JPH098329A - Pressure sensor - Google Patents

Abstract

PURPOSE: To obtain a pressure sensor in which fluctuation in the force for supporting a sensor chip can be suppressed. CONSTITUTION: The insulator 11 of a pressure sensor 1 is provided with leaf springs 12, 13 projecting from the inner side face of the insulator 11. The leaf springs 12, 13 are bent toward the opposite ends of a sensor chip 9 and have a C-shaped cross-section at the forward end thereof. The sensor chip 9 is pressed by the leaf springs 12, 13 operating within the plastic deformation region and held against a diaphragm 3 with a load being applied to the leaf springs 12, 13.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a pressure sensor.

[0002]

2. Description of the Related Art FIG. 5 is a front view of a conventional thin film strain gauge type pressure sensor (hereinafter, simply referred to as a pressure sensor) 50, and FIG.
FIG. 4 is a sectional view of the pressure sensor 50.

A diaphragm 52 is formed on a body 51 of the pressure sensor 50, and a sensor chip 53 is provided on the diaphragm 52. The sensor chip 53
Is positioned by a positioning ring 54 so that the center of the sensor chip 53 and the center of the diaphragm 52 coincide with each other, and the leaf spring 5 attached to the insulator 55 is attached.
The elastic force of 6 holds the diaphragm 52 against pressure. The sensor chip 53 has the introduction hole 57.
It is designed to bend together with the diaphragm 52 by the pressure of the fluid introduced from.

As shown in FIG. 5, thin film strain gauges R1 to R4 are formed on the upper surface of the sensor chip 53.
The thin film strain gauges R1 to R4 are compressed or expanded by the stress due to the bending of the sensor chip 53, and the resistance value changes according to the compression or expansion. Therefore, the resistance values of the thin film strain gauges R1 to R4 change according to the pressure of the fluid to be detected. The thin film strain gauges R1 to R4 form a voltage dividing resistor that divides a predetermined voltage supplied from an amplification circuit unit (not shown). And, the thin film strain gauge R1
The divided voltage by R4 is amplified by an amplifier circuit section (not shown) and output as an output voltage to the outside of the pressure sensor 50.

[0005]

By the way, the leaf spring 56 is used.
Holds the sensor chip 53 against the diaphragm 52 within its elastic deformation region. Therefore, depending on the thickness of the sensor chip 53 or the dimensional accuracy of the insulator 55, the pressing force for holding the sensor chip 53 may be different for each pressure sensor 50. When the pressing force is different, when the diaphragm 52 is bent by the fluid pressure, the bending of the sensor chip 53 is different for each pressure sensor 50, and the resistance values of the thin film strain gauges R1 to R4 are different. As a result, there is a problem in that the output voltage output from each pressure sensor 50 varies for the same fluid pressure. This variation in the output voltage can be suppressed by individually changing the amplification factor of the amplification circuit unit (not shown), but the amplification factor must be set individually due to the variation in the output voltage, which is a troublesome problem. was there.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a pressure sensor capable of suppressing variations in force for supporting a sensor chip.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a diaphragm is formed on a body and is bent by the pressure of a fluid, and a piezoelectric transducer is formed on the upper surface of the diaphragm. Pressure provided with a sensor chip that outputs a detection signal that detects the stress due to bending, an insulator fixed to the body, and an elastic body that is attached to the insulator and presses and holds the sensor chip against the diaphragm. In the sensor,
The gist is that the elastic body presses and holds the sensor chip in a plastic deformation region.

According to a second aspect of the present invention, in the pressure sensor according to the first aspect, the body is provided with a positioning ring having a positioning portion for determining the position of the sensor chip with respect to the diaphragm. The positioning ring is bonded to the body together with the insulator.

The elastic body is a leaf spring made of stainless steel.

[0010]

Therefore, according to the first aspect of the present invention, the sensor chip is pressed and held with respect to the diaphragm by the elastic body that operates in the plastic deformation region.

According to the second aspect of the invention, the body is provided with a positioning ring bonded together with the insulator. The position of the sensor chip with respect to the diaphragm is determined by the positioning portion of the positioning ring.

The elastic body is composed of a stainless steel plate spring.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. FIG. 1 is a pressure sensor 1 of this embodiment.
2 is a front view of the pressure sensor 1. FIG.

A diaphragm 3 is formed on the body 2 of the pressure sensor 1, and the diaphragm 3 is bent by the pressure of the fluid introduced from the introduction hole 4. A recess 5 is formed in the body 2 along the circumferential direction of the diaphragm 3, and a positioning ring 6 is formed in the recess.
Is housed. Positioning portions 7 and 8 are formed on the positioning ring 6 so as to project toward the center thereof.
The positioning portions 7 and 8 are arranged on the upper surface of the peripheral portion of the diaphragm 3 (left side surface in FIG. 1).

Further, the pressure sensor 1 is provided with a sensor chip 9. The sensor chip 9 is arranged by the positioning portions 7 and 8 so that its center coincides with the center of the diaphragm 3. The convex portion 3a is provided on the upper surface of the diaphragm 3.
The convex portion 3a applies a stress due to the deflection of the diaphragm 3 only to the center of the sensor chip 9, and the stress causes the sensor chip 9 to bend.

As shown in FIG. 2, thin film strain gauges R1 to R4 are formed on the upper surface of the sensor chip 9, and the resistance values of the thin film strain gauges R1 to R4 change according to the deflection of the sensor chip 9. It is like this. Further, pads 10a to 10f are formed on the upper surface of the sensor chip 9. The thin film strain gauges R1 and R3 are the pads 10a-
Directly connected between 10c, thin film strain gauge R2, R4
Are connected in series between the pads 10d to 10f.

The pressure sensor 1 has an insulator 1
1 is provided. The insulator 11 is made of resin and has a substantially cylindrical shape. Insulator 11
Is inserted into the recess 5 and is bonded together with the positioning ring 6.

The insulator 11 has leaf springs 12, 13
Is provided. The leaf springs 12 and 13 are made of stainless steel, for example, and are attached so as to project from the inner side surface of the insulator 11. The leaf springs 12 and 13 are formed so as to be bent toward both ends of the sensor chip 9, and the tips thereof are formed in a C-shaped cross section. And the leaf springs 12 and 1
3 operates in the plastic deformation region and presses the sensor chip 9 toward the diaphragm 3.

The leaf spring 12, which has undergone plastic deformation,
13 transmits the applied load to the sensor chip 9. Then, the sensor chip 9 is pressed by the load applied to the leaf springs 12 and 13. Therefore,
The thickness of the sensor chip 9 may be different, or the insulator 1
Even if the dimensional accuracy of No. 1 varies, the sensor chip 9 is pressed by the load applied to the leaf springs 12 and 13, so that the pressing force can be made constant and the variation for each pressure sensor 1 can be suppressed. it can.

The insulator 11 has a plurality of terminals 1
4 are provided, and the terminals 14 are electrically connected to the pads 10a to 10f formed on the upper surface of the sensor chip 9 through the wires 15. An amplifier circuit section 16 is provided at the terminal 14.
The board 17 on which the electronic components constituting the above are mounted is connected. The amplifier circuit unit 16 operates based on a driving power supply supplied from an external terminal 19 provided in the connector unit 18, amplifies the output voltage output from the sensor chip 9 and the pressure sensor 1 via the external terminal 19. It is designed to output to the outside.

Next, the operation of the pressure sensor 1 configured as described above will be described. In the sensor chip 9, a chromium thin film is formed on a silicon wafer having a thermal oxide film formed on its surface, and the thin film strain gauges R1 to R4 are formed by a photolithography process on the chromium thin film. Then, the silicon wafer is cut by the dicer, and the sensor chip 9
Is formed. The sensor chip 9 thus formed is arranged on the positioning portions 7, 8 of the positioning ring 6 such that the center of the sensor chip 9 coincides with the center of the diaphragm 3, and then the insulator 11 having the leaf springs 12, 13 attached thereto. Are bonded and fixed to the body 2 together with the positioning ring 6.

At this time, the leaf springs 12 and 13 are flexibly plastically deformed by the applied load. Then, the sensor chip 9 is pressed and held by the plastically deformed leaf springs 12 and 13. The pressing force applied to the sensor chip 9 becomes the load applied to the leaf springs 12 and 13. Therefore, even if the plate thickness of the sensor chip 9 varies, the sensor chip 9
It is possible to suppress the variation in the pressing force with respect to, and each pressure sensor 1 outputs a constant output voltage for the same fluid pressure. As a result, it is not necessary to set the amplification factor for each pressure sensor 1, and there is no trouble.

As described above, the pressure sensor 1 of this embodiment
According to the above, the leaf spring 12, which presses and holds the sensor chip 9,
The leaf springs 12 and 13 are subjected to a load so that the leaf springs 12 and 13 operate in the plastic deformation region. As a result, even if the plate thickness of the sensor chip 9 or the dimensional accuracy of the insulator 11 varies, the sensor chip 9 can be pressed and held by the load applied to the plate springs 12 and 13, so that the pressing force on the sensor chip 9 varies. Can be suppressed.

It should be noted that the present invention may be modified as follows, and in that case, the same operation and effect can be obtained. 1) In the above embodiment, the leaf springs 12 and 13 were used as the elastic body, but it is also possible to use a spring such as a coil spring to plastically deform the spring.

2) In the above embodiment, the leaf springs 12 and 13 made of stainless steel were used, but other materials such as beryllium copper may be used. 3) In the above embodiment, the thin film strain gauges R1 to R4 are formed on the upper surface of the sensor chip 9, but a diffusion strain gauge may be formed.

Although the respective embodiments of the present invention have been described above, technical ideas other than the claims which can be understood from the respective embodiments will be described below together with their effects. A) The pressure sensor according to any one of claims 1 to 3, comprising an amplifier circuit section 16 for amplifying and outputting a detection signal from the sensor chip 9. With this configuration, it is possible to amplify and output a signal according to the fluid pressure.

(B) In the pressure sensor according to the third aspect, the piezoelectric conversion elements are thin film strain gauges R1 to R4.
With this configuration, the stress due to the deflection of the diaphragm 3 can be easily detected.

[0028]

As described above in detail, according to the present invention, it is possible to provide the pressure sensor capable of suppressing the variation in the force for supporting the sensor chip.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pressure sensor according to an embodiment.

FIG. 2 is a front view of a pressure sensor according to an embodiment.

FIG. 3 is a cross-sectional view showing an entire pressure sensor of one embodiment.

FIG. 4 is a sectional view of a conventional pressure sensor.

FIG. 5 is a front view of a conventional pressure sensor.

[Explanation of symbols]

2 ... Body, 3 ... Diaphragm, 6 ... Positioning ring,
7, 8 ... Positioning part, 9 ... Sensor chip, 11 ... Insulator, 12, 13 ... Leaf spring as elastic body, 16 ...
Amplifier circuit section, R1 to R4 ... Thin film strain gauge as a piezoelectric conversion element.

Claims (3)

[Claims] 1. A diaphragm (3) which is formed on a body (2) and is bent by the pressure of a fluid, and piezoelectric conversion elements (R1 to R4) are formed on the upper surface of the diaphragm (3) to detect the stress due to the bending of the diaphragm (3). A sensor chip (9) for outputting a detection signal; an insulator (11) fixed to a body (2); and a sensor chip (9) attached to the insulator (11) and attached to the diaphragm (3). A pressure sensor comprising: an elastic body (12, 13) for pressing and holding the sensor chip (9) in a plastic deformation region of the elastic body (12, 13). 2. The pressure sensor according to claim 1, wherein the body (2) has positioning portions (7, 8) for determining the position of the sensor chip (9) with respect to the diaphragm (3). A pressure sensor provided with a formed positioning ring (6), the positioning ring (6) being bonded to the body (2) together with the insulator (11). 3. The pressure sensor according to claim 1, wherein the elastic body is a leaf spring (12, 13) made of stainless steel.