JPH021404B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a variable inductance element that uses a high frequency magnetic core to vary inductance, and a variable capacitance diode, and a variable resistor that varies in conjunction with the variable inductance element. 1 variable voltage circuit and a 2nd variable resistor circuit.
A tuning device comprising a variable voltage circuit and a third variable resistor connecting variable resistors of each of the variable voltage circuits in a bridge manner, the variable terminal of the third variable resistor being connected to the voltage application point of the variable capacitance diode. At least two circuits are provided, and the first variable voltage circuit in each of the tuned circuits is shared by one first variable voltage circuit, thereby making it possible to correct the tuned frequency characteristics, and to adjust tracking between the tuned circuits. This is intended to facilitate the processing and improve the sensitivity characteristics of the receiver.

2. Description of the Related Art In general, L variable tuners made of variable inductance elements are widely used in car radios and the like. The reason for this is that the strong input characteristics are extremely good, and the reception characteristics do not change or the operation becomes unstable due to external vibrations, large changes in temperature and humidity, or the influence of dust, and the product is uniform. This is because it has an advantage over a C variable tuner in that it can be easily tuned. However, a problem with variable inductance tuners is that it is extremely difficult to accurately adjust the tracking between the tuned circuits, and the gain decreases at higher frequencies, while the gain becomes abnormal at lower frequencies. As a result, the operation of the receiver becomes unstable, and it is impossible to improve the performance of the receiver by increasing the number of tuning circuits.

That is, as is well known, a variable inductance tuner is equipped with a variable inductance element in each tuning circuit of the antenna circuit, RF circuit, and OSC circuit.
This method achieves tuning by manually operating each variable inductance element using the same sliding member to vary the L of each tuning circuit.
There are differences in the frequency characteristic curves of each variable inductance element due to manufacturing errors, etc., and conventionally, this difference in frequency characteristic curves has been corrected by adjusting the protruding and retracting reference point position of the frequency magnetic core with respect to the coil pair, or by adjusting μ. Tracking adjustment between the tuned circuits was achieved by exchanging different high-frequency magnetic cores.

However, in the former case, even if the position of the protruding and retracting base point is adjusted, the frequency characteristic curve of the variable inductance element is almost always shifted in parallel. Even if they are tuned to one point, the frequency curves will not match the former frequency. Therefore, even if the position of the protrusion and retrieval base point of the high-frequency magnetic core with respect to the coil body is adjusted, the frequency characteristic curves between the tuned circuits will not match each other. It is only an approximation,
Furthermore, since the variable stroke of the variable inductance element is determined by the mechanical sliding stroke of the sliding member in the tuner, it can be obtained by adjusting the protrusion/retraction base position of the high frequency magnetic core with respect to the coil body of the variable inductance element. Both the upper and lower limit positions of the tuning frequency change, and therefore it is extremely difficult to perform accurate tracking adjustment only by adjusting the position of the protrusion/retraction base point of the magnetic core with respect to the coil body.

In addition, in the latter case, the task of measuring and classifying the μ characteristics of the high frequency magnetic core into numerous ranks and exchanging them is extremely troublesome and greatly lacks workability. Furthermore, the variable inductance tuner has the disadvantage that the gain decreases at higher frequencies, making it impossible to obtain a stable and uniform gain over the entire tuning frequency band.

Therefore, in the present application, L and C, which set the tuning frequency, are varied in an interlocking relationship, and the variable magnification of C is adjustable, thereby improving the above-mentioned defects.
In FIG. 1, a tuning circuit is constructed from a variable inductance element 1 and a variable capacitance diode 2, and
a first variable voltage circuit ₃ comprising a variable resistor R3 that varies in conjunction with the variable inductance element;
a second variable voltage circuit 4 consisting of a variable resistor R ₄ ;
Both circuits 3 and 4 are provided with a third resistor R 3 in which each of _the variable resistors R ₃ and R ₄ are bridge-connected, and the variable terminal of the third variable resistor R ₅ is connected to the voltage applied to the variable capacitance diode. It is made by connecting points. 6
is a fixed capacitor for temperature compensation. Let the lower limit of the bandwidth of the tuned frequency be fmin, and its upper limit be
If fmax, then the resonant frequency f is Since it is expressed as However, Lmin is the minimum value of the variable inductance Lmax is the maximum value of the variable inductance Cmin is the minimum capacitance value of the variable capacitance diode Cmax is the maximum capacitance value of the variable capacitance diode, and the relationship between the variable magnification of L and C and the tuning frequency is expressed as Lmax・Cmax/Lmin・Cmin=(fmax/fmin) ² ...

Now if fmin is 510KHz and fmax is 1650KHz,
Assuming that all of this AM band is covered, for example, only by variable L, the variable magnification of L is 10.47 from the equation Lmax/Lmin=(fmax/fmin) ² =(1650/510) ² .

On the other hand, the present application attempts to obtain the bandwidth of the tuned frequency by multiplying the variable magnification Lmax/Lmin of L and the variable magnification Cmax/Cmin of C, and now the variable magnification of L is set to, for example, 7. From the formula (X/510) ² = 7, X or fmax is 1349KHz, and AM
Since there is a lack of selection of tuning frequencies in the band width range of 1349 KHz to 1650 KHz, if we try to compensate for this lack of band width with the variable magnification of C, from the formula (1650/510) ² = 7 x X, When calculating the variable magnification of C, X is approximately 1.5.

Therefore, by setting the variable magnification of the variable capacitance diode 2 of the tuning circuit to 1.5, the required bandwidth can be covered when the variable magnification of L is 7, and this relationship can be illustrated as shown in Fig. 4. It becomes like this. That is, F ₁ is the tuning frequency characteristic curve obtained when the protrusion and retraction stroke of the magnetic core is, for example, 10 mm in a variable inductance element in which a high frequency magnetic core protrudes and retracts from the coil body, and F ₂ is the protrusion and retraction stroke of the magnetic core, for example. 8mm, and this shows the tuning frequency characteristic curve when the insufficient band width is supplemented by the variable magnification of C.As is clear from both characteristic curves, only the variable magnification of L can be compensated for by the variable magnification of C. It is understood that the required band width can be obtained with a short retraction stroke of the magnetic core by varying the slope of the characteristic curve F ₁ according to the equation.

However, in general, if the variable magnification of L shows a value around 7 due to manufacturing errors, or if there is variation in the variable range of the variable capacitance diode used, as a compensation for such cases, if the variable magnification When the inductance element is composed of a coil body and a high-frequency magnetic core that moves in and out of the coil body, and the base position of the high-frequency magnetic core with respect to the coil body can be adjusted, the coil body of the high-frequency magnetic core If you adjust the base point position of the tuning frequency, as mentioned above, the characteristic curve of its tuning frequency will shift in parallel, so even if the base position of the tuning frequency characteristic curve is 500KHz or 520KHz, you can change the mode of the characteristic curve. Without,
You can tune it to 510KHz.

However, as shown in FIG. 6, for example, a high frequency magnetic core 13 having a saturation magnetic circuit, which is sandwiched between a pair of magnetically conductive plates 11 and a coil 12 wound in the sandwiching direction, and a pair of magnetically conductive plates on the magnetized side. The magnets 15 held by the plates 14 are arranged close to each other so that the side edges of the pair of magnetically conductive plates 11 and 14 face each other, and are moved relative to each other along the opposing surfaces to achieve saturation. The number of magnetic fluxes passing through the magnetic circuit is made variable, and at the final position where the opposing surfaces are separated by relative movement, a pair of magnetically conductive plates 14 holding either the magnet 15 or the magnetic core 13 are magnetically short-circuited. For example, the variable inductance element shown in Japanese Patent Publication No. 51-32380 or Japanese Patent Publication No. 49-3274 and No. 51
- As shown in Publication No. 32381, in the case of a variable inductance element that does not have an error adjustment mechanism, the base point position of the tuning frequency characteristic curve cannot be corrected, so tracking adjustment is performed by matching the tuning circuits. This has the disadvantage that it is extremely difficult to do so.

Therefore, the present application proposes a tuner having a tuning circuit based on variable L and C, which can be effectively applied even when variable inductance is performed using a variable inductance element that does not have an error adjustment mechanism as described above. More specifically, by adjusting the voltage value applied to the variable capacitance diode 2 via the first variable voltage circuit 3 and its voltage variable range by the second variable voltage circuit and the third variable resistor, the tuning frequency characteristic curve can be adjusted. The desired band width and its operating reference position can be easily adjusted.

The operation and effect of the present application will be explained in detail in FIG _.
Assuming that the first variable voltage circuit 3 changes from 10V to 0V by , and the movable contact of the third variable resistor _R5 is adjusted to its center position, if When the movable contact of variable resistor _R4 in circuit 4 is set to the highest potential point A, and the movable contact of variable resistor _R3 is also located at the highest potential point A', points A and A' are at the same potential. Since 10V is applied to the variable capacitance diode 2, when the movable contact of the variable resistor _R3 reaches the lowest potential L', the potential difference between points A and B' becomes
Since the voltage is 10V, 1/2 of that voltage, 5V, will be applied to the variable capacitance diode 2 (hereinafter referred to as the first example). Next, in the above circuit condition, the variable resistor R ₄
When adjusting the movable contact to the intermediate position C,
When the movable contact of the variable resistor _R3 is located at the highest potential point A', since the point C is 5V and the point A' is 10V, the variable capacitance diode 2 has a potential of 7.5V, which is the middle potential. Furthermore, when the variable resistor R ₃ reaches the lowest potential point B', the intermediate potential of 2.5 V is applied to the variable capacitance diode 2 because the point C is 5 V and the point R' is 0 V. Furthermore, when adjusting the movable contact of variable resistor R ₄ to its lowest potential point B in the circuit state described above, when the movable contact of variable resistor R ₃ is located at its highest potential point A', , since the potential difference between the point B and the point A' is 10V, half the voltage of 5V is applied to the variable capacitance diode 2, and the variable resistor R ₃
When the movable contact is located at the lowest potential point RO', since the RO and RO points are at the same potential and 0V, 0V is applied to the variable capacitance diode 2 (hereinafter referred to as 3rd point).
example).

That is, from the first to third examples above, when the variable resistor R ₅ is kept constant and the variable resistor R ₄ is adjusted, the voltage applied to the variable capacitance diode 2 changes from 10V to 5V in the first example, and from 10V to 5V in the second example. In the example, from 7.5V to 2.5V, the third
In the example, the variable potential difference is constant at 5V, such as 5V to 0V, and the operating voltage applied to the variable capacitance diode 2 is 10V, 7.5V, and 5V at the upper limit.
It is also understood that the lower limits are regulated to 5V, 2.5V, and 0V, respectively.

Next, the movable contact of the variable resistor R4 of the second variable voltage circuit ₄ is adjusted to the intermediate point C, and in this state, the movable contact of the third variable resistor _R5 is adjusted to the upper point E, the intermediate point, and the lower position. and the first point.
A case will be considered in which the variable resistor R ₃ of the variable voltage circuit 3 is varied in conjunction with the variable inductance element 1. First, the movable contact of variable resistor _R5 is located at the upper point E, and in this state, when the movable contact of variable resistor _R3 is at the highest potential point A', the variable resistor _R5
Since the movable contact is directly connected to the intermediate point C of the variable resistor _R4 , a voltage of 5V is applied to the variable capacitance diode 2, and this 5V voltage is independent of the variable resistance of the variable resistor _R3 . (hereinafter referred to as the fourth example). Furthermore, when the variable resistor R ₃ is varied while the movable contact of the variable resistor R ₅ is adjusted to its midpoint, the voltage applied to the variable capacitance diode 2 is 7.5 V to 7.5 V as in the second example. Changes to 2.5V,
Furthermore, adjust the variable contact of variable resistor _R5 to the lower point G, and when the movable contact of variable resistor _R3 changes in this state, the movable contact of variable resistor _R5 will be adjusted to the lower point of the variable resistor _R3 . Since it is directly connected to the movable contact, the voltage applied to the variable capacitance diode 2 changes from 10V to 0V, which is equal to the variable voltage range of the first variable voltage circuit 3 (hereinafter referred to as the fifth example). That is, as is clear from the fourth, second, and fifth examples described above, the second variable voltage circuit 4 is kept constant and the third variable resistor _R5 is adjusted, and in this state, the first variable voltage circuit 3 is When the voltage is varied, the voltage applied to the variable capacitance diode 2 is independent of the variation in the fourth example.
It is constant at 5V, changes from 7.5V to 2.5V in the second example, and changes from 10V to 0V in the fifth example. That is, it is understood from this that the variable range of the voltage applied to the variable capacitance diode 2 can be adjusted by adjusting the third variable resistor _R5 .

Therefore, between the variable capacitance diode and the first variable voltage circuit, a second variable voltage circuit comprising a variable resistor connected in parallel to the first variable voltage circuit, and between the first and second variable voltage circuits, Each of the variable resistors is connected to a third variable resistor that is bridge-connected, and this third variable resistor is connected as a bridge.
Connecting the variable terminal of the variable resistor to the voltage application point of the variable capacitance diode has the following advantages. In other words, the characteristic curve of the capacitance versus applied voltage of a variable capacitance diode is expressed as a quadratic curve as shown in FIG. The variable magnification by the variable capacitance diode can be easily selected by using the characteristic curve between Vb and Vb' or the characteristic curve between Va and Vc with different variable widths. It is possible to obtain a degree of freedom in setting the variable magnification of C with respect to the variable magnification of The base point position of the tuning frequency caused by this and its characteristic curve can also be easily corrected, which is convenient for tracking adjustment.

In the above, the variable resistor R ₃ and the second variable resistor R ₄ of the first variable voltage circuit 3 are connected to +B.
Although the case where they are connected in parallel to the power supply is shown, the power supply voltage to be applied to the first variable voltage circuit 3 and the second variable voltage circuit 4 may be provided separately, and as shown in FIG. Circuit 4 and third variable resistor _R5
When configured with variable resistor R ₄ and fixed resistor R ₄ ′ and variable resistor R ₅ and fixed resistor R ₅ ′,
Fine adjustment of the variable resistors R ₄ and R ₅ is sufficient, and furthermore, as the first variable voltage circuit 3 in the above embodiment, a transformer coil and a transformer coil as described in candidate Utility Model Publication No. 52-23206 are used. A constant frequency is applied to a transformer consisting of a magnetic core that moves in and out of the coil, the magnetic core moves in and out of the coil in conjunction with the variable inductance of the variable inductance element, and the voltage obtained thereby is rectified to produce a first variable inductance. Of course, it may also be used as a voltage circuit. FIG. 3 shows that the tuning circuit shown in FIG. 1 shows a circuit diagram of a tuner when the variable voltage circuit 3 is used in common for each of the tuning circuits A to D.

According to the present application, the variable magnification of C by the variable capacitance diode and its operating reference position can be adjusted by mutual adjustment of the second variable voltage circuit and the third variable resistor among the plurality of tuning circuits constituting the tuner. A tuning circuit using a variable inductance element that can be easily adjusted, is extremely effective in tracking adjustment between tuning circuits, and does not have a means for adjusting the operating reference point position of a high frequency magnetic core with respect to a coil body. In addition, it is possible to use variable capacitance diodes with different capacitance characteristics or a large variable capacitance range, and has the advantage of being versatile.

Furthermore, as is well known, in a tuner with variable L, the gain Q is high at low frequencies (the state where the magnetic core is immersed in the coil body), and is high at the high frequency side (the state where the magnetic core has escaped from the coil body). On the other hand, the C variable tuning circuit has a Q characteristic that is opposite to that of the L variable tuning circuit, and therefore, according to the present application, the L and C variable tuning circuit Since it is a tuned circuit, the Q can be obtained almost uniformly over the entire band width of the tuned frequency, and stable Q characteristics can be obtained.As already mentioned, the L variable tuning circuit can select, for example, the entire width of the AM band. In the case of Since it can be obtained small, the variable stroke of the variable length inductance element can be shortened, which is effective for downsizing the tuner.
Since it is equipped with multiple tuning circuits that are extremely easy to adjust for tracking, it is extremely effective in improving the selectivity of radio receivers, eliminating interference waves, improving sensitivity, stable operation, and improving various characteristics. Since the first variable voltage circuit is shared by a plurality of tuning circuits, the number of components can be omitted, which is advantageous in terms of design and manufacturing.

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and FIGS. 1 and 2 are tuning circuit diagrams, FIG. 3 is a circuit diagram of a tuner equipped with the tuning circuit of FIG. 1, and FIG. 4 is a tuning frequency characteristic curve. Figure 5 is a diagram showing the characteristic curve of capacitance versus applied voltage in a variable capacitance diode.
The figure is a configuration diagram of a variable inductance element. In the figure, 1 is a variable inductance element, 2 is a variable capacitance diode, 3 is a first variable voltage circuit, 4 is a second variable voltage circuit, R ₃ , R ₄ , R ₅ are variable resistors,
R ₄ ′ and R ₅ ′ are fixed resistors.

Claims (1)

[Claims] 1. A first variable device comprising a variable inductance element that varies inductance using a high-frequency magnetic core and a variable capacitance diode, and having a variable resistor that varies in conjunction with the variable inductance element. A voltage circuit, a second variable voltage circuit having a variable resistor, and a third variable resistor connecting the variable resistors of each of the variable voltage circuits in a bridging manner,
At least two tuning circuits each have a variable terminal of a variable resistor connected to a voltage application point of the variable capacitance diode.
1. A tuner characterized in that the first variable voltage circuit in each of the tuning circuits is shared by one first variable voltage circuit. 2. The variable inductance element consists of a high frequency magnetic core with a saturation magnetic circuit and a magnet,
2. The tuner according to claim 1, wherein the inductance is varied by varying the number of cross magnetic fluxes between the magnet and the high-frequency magnetic core.