JPS6090696A - Pressure-sensitive sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a pressure sensor provided in a robot hand, etc., and in particular, the present invention provides a pressure sensor capable of measuring contact pressure with a gripped object. do.

<Background of the Invention> Conventionally, a pressure sensor formed using pressure-sensitive conductive rubber has been used in a robot hand. However, pressure-sensitive conductive rubber lacks linearity in its output characteristics and exhibits significant phenomena such as hysteresis and creep, so although it is possible to recognize patterns on objects, it is not suitable for measuring contact pressure.

<Object of the Invention> The object of the present invention is to provide a pressure sensor capable of measuring contact pressure by using silicon, which has output characteristics with excellent linearity and is extremely free from phenomena such as hysteresis and creep. shall be.

<Configuration and Effects of the Invention> In order to achieve the above object, the present invention forms a pressure-sensitive sensor by forming a plurality of diaphragms in a matrix on a silicon substrate and forming and disposing a piezoresistor for each diaphragm. For this pressure sensor, by connecting and deploying pressure receiving parts that protrude corresponding to each diaphragm,
It was decided to measure the pressure acting on each pressure receiving part using a piezoresistor via a diaphragm.

According to the present invention, the state of contact pressure can be accurately measured using the ideal output characteristics of silicon. In addition, since the diaphragm is formed on a silicon substrate, it is possible to process the diaphragm with high precision using anisotropic etching, etc., and the integral formation of piezoresistors facilitates arraying and integration. It achieves its purpose and produces excellent results.

<Description of Embodiments> FIGS. 1 to 3 show configuration examples of a pressure sensor according to the present invention.

The illustrated pressure sensor is constructed by stacking a protection plate 3 on top of the pressure sensor 1 via a spacer 2, and further overlaying a silicone rubber sheet 4 thereon.

The pressure-sensitive sensor 1 has piezoresistors 11 to 14 formed and arranged on a silicon single crystal substrate 10 by boron diffusion, and after bridge-connecting the resistances with a metal electrode 15 such as aluminum, an anisotropic wire is formed on the opposite side of the substrate. The diaphragm 16 is formed by etching. For this anisotropic etching, an etching solution such as potassium hydroxide or a mixed solution of pyrocaracol and ethylenediamine is used, and a plurality of diaphragms 16 are simultaneously formed in a matrix on the substrate 10. The four piezoresistors 11 to 14 are arranged correspondingly to each diaphragm 16, for example, the piezoresistor 11 is placed on the diaphragm 16 and the other piezoresistors 12 to 14 are placed outside the diaphragm 16.

A diaphragm 16 is attached to the spacer 2 and the protection plate 3.
A through hole 21.3'l is formed at a position corresponding to the through hole 21.3'l, and the continuous through hole 21.31 is filled with silicone oil 5, which is a pressure transmission medium. By using a material having the same coefficient of thermal expansion as silicon for the spacer 2, the temperature characteristics of the pressure-sensitive sensor can be improved.

Further, the silicone rubber sheet 4 is integrally formed with a disc-shaped pressure receiving part 40 at a position corresponding to the diaphragm 16.
The compressive force acting on each pressure receiving part 40 is transmitted to the diaphragm 16 of the pressure sensor 1 via the silicone oil 5.

FIG. 4 shows a bridge circuit connecting the piezoresistors,
Moreover, FIG. 5 shows the entire circuit in which each bridge circuit is connected. In FIG. 4, terminals 6 and 60 are input terminals to which a constant voltage is applied, and terminals 7 and 70 are output terminals for detecting changes in the balance of the bridge circuit. If the piezo resistors 11 to 14 are set to a common resistance value k, if the pressure deformation of the diaphragm 16 increases the resistance value Δ of the piezo resistor 11, the output terminals 7 and 70 will have an output voltage ΔV expressed by the following equation. appears.

In this circuit configuration example, the potential of the output terminal 70 is always constant regardless of whether pressure is applied or not, so in the overall circuit shown in FIG.
The number of terminals can be reduced by setting a common output terminal 71 that has a common output terminal. Thus, a constant voltage is applied to the common input terminals 61 and 62■
By applying this and scanning the output terminal 7 of each bridge circuit, the magnitude of the pressure acting on each pressure receiving section 40 can be measured as a voltage change.

Figure 6 shows each piezoresistor 11 to J4 connected to a diaphragm 16.
FIG. 7 shows the entire circuit in which the bridge circuits are connected. A constant current ■ is passed between the input terminals 6 and 60 of the younger brother 6, and each piezo resistor 1
If the resistance values of 1 to 14 increase to Δ due to pressure deformation of the diaphragm 16, an output voltage ΔV shown by the following equation appears at the output terminal 7.70.

ΔV: ΔR,I Therefore, in the overall circuit of FIG. 7, the common input terminal 61.
62, and scan the output terminals 7, 70 of each bridge circuit, the magnitude of the pressure acting on each pressure receiving part 40 can be measured as a pressure change, as described above.

FIG. 8 shows another configuration example of the pressure sensor according to the present invention. The pressure sensor of the illustrated example has spacer 2 superimposed on pressure sensor 1-J= and spacer 2 in through-holes 21, 31 of protection plate 3.
An elastic body 41 made of silicone rubber is inserted, and the elastic body 41 is positioned on the diaphragm]6''-, and the elastic body 41
It has a structure in which the pressure receiving part 40 of the protector plate 3 is projected onto the protection plate 3. Although the elastic bodies 41 in the illustrated example are connected to each other to simplify the assembly work, the present invention is not limited to this.
It is also possible to design and use such as making 1 independent.

When an object is pressed against the pressure sensor, the pressure receiving part 40 in contact receives a compressive force. This compressive force is the first and second
It is transmitted to each diaphragm 16 of the pressure-sensitive sensor 1 via the silicone oil 5 in the example shown, and via the elastic body 41 in the example shown in FIG. As a result, the diaphragm 16 is compressed and deformed, and stress is applied to the piezoresistor 11 located on the diaphragm 16, causing a change in resistance value. By detecting this change as an output change of the bridge circuit, the contact pressure of each pressure receiving part 40 can be grasped.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the pressure sensor according to the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, and Fig. 3 is a diaphragm.
Wiring explanatory diagram showing the connection state between piezoresistors in 2.
Figure 4 is an electrical circuit diagram showing the bridge connection of piezoresistors.
5 is an electrical circuit diagram of the entire circuit connecting bridge circuits, FIG. 86 is an electrical circuit diagram of a bridge circuit showing another embodiment, FIG. 7 is an electrical circuit diagram of the entire circuit of the embodiment shown in FIG. 6, FIG. 8 is a sectional view showing another structural example of the pressure sensor. 1...Pressure sensor 10...Silicon single crystal nail plates 11-14...Piezo resistor 16...Diaphragm 40...Pressure receiving part 2 times 3 Figure 4 Fu 6 .7. Site map 7

Claims (1)

[Claims] ■ A pressure-sensitive sensor is formed by forming a plurality of diaphragms in a matrix on a silicon substrate, and piezoresistors are formed and arranged in the cage of each diaphragm. A pressure sensor with a pressure receiving part that protrudes in correspondence with the tire flam. (2) The pressure sensor according to claim 1, wherein the diaphragm is formed by subjecting a silicon substrate to anisotropic etching. (2) The pressure sensor according to claim 1, wherein the piezoresistor is formed by diffusing boron into a silicon substrate.