JPS6381274A - Acceleration sensor - Google Patents

Abstract

PURPOSE:To obtain an acceleration sensor which has large electric and mechanical strength and is easily manufactured by providing a weight part formed on a substrate, a detection part and an electric circuit mount part, and a strain gauge formed at the detection part. CONSTITUTION:The substrate 10 is made of photosensitive glass and has the weight part 10a with an overlap function at one end, and its size is determined by the acceleration to be measured, the mass of the substrate 10, and the detec tion part 10b. The electronic circuit mount part 10c where an electronic circuit component which performs necessary processing for obtaining an electric signal corresponding to the acceleration is formed at the other end part. Further, the detection part 10b which reduces the sectional area of the substrate 10 is formed by etching between the weight part 10a and mount part 10c. A thin film on the substrate 10 is etched to form a metal resistance on the opposite surface from the detection part 10, thereby constituting the strain gauge. Conse quently, the weight part 10a is formed of one substrate, so the number of components may be small, and the detection part is formed by etching, so fine working and accurate working are easily carried out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an acceleration sensor, and in particular, an acceleration sensor that outputs the magnitude of acceleration in analog or digital form, an acceleration sensor that obtains a switching output depending on the magnitude of acceleration, etc. The present invention relates to the structure of an acceleration sensor that can be used for.

[Prior art] As a conventional acceleration sensor of this type, Japanese Patent Application Laid-Open No. 60-22
The technique disclosed in Japanese Patent No. 8966 can be mentioned. FIG. 3 is a sectional view of the conventional acceleration sensor disclosed in the above publication, and FIG.
Explanatory diagram illustrating the principle of the conventional acceleration sensor shown in Fig. 5.
This figure is a circuit diagram of the impedance conversion circuit of the conventional acceleration sensor shown in FIG. 3.

In FIG. 3, a weight 1, which is an inertial mass, is provided so as to be in contact with the periphery of a ceramic 2, and the center of the ceramic 2 is supported by an exterior case 3 to constitute an acceleration detection section for detecting acceleration.

Note that the braking resistor 4 functions to control the resonance peak.

Next, the operation of the acceleration sensor shown in FIG. 3 will be explained using FIG. 4.

The outer case 3 is connected to a vibration source, and vibrations are applied to the outer case 3 constituting the acceleration detection section.

This vibration is transmitted to the ceramic 2, and due to the weight 1 provided at the tip thereof, the vibration transmitted from the exterior case 3 is delayed in time, and stress is applied to the ceramic 2. Therefore, due to the piezoelectric effect of the ceramic 2, a voltage generated between the terminals A and B at both ends of the ceramic 2 is obtained as the output of the sensor.

Normally, the voltage output generated between terminals A and B of the sensor is impedance-converted using a circuit using an FET as an impedance conversion element shown in FIG. 5, and then output.

Therefore, terminal A in the figure.

The voltage output generated between 8 and 8 is the terminal C of the ceramic 2.
, D becomes the output voltage vout.

[Problems to be Solved by the Invention] However, in the conventional acceleration sensor, an acceleration detection section that detects acceleration and an electronic circuit section such as an impedance conversion circuit that processes the detection output as a signal are separated. The manufacturing process is complicated, and! ! ! It was difficult to manage the manufacturing process.

In addition, since the acceleration detection section and the electronic circuit section that processes the detection output are connected by means such as adhesive,
There were problems such as being electrically and mechanically weak against mechanical external forces such as impact force.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and aims to provide an acceleration sensor that has strong electrical and mechanical strength and is easy to manufacture.

[Means for Solving the Problems] The acceleration sensor according to the present invention includes a weight portion, a detection portion, and an electronic circuit mounting portion formed on a substrate, an electronic circuit component attached to the electronic circuit mounting portion, and a detection portion. It is equipped with a strain gauge formed in

[Function] In the present invention, one end of the board is used as a weight part that functions as a weight, the other end of the board is used as an electronic circuit mounting part to which components of an electronic circuit that electrically processes acceleration detection output are attached, and in between, A detection part is formed with a small cross-sectional area of the board, and when the strain gauge of the detection part formed on the board detects acceleration, the signal is processed by the electronic circuit of the electronic circuit mounting part formed on the same board, and the acceleration sensor is This is the output.

[Example] Fig. 1 is a plan view of an acceleration sensor according to an embodiment of the present invention, and Fig.
The figure is also a central cross-sectional view of a plan view of an acceleration sensor according to an embodiment of the present invention.

In the figure, a substrate 10 is made of photosensitive glass (for example, "Photoceram" manufactured by Corning Inc.), and one end of the substrate 10 is a weight portion 10a that functions as a weight, the size of which is determined by the acceleration of the object to be measured and the mass of the substrate 10. , and the detection unit 10b, which will be described later. The other end of the board 10 is an electronic circuit mounting part IC)C to which is attached an electronic circuit component 12 constituting an electronic circuit that performs processing necessary to obtain an electrical signal corresponding to acceleration as an acceleration detection output. This electronic circuit mounting portion 10c includes a power supply circuit, an amplifier circuit,
switching circuits such as Schmitt circuits or comparison circuits;
Electronic circuit components 12 are attached to form one or more types of circuits such as A-D conversion circuits. Between the weight part 10a and the electronic circuit@neck part 10G, there is a detection part 10b with a reduced cross-sectional area of the substrate 10.
is formed by etching. The detection section 10b
On the opposite side etched by the etching process, there is a substrate 10.
A metal resistor 11 is formed by etching on the upper thin film, thereby forming a strain gauge. A strain gauge made of a metal resistor formed by etching a thin film on the substrate 10 is formed together with the circuit pattern of the electronic circuit mounting portion 10G.

The acceleration sensor configured in this manner can operate as follows.

First, the electronic circuit mounting portion 10C side of the board 10 is firmly attached to the object to be measured to form a cantilever shape. When acceleration is applied in this state, the detection section 10b is deflected due to the load of the weight section 10a, and the resistance value of the metal resistance 11 formed on the detection section 10b changes due to changes such as expansion or contraction. This change in resistance value is converted into a predetermined detection signal according to the acceleration by an electronic circuit made up of the electronic circuit components 12.

As described above, the acceleration sensor of the present embodiment includes a single board 10 having a mounting section 10a, a detection section 10b, and an electronic circuit mounting section 10C, and an electronic circuit component 12 attached to the electronic circuit mounting section 10C. and a strain gauge such as a metal resistor 11 formed on the detection section 10b, and the weight section 10a, the detection section 10b, and the electronic circuit mounting section 10C are formed on the - number of substrates 10. Therefore, the number of parts is small, and the detection part 10b can be formed by etching, so that microfabrication and precision machining are easy.

Further, the detection section 10b of the board 10 and the electronic circuit mounting section 10
C. Since the circuit pattern is formed using printed circuit board technology, there is no misalignment between the two.
Inconsistency in precision is less likely to occur in the product, making product quality control easier.

Then, the detection section 10b of the board 10 and the electronic circuit mounting section 1
Since it is equipped with a strain gauge and an electronic circuit integrally with the 0G, it can be miniaturized and has the strength to withstand electrical and mechanical external forces.

In the above embodiment, photosensitive glass is used as a single substrate having the weight section, the detection section, and the electronic circuit mounting section, but a metallic substrate may also be used. In particular, the selection of the substrate material is based on the following prerequisites: that the weight part has the necessary mass, that the detection part can be etched, that the detection part can withstand more than a specified elastic force, that it is an insulator, etc. However, for example, even if it is not an insulator, it is easy to form an insulating film with a bonding strength above a specified level,
Even if it cannot be etched, it can be used as the substrate material if it can be mechanically cut. However, when mechanical cutting is performed instead of etching, the finishing accuracy is generally lower than that of etching.

In addition, when acceleration is applied to the board, it is preferable that only the detection part flexes and the electronic circuit mounting part does not. Therefore, it is preferable that the thickness of the electronic circuit mounting part is as thick as possible. This can be replaced by reducing the thickness of .

Although the detection portion is etched from one side, it can also be etched from both sides, one side plus three sides, or two sides plus four sides.

The electronic circuit components attached to the electronic circuit mounting portion can constitute an electronic circuit that outputs the magnitude of acceleration in analog or digital form, or a switching circuit that obtains a switching output based on the magnitude of acceleration.

Furthermore, the strain gauge formed in the detection part is a semiconductor strain gauge,
It can also be a pressure sensitive diode or a pressure sensitive transistor.

[Effects of the Invention] As described above, the acceleration sensor of the present invention includes a single board having a weight part, a detection part, and an electronic circuit mounting part, an electronic circuit component attached to the electronic circuit mounting part, and the Since the weight part, the detection part, and the electronic circuit mounting part are formed on one board, the number of parts is small, and
Since the detection portion can be formed by etching, microfabrication and precision machining are easy. Further, since circuit patterns can be formed on the detection section and the electronic circuit mounting section of the board using printed circuit board technology, misalignment between the two is less likely to occur, and no irregularities in precision occur in the product.

Therefore, product quality control becomes easy.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an acceleration sensor according to an embodiment of the present invention, and FIG.
The figure is also a central cross-sectional view of the plan view of the acceleration sensor according to the embodiment of the present invention, FIG. 3 is a cross-sectional view of the conventional acceleration sensor of the above publication, and FIG. The explanatory diagram, FIG. 5, is a circuit diagram of the impedance conversion circuit of the conventional acceleration sensor shown in FIG. In the figure, 10: board, 10a: weight section, 10b: detection section, 10C: electronic circuit mounting section, 11: metal resistor, 12: electronic circuit component. In addition, in the figures, the same reference numerals and the same symbols indicate the same or equivalent parts.

Claims (5)

[Claims] (1) A single board having a weight section, a detection section, and an electronic circuit mounting section; an electronic circuit component attached to the electronic circuit mounting section; and a strain gauge formed on the detection section. acceleration sensor. (2) The acceleration sensor according to claim 1, wherein the detection portion of the substrate is formed by etching. (3) The acceleration sensor according to claim 1 or 2, wherein the strain gauge formed in the detection section is a resistance strain gauge. (4) The acceleration sensor according to claim 1 or 2, wherein the strain gauge formed in the detection section is a resistance strain gauge formed by etching a thin film on a substrate. (5) The acceleration sensor according to any one of claims 1 to 4, wherein the substrate having the weight part, the detection part, and the electronic circuit mounting part is made of photosensitive glass. .