JP2688933B2 - Tilt angle detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a tilt angle detector for electrically detecting a tilt angle of an object to be measured with respect to a horizontal or gravity direction.

(Prior Art) As a conventional inclination angle detector, a bubble tube formed by enclosing a gas and a transparent liquid in a transparent container having an upper inner surface formed into a spherical concave surface, and a bubble tube from above or below toward the bubble tube. A bubble sending device for irradiating light, a circular four-division type position detection light receiving element for converting light transmitted through the bubble tube into an electric signal, and an operation unit for calculating an inclination angle by the electric signal are provided. The light from the light-transmitting portion that has passed through the tube is received by the light receiving element,
As shown in the figure, the change in the light amount distribution caused by the relative change of the position of the bubble shadow b formed on the light receiving element a on the light receiving element a according to the tilt angle is recognized as an electrical change by the light receiving element a. It is known that the change angle is calculated by a calculation unit and the tilt angle is measured photoelectrically.

(Problems to be Solved by the Invention) However, according to the above-described conventional tilt angle detector, due to variations in bubble diameter, light emission intensity of the light transmitting unit, photoelectric conversion sensitivity of the light receiving element, and the like due to temperature changes, There is an inevitable inevitability that a large error is introduced into the measurement result.

(Means for Solving the Problem) The present invention is intended to eliminate the above-mentioned inconvenience, and in the invention according to claim 1, a transparent container in which an upper inner surface is formed into a spherical concave surface is transparent to gas and transparent. It comprises a bubble tube enclosing a liquid, a light transmitting section for irradiating the bubble tube with light from above or below, and four light-receiving pieces for converting the light transmitted through the bubble tube into an electric signal. In a tilt angle detector including a light receiving element and a calculation unit for calculating tilt angles θ _X and θ _Y in the X direction and the Y direction based on the electric signal, the light receiving element is used to receive light for position detection within a movable range of a bubble shadow. Part and a reference light-receiving part outside the movable range, the both light-receiving parts are arranged in proximity to each other,
The calculation unit uses the outputs of the four light-receiving pieces and However, R: radius of curvature of the inner surface of the top of the bubble tube C: output of the reference light receiver V ₁₃ = KS ₁₃ S ₁₃ : area of the reference light receiver K: coefficient A: output of the light receiver on one side in the X direction (V ₁₄ + V ₁₅ ) -Output of light receiving element on the other side (V ₁₆ + V ₁₇ ) = K {(S ₁₄ + S ₁₅ )-
(S ₁₆ + S ₁₇ )} S ₁₄ and S ₁₅ : Areas of light-receiving portions of the light-receiving pieces on one side in the X direction S ₁₆ and S ₁₇ : Light-receiving pieces on the other side in the X direction, respectively Area of the light-irradiated part of S: Total area of four light-receiving pieces D: The tilt angle in the X direction is calculated based on the diameter of the bubble, and the tilt angle in the Y direction is also calculated based on the above formula by replacing S ₁₅ and S ₁₆ of A above. In the invention of item 2,
A bubble tube formed by enclosing a gas and a transparent liquid in a transparent container having an upper inner surface formed into a spherical concave surface, a light transmitting unit for irradiating light toward the bubble tube from above or below, and the bubble tube. A light receiving element composed of two light receiving pieces for converting the transmitted light into an electric signal, and an inclination angle θ in the X direction or the Y direction by the electric signal
_{In a} tilt angle detector including a calculation unit for calculating _X or θ _Y , the light receiving element is composed of a position detection light receiving unit within a movable range of a bubble shadow and a reference light receiving unit outside the movable range, The light receiving units are arranged close to each other, and the arithmetic unit uses the outputs of the two light receiving units, However, R: radius of curvature of the upper inner surface of the bubble tube C: output of the reference light receiving part V ₃ = KS ₁₃ S ₁₃ : area of the reference light receiving part K: coefficient A: light reception on one side in the X or Y direction Output of one side V ₁₄ ′ -Output of light receiving piece on the other side V ₁₆ ′ = K (S ₁₄ ′ −S ₁₆ ′) S ₁₄ ′: Irradiation of light on the light receiving piece on one side in the X or Y direction Area S ₁₆ ′: Area of the part of the light-receiving piece on the other side in the X or Y direction that is irradiated with light S: Total area of the two light-receiving pieces D: The tilt angle in the X direction or the Y direction is calculated based on the diameter of the bubble.

(Operation) According to the present invention, the light from the light transmitting unit transmitted through the bubble tube is irradiated on the light receiving unit for detecting the position of the light receiving element so as to form a bubble shadow. At the same time, the light is irradiated onto the reference light receiving unit. The position-detecting light-receiving unit mainly outputs the change in the light amount distribution caused by the relative change of the position of the bubble shadow depending on the tilt angle as an electrical change, and the reference light-receiving unit mainly outputs the light-transmitting unit. Changes in emission intensity, photoelectric conversion sensitivity, etc. are output as electrical changes. Outputs from the respective light receiving units, which are proportional to the irradiation area, the irradiation intensity, and the like, are input to a calculation unit, where they are calculated to obtain the inclination angle. In this way, even if the temperature changes and the emission intensity and photoelectric conversion sensitivity of the light sending part change, this change is reliably captured by the reference light receiving part, compensated by the calculation part, and the bubble diameter Since the error due to the change of is also compensated for by the calculation unit, there is no room for a large error to be entered in the measurement result, and the tilt angle can be accurately measured.

(Example) Next, an example of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, reference numeral 1 denotes a bubble tube. This bubble tube 1 is formed by enclosing a transparent liquid 5 in which a bubble 4 exists in a transparent container 3 whose upper inner surface is formed into a concave surface 2 having a spherical shape. .

A light transmitting unit 6 is disposed below the bubble tube 1, and this light transmitting unit 6 emits light from a light source such as a light emitting diode to a lower portion of the bubble tube 1 via a slit plate 8. And a lens 9 for irradiating in parallel.

A light receiving element 10 such as a PSD is arranged above the bubble tube 1, and this light receiving element 10 converts the light transmitted through the bubble tube 1 into an electric signal to obtain a two-dimensional tilt angle, that is, a tilt angle in the XY directions. The position detection light-receiving unit 12 is provided within the movable range of the bubble shadow 11, and the reference light-receiving unit 13 is provided outside the movable range of the bubble shadow 11 so as to be close to it.

The position detecting light receiving portion 12 is formed by dividing a disc-shaped light receiving portion into four light receiving pieces 14, 15, 16 and 17.

The reference light receiving portion 13 is arranged so as to surround the position detection light receiving portion 12.

Reference numeral 18 denotes a calculation unit that receives the electric signals output from the light receiving units 12 and 13 and calculates the tilt angle.

At this time, the light from the light source 7 that has passed through the bubble tube 1 is irradiated so as to form the bubble shadow 11 on the four light receiving pieces 14, 15, 16, 17 which are the position detecting light receiving portions 12. The reference light receiving portion 13 is also irradiated. Electrical outputs from both light receiving units 12 and 13 proportional to the irradiation area, the irradiation intensity, etc. are input to the calculation unit 18.

The calculation unit 18 performs the following calculation to obtain the tilt angle in the XY directions.

Here, the position detection light receiving portion 12 is a light receiving piece 14, 15, 16, 17
The total area S, S ₁₄ the area of the illuminated by that portion of the light of _{which, S 15, S 16, S} 17, the area of the reference light receiving unit 13 a S of
₁₃ , the components of the tilt angle in the XY direction are θ _X and θ _Y (θ _X , θ _{Y, respectively)}
<< 1), K is a coefficient that takes into consideration the radius of curvature R of the inner surface of the upper portion of the bubble tube 1, the emission intensity of the light transmitting unit 6, the photoelectric conversion efficiency of the light receiving units 12 and 13, and the diameter of the bubble 4 is D .

 First, the following values A, B and C are obtained.

A = (output V _{14 of} light receiving element ₁₄ + output V _{15 of} light receiving element ₁₅ ) − (output V _{16 of} light receiving element ₁₆ + output V ₁₇ of light receiving element ₁₇ ) = K {(S ₁₄ + S ₁₅ ) − (S ₁₆ ＋ S ₁₇ )} ＝ －2RKDθ _X C = output of the reference light receiving portion 13 V ₁₃ = KS ₁₃ The tilt angle θ _X in the X direction can be calculated by the following equation from the values of A, B and C.

That is, the output of each light receiving piece 14, 15, 16, 17 and the light receiving portion 13
If each value of A, B and C is obtained from the output of and the θX is calculated by the equation (1), the bubble diameter D which changes with temperature and the photoelectric coefficient K of the light transmitting section 6 and the light receiving sections 12 and 13 are offset. Therefore, the correct tilt angle in the X direction can be obtained without depending on the temperature, the emission intensity of the light transmitting unit 6, and the photoelectric conversion sensitivity of the light receiving units 12 and 13.

The tilt angle in the Y direction is also A = K {S ₁₄ + S ₁₅ ) − (S ₁₆
It is clear that S ₁₅ and S ₁₆ in + S ₁₇ )} can be interchanged to obtain based on equation (1).

The position detecting light receiving portion 12 and the reference light receiving portion 13 are not limited to those of the above-described embodiment, and may be those shown in any of FIGS. 3 to 7, of course. 6
In the embodiment shown in FIG. 7 and FIG. 7, for example, the area of one of the light-receiving pieces 12 in the X direction irradiated with light is S ₁₄ ′, and the output of the light-receiving piece 12 is V ₁₄ ′. The other receiver 1
2 is the area of the light-irradiated portion S ₁₆ ′, the light-receiving piece 12
If the output of V is ₁₆ V, then A = K {(S ₁₄ + S ₁₅ ) −
(S ₁₆ + S ₁₇ )} is A = (output V ₁₄ ′ of the light-receiving piece 12 on one side in the X direction) − (output V ₁₆ ′ of the light-receiving piece 12 on the other side) = K
(S ₁₄ ′ −S ₁₆ ′), and using this A, the tilt angle in the X direction can be obtained from the above equation (1).

(Effect of the invention) As described above, according to the present invention, the light receiving element for converting the light transmitted through the bubble tube into the electric signal is provided with the position detecting light receiving portion within the movable range of the bubble shadow and the reference light receiving outside the movable range. Since it is composed of two parts, the electric output from both light receiving parts is processed by the calculation part to cancel the measurement error due to changes in bubble diameter due to temperature etc. and changes in photoelectric characteristics of the sending and receiving parts. Therefore, there is an effect that the detection accuracy can be maintained even under the condition that the temperature changes, the emission intensity of the light transmitting unit changes, and the photoelectric conversion sensitivity of the light receiving unit changes.

Furthermore, since both light receiving parts are arranged close to each other, there is an effect that the detector can be made compact.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a first embodiment of the present invention, FIG. 2 is a positional relationship diagram of a light receiving element and a bubble shadow, and FIGS.
FIG. 8 is a positional relationship diagram of the light receiving elements and bubble shadows of the second to fifth embodiments of the present invention, and FIGS. 8 and 9 are positional relationship diagrams of the light receiving elements and bubble shadows of two conventional examples. 1 ... Bubble tube 2 ... Concave surface 3 ... Transparent container 4 ... Bubbles 5 ... Transparent liquid 6 ... Light transmitting unit 10 ... Light receiving element 11 ... Bubble shadow 12 ... Position detecting light receiving unit 13 ... Reference light receiving part 18 …… Calculator

Claims (2)

(57) [Claims] 1. A bubble tube in which a gas and a transparent liquid are enclosed in a transparent container having an upper inner surface formed into a spherical concave surface, and a light transmitting section for irradiating the bubble tube with light from above or below. A light-receiving element including four light-receiving pieces for converting light transmitted through the bubble tube into an electric signal, and an arithmetic unit for calculating tilt angles θ _X and θ _Y in the _X and Y directions based on the electric signal. In the tilt angle detector, the light receiving element is composed of a position detecting light receiving section within the movable range of the bubble shadow and a reference light receiving section outside the movable range, and the both light receiving sections are arranged close to each other. Is
Using the outputs of the four light-receiving pieces, However, R: radius of curvature of the inner surface of the top of the bubble tube C: output of the reference light receiving part V ₁₃ = KS ₁₃ S ₁₃ : area of the reference light receiving part K: coefficient A: output of the light receiving element on one side in the X direction (V ₁₄ + V ₁₅ ) -Output of light receiving element on the other side (V ₁₆ + V ₁₇ ) = K {(S ₁₄ + S ₁₅ )-
(S ₁₆ + S ₁₇ )} S ₁₄ and S ₁₅ : Areas of light-receiving portions of the light-receiving pieces on one side in the X direction S ₁₆ and S ₁₇ : Light-receiving pieces on the other side in the X direction, respectively Area of the area where light is irradiated S: Total area of four light-receiving pieces D: An inclination angle calculated in the X direction based on the bubble diameter, and an inclination angle in the Y direction is also calculated based on the above equation by replacing S ₁₅ and S ₁₆ in A above. Corner detector. 2. A bubble tube formed by enclosing a gas and a transparent liquid in a transparent container having an upper inner surface formed into a spherical concave surface, and a light transmitting section for irradiating the bubble tube with light from above or below. A light-receiving element formed of two light-receiving pieces for converting light transmitted through the bubble tube into an electric signal, and an arithmetic unit for calculating an inclination angle θ _X or θ _Y in the X-direction or the Y-direction based on the electric signal. In the tilt angle detector, the light receiving element is composed of a position detecting light receiving section within the movable range of the bubble shadow and a reference light receiving section outside the movable range, and the both light receiving sections are arranged close to each other. Is
Using the outputs of the two light-receiving pieces, However, R: radius of curvature of the upper inner surface of the bubble tube C: output of the reference light receiving part V ₃ = KS ₁₃ S ₁₃ : area of the reference light receiving part K: coefficient A: light reception on one side in the X or Y direction Output of one side V ₁₄ ′ -Output of light receiving piece on the other side V ₁₆ ′ = K (S ₁₄ ′ −S ₁₆ ′) S ₁₄ ′: Irradiation of light on the light receiving piece on one side in the X or Y direction Area S ₁₆ ′: Area of the part of the light-receiving piece on the other side in the X or Y direction that is irradiated with light S: Total area of the two light-receiving pieces D: A tilt angle detector characterized by calculating a tilt angle in the X direction or the Y direction based on the diameter of the bubble.