JPH066251A - Tuner for am broadcasting reception - Google Patents

Abstract

PURPOSE:To provide a tuner for AM stereo broadcasting reception by which an AM stereo reception can be attained without changing the number of the output terminals of a tuner for a conventional AM monaural broadcasting reception. CONSTITUTION:An IC 21 for an AM broadcasting reception adopting a super heterodyne system is equipped with a monaural voice signal output terminal 216 and a terminal 215 for a peaking transformer connection, and the primary coil 221 of an outside peaking transformer 22 is connected with the terminal 215. A monaural voice signal is transmitted through a low pass filter 23, supplied to the secondary coil 222 of the peaking transformer 22, and outputted from a tuner output terminal 27 after an intermediate frequency is superimposed on it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AM broadcast receiving tuner, and more particularly to an AM stereo broadcasting receiving tuner that can be used without increasing the number of terminals of the AM monaural broadcasting receiving tuner.

[0002]

2. Description of the Related Art Recently, AM broadcasting has also been converted to stereo, and commercialization of receivers for receiving AM stereo broadcasting is progressing. The AM monaural receiver generally employs a so-called super-heterodyne reception method, and the high frequency amplification section, the frequency conversion section, the intermediate frequency amplification section, and the detection section are AM.
It is integrated into a receiving IC.

It is general that an integrated circuit is integrated as a tuner unit by externally attaching a peaking transformer for intermediate frequency, a low-pass filter for removing high frequency components, and the like around the integrated circuit. However, in order to be able to receive the AM stereo broadcast, the detection unit and the low-pass filter are not necessary, and it is necessary to extract the intermediate frequency signal and separate the left and right signals by the stereo decoder unit.

[0004]

Therefore, the conventional tuner unit for receiving AM monaural broadcast cannot be used as it is, and it is necessary to change the circuit pattern of the tuner unit and newly provide a terminal for taking out an intermediate frequency signal. However, the tuner unit has been established as a component of an integrated body, and it is not a good idea from the viewpoint of reliability and economy to make a design change by newly adding a terminal.

The present invention has been made in view of the above problems, and provides an AM stereo broadcast receiving tuner capable of performing AM stereo reception without changing the number of output terminals of a conventional AM monaural broadcast receiving tuner. The purpose is to do.

[0006]

FIG. 1 is a basic configuration diagram of an AM broadcast receiving tuner according to the first invention.
Receiving IC 11, AM frequency peaking transformer 12 externally attached to AM receiving IC 11, and AM receiving IC
A low-pass filter 13 that is connected to the subsequent stage of 11 to remove high frequency components from the output signal of the AM receiving IC 11
And a mixer 14 for mixing the AM monaural signal output from the low-pass filter 13 and the intermediate frequency signal supplied to the AM stereo decoder output from the peaking transformer connection terminal provided in the AM receiving IC 11,
The AM monaural signal and the intermediate frequency signal supplied to the AM stereo decoder are output from the same terminal.

In the second invention, the mixer 14 is composed of a secondary winding installed in a peaking transformer.

[0008]

According to the first invention, the monaural signal and the intermediate frequency signal supplied to the AM stereo decoder are mixed and output from one terminal of the tuner for receiving AM broadcast.
According to the second invention, the mixer is a secondary winding provided in the intermediate frequency peaking transformer.

[0009]

FIG. 2 is a functional diagram of an embodiment of an AM broadcast receiving tuner according to the present invention. The AM broadcast receiving tuner is an AM broadcast receiving IC 21 and a peaking transformer 2.
2. It comprises a low pass filter 23. The AM broadcast receiving IC 21 includes a high frequency amplifier 211, a frequency mixer 212, an intermediate frequency amplifier 213, and a detector 214.

A connection terminal 215 for connecting the peaking transformer 22 is provided from the middle stage of the intermediate frequency amplifier 213 in order to increase the sensitivity of the intermediate frequency. This connection terminal has primary windings 221 and 1 of the peaking transformer 22.
The capacitor 25 and the resistor 26 connected in parallel to the next winding 221 are connected. A monaural audio signal detected by the detection unit 214 is output from the output terminal 216 of the AM broadcast receiving IC 21.

This monaural audio signal is supplied to the secondary winding 222 of the peaking transformer 22 after passing through a low pass filter 23 for removing high frequency components.
The secondary winding 222 has a flow 455 flowing in the primary winding 221.
Since the intermediate frequency of KHz is induced, the secondary winding 222
The monaural audio signal and the intermediate frequency of 455 KHz are mixed from the output terminal of the above and output from the tuner output terminal 27 of the tuner for receiving AM broadcast.

A capacitor 25 and a resistor 26 connected in parallel with the primary winding 221 of the peaking transformer 22.
Is installed to determine the tuning frequency and damping degree. When the tuner for AM broadcast reception is applied to a monaural broadcast receiver, a low-pass filter 28 for cutting off an intermediate frequency of 455 KHz and passing a monaural audio signal is connected to a stage after the tuner output terminal 27,
After being amplified by an amplifier (not shown), it is output as sound from a speaker (not shown).

When the tuner for AM broadcast reception is applied to a stereo broadcast receiver, a high-pass filter 29 for cutting off a monaural audio signal and passing an intermediate frequency is connected to a stage behind the tuner output terminal 27, and a stereo decoder (see FIG. It is separated into left and right audio signals by a not shown), amplified by an amplifier (not shown), and then outputted as a voice from a speaker (not shown).

FIG. 3 is a perspective view of the peaking transformer 22. The bottom surface 225 has four to six terminals 226a ...
226f is provided. The ferrite core 227 in the housing 226 has a primary winding 221 and a secondary winding 2
22 is installed. Both ends of the primary winding 221 are connected to the terminals 226a and 226c, and both ends of the secondary winding 222 are connected to the terminals 226d and 226f.

Although the peaking transformer 22 which has been conventionally used is not provided with a secondary winding, it is provided with about six terminals for fixing it to a printed circuit board.
Although a coil was connected to the two terminals 226a and 226c, the remaining four terminals were dummy terminals and were used only for fixing. Therefore, even if the secondary winding is added in the present invention, it is not necessary to add a terminal.

[0016]

According to the present invention, by providing a secondary winding in a peaking transformer of an AM monaural broadcast receiving tuner, it can be used as an AM stereo broadcast receiving tuner without increasing the number of tuner output terminals. It will be possible. Even if a secondary winding is added to the peaking transformer, it is not necessary to increase the number of peaking transformer terminals. Therefore, it is not necessary to significantly change the pattern on the printed circuit board of the tuner, and it is also necessary to increase the number of output terminals. Nor.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an AM broadcast receiving tuner according to the present invention.

FIG. 2 is a circuit diagram of an embodiment of an AM broadcast receiving tuner.

FIG. 3 is a perspective view of a peaking transformer.

[Explanation of symbols]

 11 ... AM broadcast receiving IC 12 ... Peaking transformer 13 ... Low-pass filter 14 ... Mixer

Claims (2)

[Claims] 1. An AM broadcast receiving IC, an intermediate frequency peaking transformer externally attached to the AM broadcast receiving IC, and an output signal of the AM broadcast receiving IC connected to a subsequent stage of the AM broadcast receiving IC. In a tuner for AM broadcast reception that includes a low-pass filter for removing high-frequency components from the AM monaural signal output from the low-pass filter and the peaking transformer connection terminal provided in the AM broadcast reception IC. A tuner for AM broadcast reception in which a mixer for mixing the intermediate frequency signal supplied to the AM stereo decoder is provided, and the AM monaural signal and the intermediate frequency signal supplied to the AM stereo decoder are output from the same terminal. . 2. The tuner for receiving an AM broadcast according to claim 1, wherein the mixer is a secondary winding installed in the peaking transformer.