JP3848690B2 - In-vehicle receiver - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a vehicle-mounted receiver, and more particularly to a receiver that can be appropriately matched to a wide variety of vehicle antennas.
[0002]
[Prior art]
An in-vehicle receiver, for example, an in-vehicle radio antenna, has a different shape and method depending on the vehicle type. In some cases, a circuit such as an antenna amplifier circuit (antenna amplifier) is connected to the radio receiver connected to the antenna. On the side, an appropriate matching constant in the antenna input circuit changes according to these conditions.
[0003]
Therefore, in an antenna input circuit of a vehicle-mounted radio or the like, it is necessary to set circuit elements of the antenna input circuit so that matching with the antenna is optimal, and to fully exhibit the performance at the time of designing the vehicle-mounted radio.
However, since in-vehicle radios, especially on-vehicle radios that are commercially available, are not determined in which car model, the antenna input circuit uses a non-tuned circuit that does not cause a problem with antenna compatibility. The work such as matching with the antenna is not performed again at the time of mounting.
[0004]
[Problems to be solved by the invention]
However, even if a non-tuned circuit is used, a difference appears in the reception performance of the in-vehicle radio due to matching with the antenna by adjusting the matching variable capacitance.
For example, as shown in FIG. 4, in the receiver, transmission line noise and the like are excluded (attenuated) outside the reception frequency に よ っ て by the antenna cable capacity and the resonance point by the coil of the antenna input circuit, but the antenna cable capacity changes. As a result, the resonance point changes and approaches the reception frequency band, or the resonance point enters the reception frequency band, resulting in a shortage of attenuation such as transmission line noise and the like, resulting in input interference. In addition, in the auto-tuned in-vehicle radio, the resonance point also changes in the sensitivity switching characteristics at the time of auto-tuning, so that the standard at the time of design cannot be maintained and the auto-tuning operation may be adversely affected.
[0005]
The present invention solves such a problem, and the antenna circuit of the vehicle on which the vehicle-mounted radio is mounted and the antenna circuit of the vehicle-mounted radio are precisely matched so that the performance at the time of designing the vehicle-mounted radio can be sufficiently exhibited. Objective.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention selects a desired broadcasting station in the normal mode, and in the adjustment mode, the characteristics of the antenna input circuit and the code input means for inputting an identification code corresponding to the vehicle type Adjustment means for adjusting so as to match with the antenna, and control means for controlling the adjustment means in accordance with the code input means.
[0007]
The adjusting means includes a plurality of capacitors and a switch for selectively connecting the capacitors to the antenna input circuit of the receiver, and the control means controls a connection state of the switches. . The adjustment means is connected to the antenna input circuit of the receiver and is composed of a voltage variable capacitance element whose capacitance changes according to the applied voltage, and the control means controls the voltage applied to the voltage variable capacitance element. It is characterized by doing.
[0008]
The code input means is a channel selection button of the receiver.
[0009]
[Action]
According to the present invention as described above, when an identification code corresponding to an antenna is input by the code input means, the control means controls the adjustment means so as to be suitable for the antenna, and the antenna input characteristics are made appropriate.
The adjusting means adjusts the switch so that the plurality of capacitors are properly matched with the antenna and connects to the antenna input circuit.
[0010]
The adjusting means applies a voltage to the voltage variable capacitance element connected to the antenna input circuit so that matching with the antenna is appropriate.
An identification code corresponding to the antenna is input by operating the channel selection button.
[0011]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a vehicle-mounted radio panel according to an embodiment of the present invention.
Reference numeral 2 is a switch for switching the reception band of the in-vehicle radio 1, which is usually a switch for switching the reception band of AM / FM. The in-vehicle radio switches to an adjustment mode for adjusting the input characteristics of the antenna input circuit.
[0012]
Reference numeral 3 denotes channel selection push buttons (six buttons from (1) to (6)). Usually, the frequency of the broadcast station to be received is stored in advance corresponding to each of the channel selection push buttons 3. The desired broadcast station can be received by pressing the channel selection push button 3 corresponding to the frequency of the desired broadcast station, but in this embodiment, the channel selection push button 3 is switched to the adjustment mode by the reception band changeover switch 2. Is a characteristic selection switch (identification code input) for selecting the input characteristic of the antenna input circuit.
[0013]
That is, for example, in the adjustment mode, by pressing (1) and (2) of the channel selection push button 3, the input characteristics of the antenna input circuit are switched so as to be appropriate for the antenna for the car A, and for channel selection When the pushbuttons (2) and (3) are pressed, the input characteristics of the antenna input circuit are switched so as to be appropriate for the antenna for the B vehicle.
As described above, the buttons (1) to (6) of the channel selection push button 3 are configured such that appropriate input characteristics of the antenna input circuit can be selected for each vehicle by a combination of pressing the buttons.
[0014]
Next, the circuit configuration of the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing a circuit configuration of this embodiment.
Reference numeral 10 denotes an in-vehicle radio that represents only the antenna input circuit portion. Reference numeral 11 represents an equivalent circuit of an antenna attached to the vehicle, and reference numeral 12 represents an electric power generated by the antenna receiving an electric wave by an antenna electromotive force. Reference numeral 13 denotes an internal resistance of the antenna, and 14 and 15 denote stray capacitances of the antenna cable.
[0015]
Reference numeral 16 denotes an antenna jack which connects the antenna 11 and the in-vehicle radio 10 so that an electromotive force 12 generated by the radio wave received by the antenna is input to the in-vehicle radio 10.
A high-frequency coil 17 forms a resonance circuit with the stray capacitances 14 and 15 of the antenna cable in the antenna 11 to remove strong input interference signals (especially, removal of transmission line noise and the like in the AM band).
[0016]
Reference numeral 18 denotes a matching capacitor (C1 to C5) which is selected and connected to perform matching of the resonance circuit. Reference numeral 19 denotes a switching circuit, which selects matching capacitors 18 (C1 to C5) according to a matching circuit selection signal from the microcomputer 20 and grounds them.
One or a plurality of (matching) matching capacitors 18 are selected and grounded. 20 is a microcomputer which outputs a matching circuit selection signal corresponding to the vehicle type (antenna) designated by operating the operation button 21 to the switching circuit 19 so that the antenna and the antenna input circuit are properly matched. Capacitors 18 (C1 to C5) are selected and grounded.
[0017]
Therefore, in this embodiment, even if the stray capacitance of the antenna cable or the like changes, if the identification code corresponding to the vehicle type (antenna) is input by the operation button 21, the matching capacity of the antenna is defined according to the vehicle type (antenna). Since the matching capacitors 18 (C1 to C5) are selected and connected to the ground so as to have a value (for example, 80 pF), the vehicle-mounted radio can always be used in a suitable state.
[0018]
Next, a second embodiment will be described with reference to FIG.
In this embodiment, since the circuit in the vicinity of the matching capacitor 18 in the embodiment shown in FIG. 2 is changed, only the changed portion will be described.
FIG. 3 is a diagram showing a circuit configuration in the second embodiment of the present invention, and shows an antenna input circuit portion of an in-vehicle radio. A digital / analog converter 22 converts a digital signal from the microcomputer 20 into an analog DC voltage and outputs it. Reference numeral 23 denotes a varicap connected to the antenna input circuit, and the capacitance changes according to the change of the applied DC voltage.
[0019]
The microcomputer 20 stores the operation content of the operation button 21 and the output data to the analog-digital converter 22 correspondingly, and the data corresponding to the operation content of the operation button 21 is output to the analog-digital converter 22. It has become so.
Next, when the operation button 21 is operated to input an identification code corresponding to the vehicle type (antenna) to the microcomputer 20, a digital signal that provides antenna input circuit characteristics suitable for the vehicle type (antenna) from the microcomputer 20 will be described. Is output to the analog-digital converter 22.
[0020]
The analog-to-digital converter 22 applies a voltage to the varicap 23 so that the capacity of the antenna input circuit is optimal for the vehicle type (antenna), and the varicap 23 is appropriately set so that the antenna and the antenna input circuit are suitably matched. Change to the correct capacity.
As described above, according to the present embodiment, as in the first embodiment, the vehicle-mounted radio can be used in a suitable state. If a large number of output voltages to the analog-digital converter 22 corresponding to the vehicle type (antenna) are stored in the microcomputer 22, a single varicap can be used for many vehicle types (antennas) without using many capacitors. Can respond.
[0021]
【The invention's effect】
As described above in detail, according to the present invention, even if the vehicle type, that is, the antenna is changed, the antenna and the antenna input circuit can be appropriately matched, so that the in-vehicle receiver can always be used in an optimum state.
[Brief description of the drawings]
FIG. 1 is a diagram showing a panel of an in-vehicle radio according to an embodiment of the present invention. FIG. 2 is a diagram showing a circuit configuration of a first embodiment of the present invention. FIG. 4 is a diagram showing a circuit configuration of an embodiment. FIG. 4 is a diagram showing a strong input disturbance elimination characteristic.
1 ·························································································· Selection push button 11 Antenna 12 ... Antenna electromotive force 13 ... Internal resistance 14 ... Antenna cable stray capacitance 15 ... Antenna cable stray capacitance

Claims (3)

In the normal mode, a desired broadcast station is selected, and in the adjustment mode, a code input means for inputting an identification code corresponding to the vehicle type;
Adjusting means for adjusting the characteristics of the antenna input circuit to match the antenna ;
A vehicle-mounted receiver comprising control means for controlling the adjusting means in accordance with the code input means. The adjusting means includes a plurality of capacitors and a switch that selectively connects the capacitors to the antenna input circuit of the receiver.
The in-vehicle receiver according to claim 1, wherein the control unit controls a connection state of the switch. The adjustment unit is connected to an antenna input circuit of the receiver, and includes a voltage variable capacitance element whose capacitance changes according to an applied voltage.
The in-vehicle receiver according to claim 1, wherein the control unit controls a voltage applied to the voltage variable capacitance element.

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