JPH0619273B2 - Tilt angle sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a two-dimensional configuration in which the inclination angle of a container containing a liquid with respect to the direction of gravity is composed of a horizontal surface of the liquid and a plane mirror attached to one side surface of the container. The present invention relates to a photoelectric tilt angle detection sensor which utilizes a single-lens mirror and converts it into a change in the reflection direction of the reflected light beam to obtain an output signal corresponding to the tilt angle.

(Prior Art) Conventionally, an inclination angle sensor that detects the inclination of a container containing a liquid has been put into practical use by utilizing that the liquid always exhibits a horizontal surface due to the action of gravity. This is because the path of the reflected light from this horizontal plane changes according to the inclination of the container, so the tilt angle is obtained by photoelectrically detecting the change in the path of the reflected light relative to the path at the reference time. It is something to try. At this time, the path of the reflected light is detected by the light receiving detector, but it is detected by the zero point fluctuation of the light receiving detector due to temperature change, sensitivity change, relative position change, etc. Since the output of the detector fluctuates, it was unavoidable that there was an error in tilt angle detection.

(Problems to be Solved by the Invention) The present invention has been made in order to eliminate a measurement error due to a temperature change or the like which is found in the conventional tilt angle sensor as described above. The purpose is to provide an angle sensor.

(Means for Solving the Problems) In FIG. 1, the inclination angle detection sensor of the present invention is a container 2 for containing a liquid 3 presenting a horizontal surface 11, and a container 2 provided with a plane mirror 1 on one side surface thereof. And a container for collimating the light from the slit 6 arranged on the focal plane thereof so that the collimated light is simultaneously incident on any of the reflecting surfaces of the double mirror constituted by the horizontal plane 11 of the liquid 3 and the plane mirror 1. Two
And a collimating system 4 fixedly arranged with respect to the collimated light reflected twice by the double mirror, and two slits 6 on the light receiving detector 7 arranged on the focal plane thereof. And a light collecting system 4'which is fixedly arranged with respect to the container 2 so as to form an image.

(Operation) When the inclination angle detection sensor of the present invention is configured in this way,
In the figure, when the plane mirror 1 is tilted by θ from the direction of gravity, two images of the slit 6 are formed on the light receiving detector 7 at intervals of d, and this interval d is proportional to the tilt angle θ. The inclination θ of the container 2 can be detected by measuring the distance d by the light receiving detector 7.

(Embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, a plane mirror 1 is provided on the side surface of a transparent container 2 whose bottom surface makes an angle of about 45 ° with one of the side surfaces, and a horizontal surface 11 of the transparent liquid 3 contained in the container 2 is provided.
The container 2 is arranged with respect to the object to be measured (not shown) so that the plane mirror 1 and the plane mirror 1 are substantially perpendicular to each other. Collimator optical system 20
The optical axis 9 of is substantially orthogonal to the line 10 of intersection of the plane mirror 1 and the horizontal plane 11, and the light source 5, the collimator lens 4 (which also serves as the condenser lens 4 ') which constitute the collimating optical system 20,
The collimator optical system 20 is fixed to the container 2 so that the slit 6, the light receiving detector 7, and the half mirror 8 are located in a plane including the optical axis 9 and substantially orthogonal to the plane mirror 1 and the horizontal plane 11. Since the slit 6 and the light receiving detector 7 are located on the focal plane of the collimator lens 4, the light of the light source 5 emitted from the slit 6 is reflected by the half mirror 8 and collimated by the collimator lens 4 to become parallel light. , Enters the liquid 3 through the bottom surface of the container 2. The parallel light is reflected in the order of reflection with a plane including the intersection line 10 and parallel to the optical axis 9 as a boundary.
(1) Horizontal plane 11-> plane mirror 1, (2) Plane mirror 1-> horizontal plane 11,
It is divided into two optical paths. Then, each reflected light passes through the half mirror 8 by the condenser lens 4 '(which is also the collimator lens 4), and two images of the slit 6 are formed on the light receiving detector 7 placed on the focal plane thereof. (2 above
An image corresponding to each optical path is formed. In the case of FIG. 1, since the plane mirror 1 and the horizontal plane 11 form a right angle, the images of the slits 6 due to the above two kinds of reflected light overlap each other to form one image.

On the other hand, as shown in FIG. 2, when the container 2 is inclined by the angle θ with respect to the direction of gravity, the angle formed by the horizontal plane 11 and the plane mirror 1 is 90 ° ± θ (plus in the case of FIG. 2). Becomes Assuming that the refractive index of the liquid 3 is n and the focal length of the condenser lens 4'is f, when θ is small, the distance d between the two images of the slit 6 formed by the above two optical paths is expressed as d = 4nθf Be done. That is, the distance d is proportional to the angle obtained by subtracting 90 ° from the angle formed by the plane mirror 1 and the horizontal plane 11, in other words, the inclination angle θ of the container 2, and therefore the inclination angle is obtained by measuring the distance d. be able to. FIG. 3 shows the relationship between the inclination angle θ and the distance d. As is clear from the above description, since the interval d is given by the inclination angle θ directly on one light receiving detector, the characteristic variation of the light receiving detector caused by the temperature variation and the like as in the conventional one, the relative No error due to position fluctuations is introduced. Fourth as slit 6
When a slit having a slit shape as shown in the figure is used, an image as shown in FIG. 5 is formed on the photodetector 7 when there is an inclination. If a CCD, a licensor or the like is used as the light receiving detector 7, the image distance d can be measured digitally,
The inclination angle θ can be obtained based on this.

6 and 7 show another example of the shapes of the slit 6 (FIG. 6) and the photodetector 7 (FIG. 7) for measuring the image distance d in an analog manner. The slit 6 is an isosceles triangular portion 21 in which the light intensity is reduced symmetrically and linearly from the center line of the slit in order to measure the distance d between the images, and a constant portion used to keep the light intensity constant. It is divided into a portion 22 having a width, and images are formed on the light receiving portions 23 and 24 of the light receiving detector 7, respectively. FIG. 8 shows the relationship between the image of the slit and the light receiving portions of the light receiving detector when there is an inclination. Two images of the slit portion 21 formed by the two optical paths are shown by a solid line and a dotted line. Light receiving unit 23
Output has a relationship as shown in FIG. 9 with respect to the tilt angle θ, and is proportional to the tilt angle θ. Here, such an important feature of the slit is that if the light receiving portion 23 is located at any position within the range where the two images of the slit portion 21 intersect, the slit portion 21 2 Since the areas of the two images are constant regardless of the position of the light receiving section 23, the detected light intensity is not changed due to the position shift of the light receiving detector due to the temperature change or the like. The shape of the slit portion 21 is not limited to the above-mentioned shape, and may be, for example, one in which the light intensity increases symmetrically from the center line to the outside. The output of the light receiving portion 24 corresponding to the slit portion 22 used to keep the light intensity constant is used to control the light emission intensity of the light source 5, keep the light intensity of the slit 21 constant, and change the light intensity. The measurement error due to is eliminated.

10 and 11 are a side view and a plan view of an embodiment in which a half mirror is not used in the collimator optical system. The slit 6 and the light receiving detector 7 are the collimator lens (also the condensing lens 4 '). On the focal plane (also serving), the optical axis 9 is arranged at a symmetrical position with respect to a plane orthogonal to the intersection line 10 (a plane perpendicular to the paper surface of FIG. 11). With such an arrangement of the optical system, the tilt angle can be obtained similarly to the tilt angle detection sensor of the embodiment shown in FIGS. 1 and 2.

In each of the above embodiments, the direction of the inclination, that is, the sign of the inclination angle θ cannot be determined. When it is necessary to determine this sign, the inclination angle detection sensor of the present invention is used only on one side from the + side to the − side of the inclination angle θ on the characteristic diagram of FIG. 3 or 9. It is used by adjusting the mounting position with respect to the object to be measured, or as shown in FIGS. 10 and 11, it is arranged between the collimator lens 4 and the slit 6 in a plane including the optical axis 9 and the intersection line 10. It is preferable to use the opaque sheet 25 or the like. This kind of cutting board 2
When 5 is used, the sign of the tilt angle θ that can be detected is only on the + side.

In the above embodiments, the collimated light from the collimator lens 4 comes from the inside of the liquid to the plane mirror 1 and the horizontal plane 11.
However, when the horizontal surface 11 of the liquid 3 is reflective, the collimated light may be incident from above the liquid 3. It will be apparent to those skilled in the art that various other modifications can be made.

(Effects of the Invention) As described above, according to the present invention, a parallel mirror is divided into two optical paths and reflected by a double mirror that is configured to be generally orthogonal to each other between a plane mirror and a liquid horizontal plane, The tilt angle is detected by measuring the distance between the two images of the slit formed by the reflected light of each optical path in the condensing system, so high accuracy that is not affected by temperature fluctuations etc. It is possible to provide the inclination angle detection sensor. The inclination angle detection sensor can detect the inclination of an object with high accuracy, and the detected electric signal can be used to feed back the inclination angle of the object or other objects related to the electric signal. It can be used for remote control.

[Brief description of drawings]

FIG. 1 is a side view of a tilt angle sensor according to an embodiment of the present invention, FIG. 2 is an explanatory view when there is a tilt, FIG. 3 is a characteristic view of tilt angle versus image distance, and FIG. 4 is a slit. 5 is a front view of an example of the shape, FIG. 5 is a front view of a slit image on the photodetector, FIG.
FIG. 7 is a front view of the other side of the slit shape, FIG. 7 is a front view of a photodetector corresponding to the slit of FIG. 6, and FIG.
FIG. 9 is an explanatory diagram showing the relationship between the slit image in the figure and the light receiving detector in FIG. 7, FIG. 9 is an output characteristic diagram with respect to the inclination angle in the case of FIG. 8, and FIGS. 10 and 11 do not use a half mirror. It is a side view and a top view of an example. 1: Plane mirror, 2: Container, 3: Liquid, 4: Collimator lens, 4 ': Condensing lens, 5: Light source, 6: Slit, 7:
Light receiving detector, 8: half mirror, 9: optical axis, 10: intersecting line, 11: horizontal surface of liquid, 20: collimator optical system, 2
1: Inclination angle measurement slit, 22: Light intensity control slit, 23: Inclination angle measurement light receiving unit, 24: Light intensity control light receiving unit, 25: Cutout plate

Claims (7)

[Claims] 1. A container containing a liquid having a horizontal surface and having a plane mirror provided on one side surface thereof, and collimating light from a slit arranged on its focal plane to collimate the collimated light with the horizontal surface of the liquid and the plane mirror. And a collimating system fixedly arranged with respect to the container so as to be incident on any reflecting surface of the double mirror at the same time, and collimated light reflected twice by the double mirror is condensed. A condenser system fixedly arranged with respect to the container so as to form two images of the slit on a light receiving detector arranged on the focal plane of the slit. A tilt angle detection sensor, which detects a tilt angle of the container by measuring a distance between two images. 2. The slit is slit-shaped, and the photodetector is configured to measure a distance between two images of the slit slit. The tilt angle detection sensor according to claim 1. 3. The slit has a shape such that the light intensity distribution of a slit image continuously changes symmetrically from the center line of the slit, and the light receiving detector is within a crossing range of two images of the slit. The inclination angle detection sensor according to claim 1, wherein the inclination angle detection sensor is configured to measure the total light intensity of a predetermined width in the slit center line direction. 4. The collimator system and the light condensing system are formed by one image forming system.
The tilt angle detection sensor according to any one of items 1 to 3. 5. A threshold plate is provided between the collimator system and the slit, and between the light converging system and the light receiving detector, according to any one of claims 1 to 4. The tilt angle detection sensor described in any of the above. 6. A collimated light beam from the collimator system is arranged so as to be incident on the horizontal plane of the liquid and the plane mirror from below the horizontal plane, as claimed in any one of claims 1 to 5. The inclination angle detection sensor described in 1. 7. The collimated light from the collimator system is arranged so as to be incident on the horizontal plane of the liquid and the plane mirror from above the horizontal plane, as claimed in any one of claims 1 to 5. The inclination angle detection sensor described in 1.