection object 1 is displaced by γ with respect to the standard surface SF, the standard point SP is positioned at SP ′. When the detected object 1 having the displacement amount γ is further inclined by β with respect to the reference line SL ′, as shown in FIG. 5, the intersection of the detected object 1 and the standard line SL moves from SP ′ to SP ″. Therefore, it can be seen that the actual displacement amount of the detection object 1 is γ ′. A method for calculating the actual displacement amount γ ′ will be described below. Reference numeral 8 in the figure denotes an image plane.

As shown in FIG. 5, the intersection between the detection object 1 whose displacement amount is γ and the inclination amount is β and the measurement light 11 emitted from the light projecting element 21 is O, and the length from the intersection point O to SP ′. X is represented by the following (Equation 6).
(Equation 6)
X = γ · tan θ
Is the incident angle of the measurement light 11 emitted from the light projecting element 21.

Next, if the length from SP ′ to SP ″ is Y, Y is expressed by the following (Equation 7).
(Equation 7)
Y = X · tanβ
= Γ ・ tanθ ・ tanβ
Here, β is the amount of inclination measured by the angle measuring light receiving element 41 as described above.

Therefore, the actual displacement movement amount γ ′ is expressed by the following (Equation 8).
(Equation 8)
γ ′ = γ−Y
= Γ-γ ・ tanθ ・ tanβ
= Γ (1-tanθ · tanβ)
Next, γ is obtained. Since W shown in FIG. 5 is measured as a position signal, W is expressed by the following (Equation 9).

(Equation 9)
W = Z + U
= 2γ · sin θ + (γ · cos 2θ · tan 2β) / cos θ
Z is an intersection point from the reference point SP, where P is the intersection point of the image plane 8 and the line that forms an angle equal to the angle between the measurement light 11 emitted from the light projecting element 21 and the reference line SL ′. The distance to P. U is the intersection of the reflected light reflected from the surface of the detection object 1 with the displacement amount γ and the inclination amount β and the image plane 8 when the measurement light 11 emitted from the light projecting element 21 is Q. Is the distance from the intersection point P to the intersection point Q.

Here, when sin θ = C ₁ , cos 2θ / cos θ = C ₂ , and tan 2β = C ₃ , the above (Equation 9) is expressed by the following (Equation 10).
(Equation 10)
_{W = 2γC 1 + γC 2 ·} C 3
γ = W / (2C ₁ + C ₂ · C ₃ )

  By substituting (Equation 10) into (Equation 8), the actual displacement amount γ ′ can be detected and corrected.

As described above, according to the displacement tilt sensor according to the present invention, even if the components of the displacement tilt sensor are reduced, the tilt amount β of the detected object 1 tilted by β with respect to the reference line SL ′ and the actual displacement amount γ. ′ Can also be detected accurately.

DESCRIPTION OF SYMBOLS 1 Detecting object 11 Measuring light 2 Light projecting part 21 Light projecting element 22 Light projecting lens 23 Means 3 for narrowing measuring light 3 Light receiving part 4 Angle detecting part 41 Angle measuring light receiving element 42 Angle measuring light receiving lens 5 Displacement detecting part 51 Displacement measuring light receiving element 52 Displacement measuring light receiving lens 6 Translucent mirror 7 Light receiving lenses A, B, C Displacement tilt sensor β Inclination amount γ Displacement amount

Claims (3)

An optical system including a light projecting unit that emits measurement light toward the detection region, and a light receiving unit that receives the measurement light reflected by the detection region,
The light projecting unit includes a light projecting element such as a light emitting diode, a light projecting lens, and a means for narrowing the measurement light emitted from the light projecting element,
The light receiving unit includes an angle detection unit and a displacement detection unit,
The angle detection unit includes an angle measurement light-receiving lens and an angle measurement light-receiving element,
The displacement detector includes a displacement measuring light-receiving lens and a displacement measuring light-receiving lens.   2. The displacement tilt sensor according to claim 1, wherein the means for narrowing the measurement light is a pinhole, a beam expander, or a small-diameter lens.   The displacement tilt sensor according to claim 1 or 2, wherein the angle measuring light-receiving lens and the displacement measuring light-receiving lens are combined with one light-receiving lens.

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