JPH05107260A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To enable a three-dimensional acceleration to be detected separately by arranging first photodetectors two-dimensionally and linear second photodetectors in multiple steps in the direction parallel to the first photodetectors and irradiating them with a first and a second light sources. CONSTITUTION:When an acceleration is applied to a sensor, an inertia force corresponding to the acceleration and an added force from eight springs 8 are applied to a metal 7 and the metal 7 changes its position. Since the metal 7 has a transmission of light of 0%, light from light sources 1 and 2 is blocked by the metal 7. Therefore, a light intensity becomes weaker at a position which corresponds to a position of the metal 7 in photodiodes 3 and 4 which constitute photodetectors 5 and 6, thus obtaining a three-dimensional position from a position of a two-dimensional metal 7 in x and y directions from the position of the photodiode 3 where the light intensity is weak and furthermore a position of the metal 7 in z direction from the position of the photodiode 4 where the light intensity is weak. Then, a three-dimensional acceleration can be obtained by using a specific expression according to the obtained position and time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor used in the field of industrial equipment for measuring and controlling mechanical vibrations, structural vibrations and the like.

[0002]

2. Description of the Related Art In recent years, as FA has advanced and the importance of industrial robots and precision automatic equipment has increased, the demand for sensors for measuring the mechanical quantity has increased, and expectations for the mechanical quantity sensors are great. Among them, the acceleration sensor is widely used because it can detect not only acceleration but also vibration, force, inclination, earthquake, shock, etc., and an inexpensive, compact, and high-performance acceleration sensor is desired. ing.

A conventional acceleration sensor will be described below. FIG. 2 is a structural diagram of a conventional acceleration sensor. In FIG. 2, 21 is a light emitting diode, 22 is a photodiode, 23 is an optical fiber A for sending light from the light emitting diode 21, 24 is an optical fiber B for sending light to the photodiode 22, and 25 is an optical fiber 23. Microlens A for converting the light from the light into parallel light, 26 is a microlens B for condensing the light on the optical fiber 24, 27 is a photoelastic element, 28 is a weight, 29 is a polarizer, 30 is an analyzer, 31
Is a quarter-wave plate.

The operation of the acceleration sensor constructed as above will be described below. First, the light from the light emitting diode 21 is guided by the optical fiber A23 and becomes parallel light by the microlens A25. This light passes through the polarizer 29 and is converted into a linearly polarized wave by the photoelastic element 27.
Is incident on. Now, when acceleration is applied in the direction of the arrow shown in FIG. 2, stress proportional to the mass of the weight 28 and the acceleration is applied to the photoelastic element 27 so that the photoelastic element 27 exhibits a birefringence index.
It becomes elliptically polarized light at the exit end of. This light is a quarter wave plate 3
The light intensity change is converted into a light intensity change by 1 and the analyzer 30, is guided to the photodiode 22 by the optical fiber 24, and is detected as a light intensity corresponding to the acceleration.

[0005]

However, in the above-mentioned conventional structure, the light intensity changes only when the weight is subjected to acceleration in one direction. Therefore, when the sensor is used alone, the light intensity changes in one direction. However, there is a problem that only the acceleration that occurs in can be detected.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an acceleration sensor capable of independently detecting three-dimensional acceleration.

[0007]

According to the present invention, there is provided a first photodetector having a plurality of photodetection elements arranged in a two-dimensional form, and the first photodetector.
First light source for irradiating the entire photodetector and a linear photodetection existing in a plane perpendicular to the first photodetector and in multiple stages in a direction parallel to the first photodetector. A second photodetector in which elements are arranged, a second light source that illuminates the entire second photodetector, an intermediate between the first and second light sources and the first and second photodetectors Which has a transmittance of less than 100% with respect to the light from the first and second light sources, and an elastic material for holding the object.

[0008]

With this configuration, when acceleration is applied to the sensor,
An inertial force corresponding to the acceleration and a force from the elastic material are generated in the object interposed between the light source and the photodetector, and the object is displaced. Since the light transmittance changes at the position where the object exists, the light intensity changes at some of the photodetector elements constituting the photodetector existing in the light emission direction of the light source corresponding to the displacement of the object. The three-dimensional position of the object in the viscous fluid can be obtained from the position of the photodetection element whose light intensity is changing, and it is added to the sensor from the relationship between the position of the object and time
Dimensional acceleration can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural diagram of an acceleration sensor according to an embodiment of the present invention. In FIG. 1, 1 is a light source A in which surface emitting lasers are arranged in a two-dimensional matrix, and 2 is a light source A1.
A light source B in which surface emitting lasers arranged in a plane perpendicular to the plane are arranged in a two-dimensional matrix, 3 is a photodiode A, 4 is a photodiode B, and 5 is a photodetector in which a photodiode A3 is arranged in a two-dimensional matrix. A and light source A1
Are arranged in the light emission direction. Reference numeral 6 denotes a photodetector B in which photodiodes B4 are linearly arranged, and is arranged in the light emitting direction of the light source B2. Reference numeral 7 is a cubic metal having a transmittance of 0% for the light from the light sources A1 and B2, and 8 is a spring for holding the metal 7. Each photodetector A5 and photodetector B6 is realized by a known configuration for performing photoelectric conversion.

The operation of the acceleration sensor configured as described above will be described. First, in a state where acceleration is not applied to the sensor, the metal 7 is moved by the spring 8 to the light source A1.
It is always held at an intermediate position between the photodetector A5 and the light source B2 and the photodetector B6.

When the acceleration a is applied, and the mass of the metal 7 is m, the metal 7 has a sensitivity-m corresponding to the acceleration a.
The resultant force F from a and the eight springs 8 is applied, and the metal 7 changes its position. If the position of the metal 7 at time t at this time is p, then (Equation 1) holds.

[0013]

[Equation 1]

A, F, and p in (Equation 1) are vector quantities having components in the x, y, and z directions shown in FIG.
To know the acceleration a from (Equation 1), it suffices to know the relationship between the position p and the time t.

Since the metal 7 has a light transmittance of 0%, the light from the light sources A1 and B2 is blocked by the metal 7. Therefore, in the photodiodes A3 and B4 forming the photodetectors A5 and B6, the light intensity to be detected is weak at the position corresponding to the position of the metal 7, so that x from the position of the photodiode A3 where the light intensity is weakened. , A three-dimensional position p can be obtained from the two-dimensional position of the metal 7 in the y direction and the position of the metal 7 in the z direction from the position of the photodiode B4 where the light intensity is weakened. ..

From the position p and the time t thus obtained, the three-dimensional acceleration applied to the sensor can be obtained by using (Equation 1).

In this embodiment, the light sources A1 and B2 are surface emitting lasers arranged in a two-dimensional matrix, but may be point light sources in which light spreads within the light receiving surface of the photodetectors A5 and B6. Further, the surface emitting lasers are arranged as the light sources A1 and B2 and the photodiodes A3 are arranged in the photodetector A5 in a two-dimensional matrix, but the arrangement is not limited to the matrix arrangement. Further, it goes without saying that the spring 8 may be another elastic material such as rubber.

[0018]

As described above, according to the present invention, a first photodetector in which a plurality of photodetection elements are arranged two-dimensionally, and a first light source for irradiating the entire first photodetector, A second photodetector, which is present on a plane perpendicular to the first photodetector and has linear photodetector elements arranged in multiple stages in a direction parallel to the first photodetector.
Second photodetector and a second illuminator for illuminating the entire second photodetector
A light source, and an object that is present between the first and second light sources and the first and second photodetectors and has a transmittance of less than 100% for the light from the first and second light sources. By providing a stretchable material for holding the object, it is possible to independently detect three-dimensional acceleration, and by using semiconductor process technology or the like in the manufacturing process, miniaturization can be achieved, and a high-performance excellent acceleration sensor Can be realized.

[Brief description of drawings]

FIG. 1 is a conceptual structural diagram of an acceleration sensor according to an embodiment of the present invention.

FIG. 2 is a structural diagram of a conventional acceleration sensor

[Explanation of symbols]

 1 Light source A 2 Light source B 3 Photodiode A 4 Photodiode B 5 Photodetector A 6 Photodetector B 7 Metal 8 Spring 21 Light emitting diode 22 Photodiode 23 Optical fiber A 24 Optical fiber B 25 Microlens A 26 Microlens B 27 Photoelastic Element 28 Weight 29 Polarizer 30 Analyzer 31 1/4 Wave Plate

Claims (1)

[Claims] 1. A first photodetector in which a plurality of photodetection elements are arranged two-dimensionally, a first light source for irradiating the entire first photodetector, and the first photodetector. Exists on a vertical surface,
A second photodetector in which linear photodetection elements are arranged in multiple stages in a direction parallel to the first photodetector; and a second light source for irradiating the entire second photodetector, The first and second
Present between the light source and the first and second photodetectors, and has a transmittance of 100% for the light from the first and second light sources.
An acceleration sensor including an object smaller than and an elastic material that holds the object.