DE2443215A1 - FUNCTIONAL ELEMENT WITH CONSTANT NATURAL FREQUENCY - Google Patents

Description

SIEMENS AKTIENGESELLSCHAFT 8 Munich 2, 1OL SEP 1974

Berlin and Munich Wittelsbacherplatz 2

74/1151

Functional element with constant natural frequency

Quartz crystals are usually used as frequency standards. turns, i.e. single crystals that are cut out in "certain directions and then by very precise mechanical shaping as well as by vapor deposition of other materials are trimmed to the nominal frequency. All of this is complex and expensive. Also, the mechanical, suspension the quartz crystal with regard to the required insensitivity to shock extremely difficult to implement.

There are also tuning fork-shaped transducers magnetic materials as frequency-determining components known, which also fine-tune the Oscillation frequency must be carried out by grinding or vapor deposition. As a result of their relatively complicated geometric shape, no Manufacture small oscillators so that high oscillation frequencies cannot be realized.

It is also known that a magnetostrictive! Ven Material-made ferrite ring cores that are azimuthally pre-polarized by an azimuthally directed magnetic Alternating fields can be excited to radial vibrations. By a Suitable composition of the ferrite ring cores, attempts have already been made to create a low temperature dependence of the natural frequency. However, the results achieved so far are for high requirements, e.g. for frequency standards for

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electronic clocks, not yet satisfactory.

The present invention is based on the object, in particular to create suitable puncture elements with constant natural frequency for electronic devices, their respective Nominal frequency against external influences, e.g. temperature, mechanical shock and the like and also over long periods of time is as constant as possible, their production should be feasible with as little effort as possible.

In the case of a puncture element with a constant natural frequency with a Perrit ring core made of magnetostrictive material, the azimuthally pre-polarized and can be excited to radial oscillations by an azimuthally directed alternating magnetic field, the invention provides a perrit ring core with a rectangular hysteresis loop to solve the problem, that by a magnetic field pulse, the strength of which is greater than the coercive field strength of the perite material, azimuthal is pre-polarized, whereby by the strength of this pre-polarization pulse the natural frequency can be changed within certain limits.

Due to the height of the field pulse, a fine tuning of the oscillation frequency can be achieved. Because the Perrit ring core is inductive is controlled, in contrast to a quartz crystal that has electrodes, there is no connection between the oscillating crystal Body with a supply line necessary, so that a low-damping and shock-absorbing bracket is easily realized can be. The invention is explained in more detail below with reference to the drawing. It shows:

Pig. 1 a first embodiment of the object according to the invention in a partially perspective and schematic Depiction;

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Pig. 2 shows the electrical equivalent circuit diagram of the functional element according to FIG. 1;

3 shows the locus curve of the impedance of the resonance circuit, the impedance being normalized to the value M L;

4 shows a second exemplary embodiment of the object according to the invention in a schematic representation;

FIG. 5 shows the electrical equivalent circuit diagram of the exemplary embodiment according to FIG. 4;

6 shows a third embodiment of the object according to the invention in a schematic representation;

7 shows a fourth embodiment of the object according to the invention in a schematic representation;

Fig. 8 is a sketch of the locus of the impedance of the resonance circuit for the embodiment
according to FIG. 7;

9 shows a fifth exemplary embodiment of the object according to the invention in a schematic representation;

Fig. 10 the dependence of the natural frequency on the temperature for several oscillators according to the invention which differ in their composition;

11 shows an exemplary embodiment for the temperature dependency the natural frequency of an oscillator according to the invention, a transducer and a transducer-transducer combination;

Fig.12 shows an embodiment for the dependency of Natural frequency of an oscillator according to the invention depends on the level of the bias pulse.

In the first exemplary embodiment of a functional element with a constant natural frequency shown in FIG. 1, a from a magnetostrictive ferrite with a rectangular hysteresis loop made toroidal core 5 by a magnetic

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Field impulse whose strength is greater than the coercive field strength H «pre-polarized azimuthally and provided with a winding 6 with connections 1, 2, which - as in that in Pig. 1 Shown embodiment is shown - can consist of only one turn in the extreme case. The ferrite ring core 5 can be excited to mechanical radial vibrations by an azimuthally directed alternating magnetic field, wherein It is always assumed that the exciting field is smaller than the coercive field strength of the material.

Pig. 2 shows the electrical equivalent circuit diagram of the puncture element after Pig. 1, assuming that the line resistance is negligibly small. It means:

L = basic inductance

k = electromechanical coupling factor Q = quality of the mechanical oscillation ⁶ ^ o = angular frequency of the natural oscillation (u / ₀ = 2TTf ₀ ).

In the case of usable ferrite cores, the electromechanical coupling factor k is in the order of magnitude of about 0.1, the quality of the mechanical oscillation is in the order of magnitude of 1000, with only ferrite cores being usable for which the condition k ² . Q ^> 1 er:
Rule of thumb:

f.

k ² . Q ^> 1 is fulfilled. The frequency f applies here

jo

d / mm

et

where d _{e is} the outer diameter of the Perrit ring core

el

is drawn.

The result is the locus of the impedance of the two-terminal network

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in the vicinity νοη ^ _Λ a circle which, when normalizing the apparent resistance to the value w .L and assuming k .Q ^ M, which also applies in the following, is the center coordinate ^ eh

ρ p

k .Q / 2 or 1 and the diameter k .Q (see Pig. 3). Between the _{normalized to Co 0} resonance frequencies JZj or * /? 2 and the quantities Q and k, the relationship applies:

j? Q
where / 1 _Λ & ~ \ un applies approximately

The relation R!. ^ K .Q ^ »JD applies to the resonance resistance Ri, which is why the inductance L must be correspondingly large if

With a given size of k .Q and the required resonance frequency f . & fß, the greatest possible resonance resistance RI is to be achieved. The inductance of the functional element depends on the remanence permeability of the material, the geometric dimensions and the square of the number of turns. With regard to other important properties, such as the coupling factor, the quality and the temperature coefficient, the remanence permeability can only be freely selected to a small extent. Since the geometric dimensions are also fixed as a result of the required resonance frequency f.

But there is a damping-free storage especially for smaller ones Ferrite ring cores are problematic if several or many turns are closed by the ferrite ring core acting as an oscillator lead, is - as shown in the second embodiment according to FIGS. 4 and 5 - the ferrite ring core 5 by means of a coupling loop 8 with a transformer core 7 inductive tiv coupled, its primary inductance L ^ in general must be so great that the condition

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is satisfied. It is also important to ensure that the ohmic Resistance in the coupling circuit is very small compared to R! is. The secondary winding applied to the transformer core 7 with the outputs 1, 2 is denoted by 9 here. According to the transmission ratio ü is the between the outputs 1, 2 occurring resonance resistance RJ !.

2
greater than R! by the factor ü.

The electrical equivalent circuit diagram of the arrangement according to Pig. 4 is in Pig. 5 shown.

Since a four-pole impedance is generally more favorable than a two-pole impedance for setting up an oscillator holding, can according to that in Pig. 6 further embodiment shown on the transformer core 7 with a second secondary winding 10 Outputs 3, 4 be applied.

Regardless of the nature of the transformer 7 and the way it is wound, an adjustable inductive coupling element 11 can be connected between the Perrit ring core and the transformer 7 (see Pig. 7), through which the operating point or zero crossing of the in Pig. 8 can be shifted schematically shown locus to slightly higher frequencies. If, namely, the inductance) vL of the inductive coupling element 11 is added to the basic inductance L, the center point M of the circle shifts parallel to the y-axis of the locus to M, with the resonance frequency- / ¹ -.

• x- ''

The following formula applies to the calculation of iL:

a * _ 1 Y2Q ² + k ² Q ² +2> Q ² -1- XY a + 1-k ² Q ² ) ² -4Q ² (A + i)

^SL \ * i

Q J / 2 (X + 1)

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With regard to the uniqueness of the resonance point must be

k ² Q ^ ₂ CT?

be, ie ) \ must not have such large values. The adjustable inductive coupling element can be used to tune the resonance frequency.

Through the in-Pig. 9 arrangement shown in the two Transmitter cores 12 via a coupling loop 8, in which there is an adjustable mutual inductance 13, to the ferrite ring core 5 are inductively coupled, a larger range of variation can be achieved, since this arrangement creates the center point M (see Fig. 8) can also be pushed under the x-axis. The secondary windings of the transformer cores 12 are here designated by '14.

As magnetostrictive materials with a rectangular hysteresis loop are preferably tempered, if appropriate, in a longitudinal magnetic field after their sintering Overstoichiometric Co-containing Ni-Zn ferrites with rectangular Hysteresis loop and the following composition of its starting components:

51-62

0-25 moles of ZnO
Rest of FiO
about 0.3 to 1 wt # CoO

is used because it - as FIG. 10 shows for the compositions below - has a very low temperature dependence own the natural frequency.

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The Pig. FIG. 10 shows the temperature dependency for three ferrite ring cores labeled "a, b and c" in the table below the natural frequency, the curves a, b and c being assigned to the cores with the same name and have a parabolic course and the position of the maximum is determined by the Co-G content according to the area of application can be.

core a 5 b 5 C. 5 Fe ₂ O, j mole $ 57 5 57. 5 57 5 NOK Mole $ 30, 475 30 * 55 30, 6th ZnO MoI ^ 12, 12, 12, CoO GewjS 0, 0, ο,

The ferrite ring cores according to the table above were tempered in a longitudinal magnetic field after sintering, in order to impress the properties for the formation of a rectangular hysteresis loop. To control the temperature range as well as the values of Q and k, other additives, e.g. CaO, BaO, can also be used.

The temperature response of the resonance frequency can be like this is shown in Fig. 11, flatten to a curve d shown by dashed lines, if one denoted by e Curve of the temperature dependence of the natural frequency of the oscillator or ferrite ring core through a corresponding one Inductance-temperature curve f of the transmitter material compensated. With a parabolic temperature response the natural frequency of the oscillator, as is the case in the example shown, the transformer must have a bell-shaped curve Have an L-shape f if the curve denoted by d is to be obtained.

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The one in Pig. 11 measured ferrite ring core had the following data:

L = 10 nH ■ " ^: '''■■ -. ■

k = 0.16

Q = 1200

f ₀ = 390 kHz.

Finally, FIG. 12 shows the one in one Magnetic field annealed ferrite ring core with 6 mm outer diameter and the following composition of its starting components:

53.0 moles of ο Fe ₂ O ₃ ';

20.0 mol io ZnO
27.0 moles f NiO
0.64 wt. > CoO

Determined dependence of the natural frequency on the level of the bias pulse I, where I _{is normalized to the coercive current I 1 of} the ferrite ring core. You can see that a variation of more than 1 $ 0 is possible.

The functional element is expediently used in a hermetically sealed housing which is equipped with a dry gas, e.g. nitrogen, is filled or, if necessary, evacuated. As with any mechanically vibrating structure the natural frequency is changed when ■ z.-B-, Dust or condensed moisture deposits. Since aucli Magnetic interference fields can influence the natural frequency, the housing should expediently consist of a magnetic conductive material.

10 claims
12 figures

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Claims (10)

Claims r 1.j functional element with constant natural frequency, with a Ferrite ring core made of inagnetostrictive material, the azimuthal pre-polarized and can be excited to radial vibrations by an azimuthally directed alternating magnetic field is characterized by a ferrite ring core (5) with a square-like hysteresis loop, which is generated by a magnetic field pulse whose strength is greater than the coercive force of the ferrite core, Is azimuthally pre-polarized, with the natural frequency in certain due to the strength of this pre-polarization pulse Boundaries is changeable. 2. Functional element according to claim 1, characterized in that that the ferrite ring core (5) is inductively coupled to a transformer (7), wherein is and with U / = angular frequency of the natural oscillation L ₁ = primary inductance of the transformer R ₁ = resonance resistance is designated. 3. Functional element according to claim 2, characterized in that on the transformer core (7) two secondary windings (9, 10) are applied. 4. Functional element according to claim 1 and one of the preceding claims, characterized in that that between ferrite ring core (5) and transformer (7) an adjustable inductive coupling element (11) is connected is. YPA 9/190/302 $ - 11 - 609813/0452 5. Function element according to claim 1 and at least one of the preceding claims, characterized by two transformers (12, 12), which over a coupling loop (8), in which there is an adjustable mutual inductance (13), to the ferrite ring core (5) inductively are coupled. 6. puncture element according to claim 1, characterized by a toroidal core tempered in a longitudinal magnetic field after its sintering, which is preferably made from a superstoichiometric Oo-containing one Ni-Zn ferrite and has a rectangular-like hysteresis loop. 7. Functional element according to claim 6, gekennzei c hnet. by a ferrite ring core with the following composition of its starting components: 51-62 moles $ Pe ₂ O ₅ 0-25 moles of ZnO
Remainder NiO
approx. 0.3 - 1 wt. $ GoO 8. puncture element according to claim 6 and 7, ge ken n records by means of a ferrite ring core with the following composition of its starting components: 57 MoI ^ Pe ₂ O ₃ 12.5 MoI ^ ZnO
30.5 moles # NiO
0.55 wt # CoO 9. puncture element according to claim 1 and at least one of the preceding claims, characterized in that the ferrite ring core (5) VPA 9/190/3026 - 12 - 609813/0452 a closed with dry gas filled or evacuated housing is used, which is made of magnetically conductive material. 10.Punction element according to claim 9, characterized in that it is ek e. indicates that the housing is marked with N _? filled YPA 9/190/3026 & U9813 / 0452 Blank page