JPS6147501A - Load position detection sensor - Google Patents

Abstract

PURPOSE:To make it possible to accurately measure the coordinates of load even when a resistance value approaches zero in the relation of the resistance of a pressure-sensitive resistor and pressure, in the constitution of a surface pressure sensor, by using a pressure-sensitive plate comprising a piezoelectric composite material in place of pressure-sensitive conductive rubber. CONSTITUTION:A thin resistance 2 is one with a thickness of 0.1mm. or less comprising indium/titanium oxide, other oxide semiconductors or an amorphous metal and a pressure-sensitive plate 3 is one with a thickness of 0.1-0.5mm. comprising a piezoelectric composite material such as lead titanate zirconate (PZT) having high voltage coefficient or a ferroelectric polymer such as polyvinylidene fluoride (PVF) in the case providing flexibility and a common electrode 4 is a copper plate. Electrodes 2a, 2b provided to two sides are provided to the resistance film 2. When there was loading at the position P of load, the voltage at this part is polarized and charge respectively moves to the electrodes 2a, 2b through the resistance film 2 and this voltage is measured to enable the measurement of u-coordinates. By this method, a sensor having extremely high accuracy is obtained and can be used as a highly accurate one.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Field of Application) The present invention relates to a surface pressure sensor used to detect the sum of changes in surface pressure applied to a surface of arbitrary shape, its center of gravity, the center of a plane, etc. It relates to a detector and is used as a position detector of an object held in a robot hand.

(Prior art) As a prior art related to the present invention, Japanese Patent Application Laid-Open No. 58-1733
There is a publication of No. 2 "Surface Pressure Detector", and the present invention relates to an improvement of this.
0 is a pressure detector (hereinafter referred to as a sensor), 21 is a resistive film, 22 is a pressure-sensitive plate made of pressure-sensitive conductive rubber, 23 is a common electrode, S and S- are electrodes provided on the resistive film, and 24 is an electrode provided on the resistive film. In the arithmetic circuit, there is a certain relationship between the x-y plane and the u, v planes, which are orthogonal planes corresponding to the shape of the sensor, and due to this, this sensor is , which can detect pressure.

However, the sensor configured as described above has a problem that in the relationship between the resistance R of the pressure-sensitive resistor made of pressure-sensitive conductive rubber and the pressure P, when the resistance value approaches O, the accuracy of determining the coordinates of the load deteriorates.

(Problems to be Solved by the Invention) Therefore, the present invention provides a surface pressure sensor that can accurately measure the coordinates of a load even if the resistance value approaches 0 in the relationship between the resistance R of the pressure-sensitive resistor and the pressure P. The technical issue is the structure of a surface pressure sensor.

[Structure of the invention]

(Means and effects for solving the problems) A means for resolving the above problems is to use a pressure-sensitive plate made of a piezoelectric composite material instead of pressure-sensitive conductive rubber in the structure of the surface pressure sensor. It is.

That is, a resistive film is sandwiched on one side of a plate-shaped surface made of a piezoelectric composite material that generates an electric charge when pressurized, and a conductive plate made of copper is sandwiched on the other side. Two pairs of electrodes are provided, and when the load on the resistive film changes, a charge is generated, the charge is divided and flows to the opposite sides, and by comparing the currents, the center of gravity position and the load of the area where the load m changes are determined. This is a sensor that determines the total amount of change.

The resistance film has a thickness of about 0.1 mm or less and is made of an oxide semiconductor or an amorphous metal, and the pressure sensitive plate is made of lead zirconate titanate, which has a high piezoelectric coefficient, or if flexibility is required. Polynylidene fluoride (PVI)
F) or a ferroelectric polymer made of vinylidene fluoride-trichloroethylene (VDF-TrFF) copolymer, or a blend of the above-mentioned PZT powder with a polymer is used.

Next, FIG. 5 shows the relationship between pressure and current for the surface pressure sensor according to the present invention. In other words, in the sensor shown in Figure 1, the output current for the load in the thickness direction is (A)
It shows the zone, and if the horizontal axis is the load W and the vertical axis is the current ■, then the load 100 within the minimum time of j, = l Osec
Indicates I=3 in , th= 2 X 10 , t
3 = 5
This shows the change in the value of .

This graph shows that the sensor of the present invention is capable of measuring current when there is a slight change in load within an extremely short period of time. When comparing the conventional sensor made of pressure-sensitive conductive rubber with this example, it succumbs to zone (B) of the graph in Figure 5, and compared to this graph, the conventional sensor has a W of 0. This indicates that even if approached, it will not function as a sensor unless W=300 or more. (C)
The zone is an area where the current is so small that it is difficult to measure it.

(Example) Examples of the above technical means are shown in FIGS. 1 to 3.

1 is a sensor, 2 is 0, 1 made of indium titanium oxide, other oxide semiconductor or amorphous metal.
■In the following thin films, 3 is a piezoelectric composite material made of lead zirconate titanate (PZT), which has a high voltage coefficient, or a ferroelectric polymer such as polyvinylidene fluoride (PZT) when adding flexibility. 0, 1 to 0.5 +n pressure sensitive plate, 4 is a common electrode made of a copper plate etc., 2a,
Reference numeral 2b denotes electrodes on two sides provided on the resistive film 2. C is a voltage measurement circuit.

P indicates the position of the load, and when there is a load on P, the voltage at this part is polarized and charges move through the resistive film to 2a and 2b, and by measuring this voltage, U
It is possible to measure coordinates. .

5 is a pressure sensor having electrodes in four directions, 6 is a resistive film, 7 is a pressure sensitive plate, 8 is a common electrode, 9a, 9b...
9d indicates the electrode of the resistive film. If electrodes are provided on all sides of the resistive film, one element can achieve X.

It is possible to detect the position on the y-plane.

Further, 11 is a sensor with a small or medium-sized thin structure, 12 is a resistive film, 13 is a pressure sensitive plate, 14 is a common electrode, 14a, 14
b is an electrode of a resistive film, and in such a structure, it is possible to detect at what position on a one-dimensional plane a load is applied.

〔Effect of the invention〕

The present invention produces the following unique effects. In other words, by using a pressure sensitive plate made of piezoelectric composite 4A material as a sensor, a highly accurate sensor can be obtained.Furthermore, the piezoelectric composite material is hardened by pressing into conventional pressure sensitive conductive rubber. , because current flows even with a small stroke, a large number of 7! (A fixed point can be set, and it can be used as a high-precision sensor.)

[Brief explanation of drawings]

FIG. 1 is a simplified explanatory diagram of this embodiment, and FIGS. 2 and 3 are other modified embodiments. FIG. 4 is an explanatory diagram of the conventional example, and FIG. 5 is a graph showing the relationship between load and load time and current in this embodiment.

Claims (1)

[Scope of Claims] An x, y plane and the following two planes in which a resistive film is sandwiched on one side of a plate-shaped piezoelectric plate made of a piezoelectric composite material that generates voltage when pressurized and a conductive plate is sandwiched on the other side. u related by the formula
In the sensor configured in the shape of -v plane, ■^2u (x, y) = ■^2v (x, y) = 0√[(∂
x/∂v)^2+(∂y/∂v)^2]/√[(∂x/
∂u)^2+(∂y/∂u)^2]=k k=constant Two pairs of electrodes are provided around the resistive film, and when the load on the resistive film changes, a charge is generated, and the charge is a load position detection sensor that divides and flows on opposite sides, and calculates the center of gravity position of the area of load change and the total sum of load changes by comparing the currents.