JPH03167432A - Pressure sensitive sensor - Google Patents

Abstract

PURPOSE:To output a potential which is proportional to compressing force by providing electrodes on both surfaces of a pressure-potential transducing element comprising a piezoelectric macromolecular film, providing a buffer body on one electrode, and providing a strain reducing body on the other electrode. CONSTITUTION:A sensor 1 is composed of a pressure-potential transducing element 2 comprising a piezoelectric macromolecular film, electrode foils 3a and 3b which are formed on both surfaces of the element 2 by printing, a buffer body 4 of silicon rubber and the like bonded to the electrode foil 3a, a strain reducing body 5 comprising polyethylene bonded to the electrode foil 3b and a noise removing body 6 comprising urethane rubber. This sensor 1 is used by attaching the noise removing body 6 to a gripper 7 of a robot hand. Therefore, when a work is held with the gripper 7, the gripping acts on the element 2 through the buffer 4, and the strain which is proportional to the stress is generated in the element 2. The potential corresponding to the strain is generated between the electrode foils 3a and 3b. When the potential between the electrode is measured, the pressure can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure-sensitive sensor. [Prior Art] Conventionally, pressure-sensitive sensors that use pressure-sensitive conductive rubber are known. j; Pressure-sensitive conductive rubber is made by dispersing a large number of conductive particles such as nickel particles in silicone rubber, and is normally electrically insulating but changes to conductive when pressure is applied. It is widely used because of its simple structure. The problem is that it can only output ON/OFF signals and has a short lifespan. Strain gauges using alloy foil are also known, but they have low output and short lifespan. Furthermore, it is known that a polymer membrane that has been subjected to a poling treatment in advance, such as a membrane of polyvinylidene fluoride, is self-polarized and generates a potential when #i impact force is applied to this polymer membrane. Therefore, by printing or vaporizing a metal such as aluminum, nickel, or copper on a pair of opposite sides of this polymer film to form electrodes, it is possible to detect the gradient generated by an external force. However, when the above piezoelectric polymer membrane is used alone, its sensitivity as a pressure sensor is too good, and even a small difference in applied force causes a large difference in output (potential). There is a problem that it is difficult to have a proportional relationship with the output, and the electrodes tend to peel off, resulting in lack of durability. [Problems to be solved by the invention] The problems to be solved by the Kihatsu IJ1 are An object of the present invention is to provide a pressure-sensitive sensor that is capable of outputting a potential proportional to pressure and has excellent durability. a pressure-potential conversion element made of a polymeric membrane, electrodes provided on a pair of opposite surfaces thereof, a buffer provided on the surface of one electrode opposite to the pressure-potential exchange element, and the other electrode. The pressure of the electrode was placed on the side opposite to the potential exchange element?
It is characterized by having an ri reducing body. Also similar! ! In order to solve the problem, it would be helpful to place a noise eliminating body on the opposite side of the strain reducing body from the electrodes. [Operation and Effects of the Invention] The acting external force is relaxed by the buffer and transmitted to the pressure-potential conversion element made of a piezoelectric polymer membrane. In this case, the pressure-to-potential conversion element generates a strain approximately proportional to the stress due to the buffer body relaxing the external force and the strain reducing body making the strain constant, and this causes 7Itg
A potential corresponding to the strain is generated between I. Therefore, by measuring the potential between the electrodes. Positive force can be detected. In addition, because the strain on the pressure-potential conversion element is reduced by the buffer body and the strain reduction body, and because the electrode is protected and no direct force acts on it, the
! ! ! Durability is improved because it is difficult to peel off from the element. Furthermore, the noise removing body can reduce noise caused by external vibrations that act from the opposite side of the buffer. [Example] Fig. 1 shows an example of the present invention, and this pressure-sensitive sensor uses a pressure-potential conversion element 2 made of a piezoelectric polymer film, and the K
Electrode foils 3a, 3b . A buffer body 4 made of an elastic material such as silicone rubber adhered to the electrode foil 3a, a strain reducing member 5 made of polyethylene and a noise eliminating body 6 made of urethane rubber adhered to the electrode foil 3b in sequence. are glued together with rubber adhesive. The pressure-to-potential conversion element 2 is made of, for example, a vinylidene fluoride copolymer that has been subjected to a poling treatment, and generates a potential when applied with pressure, and the electrode foils 3a and 3b are made of aluminum, nickel, copper, etc. It is made of a material that has low electrical resistance and is resistant to rust. Further, the buffer body 4 reduces the force acting on the pressure sensor l and transmits it to the pressure-potential conversion element 2, and the strain reduction body 5 reduces the force acting on the pressure-sensitive sensor l and transmits it to the pressure-potential conversion element 2.
The noise remover 8 reduces noise caused by external forces such as external vibrations acting on the pressure sensor 1. The above-mentioned pressure sensor 1 is, for example, a gripper of a robot hand?
When the gripper 7 grips a workpiece (not shown), this gripping force is applied to the pressure-ilE position conversion element 2 via the buffer 4, thereby causing the element 2
A strain proportional to the stress occurs. Note that the sensitivity of the pressure sensor 1 changes depending on the J1 level of each part, and for example, when the pressure-potential conversion element 2 is set to H, the output becomes smaller. The hardness of each of the above members is as follows: the buffer body 4 has JIS hardness (JISK
8301) at 30 degrees or more, preferably 50 to 70 degrees,
The strain reducing body 5 is Situa D (A.S.T.M. D 785
) is 50 to 80 degrees, preferably 60 to 70 degrees, and the noise removing body 6 has a JIS hardness of 70 degrees or less, preferably 40 degrees.
It is best to set the temperature to ~60 degrees. FIGS. 2 and 3 show that in the pressure-sensitive sensor 1, the pressure-potential conversion element 2 is 28gm, and the electrode foils 3a and 3b are 18gm.
pLm. l impactor 4 is 2■, strain reduction body 5 is 0.5++ua
, a noise removing body 6 with a thickness of 2 mm was attached to the gripper 7 of the robot hand on the opposite side of the noise eliminating body 6 from the buffer body 4, and a cylindrical workpiece with a diameter of 17 mm was set at a temperature of 25°C and an operating frequency of 2 cps. It is a diagram showing the change in output (potential) with respect to the pressure supplied to the hand and the output signal of the piezoelectric polymer membrane when the device is grasped. As is clear from the description in FIG. 2, it is possible to obtain an output that changes approximately linearly with respect to the supply pressure, and moreover, it is possible to reduce the change in the output with respect to the supply pressure. Furthermore, even if the above pressure-sensitive sensor is operated 10 million times,
No abnormalities were observed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal section of an embodiment of the present invention {threshold, FIGS. 2 and 3
The figure shows the relationship between supply pressure and output, and the output signal of the pressure-potential conversion element. 1...Pressure sensor, 2...Pressure level change element, 3a, 3b...electrode foil, 4...Buffer body, 5...Strain reduction body, 6...Noise removal approximately. Special fraud applicant SMC Co., Ltd.

Claims (1)

[Claims] 1. A pressure-potential conversion element made of a piezoelectric polymer membrane, electrodes provided on a pair of opposite surfaces thereof, and one electrode on the opposite side of the pressure-potential exchange element. A pressure-sensitive sensor comprising: a buffer body provided on a surface; and a strain reduction body provided on a surface opposite to the pressure-potential exchange element of the other electrode. 2. The pressure-sensitive sensor according to claim 1, wherein a noise removing member is provided on a surface of the strain reducing member opposite to the electrode.