JPS607371A - Apparatus for measuring capacity and resistance of highly stable superlow impedance with wide frequency range - Google Patents

Abstract

PURPOSE:To enable the measurement of capacity and resistance of a sample of a superlow impedance with a wide frequency range by measuring the output of a phase discriminator depending on the capacity of the sample and then, the output of an amplitude detector depending on the resistance thereof by the zero-setting method. CONSTITUTION:A metal ring R is mounted intermediately between coils l2 and l2' of a bobbin and is displaced finely sideways to be adjusted so that voltages ex and ex' induced in the coils l2 and l2' will be equal completely to make the bias at P zero by setting the input voltage to a phase discriminator P at er=er' while the bias at A zero by setting the input voltage to a loss detector A at eR=eR'. Under such a condition, a sample RX.Cx through a variable inductance Lv or a variable capacitance Ci connected in series to a high frequency coaxial cable. Initially, the output of P is made zero by the standard variable capacitance C2v to measure Cx from changes in the C2v and then, the output of A is made zero by a high frequency variable resistor Cd to measure Rx by a computation using the current capacitance value on the insertion side of the resistance (r) of a differential capacitor. Thus, the capacitor and resistance of a superlow impedance can be measured.

Description

[Detailed Description of the Invention] A biological body such as a plant and a human body can be expressed as a parallel circuit with a capacitance Cx and a resistance 1 (,
It is.

(however, ω-2πf, f is the frequency, and low-impedance capacitance Cft/with QX smaller than 1) can be accurately measured using conventional methods, which connect the sample and ignore the influence of the slight i/ductance of the lead. It is impossible to accept.

The method according to the present application allows the measurement of trial capacitance and resistance for Qx( ) over a wide frequency range.

In Figure 1 (A), an ultra-low impedance resistor TLx +
The circuit diagram of the measuring device of capacitance Cx is shown. Sample measurement side tuning circuit 1-rI10B+ -CIv -CI CI at C2
, from the connection point TI of C2, connect the high frequency coaxial cable and variable capacitance C1 or variable inductance Lv to the measurement target (Cx, II, x) by switch S2, and first connect Cx.
The output of the phase discriminator ■ is measured by the zero method using a variable standard capacitor C2V.The output of the amplitude detector ■ is measured by the zero method using a town frequency standard variable resistor using a differential capacitor Cd. , x will be open for business in January.

In this case, the conditions to be satisfied for the circuit constants including the coaxial cable are: o) 2LX C2''' 1・・・・・・・・・(1)
is necessary.

] And Lx-2L + ,, 2 stones...(2)
Or LX=Ll + LV・・・・・・・・・(3)C
2=C20+Cc+C2v=-...=(4
) However, Ll is the total inductance of the coaxial cable.

Cc is the total distributed capacity of the coaxial cable.

The length of high-frequency coaxial cable varies depending on the purpose of use, but it is about 1 to 50 meters long, and the operating frequency is high (υ”LiC
2>], as shown in FIG. The expression (1
), and the frequency used is low ω2L l (', ', If 2 < 1, insert a variable inductance liv in series with Ll and set Lx - tuna → -Lv as Equation (1) 1. Adjust V to satisfy the conditions of (1). Under the conditions of equation (1), the ultra-low impedance capacitor Cx is set to a standard variable capacitor with a resistance value of 1 (regardless of It is possible to measure by C2V. (
To adjust Lv, insert a copper round rod or copper pipe into the cylindrical coil bobbin, and adjust the degree of insertion to freely and continuously change the inductance of IJv. I can do it. That is, according to this method, by adjusting Lv or CI, which is related to the length of the high-frequency coaxial cable and the magnitude of the measurement frequency, ω of equation (11)
2Lx (,,'2-1 condition can be satisfied.

Next, the 90 degree phase conversion circuit will be explained.

The voltage ez of the tuned circuit (C1) is connected to the voltage ez of the tuned circuit through the capacitor C02.
When (C3+C02)-1・(5) is satisfied, the terminal voltage e2 of the tuned circuit becomes maximum and e22JωCo
2 0L21 which becomes R2C4°°゛°°°゛°° (6)
The voltages CX, eX' and [
The phase relationship between the voltage ep taken out from the connection point of the inductance L1'+131' of the old tuning circuit is as shown in FIG. 2 (A,), and Cp,! : eX and eX' have a phase difference of 90 degrees. In this state, if eX and CX' are completely equal, the vector composite voltages er and ebi of ex and Cp, eX' and ep are completely equal, and the output of the phase discriminator (2) is zero. In this case, as shown in Figure 2 03), the sample ■ also becomes e) (-+ e) q, e
Even if Xl', CX1-eX1' is satisfied and the output of (2) is zero. That is, the phase discrimination detector has zero sensitivity to ILx of the sample and has sensitivity only to CX of the sample. Cx
Therefore, as shown in FIG. 2(C), when the phase of <eX is shifted by 0, the vector composite voltage er1>er1' of exl and cp, eX1' and ep becomes the output I of the phase discriminator ■.
g c Id, ] gc = 4 Kep, exl
tatθ On the other hand, as shown in Fig. 2 (1)), if Cx and eX' are equal to 17 (ex ) ex', in order to make the output 1gc of the phase discriminator zero as the initial adjustment, eX
When the phase angle between and ep is α, er:e,' and Igc is zero. In this case, eX
The 6-ctor composite voltage of l, ep・eX1' and 0p is the second
As shown in the figure (IC), (er, l) becomes Crt and Rx
This causes the output of the phase detector and causes a large error in the measurement of Cx.

When there is no sample (R, X, Cx), CX is completely (X
The structure of the wire ring -02,-/h' for taking out the wire 1.121 L2' and ex, eX' of the [11] tuning circuit for phase detection is as shown in Fig. 3. Winding Ll e2'+ L2'-82' on the same bobbin with mutual induction coefficient Mp, Mp' f Ll-1-12+
02 ・-pz' + If we wind the wire to satisfy the condition of Chiji Ml, the voltages e -1, r2'+ p2・-right', Mp=
It is difficult to make each wire ring S' so as to satisfy the condition of Mp', and in order to solve this problem, in this application, the wire ring S' is placed between the wire rings &+4+' on the bobbin as shown in Fig. 3. By slightly displacing the metal ring R (=J) to the left and right as shown by the arrow, the voltages eX and eX' induced at 82+-/h' can be adjusted so that they are completely equal. Thus, the tuning circuit of Fig. 1 (A) [1]
Between each circuit constant of [ll:] and [U(], ω2(L+
+-g+) (Co1+Q v+ animals)-1, and under the conditions of C2=C2o+C2v-1-CcC1+02, %-ey・, eX and ep have a phase difference of 90 degrees, and Fig. 2 (A, When the input voltage to the phase discriminator [F] shown in , It is. In this state, 82 passes the sample (
Connect (It, When the output of Yoshi is zero, then from the capacitance value Cdx of the differential capacitor on the resistance r insertion side.

[Brief explanation of drawings]

Accompanying drawing Figure 1 (A) is an example of a capacitance and resistance measurement device with a wide frequency range and a highly stable ultra-low impedance suitable for carrying out the present invention, and the same figure ([1) shows a diagram of phase and resistance measurement equipment. Figure 2 (A) shows the amplitude product U'' circuit, where e, ='e,'
Figure 2 shows the relationship between the phase and magnitude of the input terminal to the phase discriminator in the case of
shows the input voltage to the phase discriminator when ((゛)
Fig. 61 shows the input terminal t-C to the phase discriminator when the resistor 1tx and the container (, χ) are connected at the same time on the constant side. Fig. 2 (1)) shows the case with no load. , where eX and eX' are equal (Cx > (in the case of 'x', the output indicator ψ of the phase discriminator) makes the deviation zero/eX+, that is, eX+!: ep Figure 2 shows the relationship between the phase and magnitude of the input voltage to the phase discriminator when the resistor 11.x is connected to the measurement terminal in this state.
1°C). Figure 3 shows the 90-degree phase converter [button tuning circuit wire]. b' and secondary circuit -g2+-fh' and Jh+-gz
The arrangement of the metal ring I for adjusting the voltages eX and eX' induced in ' are equal. Patent applicant - Fumi Jo

Claims (1)

[Claims] Frequency J' as detailed in the text and clearly shown in the accompanying drawings.
Two tuned circuits L1+CIV+C, -C2 and C+v-C+v+Cd+CI' and C2' having the same structure and constants are capacitively coupled through the high-voltage side terminal of the output "tank" circuit of the high-frequency oscillator. 11
The wire A2 is electromagnetically coupled with the degree of coupling equal to L2 + L2' under the condition that the wires with equal inductances L2 + Lz'& are connected in parallel through the connection point of and the variable capacitor Cs through the capacitance Co2 to form a tuned circuit. + 4
32' is equipped with an adjustment ring so that the voltages eX and eX' induced in the terminals are completely equal to each other, and by utilizing the fact that there is a 90 degree phase difference between the terminal voltages ep and ex and ex' at the terminals 32' and 32'. ep and e) Use elf and ell' as inputs to the amplitude detector. Measure Cx + Rx of the measurement target using the zero-level method, and then connect a high-frequency coaxial cable with an inductance Li from the connection point of C, C2 of the [I] tuned circuit. , a variable capacitance Ci or variable inductance Lv is connected in series to Li according to the measurement frequency, and in the case of Ci, C2 (Li,
,,z(H; ) If C2=l + Lv, then C2(L
A highly stable ultra-low impedance capacitance/resistance measurement device over a wide frequency range, characterized in that it can measure an ultra-low impedance capacitance Cx of 1(, regardless of the value of x) by satisfying the condition of U27I (i + Lv).