JPS62130309A - Tilt angle sensor device - Google Patents

Abstract

PURPOSE:To detect a tilt angle with higher accuracy by summing up outputs of light receiving elements by an adding circuit and making the quantity of light emission of a light emitting element constant by a light quantity controller according to the sum output signal. CONSTITUTION:The adder circuit 17 which sums up the output signals of amplifier circuits 11 and 12, a light quantity control circuit 18 which ocntrols electric power supplied from a power source 16 according to the sum output signal, etc., are provided. Then when the case 1 of a tilt detection part slants by an angle theta1, the output signals of the light receiving elements 6 and 7 are processed 10, so that an output signal corresponding to the angle theta1 appears at a terminal 15. The tilt angle is detected from the level of the output signal and the tilt direction is detected from its polarity. Then, when the temperature of the element 2 varies and its light output varies, the output signal of the circuit 17 also varies. The circuit 18 controls a current or voltage supplied from the power source 16 to the element 2 according to the variation to hold the output of the element 2 at an invariably specific level. Consequently, the output variation of the element 2 is corrected and error components are removed from the output signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tilt angle sensor, in particular, to a tilt angle sensor in which the incident angle of light to a light receiving surface is changed in accordance with the tilt angle.

This invention relates to a device that can detect an inclination angle by utilizing changes in the amount of light on a light-receiving surface.

Conventional technology As a device for measuring the inclination angle of an object, there have been magnetic type devices using magnetoresistive elements and Hall elements (Japanese Patent Laid-Open No. 69-120810, Japanese Patent Laid-open No. 59 -128408), and a torque balance system consisting mainly of a meter mechanism and a photocoupler, combined with an electronic circuit (Japanese Patent Publication No. 59-48044).
Publication No.) is known.

Problems to be Solved by the Invention In such inclination angle sensor devices, magnetic type devices are susceptible to the influence of external magnetic fields, which tends to cause detection errors, and furthermore, the response speed is slow. There is. On the other hand, torque balance type devices have problems such as stable characteristics against temperature changes, complicated mechanisms for improving resolution, and the need to use expensive precision parts. there were.

As a device for solving the above-mentioned problems, the inventors arranged at least one pair of light-receiving elements in one light-emitting element so as to face each other at a predetermined interval, and at least one of the light-emitting element and the light-receiving element A device in which one side is configured to maintain a constant relationship with the vertical axis, and the other is configured so that the direction of its optical axis changes according to the inclination, and the angle of inclination can be detected from the difference in the output of the light receiving element. (Japanese Patent Application No. 1986-202086).

The configuration and operation thereof will be explained below using FIGS. 3 and 4.

FIG. 3(a) is a sectional view showing the structure of the inclination detection section in this device, and FIG. 3(b) is a sectional view taken along the person-A line. FIG. 4 is a block diagram thereof.

In FIG. 3, reference numeral 1 denotes a case, and a light emitting source 2 of a light emitting device (not shown) is attached to the upper part of the case 1.

As the light source 4, for example, a light emitting diode that emits infrared light with wide directivity is used. A light receiving block 3 is disposed on a vertical axis extending vertically from the light emitting source 2. The light-receiving block 3 has two surfaces 4 and 6 that intersect with each other at an angle Ai and face the light-emitting source 2 side, and a light-receiving element 6.7 is provided on each surface 4.6. The light-receiving element 6.7 is mounted so that its light-receiving surface faces the light-emitting source 2, and uses, for example, a photodiode that generates a current proportional to the amount of incident light.

The light receiving block 3 is rotatably supported on a shaft 8,
The shaft 8 is supported by the case 1. Also, a weight 9 is suspended on the light receiving block 3, and the weight 99 rotates the light receiving block 3 about the shaft 8 so that it always maintains a constant positional relationship with respect to the vertical axis.

Place the inclination detection section on the surface of the object to be measured. When it is tilted by an angle θ1, the light receiving block 3 rotates by an angle θ1. This causes an angular difference between the center line of the light receiving block 3 and the center line of the light emitting source 2 by the same angle 01 as the inclination angle θ1. In this state, the amount of light P1 received by the light receiving element 6 increases, and the amount P2 of light received by the light receiving element 7 decreases. As the inclination angle θ1 increases, the difference ΔP in the amount of light received by the light receiving element 6.7 increases. Here, considering the relationship between the light emitting source 2 and the light receiving element 6.7, due to the inclination of the case 1, the light emitting source 4 and the light receiving element 6.7
The distance between them changes, albeit slightly. It is possible that this variation in distance is a cause of measurement error, but in reality,
The change in the distance between the light emitting source 2 and the light receiving element 6.7 is minute, and its influence on the change in the amount of light can be ignored.

Of course, it would be better if the type of light emitting source, the mutual positional relationship between the light receiving elements, or the positional relationship between the light emitting source and the light receiving block could be adjusted.

The basic configuration of the tilt angle sensor device is as shown in FIG. 4, and the light receiving element 6.7 is connected to an arithmetic unit 10 for processing an output signal corresponding to the amount of light received. The arithmetic unit 1o includes amplifier circuits 11 and 12 that amplify the output signals of the light receiving elements 6 and 7, respectively, and these amplifier circuits 11.
The subtraction circuit 13 takes the difference between the 12 output signals, and the amplification circuit 14 amplifies the subtraction output signal.

This arithmetic unit 1o determines the output difference of the light receiving elements 6.7, and generates an output signal corresponding to the inclination angle θ1 at the output terminal 16. Note that 10 is a power source for feeding power to the light emitting element 2.

According to this device, the posture caused by the nuisance can be detected using light, so it is essentially unaffected by external noise and is extremely stable compared to the device that uses electromagnetic effects mentioned above. This has the advantage that the detection error is small. moreover.

It also has the advantage of being very simple in structure and inexpensive.

However, even though the tilt angle is calculated from the difference in the output of multiple light emitting elements, there is a risk of errors occurring during actual use due to changes in the temperature of the light emitting elements and deterioration of their characteristics. result.

It became clear.

The present invention aims to solve the problems with this device and provide a more accurate tilt angle sensor.

Means for Solving the Problems The first device of the present invention is one in which the output signals of the light-receiving elements are added by an adding circuit, and the amount of light emitted by the light-emitting element is made constant by a light amount control device in accordance with this added output signal. It is. Further, the second device corrects the subtraction output signal of the subtraction circuit in accordance with the change in the light amount of the light emitting element using a division circuit or a multiplication circuit in accordance with the addition output signal.

Operation In the first device of the present invention, the light output of the light emitting element is corrected based on the sum of the outputs of the light receiving elements, the light output is held constant, and fluctuations in the light output of the light emitting element are corrected. .

In the second device of the present invention, since the subtracted output signal corresponding to the tilt angle is corrected by the sum of the output directions of the light receiving elements, the amount corresponding to the output fluctuation of the light emitting elements included in the subtracted output signal is be excluded. -Embodiment FIG. 1 is a block diagram of an embodiment of a tilt angle sensor device according to the present invention. In this figure, the same components as in the apparatus of FIG. 4 are given the same reference numerals.

The biggest difference between this embodiment and the device shown in FIG.
7, and the power supply 1 according to the addition output signal of this addition circuit 17.
6 to the light emitting element 2, and a light amount control circuit 1B that controls the power supplied from the light emitting device 6 to the light emitting element 2 and makes the amount of emitted light constant. In other words, the power source 16 and the light amount control circuit 18 form a variable power supply system in which the power supplied is controlled according to the sum of the output signals of the light receiving element 6 and the light output 7, or in other words, the light output of the light emitting element 2. M1
9 is composed.

As shown in the figure, when the case 1 is tilted by an angle θ1, the output signal of the light receiving element 6.7 is processed by the arithmetic unit 10 as described above, and an output signal corresponding to the angle θ1 is obtained at the terminal 16. The angle of inclination can be detected by the magnitude of the output signal applied to the terminal 16, and the direction of the inclination can be detected by its polarity.

During actual use, for example, due to changes in the surrounding area, the light emitting element 2
When the temperature of the light emitting element 2 changes and the light output of the light emitting element 2 changes accordingly, the sum of the blade signals of the amplifier circuits 11 and 12, that is, the output signal of the adder circuit 17 also changes, as a matter of course.

The light amount control circuit 1B controls the current or voltage supplied from the power supply 16 to the light emitting elements 2 in accordance with changes in the output signal of the adding circuit 17, so that the light output of each light emitting element 2 is always at a predetermined level. Works to maintain it. As a result, fluctuations in the output of the light emitting element 2 are corrected, and errors in the output signal are removed.

FIG. 2 is a block diagram of another embodiment of the tilt angle sensor device according to the present invention. Components corresponding to those in the device described above are given the same reference numerals.

In this device, a division circuit 2o is provided between the subtraction circuit 13 and the amplifier circuit 14 of the arithmetic unit 1o, and in the division circuit, the output of the addition circuit 1a is calculated by adding the output signals of the amplifier circuits 11 and 12. The output signal of the subtraction circuit 13 is divided according to the signal. That is, the division circuit 20 divides the output signal of the subtraction circuit 13 according to fluctuations in the light output of the light emitting element 2,
Removes fluctuations in optical output. As a result, output terminal 1
6, an output signal corresponding to the angle θ1 is obtained.

It goes without saying that a multiplication circuit may be used in place of the division circuit 20 to compensate for fluctuations in the optical output of the light emitting element 2.

Furthermore, even if the light emitting element 2 is mounted on a movable body and configured so that it always has a constant positional relationship with respect to the vertical axis, and the light receiving block 3 is mounted on the case 1 at a position facing it, it is equivalent to the above embodiment. effect can be obtained. moreover,
It is also easy to use a plurality of pairs of light receiving elements and detect the inclination angle in one various direction based on the output signal of each seal.

As described in detail of the invention, according to the device of the present invention, the light output of the light emitting element is corrected and made constant according to variations in its characteristics, or the output signal corresponding to the inclination is adjusted to the light output of the light emitting element. Since the correction is made based on the fluctuation of

[Brief explanation of drawings]

1 and 2 are block diagrams of embodiments of the inclination angle sensor device according to the present invention, and FIG. 3 (IL) is a front sectional view of the inclination detection section used in these embodiments, and FIG.
b) is a sectional view taken along the line A-A. FIG. 4 is a block diagram of a device studied before the invention was completed. 2... Light emitting element, 3... Light receiving block, 6.7... Light receiving element, 8... Axis, 9
... Weight, 10 ... Arithmetic device, 13
...Subtraction circuit, 16...Power supply, 17.
... Addition circuit, 18 ... Light amount control circuit,
19... Power supply device, 2o... Division circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure (αn (1) 7A

Claims (2)

[Claims] (1) A light receiving device having a light emitting element and a plurality of light receiving elements arranged opposite to the light emitting element, each of which generates a signal corresponding to the amount of light from the light emitting element,
an inclination angle detection section in which one of the light emitting element and the light receiving element is held in a fixed relationship with respect to a vertical axis, and the other is movable according to an inclination angle to be measured; and outputs of the plurality of light emitting elements. an arithmetic device that calculates based on the signal and generates a signal corresponding to the tilt angle; an adder circuit that adds the output signals of the plurality of light receiving elements; and an adder that calculates the amount of light emitted from the light emitting element based on the output signal of the adder circuit. A tilt angle sensor device comprising: a light amount control circuit that controls constant light amount. (2) a light receiving device having a light emitting element and a plurality of light receiving elements arranged opposite to the light emitting element, each of which generates a signal corresponding to the amount of light from the light emitting element;
an inclination angle detection section in which one of the light emitting element and the light receiving element is held in a fixed relationship with respect to a vertical axis, and the other is movable according to an inclination angle to be measured; and outputs of the plurality of light emitting elements. an arithmetic device that calculates based on the signal and generates a signal corresponding to the tilt angle; an adder circuit that adds the output signals of the plurality of light receiving elements; and an adder circuit that adds the output signals of the arithmetic device based on the output signal of the adder circuit A tilt angle sensor device comprising a division circuit or a multiplication circuit that performs division or multiplication.