JPS61181969A - Acceleration detector - Google Patents

Abstract

PURPOSE:To enable the detection of acceleration with a simple construction, by measuring the cycle period of an output signal from a displacement detecting means to determine whether the value is any frequency of an object or not. CONSTITUTION:The time constant of a timer 21 is set for the cycle of the upper limit frequency in the band range of acceleration to be detected while the time constant of the other time 22 for the cycle of the lower limit frequency in the band range thereof and both 21 and 22 are reset. Then, after the output signal of a light receive 13 is inputted, the output of one flipflop 23 moves to the L level only when a pulse signal having the cycle between binary time constants is inputted while the output of the other flipflop 24 moves to the H level and the output of the exclusive OR 25 moves to the H level. Thus, depending on the output of the exclusive OR reaching the H level, it can be judged whether the pulse signal obtained from the light receiver 13 is held within a specified band range or not. The acceleration having the frequency above the specified value and within the specified band range can be detected with a very simple construction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an acceleration detector capable of detecting an acceleration having a predetermined arbitrary frequency and a predetermined arbitrary magnitude or more.

(Prior Art) Acceleration detectors have been proposed as sensors used in suspension control to improve riding comfort in automobiles, mount control to prevent vibrations, and the like.

Figure 7 is a diagram showing an example of a conventional acceleration detector (generally called a piezoelectric type).
0) uses a piezoelectric element (41) as a spring element, and the quality Q
(42) are combined to form a seismic system, which serves as a detector that obtains electrical output in response to vibrations.

(Problems to be Solved by the Invention) By the way, this conventional detector (40) uses a piezoelectric element (41
) is used as a sensor, the output impedance is capacitive, so a charge amplifier etc. (43) must be used, pressure TF, element (41), mass (42).
In addition, since it is an analog output, various processing circuits such as a filter (44) and a comparator (45) are required to detect acceleration with a predetermined frequency. Due to the complicated configuration of Become something.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide an acceleration detector that has an extremely simple configuration and is inexpensive when detecting an acceleration of a predetermined arbitrary magnitude or more having a predetermined arbitrary frequency. .

(Means for Solving the Problems) In order to solve the above problems, the present invention has a predetermined mass, receives a force due to the acceleration to be measured, and is supported so as to be able to be displaced in response to this force. Object (4) and the object (
0 is displaced by a predetermined value or more, and the period time of the output signal from this displacement detection means (9) is measured, and the value is determined to be the same as any arbitrary value of the object (4). and a discriminating means (20) for discriminating whether or not the frequency is the same.

(Operation) The above technical means operates as follows. That is, the object (0
receives a force proportional to the acceleration.

Since this amount of displacement corresponds to acceleration, when the displacement detecting means (9) detects when the object (4) is displaced by a predetermined value or more, acceleration having a magnitude greater than the predetermined value is detected. Further, by measuring the cycle time of the output signal from the displacement detecting means (9) and determining whether or not the value corresponds to an arbitrary frequency of the object using the determining means (20),
It is possible to detect acceleration having a predetermined arbitrary frequency and a predetermined arbitrary magnitude or more.

(Embodiments) Below, preferred embodiments of the invention will be described based on the accompanying drawings.

FIG. 1 is a sectional view of an acceleration detector according to the present invention, and FIG. 2 is a plan view of the same sectional view. The acceleration detector (1) has a detection section (2
) and a case (3) in which this is arranged and attached to the object to be measured.
4) has a substantially rectangular parallelepiped shape, and its rear end is an arm support part (
The arm is swingably supported by the arm 5), and has a narrow protrusion (4a) formed in the center by providing step-shaped notches on both left and right sides at the distal end thereof.

In the arm support part (5), symbols (8), (8)
are support pieces that have a predetermined width (larger than the width of the arm (4)) and are provided facing each other near one end of the inner bottom surface (3a) of the case (3). Support piece (8
) and (6) so as to be movable via a shaft (7) pivotally supported in the upper part. And the pivot axis of this arm (4) (
7) One end of a spring (8) having a predetermined spring constant is attached to a position a predetermined distance forward (other end), and the other end is attached so as to hang vertically on the inner bottom surface (3a) of the case.

Thus, the arm (4) is an object according to the present invention that has a predetermined mass and receives a force due to the acceleration to be measured, and the spring (8) responds to this force in response to the force that the arm (4) receives. An elastic body according to the present invention that allows the arm (4) to be oscillated about the oscillation axis (7), and the arm (4)
The amount of rocking displacement with respect to the acceleration is determined by parameters such as the mass and length of the arm (4), the spring constant of the spring (8), and the position of its attachment.

Now, near the protruding part (4a) of the arm (0), there is a displacement detecting means (9) for detecting the swinging of the arm tip by a predetermined amount or more.
) is provided. The displacement detecting means (8) are arranged on bases (10) and (10) at a predetermined distance on the left and right (only one is shown).
A light projector (12) and a light receiver (13) are provided on the rear surface of a support plate (11) which is attached to the top end of each base so as to be located on the base. The projector (12) and receiver (13) are in a rectangular parallelepiped case (14).

One slit (14a) in the center of (15),
(15a) ((+5a) not shown), one slit (14a) has a light emitting element (16) such as a photodiode, and the other slit (15a) has a light receiving element (16) such as a phototransistor. 17), and these (12) and (13') are the respective sleeves) (14a)
, (+5a) and each sleeve) (
14a) and (15a), respectively, at a height where the upper edges of the protrusion (4a) and the road surface are - (+
It is arranged so as to face between 2) and (13).

With the above configuration, when the arm (4) receives a force due to acceleration and its protrusion (4a) is displaced by a predetermined amount or more, the arm (4) blocks the opposing sleeves (14a) and (15a). , from the light emitting element (16) to the light receiving element (1
7) is blocked. Therefore, at this time, by detecting a change in the output signal of the light receiver, that is, the light receiving element (17), it is possible to detect whether the arm (4) has been displaced by a predetermined amount or more, and therefore, it is possible to detect whether the arm (4) has been displaced by a predetermined amount or more. Acceleration is detected. Considering the frequency of this acceleration, the arm (4) also vibrates accordingly, and the output signal from the optical receiver (subjected to waveform shaping by a limiter, etc. as necessary) becomes a pulse as shown in Figure 3. It becomes like this.

Therefore, by measuring the cycle time from the rise of this pulse to the rise of the next pulse, the frequency of acceleration can be measured.

FIG. 4 shows a determination circuit that determines whether the frequency of the pulse in the output signal from the light receiver (FIG. 3) is a detection target in this acceleration detector (1).

This discrimination circuit (20) will be explained below.

In the discrimination circuit (20), symbols (21) and (22) are monostable multivibrators (hereinafter referred to as timers), and each timer (21) and (22) is connected to a respective capacitor (2
1a), (22a) and resistors (21b), (22b
) can change the time period during which the output is inverted (temporarily set to H level in this embodiment). Then, the output terminals of each timer (21) and (22) are connected to the flip-flow, flop (D flip-flop) (2
3) and (24), and the output terminals of each flip-flop (23) and (24) are connected to both input terminals of an exclusive OR circuit (25). Input terminals (21c) and (22) of each timer (21) and (22)
c) and the clock terminals (23a), (24a) of each flip-flop (23), (24).
) output terminal. Now, the time constant (inversion time) of one timer (21) is set to the period of the upper limit frequency in the acceleration bandwidth to be detected, and the time constant (inversion time) of one timer (22) is
setting the time constant to the period of the lower limit frequency in the bandwidth and resetting each timer (21) and (22),
When the output signal of the light receiver (13) shown in Fig. 3 is input, the output of one flip-flop (23) goes to L level only when a pulse signal having a period between the above two value time constants is input. , and at this time the other flip-flop (
The output of 24) becomes H level, and the output of exclusive OR (25) becomes H level. At this time, due to the setting of the time constant, it is possible that the output of one flip-flop (22) becomes L level and the output of the other flip-flop (23) becomes H level, contrary to the above, so the output of the exclusive OR It is possible to determine whether the pulse signal obtained from the light receiver (13) is within a predetermined bandwidth based on whether or not the pulse signal reaches the H level.

As described above, according to the present invention, it is possible to detect acceleration having a magnitude greater than a predetermined value and a frequency within a predetermined band with an extremely simple configuration.

Note that the present invention is not limited to the embodiments described above; for example, the displacement detecting means may be a magnet (31) provided on a part of the arm (30) and a displacement of this arm (30) as shown in FIG. A Hall element (which is provided at a predetermined position in the direction (the position where the light receiving element is provided in this embodiment) and detects the swing of the arm (30) by a predetermined value or more by detecting the magnetic field of the magnet.
32), or a coil (33) as shown in FIG. 6 may be used instead of the Hall element (32).

Moreover, the determination means (20) is also replaced with that shown in the embodiment,
For example, the frequency may be determined by counting the number of pulses with a counter and comparing the output of this counter with a predetermined value using a comparator or the like, or a filter may be used.

Furthermore, the arm shown in this embodiment has a rectangular parallelepiped shape and is provided so as to be able to swing and displace in response to the force it receives, but the object according to the present invention does not need to be limited to this shape, and can be moved left and right by a spring or the like. .

Alternatively, it may be supported so that it can be moved up and down.

Furthermore, the spring may be omitted by constructing the arm itself from an elastic body.

(Effects of the Invention) As is clear from the following explanation, according to the present invention, the output signal from the detection section is obtained as a pulse signal, and subsequent signal processing can be performed digitally. )
A detection section such as the can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an acceleration detector according to the present invention. Fig. 2 is a cross-sectional plan view of the same, Fig. 3 is an output signal from the light receiver, Fig. 4 is a discriminating means, Fig. 5 is a diagram showing a second embodiment of the displacement detecting means, and Fig. 6 is a diagram showing the third embodiment of the same. FIG. 7 is a diagram showing a conventional example. In the drawing, (4) is an object, (8) is an elastic body, and (9)
is a displacement detection means, (1B) is a light emitting element, (17) is a light receiving element, (20) is a discrimination means, (31) is a magnet, (32)
is a Hall element, and (33) is a coil. Patent applicant: Showa Seisakusho Co., Ltd.
Patent attorney representing Honda Motor Co., Ltd. 1) Department of Engineering
Patent Attorney: Kuni Ohashi, Patent Attorney: Yu Koyama Figure 5 Figure 6

Claims (5)

[Claims] (1) An object that has a predetermined mass, receives a force due to the acceleration to be measured, and is supported so that it can be displaced in response to this force, and a displacement that detects when the object is displaced by a predetermined value or more. measuring the period time of the output signal from the detection means and the displacement detection means;
An acceleration detector comprising determining means for determining whether the value is an arbitrary frequency of the object. (2) The displacement detecting means has a light emitting element and a light receiving element facing each other across a predetermined position in the displacement direction of the object, and when the object is displaced by a predetermined value or more, light from the light emitting element to the light receiving element is transmitted to the light receiving element. The acceleration detector according to claim 1, which is provided so as to be blocked by an object. (3) The displacement detection means comprises a magnet provided on the object and a magnetic field detector attached at a predetermined position in the displacement direction of the object to detect the magnetic field of the magnet.
Acceleration detector described in section. (4) The acceleration detector according to claim 3, wherein the magnetic field detector comprises a Hall element. (5) The acceleration detector according to claim 3, wherein the magnetic field detector comprises a coil.