JPH03216514A - Inclination sensor - Google Patents

Abstract

PURPOSE:To obtain an inclination value without an error by dividing a light beam from one light emitting element into two light beams to irradiate a colored liquid and calculating an inclination from a difference between the attenuation quantities of the two light beams. CONSTITUTION:The intensities of two parallel light beams emitted from one laser diode (LD) 6 of a light irradiating unit 3 are adjusted by a variable beam splitter (ABS) 7 so that the intensity ratio of the two light beams after reflected by returning mirrors 8a, 8b and 8c is equal to 1:1. When a transparent container 2 is inclined by an angle theta, one of the two parallel light beams from the light irradiating unit 3 is transmitted through a colored liquid 1 by a distance corresponding to a length H1 and the other light beam is transmitted through the liquid 1 by a distance corresponding to a length H2 and received by photosensitive elements 4 and 5, respectively. The resultant photoelectric outputs of the elements 4 and 5 are measured and an inclination theta is calculated by using a prescribed equation. Thus, since two light emitting elements are not used, an accurate measured value can be obtained without a drift generated with elapse of time and a difference between characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inclination sensor, and particularly to an inclination sensor that can be applied to detecting the inclination of a spirit level or an apparatus.

[Conventional technology]

Conventionally, this type of tilt sensor uses two light-emitting elements, and this tilt sensor consists of a homogeneous colored liquid with a constant light absorption coefficient, a transparent rectangular parallelepiped container containing this colored liquid, and a transparent rectangular parallelepiped container containing the colored liquid. , on either the top or bottom of this container, 2
Two light-emitting elements are installed at a certain distance apart so that parallel light beams of the same intensity are irradiated perpendicularly to the facing surface of the book. It is configured to include two light-receiving elements installed at positions that respectively receive the two lights that have passed through the colored liquid.

FIG. 2 is a configuration diagram showing an example of the above-mentioned tilt sensor.

The tilt sensor shown in Fig. 2 consists of a homogeneous colored liquid 1 with a constant light absorption coefficient, a transparent rectangular parallelepiped container 2 containing the colored liquid 1, and two tubes of equal strength on the bottom surface of the transparent container 2. A laser diode (hereinafter referred to as LD) 9 and LDIO as two light emitting elements installed at a certain distance so as to irradiate parallel light beams perpendicularly to the facing surface;
Two light receiving elements (hereinafter referred to as PD) 4 are attached to the upper surface of the transparent container 2 so as to receive the two beams of light irradiated from the LD 9 and LDIO and passed through the colored liquid 1, respectively.
and PD5.

In the above configuration, when the transparent container 2 is tilted at an angle θ with respect to the horizontal, H1 is the length of the light beam emitted from the LD9 passing through the colored liquid 1, and H1 is the length of the light beam emitted from the LDIO passing through the colored liquid 1. Let H2 be the distance between LD9 and LDIO. Also, both the intensities of the light beams emitted from LD9 and LDIO are set to φ. , the intensity of the light beam received by PD4 is φ2, the intensity of the light beam received by PD5 is φ2, and the light absorption coefficient of the colored liquid 1 is μ. At this time, the intensity of light passing through a material with a constant light absorption coefficient has the property of attenuating exponentially with the thickness of the material (Lambert's law). Therefore, equations (1) and (2) hold true.

φ,=φ. e-1...
...(1)φ2=φ. e1H''
(2) Also, equation (3) holds true geometrically.

l tanθ= (H2Hl) D Therefore, formula (4) is derived from formulas (1) to (3).

......(3) Here, if the value of the output a of PD4 is , and the value of the output b of PD5 is 2, then , and , are values proportional to φ1 and φ2, respectively, so Equation (4) becomes, and by measuring ■ and I2, the angle θ can be determined.

[Problem to be solved by the invention]

The conventional tilt sensor described above detects the tilt angle based on the difference in the amount of attenuation of two beams of light passing through the colored liquid.
Since the irradiation source of the book's light is a separate light emitting element, due to the drift over time and differences in the characteristics of the light emitting elements, the light intensity when emitted will differ between the two lights, and the amount of attenuation will not be calculated correctly. However, there is a drawback that an error may occur in the detected angle of inclination.

[Means to solve the problem]

The tilt sensor of the present invention consists of a homogeneous colored liquid with a constant light absorption coefficient, a transparent rectangular parallelepiped container containing the colored liquid, and a light emitting element that splits light into two beams of the same intensity. and a light irradiation unit that separates the two lights for a certain period of time and irradiates the rectangular parallelepiped container vertically from either the upper or lower surface to the opposite side;
and two light receiving elements installed at positions facing the light irradiation part of the rectangular parallelepiped container and respectively receiving two lights irradiated from the light irradiation part and passed through the colored liquid. configured.

[Actual travel example]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

The tilt sensor shown in FIG. 1 includes a homogeneous colored liquid 1 having a constant light absorption coefficient, a rectangular transparent container 2 containing the colored liquid 1, and a rectangular parallelepiped transparent container 2 that is attached to the bottom surface of the transparent container 2. A light irradiation unit 3 that irradiates two parallel light beams perpendicularly to each other facing each other, and a light irradiation unit 3 that is located on the top surface of the transparent container 2 and receives two rays of light that have been irradiated from the light irradiation unit 3 and passed through the colored liquid 1, respectively. It is configured to include two PD4 and PD5 attached to the position. The light irradiation unit 3 includes one LD 6 as a light emitting element and a variable beam splitter (hereinafter referred to as A B .S)7 and ABS7
three folding mirrors 8 which fold back the two beams of light split by
a, 8b and 8c.

In the above configuration, by adjusting the ABS 7, the intensity of the two parallel light beams irradiated from the light irradiation unit 3 can be adjusted by adjusting the intensity of the two parallel light beams after being reflected by the folding mirrors 8a, 8b and 8C and before passing through the colored liquid 1. Make it 1:1 at this point.

When the transparent container 2 is tilted at an angle θ with respect to the horizontal, the length of one of the two parallel light beams emitted from the light irradiation unit 3 passing through the colored liquid 1 is H1, and the length of the other light beam passing through the colored liquid 1 is H1. Let the length be H2 and the distance between the two parallel rays be D. In addition, the intensity of the two parallel light beams before passing through the colored liquid 1 is φ, the intensity of the light beam received by the PD5 is φ, the intensity of the light beam received by the PD6 is φ2, and the light absorption coefficient of the colored liquid 1 is μ. shall be. Also, if the value of the output a of PD4 is , and the value of the output b of PD5 is , then as explained in the above conventional technology, the angle θ can be found by measuring It and I2. I can do it.

〔Effect of the invention〕

As explained above, the inclination sensor of the present invention detects the inclination angle from the difference in the amount of attenuation of the two lights passing through the colored liquid. Instead, the light from one light emitting element is divided into two beams and irradiated, which eliminates variations in light intensity due to drift over time or differences in characteristics of the light emitting elements, and provides an error-free slope value. There is.

4

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of an example of a conventional tilt sensor. 1... Colored liquid, 2... Transparent container, 3...
・・・・Light irradiation part, 4.5-・・・Photo-receiving element (P D
), 6, 9.10-... Laser diode (LD)
, 7... variable beam splitter (ABS), 8
a, 8 b, 8 c--Folding mirror

Claims (1)

[Claims] A homogeneous colored liquid with a constant light absorption coefficient, a transparent rectangular parallelepiped container containing this colored liquid, and a light emitting element that splits the light into two beams of the same intensity. a light irradiation section that irradiates vertically to the opposite surface from either the upper or lower surface of the rectangular parallelepiped container while separating the liquid for a certain period of time; A tilt sensor comprising: two light-receiving elements mounted at positions that respectively receive two passing beams of light.