JPS59115614A - Tuner - Google Patents

Abstract

PURPOSE:To improve the sensitivity characteristic and to make the tuner stable against a strong input and the tracking adjustment easy by providing an adjusting circuit where tuning circuits of variable L and C are combined suitably in plural tuning circuits and the operating range of a varactor diode being a component of the tuning circuits is adjusted. CONSTITUTION:Variable inductance elements 1a, 4a of an antenna circuit 4 and an oscillating circuit 4 and a variable resistor 5b of a variable voltage circuit 5 are changed interlockingly in tuning operation, its voltage is applied to varactor diodes 2b, 3b of high frequency amplifier circuits 2, 3 via adjusting circuits 62, 63 so as to vary the capacitance for attaining the channel selection. A varactor diode 1c is provided to the circuit 1 and adjusting circuits 61, 62, 63 are connected to the circuits 1, 2, 3 and the tracking is adjusted by adjusting the said circuits so as to provide a difference of the applied voltage from the circuit 5 to the diodes 1c, 2c and 3c.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tuner consisting of a plurality of variable tuning circuits, and in particular aims to improve sensitivity characteristics, is stable against strong input, and facilitates tracking adjustment! Embodiments of the present application will be described in detail below with reference to the drawings.

The drawing shows the antenna circuit (1) and the high frequency fifth stage amplifier circuit (
21, the frequency control second stage amplifier circuit (3), and the excavation circuit (4).
Bv, antenna circuit +11 Fi, for example, a variable inductance element that causes a magnetic core to appear and disappear in a pronating coil (1) consisting of a and a tuned capacitor flTo with a constant %C With a variable tuning circuit,
The tuning circuit (1) is connected to a variable capacitance diode (21a) for compensation for tracking adjustment.The high frequency first stage amplifier circuit (2) is connected to a tuning coil (21a) with a constant L.
This is a C variable tuning circuit consisting of a variable capacitance die sleeve (2To), and a fixed capacitor (21c) is auxiliary connected to the tuning circuit (21).
) is also a C variable tuning circuit consisting of a tuning coil +31a with constant L, a variable capacitance diode +3To, and an auxiliary fixed capacitor (3)c, similar to the above amplifier circuit (2), and furthermore The oscillation circuit (41 is a variable inductance element (4) a similar to the antenna circuit (1), and C
This is an L variable tuning circuit consisting of a tuning capacitor with a constant value.

In the above configuration, the variable capacitance value of the variable capacitance diode (11c) of the antenna circuit (1) is the same as that of the variable capacitance diode (21b) of the high frequency first and second stage amplifier circuits (21 and (31).
, (b of 3To) smaller than the capacitance value is used. (5) is each variable capacitance diode file, 12
A variable voltage circuit that applies a variable voltage to +3To, and a variable resistor f5To that is controlled in conjunction with the amplification transistor (5)a and the variable inductance element (11a).
This is connected to a 10B power supply. (61
1, (612, (613 is variable capacitance diode file
, (21b, (31o) to adjust the variable operating range kllfl of each tuning circuit fi+, +21. (31 variable capacitance diode (Llc).

An adjustment circuit connected intermittently between +2To,t,% and the variable voltage circuit (5), which includes a first variable resistor (61a) connected to the +Bt source and a transistor (of the variable voltage circuit (5)). 5) Second variable resistor f6To connected to the a side
It is composed of. 5(7) is an intermediate frequency transformer, and audio circuits, speaker circuits, etc. are omitted.

However, when tuning is performed to achieve channel selection, the antenna circuit 1Nr (11) and the variable inductance elements (1)b and (41a of the oscillation circuit (41) change, and the variable resistor (5To) in the variable voltage circuit +51 also moves. Changed,
The variable voltage is applied to the adjustment circuit +612, (61a
The high frequency twelfth and second stage amplifier circuits (2) and (3)
) are applied to the variable capacitance diodes (2.b and (3)b, respectively, to change the capacitance value, and each tuning circuit is tuned to the station frequency to achieve tuning.

By the way, in the above configuration VC'Bb, in order to improve the tuning accuracy, it is necessary to adjust the tracking between the tuning circuits, and for this purpose, the present IMffl includes an antenna circuit which is an L variable tuning circuit. (11 is equipped with a variable capacitance diode (llci) for tracking adjustment, and the antenna circuit (11 and high frequency 11 second stage amplifier circuit + 2
1. Adjustment circuits 161x, f61z, (613f) each consisting of variable resistors [61a and f6 are connected to +31.And this adjustment circuit 161i, (
By adjusting each of 61z and +613.

In addition, each variable capacitance diode (ll
c.

The configuration is such that the opening force 0 voltage Vr-difference is given to 121b and 13To, and the entire operating range of these diodes is adjusted.

In other words, the characteristic curve of a variable voltage circuit of a variable capacitance diode is generally expressed as a quadratic curve. Characteristics are easily obtained.

However, in the present application, the adjustment circuits (61t, (61
2, (613) to adjust each corresponding variable capacitance diode (1!c, (21b.

(By installing all base points of the input force lN1f pressure to 31b, the antenna circuit (II and high frequency first and second stage amplifier circuits (
2j.

(31 tracking can be easily adjusted, and in this configuration, the variable inductance element (l la
*(This is effective when a variable inductance element having a self-adjustment mechanism is used as 41a, for example, as shown in Japanese Patent Publication No. 46-12494.

If the variable inductance (lla, In this case, the antenna circuit (1) includes a variable capacitance diode (1) c and a corresponding adjustment circuit f611.
can be abbreviated to

Therefore, according to the present application, there are advantages as described below.

That is, in general, the sensitivity characteristics of a tuned circuit are high at lower frequencies in the L variable tuning circuit and lower at higher frequencies in the L variable tuning circuit, and increase two-dimensionally as the frequency becomes higher in the C variable tuning circuit.

Therefore, in this application, by utilizing such characteristics, at least one of the tuning circuits constituting the tuner is made into a C variable tuning circuit, so that the obtained sensitivity characteristics are made uniform over the entire frequency bandwidth, and the performance of the tuner is improved. By appropriately combining the L variable tuning circuit and the C variable tuning circuit among the plurality of tuning circuits, it is possible to easily obtain sensitivity characteristics that are most suitable for that tuner.
Since the antenna circuit is an L03-variant tuned circuit, all the tuned circuits are effective against strong inputs. ]Equipped with an adjustment circuit that adjusts the operating range of the 7g capacitance diode,
This has the advantage that tracking adjustment can be easily performed.

[Brief explanation of the drawing]

Is the drawing an example of the tuner of this application? FIG. In the figure, (1) is the antenna circuit, tlia, (41a is the variable inductance, (11b, (51b is the tuning capacitor, (llc, (21b), (3To is the variable tone diode, (2) is the high frequency first stage amplifier circuit (21+a, (31a is a tuning coil, (41 is an oscillation circuit, (51 is a variable voltage circuit, F511) is a variable resistor,
03+1, (GH2, f6+3u

Claims (1)

[Scope of Claims] (1) In a tuner consisting of a μ tuning circuit including all variable inductance elements, at least one tuning circuit other than the antenna tuning circuit is a C tuning circuit having a variable capacitance diode, and A tuner comprising a variable voltage circuit that varies in conjunction with an inductance element, and applies the variable voltage of the circuit to the variable capacitance diode. (In a tuner consisting of a μ-tuned circuit equipped with all 21 angle variable inductance elements, at least one tuning circuit other than the antenna tuning circuit is a C-tuned circuit having a variable capacitance diode, and is variable in conjunction with the variable inductance element. A variable voltage circuit that applies a variable voltage of the circuit to the variable capacitance diode and adjusts the operating range of the variable capacitance diode, and a total adjustment circuit between the variable capacitance diode and the variable voltage circuit. (3) In the tuner consisting of a μ tuning circuit equipped with a variable inductance element, at least one tuning circuit other than the antenna tuning circuit is a C tuning circuit having a variable capacitance diode. A variable capacitance diode for correction is connected to the antenna circuit, and a variable voltage circuit that varies in conjunction with the variable inductance element is provided, and the variable voltage of the circuit is applied to the variable capacitance diode, A tuner characterized in that an adjustment circuit for adjusting the operating range of the variable capacitance diode is provided between them.