JPS6241480Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a receiver that has the ability to receive FM signals and AM signals in a frequency band different from that of the FA signals, and is provided with a local oscillator switch that switches in conjunction with a mono/stereo switch that controls switching between mono and stereo reception of the FM signal, thereby simplifying the circuit configuration and making it less expensive.

Conventionally, shortwave band FM signals were used along with very high frequency band FM signals.
A receiver that receives an AM signal is configured to switch and control the AM local oscillation frequency of an AM local oscillation circuit to receive an AM signal of, for example, 3.2MHz to 12.0MHz, i.e.
Some devices perform reception of AM shortwave signals and preset reception of first Japanese shortwave broadcast signals transmitted at 3.925 MHz, 6.055 MHz, and 9.595 MHz, respectively, among AM short wave signals.

It has the ability to receive FM signals, AM shortwave signals, and AM medium wave signals, as well as AM local oscillation frequency switching control.
A conventional receiver that receives an AM shortwave signal and presets reception with the first Japanese shortwave broadcast signal is as follows:
As shown in FIG. 1, the rod antenna 1 is connected to the common contacts c and c' of the first band changeover switch S1, and the FM contact f,
First and second short wave contacts sa, sb and medium wave contact mw are provided, and based on band switching operation, FM
When receiving, FM contact f is connected to common contacts c and c', when receiving AM shortwave, the first and second shortwave contacts sa and sb are respectively connected to common contacts c and c', and when receiving AM medium wave, A medium wave contact mw is connected to the common contacts c and c'.

And when receiving FM, FM is transmitted via FM contact f.
The signal is input to the FM mixing circuit 3 via the FM high frequency circuit 2, and at this time, the frequency of the FM signal is frequency-converted to the FM intermediate frequency by the operation of the FM local oscillation circuit 4, and the frequency-converted FM signal is
The signal is input to the FM intermediate frequency amplification/detection circuit 5 and from the PLL multiplex integrated circuit element via the FM contact f of the second band changeover switch S2 connected to the circuit 5 and the common contacts c and c' of the switch S2. The detected FM signal, that is, the FM audio signal is input to the stereo demodulation circuit 6, and at this time, the monaural/stereo changeover switch is turned on.
By switching SX, common contact c of switch SX connected to positive power supply terminal +Ba becomes monaural contact mo.
, the stereo demodulation circuit 6 is controlled to receive monaural signals, and monaural FM audio signals are output from the left and right audio output terminals L and R.

In addition, the monaural contact mo of the switch SX is connected to the monaural terminal M of the stereo demodulation circuit 6, and the stereo contact st of the switch SX is an idle contact, so that by switching the switch SX,
When the common contact c of the switch SX is connected to the stereo contact st, the stereo demodulation circuit 6 is controlled to perform stereo reception, and stereo FM audio signals are output from the left and right audio output terminals L and R.

Further, the switch S2 is switched in conjunction with the switch S1, and like the switch S1, the switch S2 is provided with first and second short wave contacts sa, sb and a medium wave contact mw.

On the other hand, when receiving AM shortwave, switches S1 and S
2 is the first shortwave contact sa or the second shortwave contact sa depending on the reception band.
The AM shortwave signal via the first shortwave contact sa or the second shortwave contact sb is switched to the shortwave contact sb.
The frequency of the AM shortwave signal is input to the AM mixing circuit 8 via the high frequency circuit 7, and at this time, the frequency of the AM shortwave signal is frequency-converted to the AM intermediate frequency by the operation of the AM local oscillation circuit 9, and the frequency-converted AM shortwave signal is
The signal is output from the AM mixing circuit 8 to the AM intermediate frequency amplification/detection circuit 10 and detected by the circuit 10.
The AM shortwave signal, that is, the AM shortwave audio signal is transmitted to the first shortwave contact sa or the second shortwave contact of switch S2.
It is output to the stereo demodulation circuit 6 via sb.

Also, when receiving AM medium waves, the AM high frequency circuit 7
An AM medium wave signal from a bar antenna (not shown) provided at An AM medium wave audio signal is output to the stereo demodulation circuit 6.

And AM high frequency circuit 7, AM mixing circuit 8, AM
Local oscillation circuit 9 is constructed as shown in FIG.

That is, as shown in FIG. 2, the switches S1,
The third to sixth switches are linked to switch S2 and have common contacts c, c', FM contact f, first and second short wave contacts sa, sb, and medium wave contact mw, similar to switches S1 and S2. Band change switch S3,
A tuning variable capacitor VC1 is provided between the common contacts c, c' of the switch S3 and the ground point.
A variable capacitor for local oscillation is connected to the common contacts c and c′ of
VC2 is provided.

Then, the AM shortwave signal via the first shortwave contact sa or second shortwave contact sb of the switch S1 is input to the primary side of the shortwave tuning coil L1 provided in the AM high frequency circuit 7 via the first capacitor C1. At this time, a resonant circuit is formed by the coil L1, the second and third capacitors C2 and C3, and the capacitor VC1, and the switch S is connected from the secondary side of the coil L1.
The frequency selected by the above-mentioned resonant circuit is applied to the base of the NPN type mixing transistor Q1 through the common contacts c, c' of 4 and the fourth capacitor C4.
AM shortwave signal is output. Note that the third capacitor C3 is formed by a trimmer capacitor, and the collector of the transistor Q1 is connected to the positive power supply terminal provided in the intermediate frequency amplification/detection circuit 10 of FIG. 1 via the first resistor R1 and the primary side of the coil L2. +Bb is connected.

On the other hand, the base of transistor Q1 is the second and third
An NPN type oscillator connected to the AM local oscillation circuit 9 is connected to the ground through the resistors R2 and R3, and is connected to the connection point between the resistors R2 and R3 through the first and second diodes D1 and D2 and the fourth resistor R4. The emitter of the local oscillation transistor Q2 is connected, and a fifth resistor R5 is provided between the connection point of the second and third resistors R2 and R3 and the base of the transistor Q2. A fifth capacitor C5 is provided between the connection point of R2 and R3 and the ground point, and a sixth capacitor C6 is provided between the base of the transistor Q2 and the ground point.

Then, the AM shortwave signal via common contacts c, c' of switch S4 and capacitor C4 is transmitted to resistor R5.
is input to the base of transistor Q2 via
At this time, the connection point between the diode D2 and the resistor R4 is connected to the negative power supply terminal -B, and the first tap ta on the primary side of the local oscillation coil L3 is connected to the collector of the transistor Q2 via the sixth resistor R6. Further, the second tap tb on the primary side of the coil L3 is connected to the common contacts c and c' of the switch S6, and a short wave is connected between the emitter of the transistor Q2 and the first short wave contact sa of the switch S6. When the band oscillation capacitor CX is provided and the switches S1 to S6 are switched to the first short wave contact sa, the coil L3, the capacitor CX, and the seventh and eighth capacitors C7 and C8 provided in parallel with the coil L3 are connected. ,
The 9th capacitor C9 and the capacitor VC2 determine the oscillation frequency of the transistor Q2, that is, the AM local oscillation frequency of the shortwave AM local oscillation signal. Note that the seventh capacitor C7 is formed by a trimmer capacitor.

By the way, when the switch S6 is switched to the first shortwave contact sa, that is, when the capacitor CX
When connected to a local oscillator circuit, the capacitor
AM local oscillation frequency is 3.2MHz ~ by VC2
The frequency changes to the reception frequency of the 12.0 MHz AM shortwave signal, and the above-mentioned signal is transmitted from the secondary side of the coil L3 to the emitter of the transistor Q1 via the seventh resistor R7, the common contacts c and c' of the switch S5, and the tenth capacitor C10. A local oscillation signal is output, and the input AM shortwave signal and the local oscillation signal are mixed by the operation of transistor Q1. Note that an eighth transistor is connected between the emitter of transistor Q1 and the negative power supply terminal -B.
A resistor R8 is provided.

Also, at the emitter of transistor Q2,
One end of three crystal units X1, The other end is connected to the second shortwave contact sb of the switch S2. Note that the first crystal oscillator circuit 1 is formed by the oscillators X1 to X3.
1 is formed.

When the first crystal resonator circuit 11 is selected by switching the switch S6, the capacitor
By operating VC2, the frequency of the local oscillation signal output from the secondary side of coil L3, that is, the AM local oscillation frequency, changes to 3.925MHz, 6.055MHz, and 9.595M.
If the position of the capacitor VC2 is set in advance and the position of the capacitor VC2 is set in advance, the first It is possible to receive preset Japanese shortwave broadcast signals.

That is, by switching the switch S6 to the first short wave contact Sa and the second short wave contact sb, the capacitor CX and the first resonator circuit 11 are connected to the AM local oscillation circuit 9.
selectively connect the AM local oscillation frequency to the local oscillation frequency for receiving AM shortwave signals of 3.2MHz to 12.0MHz based on the capacitor CX, and the first Japanese shortwave broadcasting signal based on the first transducer circuit 11. The local oscillation frequency for reception can be switched and controlled.

Furthermore, switches S1 to S6 are AM medium wave contacts.
When switching to mw, the 10th and 11th capacitors C1 are connected to capacitor VC1 via switch S1.
0', C11 and bar antenna coil L4 1
The secondary side of the coil L4 is connected in parallel, and one end of the secondary side of the coil L4 is connected to the base of the transistor Q1 via the switch S4 and the capacitor C4, and an AM medium wave signal is input to the base of the transistor Q1.

Further, the other end of the secondary side of the coil L4 is connected to the tap tc on the secondary side of the coil L2 via the first capacitor C12, and at this time, the secondary side of the coil L2 has 13th and 14th capacitors C13, C14 is connected in parallel, and a series circuit of the 15th capacitor C15, the medium wave contact m of switch S2, and capacitor VC2 is connected in parallel with capacitor C14, and the coil L is connected in parallel by the operation of capacitor VC2.
The frequency on the secondary side of 2 changes to the local oscillation frequency for receiving the AM medium wave signal, and the AM medium wave signal can be received. Note that the capacitors C11 and C13 are formed by trimmer capacitors.

By the way, the switch S6 is provided only for selecting between the capacitor CX and the first crystal resonator circuit 11 when receiving the AM shortwave signal, and the switches S1 to S5 also have the first shortwave contacts sa and Since the second short wave contact sb is provided, the number of contacts of each switch S1 to S6 increases, and the circuit becomes complicated and expensive.

This invention was made with the above points in mind and with the focus on the fact that the monaural/stereo selector switch is used only when receiving FM signals. It has the ability to receive AM signals,
A band switching switch that switches and controls the receiving frequency band, a monaural/stereo switching switch that switches and controls the FM signal between monaural reception and stereo reception, and a local oscillation switch that switches and controls the AM local oscillation frequency in conjunction with the switching switch. It is a receiver equipped with a switch.

Therefore, since the AM local oscillation frequency is switched and controlled by the local oscillation changeover switch, the band changeover switch, for example, the first
It is possible to use a 5-contact band changeover switch in which the second shortwave contacts sb of the first to fifth band changeover switches S1 to S5 in FIGS. There is no need to provide a circuit, which simplifies the circuit and reduces the cost.

Next, an embodiment of the receiver of this invention will be described in detail with reference to FIG. 3 and the following drawings.

First, FIGS. 3 and 4 showing one embodiment will be explained. In FIG. 3, the same symbols as in FIGS. 1 and 2 indicate the same things, and the difference is that common contacts c, c ', FM contact f, short wave contact sc, medium wave contact mw
7th to 11th band changeover switches S7 to S11 are provided, respectively, and in place of the sixth band changeover switch S6 in FIG.
In conjunction with the monaural/stereo changeover switch SX, the common contact c connected to the second tap tb of the coil L3, the first short wave contact sa connected to the other end of the capacitor CX, and the first crystal resonator circuit 11. The point is that a local oscillation changeover switch SY is provided with a second short-wave contact sb connected thereto.

When receiving an AM shortwave signal, switch S1 to S5 to shortwave contact sc, and connect capacitor CX to AM local oscillator circuit 9 to 3.2M
When receiving AM shortwave signals from Hz to 12.0MHz,
Switch the switch SY to the first shortwave contact sa, and conversely connect the first crystal oscillator circuit 11 to the AM local oscillation circuit 9 to receive the first Japanese shortwave broadcasting signals of 3.925MHz, 6.055MHz, and 9.595MHz, respectively. When doing so, by connecting switch SY to the second shortwave contact sb, it is possible to receive AM shortwave signals from 3.2MHz to 12.0MHz and to receive the first shortwave signal based on the same operation as in Figures 1 and 2. Preset reception of Japanese shortwave broadcasting signals can be performed; in this case, both switches
A two-circuit, two-contact changeover switch can be used as SX and SY, and as shown in FIG. 4, it is possible to display the switching of both switches SX and SY.

Therefore, according to the embodiment, by providing the local oscillation switch SY that is linked to the monaural/stereo switch SX, the seventh
or 11th band changeover switch S7 to S11
, the second short wave contacts sb of the first to fifth band changeover switches S1 to S5 in FIGS. 1 and 2
It is possible to use a changeover switch with the 6th band changeover switch S6 removed.
can be omitted, simplifying the circuit configuration and reducing the cost.

Next, another embodiment will be described with reference to FIGS. 5 and 6.

In Fig. 5, the same symbols as in Fig. 3 indicate the same things, and the difference from Fig. 3 is that instead of the shortwave band oscillation capacitor CX in Fig. 3,
The second signal is transmitted at 6.115MHz and 9.760MHz respectively.
3 crystal oscillators for receiving Japanese shortwave broadcast signals
4, X5, X6'' second crystal resonator circuit 1
2 is provided, and when receiving an AM shortwave signal, both vibrator circuits 11 and 12 are selectively connected to the AM local oscillation circuit 9 by switching the local oscillation changeover switch SY.

Then, by switching the switch SY to the first shortwave contact sa, preset reception of the second Japanese shortwave broadcasting signal can be performed, and the second shortwave contact sb
By switching to , the preset reception of the first Japanese shortwave broadcasting signal can be performed, and in this case, the second shortwave contacts sb of the first to fifth band switching switches S1 to S5 in FIGS. 1 and 2 are deleted. In addition, the sixth band changeover switch S6 can be omitted, simplifying the circuit configuration and reducing the cost. In addition, as shown in FIG. 6, switching display of both switches SX and SY can be performed.

In addition, in the case of both of the above embodiments, the FM signal and
Although it was applied to a receiver that has the function of receiving AM shortwave signals and AM medium wave signals, the same effect can be obtained when applied to a receiver that only receives FM signals and AM shortwave signals. Of course.

Furthermore, first and second crystal resonator circuits 11 and 12
Of course, the number of crystal oscillators may be increased or decreased, and the frequency of the crystal oscillators provided in both crystal oscillator circuits 11 and 12 may of course be changed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an example of a receiver, Fig. 2 is a wiring diagram of a part of a conventional receiver, Fig. 3 and the following drawings show an embodiment of the receiver of this invention. 1
FIG. 4 is a diagram of a display example of FIG. 3, FIG. 5 is a wiring diagram of a part of another embodiment, and FIG.
The figure is a diagram of a display example of FIG. 5. 6... Stereo demodulation circuit, 9... AM local oscillation circuit, 11, 12... First and second crystal oscillator circuits, CX... Oscillation capacitor, SX... Monaural/stereo changeover switch, SY... Local Oscillation selection switch.

Claims (1)

[Claims for Utility Model Registration] A band switching switch that has the function of receiving an FM signal and an AM signal in a frequency band different from the FM signal, and that switches and controls the reception frequency band, and a switch that controls monaural reception and stereo reception of the FM signal. A receiver equipped with a monaural/stereo changeover switch that switches and controls the AM local oscillation frequency, and a local oscillation changeover switch that switches and controls the AM local oscillation frequency in conjunction with the changeover switch. Claims for registration of a utility model in which an oscillation capacitor and a vibrator circuit are provided in an AM local oscillation circuit, and the oscillation capacitor and the vibrator circuit are selectively connected to the AM local oscillation circuit by a local oscillation changeover switch. Receiver according to paragraph 1. Two oscillator circuits are provided in the AM local oscillation circuit, and the local oscillation changeover switch allows the
The receiver according to claim 1, wherein both of the vibrator circuits are selectively connected to an AM local oscillation circuit. The AM local oscillation circuit is equipped with a shortwave band oscillation capacitor and a crystal oscillator circuit for receiving Japanese shortwave broadcasting, and the local oscillation selection switch
The receiver according to claim 1, wherein the oscillation capacitor and the crystal resonator circuit are selectively connected to an AM local oscillation circuit. 2 for receiving Japanese shortwave broadcasting in the AM local oscillator circuit.
2. The receiver according to claim 1, wherein a plurality of crystal resonator circuits are provided, and each of the two crystal resonator circuits is selectively connected to the AM local oscillation circuit by a local oscillation changeover switch.