JPH0961203A - External force, magnetic or metal sensing element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the occurrence of the external operating state for disturbing a vibration by providing a housing for containing a vibrating part vibrating in a natural frequency, a driving circuit and a sensing circuit for generating a sense signal when the change from a predetermined vibrating state is detected by monitoring a vibrating state. SOLUTION: A multidirectional external force sensing element comprises a base 10, and a cover 20 covering the base 10, a positioning boss 11 formed on the lower surface of the base, and a strut 12 formed on the upper surface of the base. A printed circuit board 30 supported to the strut 12 is mounted on the base 10, a sound spade 40 mechanically vibrating in a natural frequency is mounted, and a piezoelectric element 50 is mounted at the base of the vibrating piece of the spade 40. A circuit which includes a driving circuit for vibrating the spade 40 and a sensing circuit for monitoring the vibrating state of the spade 40 to generate a sense signal when the change from its predetermined vibrating state is detected is mounted on the board 30. A dustproof sealing material 13 for an inner space surrounded by the base 10 and the case 20 is provided on the lower surface of the base 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detecting element for detecting an external force, an external magnetism, or an approach of an external metal.

[0002]

2. Description of the Related Art Detecting elements for detecting external force or detecting approach of external magnetism or external metal are used in various industrial fields, especially for automatic control in production lines and various equipment. It has a wide range of fields of use as limit switches, etc. Conventionally, there are various types of detecting elements of this type, but when roughly classified, there are a contact type detecting element and a non-contact type detecting element. Non-contact type sensing elements include Hall element, magnetoresistive element,
There is a photo interrupter using light.

[0003]

However, the conventional contact-type sensing element has some problems as follows. First, there is a lack of reliability in that the actuating force is limited and only responds to a large actuating force to some extent. Secondly, there is a limit on the working distance (on / off position), and in this respect as well, there is a surface lacking reliability. Third,
It is difficult to set a plurality of operating positions, and it is difficult for one element to detect external forces from different directions. Fourthly, the waterproof structure and the dustproof structure are complicated because the operating portion for reliably operating the contact is exposed to the outside. Fifth, contact failures were easy to occur.

Further, among the non-contact type detection elements, magnetic detection type elements such as Hall elements and magnetoresistive elements require a bias magnetic field, and there are restrictions on the arrangement of magnets and magnetic field strength for this purpose. In the case of using a light such as a photo interrupter, the light emitting surface and the light receiving surface are inevitably deteriorated by dust, and the reliability is lost when the device is used as it is for a long time. In addition, it is necessary to have a means to prevent malfunction due to ambient light, such as electrical modulation,
The configuration has become quite complicated, such as using filters.

In addition to these, there are an ultrasonic type, a proximity switch type, a differential coil type, an operating capacitance type and the like, but these are relatively expensive and can be used only for special purposes.

In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a contact type detection element or a non-contact type detection element used in a dusty place or in an environment requiring a waterproof function. Another object of the present invention is to provide an external force, magnetism, metal, etc. detecting element which can make up for defects such as a Hall element, a magnetoresistive element and a photo interrupter utilizing light.

[0007]

A sensing element according to the present invention comprises a housing containing a vibrating section that mechanically vibrates at a natural frequency, a drive circuit for vibrating the vibrating section, and the vibrating section. And a detection circuit that generates a detection signal when a change from the predetermined vibration state is detected, and an external action state that prevents vibration at the natural frequency of the vibrating section is generated. It is characterized by detecting.

According to one embodiment of the present invention, the vibrating portion is made of a tuning fork or a tuning piece, and the casing is provided with an operating button, and the operating button contacts the vibrating portion. By doing so, the external force detecting element can be configured by generating the external action state. In such an embodiment, by providing a plurality of actuating buttons so that each actuating button can contact the vibrating portion from different directions, a multidirectional external force sensing element can be obtained.

According to another embodiment of the present invention, the vibrating portion is made of a tuning fork or a tuning piece, and at least a part of the tuning fork or the vibrating piece of the tuning piece is made of a magnetic material. The magnetic sensing element can be formed by configuring the external action state to be generated by the approach of external magnetism to the body.

According to yet another embodiment of the present invention,
The vibrating section is composed of a tuning fork or a tuning piece, and at least a part of the tuning fork or the vibrating piece of the tuning piece is magnetized so that the external action state is generated when an external metal approaches the housing. By doing so, a metal detection element can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a horizontal sectional view of a multidirectional external force detecting element as one embodiment of the present invention, and FIG. 2 is a vertical sectional view of the multidirectional external force detecting element of FIG. FIG. 3 is similar to FIG.
FIG. 4 is a bottom view of the multidirectional external force detection element of FIG. 4, and FIG. 4 is a side view of the multidirectional external force detection element of FIG. 1. As shown in these drawings, the multidirectional external force detection element of this embodiment includes a base 10 and a case 20 placed on the base 10. A positioning boss 11 is provided on the lower surface of the base 10.
Are formed, and the columns 12 are formed on the upper surface of the base 10. A printed circuit board 30 is attached to the base 10 so as to be supported by the columns 12, and a tuning fork 40 as a vibrating portion that mechanically vibrates at a natural frequency is attached. This tuning fork 4
A piezoelectric element 50 is attached to the base of the vibrating piece 0.

As can be seen from FIGS. 1, 2 and 4, the case 10 has three parts on both side surfaces and an upper surface thereof.
Actuating buttons 60, 70 and 80 are provided near the tip of the vibrating piece of the tuning fork 40. As shown in FIG. 2, a drive circuit for vibrating the tuning fork 40 and a vibration state of the tuning fork 40 are monitored on the printed circuit board 30 and detected when a change from the predetermined vibration state is detected. Circuit 100 including a detection circuit for generating a signal
Has been implemented. On the printed circuit board 30, a connection terminal 31 electrically connected to the circuit 100 is provided on the base 1.
It is attached so that it extends through 0 and is drawn to the outside. A sealing material 13 is provided on the lower surface of the base 10 for waterproofing and dustproofing the internal space surrounded by the base 10 and the case 20.

In this embodiment, the operation buttons 60, 70 and 80 provided on the case 20 are formed integrally with the case 20, and as shown in the partially enlarged sectional view of FIG. The external force acting portion 61 and the tuning fork contact portion 62 are connected to the main portion of the case 20 by the flexible thin portion 63. When no external force is applied to the external force acting portion 61, as shown in FIG. 5, the upper surface of the external force acting portion 61 is held at a position protruding by the stroke distance S from the surface of the case 20. As shown in FIG. 6, when the external force P acts on the external force acting portion 61,
The upper surface of the external force acting portion 61 is pushed into the case 20 by the stroke distance S against the elastic force of the flexible thin portion 63, and the tuning fork contact portion 62 is also corresponding to the case 20.
It will be pushed in. When the external force P is released, the flexible thin portion 63 is brought into the state as shown in FIG.
It is restored by the elastic force of. Actuating buttons 70 and 80 have the same configuration as actuating button 60 and perform similar operations, and therefore will not be described repeatedly.

Next, the detailed structure of the circuit 100 mounted on the printed circuit board 30, particularly, FIGS. 7 to 10 will be described.
This will be described with reference to FIG. FIG. 7 is a block diagram showing the overall configuration of the circuit 100 connected in connection with the tuning fork 40.
As shown in FIG. 7, the circuit 100 includes a drive circuit 110,
It includes a filter circuit 120 and an oscillation detection circuit 130. 8 is a detailed circuit diagram of the drive circuit 110, FIG. 9 is a detailed circuit diagram of the filter circuit 120, and FIG. 10 is a detailed circuit diagram of the oscillation detection circuit 130.

In this embodiment, the drive circuit 110 urges the piezoelectric element 50 attached to the base of the vibrating piece of the tuning fork 40 to mechanically vibrate the tuning fork 40 at its natural frequency. Then, the filter unit 111 and the inverting amplifier 112 connected to the feedback circuit between the piezoelectric elements 50 are included. The drive signal from the external drive source is the connection terminal 3
When applied to one of the piezoelectric elements 50 through one of the ones, the corresponding vibrating bar of the tuning fork 40 vibrates, and the vibration causes the vibrating bar of the opposite side to resonate, and the vibration is attached thereto. From one piezoelectric element 50 to the filter unit 111
Then, the tuning fork 40 is fed back to the one piezoelectric element 50 through the inverting amplifier 112, and the tuning fork 40 is mechanically vibrated at its natural frequency. Since such a configuration and operation are the same as those of a normal tuning fork oscillator,
No further details will be given.

The filter circuit 120 is not necessarily provided, but it is preferably provided in order to stably detect a change in the vibration state of the tuning fork oscillator. For example, the circuit configuration shown in FIG. 9 is used. You can take it.

As shown in FIG. 10, the oscillation detecting circuit 130 receives a drive signal from the drive circuit 110 of FIG. 8, detects it by the diode 131, and integrates the detected signal by the integrating circuit 132. This integrated output is the tuning fork 40
As long as it is oscillated at its natural frequency, it becomes a signal of a predetermined -E volt, and the switching transistor 1
33 is kept off. Therefore, the detection output is
It does not occur.

Here, in FIG. 1, an external force acts on the external force acting portion 61 of the actuating button 60, the actuating button 60 is pushed into the case 20, and the tuning fork contact portion 62 thereof becomes a vibrating piece of the tuning fork 40. Assume that the tip is brought into contact. Then, the tuning fork 40 that continued to vibrate at the natural frequency until then.
Vibration is stopped, oscillation is stopped, and the integrated output of the integration circuit 132 of the oscillation detection circuit 130 of FIG. 10 rises from the predetermined −E volt to 0 volt. As a result, the switching transistor 133 that has been in the off state until then is turned on, and a predetermined detection output is generated. The generation of this detection output makes it possible to know that an external force is applied to the operation button 60. This is the activation button 70 or 8
The same applies when an external force is applied to 0. Therefore, according to the detecting element of this embodiment, external forces from three directions can be detected. In addition, the circuit configuration of FIG.
Although it is composed of a transistor, an integrating circuit, and the like, it may be composed of an OP amplifier or the like instead of them.

In the above-described embodiment, three actuating buttons are provided to detect the external force from three directions. However, the present invention is not limited to this, and one or two actuating buttons are provided. It also includes the case of providing an arbitrary number of one or more. Further, although the tuning fork is used in the above-described embodiment, a tuning piece may be used instead of the tuning fork. Furthermore, although the piezoelectric element is used as the driving means, an electromagnetic coil may be used instead of the piezoelectric element.

Further, although the above-mentioned embodiment is an external force detecting element, the present invention can be applied to a magnetic detecting element or a metal detecting element by utilizing the same constitution.
For example, when the magnetic sensing element is used, in the above-described embodiment, the operation buttons 60, 70 and 80 are used as the case 20.
Alternatively, at least a part of the resonator element of the tuning fork 40 may be made of a magnetic material. In this case, when external magnetism such as a magnet approaches the case 20, the vibration at the natural frequency of the tuning fork is disturbed, and the oscillation is stopped, so that the detection output is generated. The presence of magnetism can be detected.

In the case of using a metal detecting element, at least a part of the vibrating piece of the tuning fork 40 should be magnetized instead of providing the operation buttons 60, 70 and 80 on the case 20 in the above-mentioned embodiment. Good. In this case, when the external metal approaches the case 20, the vibration at the natural frequency of the tuning fork is disturbed, and the oscillation is stopped, so that the detection output is generated. Therefore, the presence of the external metal exists. Can be detected.

Furthermore, in the above-mentioned embodiment,
Although it has been described that the vibration of the tuning fork or the tuning piece is completely stopped by the approach of the external force or the external magnetic field or the approach of the external metal, the present invention is not limited to this. It is also possible to detect that the vibration frequency of the tuning fork or the tuning piece is changed by the approach of the metal. In this case, the bandpass filter circuit 120 shown in FIG. 9 is effective.

Further, in the above-mentioned embodiment, the drive circuit and the oscillation detection circuit are also incorporated in the case, but these circuits may be provided outside the case.

[0025]

The effects of the sensing element of the present invention are listed below. (1) Since the operating force is used only for suppressing the vibration of the tuning fork or the tuning piece, there are few restrictions. (2) Similarly, the working distance is less restricted. (3) The waterproof structure is simplified because it is sufficient to have an operating force and an operating distance sufficient to suppress the vibration of the tuning fork or the tuning piece. (4) No contact failure occurs. (5) Operating part (mechanism to stop vibration of tuning fork or tuning piece)
You can set multiple. (6) There is no restriction on the arrangement of the bias magnetic field (the Hall element needs to select the direction and strength of the bias magnetic field). (7) Not affected by dust. (8) There is a degree of freedom in setting the position of the external force detection portion.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view of a multidirectional external force detection element as one embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the multidirectional external force detection element of FIG.

FIG. 3 is a bottom view of the multidirectional external force detection element of FIG.

FIG. 4 is a side view of the multidirectional external force detection element of FIG.

5 is a partially enlarged sectional view showing a detailed structure of an operation button of the multidirectional external force detection element of FIG.

FIG. 6 is a partially enlarged cross-sectional view showing a pressed state of the operation button shown in FIG.

7 is a block diagram showing an overall configuration of a circuit connected in relation to a tuning fork of the multidirectional external force detection element of FIG.

FIG. 8 is a detailed circuit diagram of a drive circuit in the circuit of FIG.

9 is a detailed circuit diagram of a filter circuit in the circuit of FIG.

10 is a detailed circuit diagram of an oscillation detection circuit in the circuit of FIG.

[Explanation of symbols]

 10 Base 20 Case 30 Printed Circuit Board 40 Tuning Fork 50 Piezoelectric Element 60 Operation Button 70 Operation Button 80 Operation Button 100 Circuit 110 Drive Circuit 120 Filter Circuit 130 Oscillation Detection Circuit

Claims (6)

[Claims] 1. A housing containing a vibrating section that mechanically vibrates at a natural frequency, a drive circuit for vibrating the vibrating section, and a vibrating state of the vibrating section are monitored and predetermined A detection circuit for generating a detection signal when a change from the vibration state is detected, and a detection element for detecting the occurrence of an external action state that prevents vibration at the natural frequency of the vibrating section. . 2. The sensing element according to claim 1, wherein the vibrating section is made of a tuning fork or a tuning piece. 3. The sensing element according to claim 1, wherein the casing is provided with an actuation button, and the external action state is generated when the actuation button contacts the vibrating portion. 4. The sensing element according to claim 3, wherein a plurality of the operation buttons are provided, and each operation button can contact the vibrating portion from different directions. 5. The detection according to claim 2, wherein at least a part of the vibrating piece of the tuning fork or the tuning piece is made of a magnetic material, and the external action state is generated by the approach of external magnetism to the housing. element. 6. The sensing element according to claim 2, wherein at least a part of the vibrating piece of the tuning fork or the tuning piece is magnetized, and the external action state is generated when an external metal approaches the housing.