DE2056586C - Electromechanical oscillator, especially for time measurement - Google Patents

Description

35

The present invention relates to an electromechanical oscillator, in particular for time measurement, with a mechanical resonator, an amplifier and an electromechanical converter, whose coil is in a branch of a Wheatstone bridge, the two capacitors connected in series has that they form components of two other successive bridge branches.

An electromechanical oscillator of this type can only be used in a wristwatch provided that no compensation inductance is required in the Wheatstone bridge. Such a Kompensationsinduktivi ^{: i} t would be too expensive and would take up too much space in the clock.

However, if no compensation inductance voi seen, the influence of the inductive part of the impedance of the coil remains the electromagnetic Converter to the fine input of the amplifier without compensation, so that parasitic vibrations occur which interfere with the desired vibrations and a Cause instability of the drive of the resonator. The clcktri should be seen for perfect functioning Oscillations in the circuit exclusively due to the mechanical oscillations of the resonator are induced and have a certain phase length to the same.

Of course, you could use the high-frequency, disruptive ones Suppress vibrations to a certain extent by using a high filter in the electrical circuit Resistance for these vibrations would be provided. However, such a solution would not be great effective and satisfactory, since a filter is only annoying Frequencies in a certain frequency band suppressed. However, this tape has no specific

Limits on. ^ 11,

The aim of the present invention is to avoid all disturbing vibrations in the electrical circuit of the oscillator and all the disadvantages resulting therefrom, without using a compensation inductance or other expensive and bulky elements. This aim is achieved according to the invention by the fact that a bridge branch adjacent to the bridge branch containing the coil is essentially formed by a simple resistor which, as a compensation resistor, compensates for the influence of the ohmic impedance component of the coil on the electrical oscillations, and that a further bridge branch, which also corresponds to the contains the coil. , the bridge branch is adjacent. an ohmsc
Has supplementary resistance, which is connected in series mn α, -m capacitor of this branch and welcivr the influence of the inductive resistance of the spooky. ·: · Compensates the electrical oscillations.

It can be proven mathematically that d. r mentioned additional resistor in series with the capacitor in the bridge branch, which is adjacent to the bridge branch containing the coil. a Ku,: - pensationsindi'ktiv can completely replace, *, - ,! this resistance the disturbing influences of the IMK: k tivity of the coil to the vibrations to _komrv:; · Sizing permitted, for all frequencies. The electrical voltages induced by the oscillation of the mechanical resonator are not influenced by the supplementary resistance and can freely control the electrical system. In the following, an ohmic resistance is always understood to mean a soft door with alternating current and direct current having exactly the same impedance

On the basis of the drawing, which shows the electrical circuit of the oscillator, a Embodiment of the invention explained in more detail.

The circuit has a Wheatstone bridge with branches 1, 2, 3 and 4, of which two adjacent ones are directly connected to one another, while the other two are connected via a power source 5 and form connections 6 and 7. These two connections 6 and 7 are with respect to the Functions of the bridge equivalent. The remaining bridges / weige are in the usual way with each other connected and form three further connections. ^ connections 8. 9 and 10.

The branches 1. 2 and 3 of the bridge are connected by a coil 11, a compensation resistor 13 and a capacitor 14 is formed. The coil 11 forms part of an electromechanical transducer, the mechanical part is connected to a resonator 12. The bridge branch 4 has a further capacitor 15, which is connected in series with an additional resistor 16. The resistor 16 is purely ohmic as well as the resistor connected to branch 2, i. that is, these resistors have the same impedance for direct and alternating current of any frequency. What is essential here is the fact that the additional resistance 16 in the bridge branch 4 from a functional point of view a compensation inductance, which in the Bridge branch 2 would have to be connected, completely replaced.

The amplifier has two transistors 17 and 18

Λ = / ₂ ; 'j = L : U ₄ - Z ₁ Z ₁ - Z ₃ Z ₄ ;

Λ =

Z ₁ +

Z ₃ + Z ₄

(D

U)

complementary type, which act as active elements, as well as three resistors 19, 20 and 21 which determine the various currents and bias voltages on the electrodes of the transistors. The emitters of transistors 17 and 18 are connected to terminals 6 and 8 of the bridge, respectively. The collector of the The transistor 18 is connected to the terminal 10, so that the transistor is conductive when the collector-emitter path can short-circuit connections 8 and 10 of the bridge. The resistor 19 is in one Connection between the collector of transistor 17 and the base of transistor 18. Terminal 7 the bridge is via the resistor 20 to the collector and via the resistor 21 to the base of the Transistor 17 connected. Terminal 9 is connected directly to the base of transistor 17.

The energy for the excitation or maintenance of the resonator oscillation is applied to the connections 8 and 10 transferred to the bridge. The input voltage for the amplifier is taken from connections 6 and 9. This control voltage is made up of a feedback voltage that passes through the bridge branches 1 and 4 is generated and transmitted, and a compensating negative feedback voltage that is generated by the branches 2 and 3 and is transmitted.

As already mentioned, part of the compensation takes place in bridge branch 4. The calculation of the values of the various switching elements is as follows:

U _A - output voltage between the

Connections 6 and 9,
U _E = input voltage between the

Connections 8 and 10,
Z ₁ , Z ₂ , Z ₃ , Z ₄ = Ir pedances of the bridge branches 1

to 4,
J ₁ , Iχ, I ₃ , / ₄ = currents in the bridge branches 1

to 4,

R ^ = ohmic resistance of coil 11, L = inductance of the electromagnetic transducer,
C ₁₄ , C ₁₅ = capacitances of the capacitors 14

and 15.

^ 1. "^ Ib = values of resistors 13 and 16, jv> = imaginary unit and angular frequency.

U _E Z ₁

Z ₁ Z ₃ - Z ₂ Z ₄ .

U _E ~ Z ₁ Z ₃ + Z ₁ Z ₄ + Z ₂ Z ₃ + Z ₂ Z ₄

. (3 a)

Condition:

U _A = 0 door all frequencies with the exception of the natural frequency of the resonator, ie:

Z ₁ Z ₃ - Z ₂ Z ₄ ..

The values of equation (4) are replaced by

Z ₁ = R _iy + i «> L (5)

(= Impedance of the transducer, the mechanical part of which is blocked).

r— * ■ -R ₁₃ ; z ₃ j j ,,, 1 [ + J (6.7) Z ₄ - Rih j
j '"C ₁₅ Cl 4 (8th) Man receives + >> / - '"C ₁₄ - . (9) ^K 13 ^K 16 R ^{Cw K} 13 ^

The real part of the equation

(9 a)

is the condition for compensating for the influence of the ohmic resistance of the coil 11. The imaginary part of equation (9):

j ", l. = y "> c ₁₄ - R ₁₃ · R ₁₆

or

_ L

It * D. C.

(9 b)

is independent of the frequency. The value of the supplementary resistor thus becomes 16 selected according to equation (9 b), the influence of the inductive resistance of the coil door is all frequencies fully compensated. That is, the resistor 16 has the same influence in this case on the relationship between the input voltage and the output voltage the bridge has as a Compensation inductance switched into bridge branch 2.

For this 1 sheet of drawing new

Claims (2)

Patent claims: 1. Electromechanical oscillator, especially for time measurement, with a mechanical resonator, an amplifier and an electromechanical transducer, the coil of which is in one branch of a Wheatstone bridge, which has two capacitors connected in series so that they form part of two other successive branches of the bridge, characterized in that that one which contains the coil (11 )- ' the bridge branch (1) adjacent bridge branch essentially by a simple resistor (13) is formed, which as a compensation resistor the influence of the ohmic impedance part of the Coil (11) compensates for the electrical oscillations, and that another bridge branch (4), which is also adjacent to the bridge arm (1) containing the coil. an ohmic one Supplementary resistor (16! Has, which is connected in series with the capacitor (15) of this branch and what the influence of the inductive resistance of the coil on the electrical vibrations compensated. 2. Oscillator according to claim 1, characterized in that the value of the supplementary resistor (16) is at least approximately equal to the inductance (L) of the electromechanical converter (11, 12), divided by the value of its ohmic resistance of the converter and the capacitance of the capacitor (15) connected to the same branch of the bridge with the supplementary resistor λ.