JPS58111517A - Mechanical coupling type electric isolator with output stabilizing means - 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 The present invention relates to electrical isolators, and more particularly to electrically coupled electrical isolators with devices for compensating for 11-temperature changes resulting from variations in the properties of an isolator film. Regarding.

Isolation of two electrical circuits requires the transfer of power and/or information through means other than electrical current.

For example, isolators that use magnetic radiation* (wireless) or light (optocouplers) exist.

Piezoelectric polymer films, such as polyvinylidene fluoride, can be used to convert applied electrical signals into mechanical strain within the film. The method is reversible, so mechanical strains are converted into electrical signals. Mechanical strain therefore becomes another means for use in isolators of electrical circuits.

Polyvinylidene buttride (PVDF or PVFI) is
It is a polymer with excellent piezoelectric properties. however,
The piezoelectric constant of a material changes over a temperature range relevant to the human environment! (El@ctricm)
l Commt+n1eatlon No, 52197
7 W, D, Cragg and N, W, Te5t@
r no r T@l@phon ding rams due*rs
umlmg Pl@io@l@ctrie Pol
ym@rFoll J) and these changes are repetitive unless a certain maximum temperature is exceeded. Above this maximum temperature, the change in sensitivity is irreversible and time dependent. (Acossmtieal
5eel@ty ofAm@r l cm No. 94
J, M, P, 0. presented in Kaikaijo, 1977. W.E.
R8's "Effects of Tempsratur"
e onth@Aging Rat@of Piezo
The present invention relates to the construction of inexpensive piezoelectric polymer film isolators. The piezoelectric bonding film may be fixed at two or more separate locations to limit the length of the bonding means and may be stressed to ensure the presence of static strain within the bonding film. has a specific pattern of conductive material on both sides of it. The conductive material forms two or more distinct active elements of the isolator. The conductive material of the pattern also forms electrical connection means for the active elements. The first pair of active elements , a second pair of active elements is connected to an electronic circuit for supplying an electrical signal thereto, and a second pair of active elements is associated with a second electronic circuit for picking up the signal induced in the pair of elements. The electronic circuit of M2 is not connected to the first electronic circuit except through pattern bonding of the film A. , the third pair of active elements are connected to the first pair
A pair of active elements is connected to the driving electronic circuit and changes its amplification according to the signal picked up by the element.

DESCRIPTION OF EMBODIMENTS Referring now to the drawings, the present invention will be described with reference to preferred embodiments. Referring to FIG. 1, a piezoelectric polymer membrane (film) 1,
A first restraint means 2 and a second restraint means 3 are shown in side view. These are arranged such that both means are connected to ensure that the length of the membrane is fixed at the restraint points 4 and 5.

The piezoelectric polymer may be poly(bi-lydenate).

The cavity between the polymer @1 and the restraining means 2 and 3 may be enclosed to protect the antinode from external acoustic signals. Regions 8 and 8' are layers of conductive material (e.g. aluminum), and regions 9 and 91 and 10
and 10' are similar regions of conductive material not connected to either 8 or 8' or to each other. Each pair of conductive regions constitutes an active element where the regions overlap. Applying an electrical signal between a pair of conductive regions, such as conductive regions 8 and 8', causes strain in the membrane due to the piezoelectric properties of the polymer membrane. This strain is present in any part of the membrane between restraint points 4 and 5 due to the piezoelectric properties of the membrane, and therefore in each pair of similar conductive regions 9 and 9' and 10 and 10'. 1 electrical signal is generated.

In FIG. 2, the electrically conductive regions are shown in plan view with respect to the surface TkJK of the membrane.

In FIG. 2, 1 is a piezoelectric polymer membrane, 4 and 5 are restraint points, 11 and 11' are optional holes for driving mechanical and acoustic protection of the active slope of the membrane, 12 and 1
2' is the connection means for the conductive regions 8j and 81, likewise! ffl, 15 and 15' and 14 and 14'
are the connection means for the conductive regions 1o and 101 and 9 and 9', respectively.

To ensure that superimposed strains of either polarity are obtained from signals of either polarity within the membrane, the membrane must be strain-like INK. Without static pressure, only superimposed tensile strains would be present.

Static pressure can be provided by deforming the membrane either by a rigid mold member 15 or by a resilient mold member, as shown in FIG. 3, after it has been clamped at the point of restraint.

The latter type provides acoustic coupling in addition to mechanical coupling between active elements on the membrane, increasing the need for protection of the membrane from external acoustic signals if that is required for the particular application of the isolator. The rigid mold member should be as shown in FIG. That is, the member 15 is
I[1 is a protrusion of the restraining means 5 so as to extend the length 4-15-5 which is longer than the length 4-5. All active elements are provided on the membrane portion between restraint points 4 and 5.

The strain in the membrane between restraint points 4 and 5 is K so that it acts equally on the active element formed by regions 9 and 9' and 10 and 10'. That is, the electrical signals produced by each of these active elements should be equal. The source impedance of active elements 9 and 91 and 10 and 101 depends on the area of these elements, and the actual electrical signal (voltage) depends on the impedance of these elements (the electrical circuit to which they are connected.Actual area is set to be inversely proportional to the actual impedance of the connected circuit, the actual voltage will be lower.

It is not necessary that both active elements be equal in area.

Therefore, their area (and their shape) in a particular embodiment is left to optimize the physical separation of the conductive regions to achieve the electrical isolation required for a particular application.

Figure @4 shows the electrical application of the mechanical system coupled by the strain K described in Figures 1-3. The piezoelectric film has active elements 8 and 8', 9 and 9' and 10 and 1
It is indicated by dots between 01 and 01. These elements are each
The dashed elements are shown as being connected to a common ground potential, thus separate grounds are shown on each side of the isolator. Input or drive elements 8 and 81 are connected to the output of input amplifier 16.

The input signal is applied from a terminal labeled Vlm to a non-inverting input terminal through a network consisting of resistors R1 and R2 and input ground. The piezoelectrically generated signals sensed in active elements 10 and 10' are coupled to the inverting input of the amplifier. The signals supplied from drive elements 8 and 81 via a network consisting of series-connected resistors R3 and R485 and a capacitor C1 connected from the junction of the resistors to ground are also connected to the inverting input of amplifier 16 and fed to the wrinkle amplifier. Ensure correct bias. Since capacitor C1 effectively routes output voltage variations to ground, the only feedback to the amplifier will be the voltage generated by elements 1o/1o'. It is taken out from Fuyo and 9'.

The amplifier may be of any convenient type and is shown with resistors R5, R6 and R7 to stabilize and control its operation.

The resulting output signal is taken out from the terminal labeled Vout.

The strain S is related to the product of the voltage V3 supplied to elements 8 and 81 and a constant constant 4, and the voltage developed across elements 9 and 9' is related to the product of the strain S and another constant K.

Similarly, Vs is related to the product of the strain S and a constant, K.

and Ks are a function of the physical structure and piezoelectric properties of the membrane).

Therefore, S=, ・Vx vy=! eS Vz = K@・S In order to satisfy the operating conditions of the amplifier 16, Vin
R7=VyR, +R.

To satisfy the operating conditions of the amplifier 17, R0 and C1 are large, i.e., where f is the lowest frequency related to the input electrical signal Vin, then K, = K.

Therefore, V7=V.

is independent from K1, K, and . That is,
The isolator's transconductor 7 becomes independent of the piezoelectric properties of the polymer membrane.

[Brief explanation of the drawing]

Figure 1 is a side view showing a piezoelectric polymer film with one conductive region, Figure 2 is a plan view showing the relative positions of the piezoelectric polymer film and the conductive region, and Figure 3 is the position of the strain inducing member. FIG. 4 is a circuit diagram showing the electrical interconnections of the isolator of the present invention. 1: piezoelectric polymer membrane 2.3: restraint means 4.5: restraint point 6.7: cavity 8.81.9.9°, 10.10': conductive region 11.
111: Kong (, 4y Agent's name: Motohiro Kurauchi 1'-””s Same as Kurauchi & Akira).

Claims (1)

[Claims] (1) a piezoelectric film as a coupling means; a first plurality of discrete electrically conductive regions disposed on opposing surfaces of the III film; a second plurality of electrically conductive regions spaced apart from the electrically conductive regions of the film; a third electrically conductive region located on opposite surfaces of the film and spaced apart from the first and 112 plurality of regions; a hexagonal amplifier with a separate electrode for each of said conductive regions and an inverting input and a non-inverting input as inputs; means for connecting said amplifier output to an electrode of said first plurality of conductive regions; and means for connecting an electrode of a third plurality of conductive regions to an inverting input of the brown1 amplifier, the amplifier having a brown1! to its non-inverting input. the first plurality of electrically conductive regions is actuated by the application of a signal to provide the signal through its corresponding electrode, and the inverting input of the amplifier is connected to the third plurality of electrically conductive regions. characterized in that the signal sensed by the plurality of conductive electrodes of the Wi3 changes the output of the amplifier and thus the corresponding signal generated on the electrode for the second plurality of conductive regions. A capacitive electrical isolator device dedicated to this purpose.