JP2992943B2 - Small tilt angle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt angle detecting device which can be incorporated in an electronic angle measuring device or the like, and more particularly to a minute tilt angle detecting device based on the direction of gravity.

2. Description of the Related Art As an example of a conventional small tilt angle measuring device based on the direction of gravity, there is a device that uses a free pendulum and optically or electrically and magnetically measures the tilt angle, displacement amount, and the like of the free pendulum. Are known. However, this device has problems with the stability and the duality of the pendulum, and in order to improve this, the device must be mechanically complicated and large. Further, as another example of the conventional minute tilt angle measuring apparatus based on the direction of gravity, there is known an apparatus that measures a shift angle of reflected light due to a mercury liquid level using a free liquid level of mercury. However, this device has the problems of mercury toxicity and high price of mercury, and mercury requires a large surface area to obtain a flat reflective surface with a large surface tension, and is sensitive to vibration due to its low viscosity. And lack stability. For this reason, conventionally, a free liquid surface of a liquid such as silicon oil having higher viscosity than mercury is used as a tilt angle measuring device of this type, and a shift angle of reflected light due to the liquid surface is set to two.
An apparatus for optically measuring a two-dimensional light receiving element has been proposed. The configuration of the device using the free liquid surface is such that a light beam from a light emitting element is made incident on an incident surface at the bottom of a liquid container constituting a liquid surface reflection system, and the incident light beam is totally reflected by the free surface of the liquid surface. Then, the reflected light beam is emitted from the emission surface, and the amount of deviation in the direction of the emitted light is measured by a light receiving position detecting element formed of a one-dimensional or two-dimensional light receiving element, thereby detecting the inclination angle. This device is not sensitive to extraneous vibrations because it uses the total reflection of the free surface of a viscous liquid,
In addition, there is an advantage that a complex property is good and a measurement with relatively high accuracy is possible with an extremely simple configuration.

[0002]

SUMMARY OF THE INVENTION Using the free liquid surface of the conventional liquid, a one-dimensional or two-dimensional direction in which a shift angle of reflected light by the liquid surface is optically measured by a one-dimensional or two-dimensional light receiving element. In the case of a small angle detection device, the liquid surface reflection system is composed of a liquid container part containing a liquid in a part of the volume and forming a free liquid surface and a prism part on the lower surface, and a bottom plate part and a prism part of the liquid container part. Although the refraction of incident light does not occur at the boundary by integrally forming with the same optical member, the bottom plate of the liquid container and the liquid have, for example, a refractive index of the optical material of the bottom plate of 1.52. Since the refractive index of the liquid is different, such as 1.4, the incident light flux is reflected at the boundary surface,
A ghost light beam is introduced into the light receiving element, and the detection signal may be slightly deviated by the ghost light beam, so that accurate measurement may not be performed.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to a method of causing a light beam from a light emitting section to enter a liquid surface reflection system as a substantially parallel light beam, and to emit reflected light reflected by a free liquid surface of the liquid surface reflection system. An optical material used for the bottom surface of a free liquid surface of a liquid surface reflection system in a minute inclination angle detection device which receives light by a light receiving element provided in a light receiving portion and detects a minute inclination angle from a deviation angle of the reflected light. Ghost removal slope at the contact surface between the liquid and the free liquid surface slopes downward from the incident direction along the reflection direction
And provided, is intended to provide a small inclination angle detection device is characterized in that is introduced into the free liquid surface the incident light through the inclined surface.

[0004]

According to the small angle detecting device of the present invention,
Since the incident light that has entered the liquid surface reflection system from the light emitting unit causes the incident light to be introduced into the free liquid surface through a ghost removal inclined surface provided at the liquid surface of the liquid container at the free liquid surface and at the contact surface of the liquid at the free liquid surface, The ghost light flux generated by reflection on the ghost removal inclined surface is deflected so as not to enter the light receiving portion, so that unnecessary ghost light flux generated by reflection of the boundary surface between the liquid container bottom surface and the liquid does not reach the light receiving element. And the cause of the erroneous detection can be eliminated.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an embodiment shown in FIG. 1. In the embodiment shown in FIG. 1, reference numeral 1 denotes a light emitting unit; This is the lens system on the light emitting unit side. The liquid surface reflection system 3 includes a liquid container 4 that forms a free liquid surface 7 by storing a liquid 6 made of silicon oil or the like in a part of the volume, and a prism unit 5 that is integrally provided at the bottom of the liquid container 4. Consists of The prism section 5 has an incident side surface 8 that transmits the light beam from the light emitting section 1 toward the free liquid surface 7 and an emission side surface 9 that transmits the light beam reflected by the free liquid surface 7 to the outside. Reference numeral 10 denotes a light splitting element including a beam splitter or the like that splits a reflected light beam in a two-dimensional XY direction. The branched reflected light beam is coupled to a one-dimensional light receiving element 12 in the X-axis direction provided as a light receiving unit 11 and Y.
It is configured to receive light with a one-dimensional light receiving element 13 in the axial direction. The light receiving elements 12 and 13 each include a one-dimensional line sensor or the like for detecting an irradiation position of the reflected light along the X-axis direction and the Y-axis direction. , So that a two-dimensional inclination angle of the apparatus with respect to the free liquid level can be obtained. 14
Is a light-receiving-side lens system that collects the reflected light flux between the liquid-surface reflecting system 3 and the light-receiving part 11 and makes the light-receiving part 11 enter the light-receiving part 11. In this case, the light-receiving part 11 is a focal position of the lens system 14. It is located in.

In the embodiments of FIGS. 2 and 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and the difference is that in order to reduce the size of the apparatus, the incident side surface 8 of the prism portion 5 is used. The light-emitting unit 1 is provided on the opposite side of the light-emitting unit 1, and the parallel light flux from the light-emitting unit 1 coming from the opposite side
And the refraction prism section 15 interposed between the incident side face 8 of the prism section 5 and refracted by the refraction prism section 15 so as to enter the incidence side face 8, and transmits the reflected light flux reflected by the free liquid surface 7 to the outside. The reflected light flux transmitted through the emission side surface 9 of the prism unit 5 and the light receiving unit side lens system 14 is reflected by the reflection optical member 16 along the longitudinal direction of the bottom of the liquid container unit 4, and is reflected on the entrance side surface 8 side of the prism 5. The light is introduced into the located light branching element 10, and the light is received by the one-dimensional light receiving element 12 in the X-axis direction and the one-dimensional light receiving element 13 in the Y-axis direction provided as the light receiving part 11. In FIG. 2, reference numeral 17 denotes the light emitting unit 1.
This is a light-emitting unit monitor that receives a part of an extra light beam of the light-emitting unit 1 via the reflecting mirror 18 to monitor the intensity of the light source.

In the case of the above embodiment, the bottom plate 19 of the liquid container 4 and the prism 5 are integrally formed by the same optical member so that the boundary does not cause refraction of incident light. The bottom plate 19 of the container 4 and the liquid 6 are shown in FIG. 4 because, for example, the refractive index of the optical material of the bottom plate 19 is 1.52 and the refractive index of the liquid 6 is 1.4. As described above, the incident light beam is reflected at the boundary surface 20, becomes a ghost light beam G, enters the light receiving unit side lens system 14, is introduced into the light receiving elements 12, 13 via the light branching element 10, and Although there is a possibility that the detection signal may be slightly deviated by the light beam G and accurate measurement may not be performed, the present invention employs the optical material and the free liquid surface of the bottom plate 19 used for the bottom surface of the liquid container 4 as shown in FIG. As a boundary surface 20 that comes into contact with the liquid 6 Ghost light flux G is provided so as to be reflected in a warped direction so as not to enter the light receiving unit side lens system 14, and the incident light is introduced into the free liquid surface 7 through the inclined surface 21. I have. In the case of the embodiment, the ghost removal inclined surface 21 is provided with a flat bottom plate portion 19 having the same thickness of the liquid container 4 and inclined downward from the incident direction to the free liquid surface 7 along the reflection direction. The ghost removal inclined surface 21 is formed by warping the reflected ghost light flux G so as not to enter the light receiving unit side lens system 14.

[0008]

As described above, according to the minute inclination angle detecting device of the present invention, the light beam from the light emitting section is made to enter the liquid surface reflection system as a substantially parallel light beam, and is reflected by the free liquid surface of the liquid surface reflection system. In a minute inclination angle detection device which emits light, receives light with a light receiving element provided in a light receiving unit, and detects a minute inclination angle from a deviation angle of the reflected light, a liquid container bottom surface of a free liquid surface of a liquid surface reflection system A ghost removing inclined surface is provided on the contact surface between the optical material used for the above and the liquid on the free liquid surface, and incident light is introduced into the free liquid surface through the inclined surface, so that the ghost light flux reflected on the inclined surface To prevent the unnecessary ghost light flux generated by the reflection of the boundary surface between the liquid container bottom surface and the liquid from reaching the light receiving element, thereby eliminating the cause of erroneous detection. The effect that can be There is.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an embodiment of the present invention with a part cut away.

FIG. 2 is a schematic plan view showing another embodiment of the present invention with a part thereof omitted;

FIG. 3 is a schematic front view schematically showing a part of the embodiment of FIG.

FIG. 4 is a schematic explanatory diagram for explaining the principle of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light emitting part 2 ... Light emitting part side lens system 3 ... Liquid surface reflection system 4 ... Liquid container part 5 ... Prism part 6 ... Liquid 7 ... Free liquid level 8. ..Incoming side face 9 ... Outgoing side face 10 ... Light splitting element 11 ... Light receiving section 12 ... Light receiving element 13 ... Light receiving element 14 ... Light receiving section side lens system 15 ... Refractive prism Unit 16: Reflective optical member 17: Light emitting unit monitor 18: Reflecting mirror 19: Bottom plate 20: Boundary surface 21: Ghost removal inclined surface

Claims (1)

(57) [Claims] 1. A light beam from a light emitting unit is incident on a liquid surface reflection system as a substantially parallel light beam, and light reflected by a free liquid surface of the liquid surface reflection system is emitted, and received by a light receiving element provided in the light receiving unit. In a minute inclination angle detecting device configured to detect a minute inclination angle from a deviation angle of the reflected light, a contact surface between an optical material used for a liquid container bottom of a free liquid surface of the liquid surface reflection system and a liquid of the free liquid surface The ghost removal slope from the incident direction to the reflection direction.
Characterized in that the light is introduced downward to the free liquid surface through the inclined surface.