JPH0464408B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an inclination angle detection device that can be incorporated into an electronic goniometer or the like, and more particularly to a minute inclination angle detection device based on the direction of gravity.

Prior Art and its Problems Various systems have been proposed and put into practical use as conventionally known tilt angle devices. These methods include photoelectrically measuring the bubble position in a bubble level or detecting the difference in the liquid level position in a U-shaped tube using a bridge circuit using appropriate electrical means. In these cases, the curvature of the vial affects the accuracy of reading the inclination angle, and although it is possible to measure rough inclination angles, it is not possible to measure inclination angles with high sensitivity on the order of seconds.

Another conventional example is a method in which a free pendulum is used to optically or electrically measure the tilt angle displacement of the free pendulum, but this method has problems with the stability and multiplicity of the pendulum. In order to solve these problems, it is necessary to complicate and enlarge the mechanism, which has disadvantages such as an increase in cost.

Furthermore, as a tilt angle detection device based on the power direction, a device is known that detects the deviation angle of light reflected by the free surface of a relatively highly viscous liquid. As one type of this tilt angle detection device, a liquid is placed in a liquid container having a V-shaped wall, and from one incident light-transmitting wall surface of the V-shaped wall of this liquid container, the direction is parallel to the free liquid surface of the liquid. Light is incident, the light reflected on the free liquid surface of the liquid is emitted from the other output transparent wall surface of the V-shaped wall of the liquid container, and is incident on the light receiving section, and the liquid is reflected from the position of the light incident on the light receiving section. 2. Description of the Related Art A device is known that calculates the angle of inclination of an object to be measured containing a container from the direction of gravity.

This conventional device is capable of measuring minute angles of inclination from the direction of gravity, but when the volume of the liquid in the liquid container changes due to temperature changes, the height position of the free liquid level changes. There was a possibility that this would lead to measurement errors.

Purpose The present invention aims to provide a minute inclination angle detection device that can suppress changes in the height position of the free liquid level due to temperature changes and measure minute inclination angles more accurately.

Configuration The present invention was completed based on the idea that if the cross-sectional area of the liquid container is expanded upward in the vicinity of the free liquid level, changes in the liquid level position due to temperature changes will be reduced.

That is, the present invention provides the above-mentioned minute tilt angle detection device, in which a liquid container having a V-shaped wall has a bottom section located below the free surface of the liquid, and a free liquid surface connected to the top of this bottom section. The cross-sectional area of this upper section in the direction parallel to the free liquid level is increased upward, and
It is characterized in that the rate of change in the cross-sectional area in the vertical direction is set larger than the rate of change in the same cross-sectional area in the bottom section.

Configuration of Embodiment An embodiment of the present invention will be described based on FIGS. 1 and 2. A light emitting element 1 and a light receiving element 2 consisting of a semiconductor position detection element are placed side by side, and a collimating lens 3 is placed on the light emitting element 1 side, and an f/theta lens 4 is placed on the light receiving element 4 side on the optical path of each of them. It is located separately at a position corresponding to .

A slit 5 is provided in the optical path on the side of the light emitting element 1, and reflective mirrors 6 and 7 are provided obliquely in each optical path.

An inverted triangular transparent prism-shaped liquid container 8 is provided in front of an intermediate position where these members are juxtaposed, and a liquid 9 is contained in the liquid container 8.

On the other hand, the light receiving element 2 has three electrodes. The light-receiving element 2 is connected to an electronic circuit section that processes the light-receiving signal.

The liquid container 8, which is a feature of the present invention, has a V-shaped wall symmetrical with respect to the vertical direction, one of the V-shaped walls (left side in the figure) constitutes an incident light-transmitting wall surface 8a, and the other (on the right) constitutes the light-emitting light-transmitting wall surface 8b.
This liquid container 8 has a free wall surface 9a of the liquid 9.
It has a bottom section l1 located lower, and an upper section l2 continuous to the top of this bottom section l1, where the free liquid level 9a is located, and in this upper section l2, the lateral cross-sectional area, that is, the free liquid level The cross-sectional area in the direction parallel to 9a increases rapidly upward. That is, the rate of change in the vertical direction of the cross-sectional area in the direction parallel to the free liquid level in the upper section l2 is larger than the rate of change in the same cross-sectional area in the bottom section l1. By increasing the cross-sectional area of the liquid container 9 upward in the vicinity of the free liquid level 9a in this way, the height position of the free liquid level 9a can be changed when the volume of the liquid 9 changes due to a temperature change. can be suppressed.

Effects of the Embodiment Next, based on the above configuration, the effects will be explained in more detail.

As shown in FIG. 1, the light beam from the light emitting element 1 is turned into a substantially parallel beam by the collimating lens 3, becomes a beam of a certain thickness by the slit 5, is reflected by the reflector 6, and is perpendicularly incident on the incident light-transmitting wall surface 8a of the liquid container 8. liquid 9
incident on . The incident light beam is totally reflected by the free liquid surface 9a of the liquid 9, exits from the output transparent wall surface 8b of the liquid container 8, is reflected by the reflecting mirror 7, and enters the f/θ lens 4. The incident light flux is polarized by f・θ lens 4 and becomes f・θ
The light enters the light receiving element 2 which is placed on the focal plane of the lens 4. As shown in the figure, the light receiving element 2 has three electrodes, and a photocurrent proportional to the position of the incident light appears on the electrodes A and B. This photocurrent is amplified to the required level by amplifiers 10 and 11 shown in FIG. The microprocessor 15 calculates the angle value and displays it on the display 16.

In the above configuration, the inclination angles of the device are θ, f, θ
The focal length of lens 4 is l, and the refractive index of liquid 9 is 1.4.
Then, the amount of movement x of the light beam from the reference point on the light receiving element 2 is expressed as x=2.8.

Here, if S1771 manufactured by Hamamatsu Photonics is used as an example of the light receiving element 2, the minimum resolution is 0.2 μm,
f・θ lens 4 required to detect a tilt angle of 1 second
The focal length is 15mm, providing high resolution with an extremely short optical path length. In the present invention, the liquid container 8 has a bottom section l1 and an upper section l2, and the cross-sectional area rapidly increases in the upper section l2, so that fluctuations in the liquid level due to temperature changes are prevented. The compressed light receiving element 2 becomes an f/θ lens 4
Even if there is a slight deviation from the focal position, the amount of error is reduced and measurement accuracy can be maintained over a wide temperature range. Furthermore, by amplifying the output of the light-receiving element 2, adding and subtracting it, A/D converting it, and converting it into an angle using a microprocessor, stable tilt angle detection with few errors can be performed with a simple circuit. can.
Furthermore, by converting it into a digital value, it is possible to easily send the tilt angle as data to a microprocessor for other purposes rather than a dedicated one. In addition, the reflecting mirror 6,
By providing 7 in the middle of the light beam, the optical path can be changed freely, which has the advantage of configuring a compact tilt angle detection device suitable for the application. In Figure 1, light emission,
Although the light receiving section is arranged below the liquid container, it is also possible to arrange the light emitting and light receiving section above the liquid container as shown in FIG. In FIG. 3, the same components as in FIG. 1 are given the same reference numerals.

Effects As described above, the present invention provides an apparatus for detecting a minute tilt angle by placing a liquid in a liquid container having a V-shaped wall and using light reflected from the free liquid surface. A bottom section and an upper section are provided, and the cross-sectional area of the upper section in the direction parallel to the free liquid level increases upward, and the rate of change of the cross-sectional area in the vertical direction is equal to the change of the same cross-sectional area in the bottom section. Since it is made larger than the ratio, even if the volume of the liquid changes due to a temperature change, the change in the height position of the free liquid level can be suppressed, and therefore more accurate measurement can be performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG.
The figure is a block diagram of an electronic circuit according to the invention, and FIG. 3 is a schematic diagram showing another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Light emitting element, 2... Light receiving element, 3... Collimating lens, 4... f/theta lens, 5... Slit, 6,
7...Reflecting mirror, 8...Liquid container, 8a...Incidence transparent wall surface,
8b...Emission light transmission wall surface, 9...Liquid, 9a...Free liquid level, 10, 11...Amplifier, 12...Subtractor, 13...
Adder, 14...A/D converter, 15...Microprocessor, 16...Display device.

Claims (1)

[Scope of Claims] 1. A liquid container having a V-shaped wall; an entrance transparent wall surface and an output transparent wall surface provided on one side and the other side of the V-shaped wall of this liquid container; A light emitting part that makes parallel light incident toward the free liquid surface of the liquid held in the container; it exits from this light emitting part, passes through the incident light-transmitting wall surface, is reflected by the free liquid surface of the liquid, and is emitted from the light-emitting light-transmitting wall surface. a light-receiving section that allows the light that has passed through the light-receiving section to be incident; and a calculation means that calculates the inclination angle from the gravity direction of the object to be measured on which the liquid container is mounted from the position of the light that enters the light-receiving section; In the detection state, the liquid container having the V-shaped wall is provided with a bottom section located below the free surface of the liquid, and an upper section continuous to the top of this bottom section where the free liquid surface is located; The cross-sectional area in the direction parallel to the free liquid surface of this upper section when the micro-inclination angle detection device is not tilted increases upward, and the rate of change of the cross-sectional area in the vertical direction is A minute inclination angle detection device characterized in that the rate of change is set larger than the rate of change of the same cross-sectional area.