JPH08261738A - Angle / tilt measuring device - Google Patents

Abstract

(57) [Summary] [Purpose] An inclinometer that aims for wide angle range, high accuracy, and quick measurement. [Structure] A polarizing plate, which is rotatably held by a horizontal axis and is perpendicular to the axis, is maintained in a constant azimuth in a vertical plane by a weight and is fixed to a table of an inclinometer. A light source that illuminates through a plurality of different analyzers and polarizers from the polarizer side, the analyzer is provided, a photodetector is provided behind each analyzer, and the output of each photodetector is input to the arithmetic circuit. The tilt angle of the inclinometer table with respect to the polarizer was calculated. [Effect] Compared to a level using a water bubble, a wide angle range can be measured accurately and quickly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device used for general angle measurement or for measuring inclination in general construction, or for inspecting horizontality and verticality when installing various devices.

[0002]

2. Description of the Related Art For angle measurement, a protractor is attached to one of two members that rotate relative to each other, and a subject is sandwiched by both members, or both members are directed toward two collimation points like a sextant. The angle between them was read on the scale of the protractor, and there was no device that could display the angle directly. Further, as a conventional inclinometer, a glass tube filled with water bubbles is used. A general-purpose spirit level cannot read the tilt angle only by looking at whether the object is horizontal or vertical. The bubble type is not suitable for reading the angle because the boundary of the bubble is unclear. One of the legs of the precision level is a micrometer, and the level is attached to the base and the micrometer is adjusted so that the base is horizontal, and the reading of the micrometer at that time is read. Lack. Also, the angular range that can be measured is large. There is also a capacitance type using a movable plate that rotates with respect to a fixed plate, but the accuracy is low and the linearity with respect to the tilt angle is low.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an angle meter or inclinometer which can measure an angle or an inclination in a wide angle range and can read the angle quickly and accurately.

[0004]

Means for Solving the Problems A polarizer is attached to each of two members which are connected to each other and are rotatable relative to each other, and light transmitted through the two members is measured and converted into an angle value. I made it visible. A polarizing plate that can be freely rotated by a horizontal axis and is held by a weight so that the orientation is kept constant in a vertical plane, and is fixed to an instrument stand. Multiple analyzers, a photometric element placed behind each of these analyzers, a light source that illuminates each of the above-mentioned analyzers through a polarizing plate, and the tilt angle of the instrument stand with respect to the polarizing plate from the output of each photometric element. The inclinometer was constituted by the calculation means for calculating.

[0005]

The constitution of the present invention is basically that the crossing angle of the azimuths of the polarizer and the analyzer is calculated by measuring the amount of light transmitted through both. The amount of transmitted light between the polarizer and the analyzer changes depending on the change in the crossing angle between the polarizer and the analyzer. Therefore, by rotating the analyzer so that the analyzer is orthogonal or parallel to the polarizer, which is always in the vertical direction, the tilt angle can be known as the angle of the analyzer with respect to the device stand, and the change in the transmitted light amount is reflected by the polarization. Since it is sensitive to the change in the intersection angle between the probe and the analyzer, it is possible to measure the tilt angle with high accuracy.

However, the fact that the analyzer is rotated as described above is very unsatisfactory because of the speed of measurement. The present invention arranges a plurality of analyzers having mutually different azimuths instead of rotating the analyzer, measures the amount of transmitted light of each analyzer, and interpolates the measurement results to obtain the relationship with the azimuth of the analyzer. Since the maximum or minimum azimuth of the amount of transmitted light is obtained, the tilt angle can be read very quickly and practically instantaneously as compared with rotating the analyzer.

Moreover, the polarizer is originally designed to be freely rotatable, and if the analyzer azimuth is arranged in the angular range of 90 ° at any angular position (with respect to the device), the tilt angle can be similarly detected. Has a wide measuring range (90 °
Is the same as measuring the full circumference angle in the range).

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 1 shows an embodiment of the present invention relating to tilt angle measurement. In the figure, the cover for shielding external light is omitted. 1
Is an L-shaped device stand, and the bottom surface 1B and side surface 1S are finished to be flat. When measuring the inclination from the horizontal, the surface 1B is applied to the object, and when measuring the inclination from the vertical, the surface 1S is the target. Hit the object. 2 is a ball bearing fixed to the device base and having an axis perpendicular to the L-shaped surface of the device base. A plate-shaped polarizer 3 is fixed to the inner ring of this bearing, and a weight 4 is attached to one place. is there. Therefore, the polarizer 3 always maintains a constant azimuth in the vertical plane due to the weight of the weight. A level 5 is attached to the device stand, and when this device is applied to an object,
It is possible to check whether the surface of the polarizer 3 is vertical. Six analyzers 61 to 66 are attached to the device table 1 behind the polarizer 3 so as to face the polarizer. These analyzers are 1
The orientation is changed by 8 °, and the orientation is fixed at 18 °, 36 °, ..., 90 °. Photodiodes 71 to 76 of photometric elements are arranged behind each analyzer. An arm is projected from the device table 1 in front of the polarizer 3, and the light source 8 is attached to the arm.
Is attached to illuminate the entire surface of the polarizer 3 from the vertical direction. The light receiving element 9 is attached to the center of the circumference of the array of the photometric elements 61 to 66, and the transmitted light of the polarizer 3 is monitored. The outputs of the photometric elements 71 to 76 are input to the data processing device together with the output of the light receiving element 9,
The result of the data processing is displayed on the display device 11 as an inclination angle from the horizontal or vertical.

The data processing device 10 uses the value obtained by dividing the output of each of the photometric elements 71 to 76 by the output of the light receiving element 9 in accordance with the input signal for use in the tilt angle calculation, and thereby the influence of the change in the light intensity of the light source 8 and the transmission of the polarizer. The effect of not being 1 is eliminated. Therefore, in calculation, both the intensity and the amplitude of the light incident on the polarizer may be considered to be 1. An example of calculation will be described. Assuming that the azimuth of the analyzer is θ with respect to the polarizer, the amplitude of the light transmitted through the analyzer is cos θ, and thus the intensity is cos ₂ θ. By the way, in the device of the present invention, the analyzer does not rotate and there are a plurality of analyzers in different azimuths. Therefore, the azimuth angles of the respective analyzers with respect to the polarizer are θ ₀ , θ ₀ + a, θ ₀ + 2a ... θ ₀ + 5a. Then, the analyzer transmitted light intensities I _{1 to} I ₆ are I ₁ = cos ² θ ₀ I ₂ = cos ² (θ ₀ + a) and the like. I _{1 to} I ₆ are actually measured, and they are arranged on the curve of cos ² θ described above. Considering the azimuth of one analyzer, for example 61, as a reference, θ ₀ represents the azimuth of the polarizer 2 with respect to this reference azimuth. Here, θ ₀ in the above equation is desired to be obtained, and since a is known to be 18 °, there are six equations for obtaining θ ₀ . Therefore, an accurate θ ₀ can be obtained by averaging the values of θ ₀ calculated by using the actual measurement values from the above equations of I ₁ , I _2, etc. If θ ₀ is 0 ° with respect to the device stand, θ ₀ immediately becomes the tilt angle of the target surface.

In principle, only one analyzer is required when using this calculation method, but in that case, the orientation of the analyzer is preferably 45 ° with respect to the bottom surface of the L-shaped table. This is because the inclination is often measured at a small angle from the horizontal or vertical, and in this case, the side of the polarizer / analyzer having an intersection angle of 45 ° is most sensitive to the inclination change.

Although the above calculation is simple, the accuracy is not so good. This is because the transmitted light amount does not generally become 0 even if the polarizer and the analyzer are made orthogonal to each other, and some transmitted light is detected. Therefore, in order to further improve the accuracy, the following calculation is performed. The measured values are _six I _{1 to} I ₆ and are arranged at 18 ° intervals. I on the curve of cos squared (cos ² θ + R) that connects them
Substituting _{1 to} I ₆ and the azimuth of each analyzer, the following equation is obtained. I ₁ = cos ² θ ₀ + R I ₂ = cos ² (θ ₀ +18) + R In the above equation, θ ₀ and R are unknowns. I _{1 to} I ₆ include measured values and include errors, and assuming the errors to be Δ1 to Δ6, Δ1 = I ₁ -cos ² θ ₀ -R Δ 2 = I ₁ -cos ² (θ ₀ +18) -R ... θ ₀ and R are determined by the method of least squares. That is, θ ₀ and R are determined so that D = Δ1 ² + Δ2 ² ... + Δ6 ² is minimized. This is D
Two expressions can be made by partial differentiation with ₀ and R, so
In this case, θ ₀ and R are obtained by making them simultaneous. For example, Δ1 ² = (I ₁ -cos ² θ ₀ -R) ² There are six equations of this form. Partial differentiation with respect to each of θ ₀ and R is as follows. Symbols of partial differentiation are described as Dθ, DR and the like. Dθ ₁ = 4 (I ₁ −cos ² θ ₀ −R) cos θ ₀ si
nθ ₀ DR ₁ = −2 (I ₁ −cos ² θ ₀ −R) If the above equation is added to 6 equations for Dθ and 6 equations for DR, two equations are created and 0 is assigned to each equation and θ ₀ and R are solved. It's good. Since this is a mere calculation, no further description will be given here, but this calculation may be performed by the data processing device.

In the above example, six analyzers are arranged at intervals of 18 °, but it is sufficient that at least two analyzers are used (because there are two unknowns to be obtained), as is clear from the above-mentioned point.
Since the least-squares method can be applied if there are more than three pieces, the accuracy increases as the number increases, but the accuracy does not increase in proportion to the number even if the surplus number is increased, so 3 to 6 pieces are suitable.

The light source 8 is adapted to project a parallel light flux which irradiates each analyzer with light in parallel with each other. The structure of the light source 8 for this purpose comprises, as shown in FIG. 2, a halogen lamp 81 as a light emitting body, a condenser lens 82, a pinhole 83, and a light projecting lens 84 focusing on the pinhole, and monochromatic light is desirable for measurement. Therefore, the filter 85 is inserted (the wavelength is selected so that the residual transmitted light when the polarizer and the analyzer are orthogonal to each other is reduced).

In the above example, the polarizer 3 is held by a ball bearing, but if the structure is floated in a liquid as shown in FIG. 3, there is no friction and the sensitivity is higher. In the figure, reference numeral 20 is a cylinder, and glass plates 22 are fixed on both front and rear sides via packings 21 to be hermetically sealed, and a liquid 23 is enclosed therein so that a small space is left in the upper part. The ring 31 having the polarizing plate 3 attached thereto is floated in this liquid so that the upper part thereof is slightly out of the liquid surface. A weight 32 is embedded in the lower portion of the ring 31, and the orientation of the polarizer is always kept constant. The liquid 23 need only be transparent to the light used and can float the polarizer ring exactly, and water is the easiest to use. Dissolve salt etc. to adjust buoyancy. The material of the ring 31 is preferably polyethylene or polypropylene (specific gravity of about 0.9). Further, in the above-described embodiment, the light is projected from the side of the polarizer, but conversely, the light is projected from the side of the analyzers 61 to 66 or the like and is received behind the polarizer 3 so as to face the analyzers 61 to 66 or the like. The elements 71 to 76, 9 may be arranged. Also, the analyzer 61 to
The angular intervals of 66 may be unequal.

FIG. 4 is an application of the present invention to angle measurement. The parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals. Reference numerals 1 and 2 are members that are interconnected and are rotatable. The member 1 has a circular window, and the circular window of the other member 2 is fitted into the circumferential convex portion 101 of the window edge so that the first and second members are relatively rotatable. Have arms 102 and 2 respectively
01 was protruding, and the subject was sandwiched by the inner side surfaces a of these arms, and the angle of the subject was measured. Member 2
A polarizer 3 is attached to the circular window. Six analyzers 61 to 66 are attached to the circular window of the member 1 along one circumference, the center is transparent, and the light receiving elements 71 to 76 are provided behind each of the analyzers and the center is also provided. The light receiving element 9 is arranged in the transparent portion. The member 2 is provided with a light source 8 which projects a parallel light beam in front of the polarizer 3. The structure of this light source is the same as that shown in FIG. Light receiving elements 71 to 7
Outputs 6 and 9 are converted into angle values by the data processing device and displayed on the display device 11. For example, in a telescope in which a mirror is attached so that an axis line passing through the center of rotation of the arm 102, 201 is included in the plane, and the light from the target body reflected by the mirror is attached to the other arm 102 of the other arm 102, 201. If you attach a semi-transparent mirror to send, it becomes a sextant.

[0016]

The device of the present invention has the above-mentioned configuration and measures the tilt by the angle of intersection between the polarizer and the analyzer.
Since the measurement of the crossing angle is based on the light quantity measurement, quantitative measurement is easy, and moreover, the light quantity change due to the crossing angle of the light passing through the polarizer analyzer is large, so that the measurement can be performed with high accuracy, and the azimuth is different depending on the rotation of the analyzer. Since a plurality of analyzers are used, the tilt angle can be immediately known, and the tilt angle can be measured from 0 to 45 °. However, the polarization analyzer has the same sensitivity to the tilt angle regardless of the value. Therefore, the tilt angle can be measured in a wide angle range without the non-linearity as in the capacitance method.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the present invention.

FIG. 2 is a side view of a light source used in the above example.

FIG. 3 is an exploded perspective view of a polarizer holder according to another embodiment.

FIG. 4 is an exploded perspective view of an example of a goniometer.

[Explanation of symbols]

 1 Device stand 2 Ball bearing 3 Polarizer 4 Weight 5 Level 61-66 Analyzer 71-76 Photometric element 8 Light source 9 Light receiving element 10 Data processing device 11 Display device

Claims (3)

[Claims] 1. Means for projecting a parallel light beam to both of the two members, which are connected to each other and are rotatable relative to each other, respectively, so that the two members are overlapped with each other in an angle measuring range.
An angle / tilt measuring device comprising: a light-receiving element that receives transmitted light of the overlapping portions of both polarizers; and a data processing device that calculates an intersection angle between the two members from the output of the light-receiving element. 2. A plurality of polarizers, each of which has a different azimuth from each other, are attached to the two members so as to be overlapped with the polarizers in an angle measuring range, and a plurality of light sources which receive the light transmitted through the polarizers of the both members are received. The angle / tilt measuring device according to claim 1, further comprising: 3. A contact surface for contacting a subject is provided on one of the two members, and the other member is always kept in a constant orientation in a vertical plane by a weight. The angle / tilt measuring device according to claim 1.