JPS59103431A - On-vehicle fm receiver - Google Patents

Abstract

PURPOSE:To search automatically a traffic information station while selecting the cassette tape reproducing mode. CONSTITUTION:A switching circuit 30 drives on/off a voltage (FM+B) with an SK signal detecting output driving a display lamp 21 outputted from an SK signal decoder 4. A switching circuit 32 is driven by an output of a timer circuit 31 delaying an output of the switching circuit 30 for a prescribed time and turns on/off a voltage +VDD. An output of the switching circuit 32 is applied to a DK signal decoder 6 as the SK signal detecting output and to the switching circuit 34 as a control signal. The output of the switching circuit 34 is applied directly to a channel selection control circuit 17-0 as an automatic search indication signal. Further, a timer control circuit 36 to which a muting signal outputted from the channel selection control circuit 17-0 and a muting control circuit 37 are provided and the output of the timer circuit 31 at the automatic searching is controlled by the output of the timer control circuit 36.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-vehicle FM receiver with a cassette tape player, and more specifically, an in-vehicle FM receiver capable of receiving specific broadcasts such as traffic information broadcast during regular broadcast programs through FM broadcasting. Regarding the receiver.

(Prior art) A traffic information system (Autofah@rRundf) that broadcasts traffic information during regular broadcast programs through FM broadcasting.
Unk Information 5yst@m), the so-called ARI system, is known.

In this traffic information system, as is well known, a transmission identification signal (S@nder Kennung signal 1, herein referred to as SK double signal) for identifying whether a broadcasting station is a traffic information station broadcasting traffic information, a traffic message An identification signal (Durehsagen Ksnnung signal, herein referred to as DK double signal) is output. 8, the signal is 57 kHz (/4 Ilot signal 19 kHz
), whose modulation rate is the maximum frequency deviation of 7
5.33% of 5 kHz or ±4 kHz.

A with 125 as DK double signal SK double signal carrier
There are M-modulated AM wave harmonics.

On the other hand, a conventional in-vehicle FMM signal equipped with a cassette tape player and capable of receiving traffic information was constructed as shown in FIG. 1, for example.

In Fig. 1, 1 is an antenna, 2 is a front end of an FM tuner, 3 is an intermediate frequency amplifier and an FM demodulator (hereinafter simply referred to as a demodulator), and 4 is a signal decoder 8 (for example, Tokyo Sanyo Electric Co., Ltd.). Company fi 5TK2200)
, 5 is a stereo demodulator, and 6 is a DK signal decoder (for example, Tokyo Sanyo Electric Co.'s RLA2211).
and a stereo demodulator 5 constitute an FM stereo tuner. The SK decoder 4 is equipped with a detection circuit that detects the presence or absence of the SK multiplied signal and drives the sensor 21 to turn on and off to display the presence or absence of the SK multiplied signal, and a 57 kHz AM demodulation circuit. Configured to double signal detection.

On the other hand, 7 indicates a magnetic head for reproduction of a cassette tape player, and 8 indicates a tape equalizer amplifier.The reproduced output signal of the magnetic head 7 is supplied to the tape equalizer amplifier 8, amplified, and then supplied to the DK signal decoder 6.

The DK signal decoder 6 is supplied with a selection signal for the FM tuner and cassette tape player, and selects the FM tuner and cassette tape player according to the selection signal.
M tuner output signal or tape equalizer amplifier 8
When the SK signal decoder 4 outputs the 9 DK signal, the tape equalizer amplifier 8 forcibly switches the output signal to the audio signal from the FM tuner and increases the volume. The SK signal detection output signal (indicator lamp 21
The alarm tone signal is output based on the SK signal detection output signal when the SK signal (drive output) is supplied and the SK multiplied signal is not detected.

FM selected and output by the DK signal decoder 6
The output signal of the tuner or the output signal of the tape equalizer amplifier 8 is sent to an output amplifier 13 via a noise reduction circuit 9, a tone control circuit 10, a balance adjustment circuit 11 that adjusts the volume and balance of the left and right channel audio signals, and a mixing circuit 12. The output amplifier 13 outputs an amplified audio signal. The other output signal from the DK signal decoder 6 is sent to an amplifier 14 for increasing the volume.
15 is configured so that it is supplied to the mixing circuit 12 via the SDK switch 16 and mixed with the output signal of the balance adjustment circuit 11. On the other hand, 15 is configured such that a part of the power supply voltage FM1B supplied to the FM tuner is supplied to the mixing circuit 12 via the SDK switch 16. is supplied to the SK signal decoder 4 and the DK signal decoder 60S with the output signal.
SDK mode control circuit that sets the operation and non-operation of the K and DK double signal detection, volume increase, and alarm tone signal generation functions (44j), while the SDK switch 16 is on, the SK
The signal decoder 4 and the DK signal decoder 6 are activated, and the SK signal decoder 4 is activated while the SDK switch 16 is off.
and controls the SK and DK double signal detection, volume increase, and alarm tone signal generation functions of the DK signal decoder 6 to be inactive. In addition, the SDK mode control circuit 15 is configured to turn off the j58DKSW 16 by the mute output during auto search from the channel selection control circuit 17-o, and stop the volume increase and alarm tone generation functions as in the next case. .

Therefore, when the SDK switch 16 is turned on and the FM tuner is selected, the DK signal decoder 6 supplies the output of the stereo demodulator 5 to the noise reduction circuit 9, and the FM broadcast can be received. In this case, when the receiving broadcast station is a traffic information station, the SK signal decoder 4 detects the SK multiplied signal, generates a low potential output from the drive output terminal of the display lamp 21, and the display lamp 21 lights up to detect the SK multiplied signal. is displayed.

If the DK double signal is detected in this state, the DK signal decoder 6
is output as a DK double signal from the SK signal decoder 4 to the DK signal decoder 6, and after the DK double signal is output, the DK decoder 6 sends an audio signal to the amplifier 14 in addition to the audio signal to the noise reduction circuit 9 during the subsequent traffic information broadcast period. It supplies the output signal from the stereo demodulator 4. The output signal of the stereo demodulator 4 supplied to the amplifier 14 is amplified by the amplifier 14), mixed with the output signal of the balance adjustment circuit 11 in the mixing circuit 12, and supplied to the output amplifier 13. Therefore, even if the sound volume is reduced by adjusting the balance adjustment circuit 11, the sound volume increases because the amplified output signal from the stereo demodulator 4 is added to the amplifier 14. Therefore, even if the volume of the traffic information broadcast following the DK double signal is reduced by the balance adjustment circuit 11, the volume is increased.

Furthermore, when the traffic information station broadcast cannot be received due to the movement of a car, etc., the SK signal decoder 4 cannot detect a signal at 8, so the SK signal detection output is not at a high potential, and the indicator lamp 21 is turned off and the SK signal is multiplied. Displays that no signal is detected. At the same time, the SK signal detection output (high potential output) is delayed by the time set by the timer circuit 22 and supplied to the DK signal decoder 6. 9 and an amplifier 14, an alarm tone signal is output superimposed on the output signal of the stereo demodulation circuit 4 to notify the need for reselection. Therefore, the listener will know that he has entered an area where he cannot receive the radio waves of the traffic information station he had been receiving until just before, and will reselect the station to receive broadcasts from other traffic information stations that he can receive.

On the other hand, when a cassette tape player is selected, the DK signal decoder 6 supplies the output signal of the tape equalizer amplifier 8 to the noise reduction circuit 9, and the reproduced sound of the cassette tape can be heard. Even when the user is listening to the reproduced sound of the cassette tape, the FM tuner continues to perform the receiving operation, and the SK signal decoder 4 continues to monitor the SK double signal. Then, when the DK double signal is detected, the DK
The decoder 6 switches the output signal to the output signal of the stereo demodulator 4, and outputs the output signal of the stereo demodulator 4 to the noise reduction circuit 9 and the amplifier 14 as a DK double signal during the subsequent traffic information broadcast period. As a result, even if the cassette tape player is selected, the traffic information can be automatically listened to with the volume increased in the same manner as in the case where the FM device was selected. Furthermore, when SK double signal monitoring becomes impossible, the DK signal decoder 6 superimposes the alarm tone on the output signal of the tape equalizer amplifier 8 as described above (as in the case where the FM tuner is selected). As a result, an alarm tone is output with the volume increased to notify the listener of the need to reselect the station.

Further, in FIG. 1, 17 is a tuning control circuit of an FM tuner that controls the front end to perform automatic tuning/manual tuning, and x'y-o is the tuning control circuit main body (hereinafter referred to as In this book, it is also referred to as a tuning control circuit), and the mode switching is performed by a mode changeover switch 18 that switches between an automatic tuning mode and a manual tuning mode. on the other hand,
andff-) 17-1 to 17-3, switch 19-
A matrix circuit 19 consisting of 1 to 19-9 is a channel selection instruction circuit, and is extracted from the channel selection control circuit 17 and shown. And C-) 17-1 to 17-5 are supplied with a power supply voltage regardless of the selection of a cassette tape player and an FM tuner, such as a storage battery voltage COM1B via a car key switch. 17-
, ~17-5 dart opening. In addition, switch 19-1 is an auto search instruction switch.
Switches 19-2 to 19-9 are manual channel selection switches. Is the output of switches 19-1..., 19-9 AND? -) It is designed to be supplied to the tuning control circuit main body 17-o via 17-1 to 17-3. Also, the switch 19 supplied via the AND gates 17-1 to 17-3
The outputs from -1 to 19-9 become valid in accordance with the instruction mode of the mode changeover switch 18. That is, when the automatic tuning mode is selected by the mode changeover switch 18, by turning on the automatic search instruction switch 19-1, the tuning operation of the front end 2 is automatically performed until all broadcast signals are received. It is configured to do the following. Further, when the manual tuning mode is selected by the mode changeover switch 18, the manual tuning switch 19-2 *...
19-9 allows manual channel selection.

However, the opening and closing of the darts of the cyan drums 17-1 to 17-3 are controlled by the output of the cassette tape and FM tuner changeover switch 20. Therefore, when the tape cassette is inserted, the selector switch 20 is switched to the cassette tape side, and
When the dart is closed, auto search instruction switch 19-1, manual selection switch 19-2 #...19
The output of -9 is not supplied to the channel selection control circuit 17-0.

Therefore, if the above-mentioned alarm tone occurs while selecting a cassette tape player, it is necessary to remove the tape cassette from the cassette tape player, switch the selector switch 20 to the FM tuner side, and then reselect the station. There are many drawbacks to this, which means that the playback of the cassette tape will be temporarily interrupted.

(Object of the Invention) The present invention has been made in view of the above, and solves the above-mentioned drawbacks, and automatically searches for a traffic information station while the cassette tape is being played when no SK signal is detected while the cassette tape is being played. In-vehicle F that can be
The purpose is to provide an M receiver.

(Structure of the Invention) The present invention includes a cassette tape player, and outputs a first broadcast signal for indicating that the station is a broadcasting station that transmits a specific broadcast and a predetermined period between the specific broadcast and transmits the specific broadcast. In the vehicle-mounted FM receiver described above, which is configured to be able to detect the second broadcast signal for indicating that the cassette tape player is in operation, the first and second broadcast signal detection is selected. In this case, even during selection of a cassette tape player, the FM receiver is controlled to be in an automatic tuning state from the time a predetermined period elapses after the non-detection output of the first broadcast signal is generated until the first broadcast signal is detected. and mute control means for inhibiting the mute operation of the audio signal during automatic channel selection by the control means during selection of a cassette tape player.

The present invention will be explained below with reference to examples.

(Configuration in one embodiment of the invention) FIG. 2 is a block diagram showing an embodiment of the invention. In FIG. 2, the same components as those of the conventional vehicle-mounted FM receiver shown in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

In one embodiment of the present invention, a switching circuit 30 that turns on and off the stain pressure FM+B by the SK signal detection output that is output from the SK signal decoder 4 and drives the display lamp 21, and an output voltage of the switching circuit 30 are provided. It is equipped with a timer circuit 31 that delays the supplied voltage for a predetermined time, and a switching circuit 32 that is driven by the output of the timer circuit 31 and turns on and off the voltage 1'vDD. 6 as an SK signal detection output, and is also supplied as a control signal to the switching circuit 34 via the resistor 33, and the output of the switching circuit 34 is directly sent to the tuning control circuit 17-0 as an auto search instruction signal, which instructs the auto search. switch 19
Supplied independently from the output of −1. In addition, the input terminal of the switching circuit 340 control signal is the mode selector switch 1.
It is selectively grounded via a switch 38 which is switched in conjunction with 8.

On the other hand, in one embodiment of the present invention, the tuning control circuit 17-
A timer control circuit 36 and a mute control circuit 3 to which a mute signal output from 0 during auto search is supplied.
7, and the output of the timer circuit 31 during auto search is controlled by the output of the timer control circuit 36. Also, the voltage FM supplied via the SDK switch 16
-1-B is supplied as a control signal and the voltage FM-)-B
A timer inhibit circuit 35 is provided which inhibits the timer operation of the timer circuit 31 based on the output when no voltage is applied. Furthermore, an OR circuit 40 is provided to which the voltage FM1B supplied via the SDK switch 16 is provided.
The output of the OR circuit 40 is AND? instead of the output of the switch 20. ) 17-1 to 17-3 to open the gates of AND GO) 17-1 to 17-5. Also, the voltage COM-) B and the power supply voltage T to the cassette tape player are 10B is applied, the voltage T+B
A prohibition circuit 39 is provided to prohibit the voltage COM-)-B from being output when the voltage COM-)-B is applied.
The output of 9 is supplied to an OR circuit 40.

Note that the switching circuits 30, 32, 34 . The timer circuit 31, timer prohibition circuit 35, and timer control circuit 36 are the third
Each of them is configured as shown in the figure.

The switching circuit 30 includes a transistor 3 that turns on and off the power supply FM+B under the control of the SDK signal detection output.
01, base bleeder resistor 302 of transistor 301
, pace current limiting resistor 303 of transistor 301,)
It consists of a resistor 305 for limiting the collector current of the transistor 301, a diode 304 for preventing transistor destruction, and a diode 306 for preventing backflow.

The timer circuit 31 includes a resistor 311 and a capacitor 312 forming a time constant circuit, an AND(f-) 313 for buffering, a diode 314 and a resistor 315 for protecting the AND(goo) input.

The switching circuit 32 includes a transistor 321 controlled by the output of the timer circuit 31, a base current limiting resistor 322 of the transistor 321, and a collector load resistor 323 of the transistor 321.

The switching circuit 34 consists of a transistor 341 which is controlled by the output of the switching circuit 32 via a resistor 33.

The timer inhibit circuit 35 includes a transistor 35 that is controlled by the voltage FM1B outputted via the SDK switch 16.
1.) pace current limiting resistor 352 of transistor 351;
) Collector (1&J) of transistor 351 Consists of load resistor 353 and backflow blocking diode 354.

The timer control circuit 36 includes a switching transistor 361 for switching the time constant, a resistor 362 connected to the timer circuit 310, a resistor 311 and a capacitor 312 forming a time constant circuit, and a resistor 362 connected to the time constant circuit of the timer circuit 310, and a resistor 362 connected to the time constant circuit of the timer circuit 310, and A resistor 363 that limits the current caused by the mute signal during auto search, a reverse current blocking diode 364, and a capacitor 3 that constitutes a time constant circuit for the mute signal.
65, resistors 366 and 367, and a diode 368 for preventing backflow and for rapid charging when selecting a channel.

Further, the mute control circuit 37 includes transistors 371 to 373, diodes 374 to 380, and 3 as shown in FIG.
90. Consisting of resistors 381 to 389 and a capacitor 391, muting is selectively applied by a mute signal from the channel selection control circuit 17-o, and a mute signal (16 ) A mute signal when the cassette tape is fast forwarded (hereinafter referred to as FF), a mute signal when the cassette tape is rewound (hereinafter referred to as REW), a mute signal when the cassette tape is reversely forwarded (hereinafter referred to as reverse), and Voltage COM
The configuration is such that the output signal of the amplifier 13 is muted when the 10B is disconnected. In addition, in FIG. 4, 10B indicates the voltage of the storage battery installed in the automobile. Further, the voltage T+B is applied to the cassette tape player while the cassette tape is being loaded, and the voltage T+B is cut off when the cassette tape is ejected.

, Here, the transistor 371 is connected to the channel selection control circuit 17-
This is a transistor for selectively inhibiting a mute operation based on a mute signal from 0. transistor 372
The transistor 37 is used to generate a mute signal from the channel selection control circuit 17-0, a mute signal at FF mode, and a mute signal at W mode, and when loading/unloading a cassette tape.
This is a transistor that drives 3 and generates a mute output. The mute signal at the time of reverse is configured to be directly outputted via a diode 374, and the diodes 374 to 380 are diodes that act as reverse flow prevention. Resistors 382 to 384 and capacitor 391 constitute a time constant circuit that sets the switching timing of transistor 371. Resistors 381, 385 and 387 are for limiting the base currents of transistors 382 and 383, respectively, and resistors 386 and 389 are for base leaders of transistors 372 and 373. resistance 38
8 is the transistor 373 when the voltage COM +B is disconnected.
This is the resistance that constitutes the base current path of .

(Operations in an Embodiment of the Invention) In an embodiment of the invention configured as described above, an antenna 1, a front end 2, a demodulator 3, an SK signal decoder 4, a stereo demodulator 5, a DK signal decoder 6, a magnetic head 7, tape equalizer amplifier 8, noise reduction circuit 9,
The operations of the tone control circuit 10, balance adjustment circuit 11, mixing circuit 12, output amplifier 13, amplifier 14, and SDK mode control circuit 15 are the same as in the conventional case, and detailed explanation thereof will be omitted.

Now, when the SDK switch 16 is turned off, the S
SK by K signal decoder 4 and DK signal decoder 6
The double signal and DK double signal detection, volume increase, and alarm tone signal generation functions are stopped. Further, since the 8DK switch 16 is in the off state, the transistor 351 of the timer inhibit circuit 35 is controlled to be in the off state, and the AND/DART 313 is controlled to be in the off state.
The input terminal of is always maintained at a high potential to stop the timer operation of the timer circuit 31. On the other hand, since the input terminal of the AND gate 313 of the timer circuit 31 is maintained at a high potential, the transistor 321 of the switching circuit 32 is in an on state, and the output of the switching circuit 32 is at a low potential.
The transistor 341 of the switching circuit 34 is controlled to be in an off state, and the switching circuit 34 does not enter the auto search state. In this case, since the SDK switch 16 is in the off state, the voltage of the power supply FM+H is not supplied to the OR circuit 40, but when the FM tuner mode is selected, the voltage of the power supply T+H is not supplied to the prohibition circuit 39.
The inhibit circuit 39 has its e-) open, and the voltage of the power source C0M-1-H is supplied to the OR gate 40, and the voltage of the power source C0M-1 is
-B voltage causes AND gates 17-1 to 17-5 to open their darts, and auto search instruction switch 19-1, manual tuning switch 19-2, . . .

19-9, an auto search function or a manual channel selection function can be activated in response to the selection of the selection switch 18-1. Further, when a tape cassette is inserted, the voltage of the power supply T1B is supplied to the inhibition circuit 39, and even though the voltage of the power supply COM+B is supplied, the output of the inhibition circuit 39 becomes a low potential, and the AND? ”-)17-
1 to 17-3, when the dart is closed, auto search is performed by the auto search instruction switch 19-1, manual channel selection switch 19-2. ...Manual channel selection using 19-9 is prohibited.

On the other hand, when the SDK switch 16 is turned on, the power FM+B is supplied to the OR circuit 40, and the output of the OR circuit 40 is at a high potential, regardless of whether a tape cassette is inserted or not. ) 17-1 to 17-5 have their darts open, auto search with auto search instruction switch 19-1, manual tuning switch 19-
Manual channel selection using zs...19-9 becomes possible. Also, since the SDK switch 16 is turned on,
The SDK mode control circuit 15 outputs an SK multiplied signal from the signal decoder 4 and the DK signal decoder 6 to the
The K-fold signal detection, volume increase, and alarm tone signal generation functions become operational. Further, since the SDK switch 16 is in the on state, the transistor 351 of the timer inhibit circuit 35 is not in the on state, and the timer inhibit circuit 35 is substantially disconnected from the timer circuit 31 by the diode 354. Then, the timer circuit 31 becomes operational.

In the above explanation, the auto search instruction switch 19- is activated only when the SIX switch 16 is in the OFF state and the tape cassette is installed in the cassette tape player.
1 auto search status and manual tuning switch x9
-2m...Although manual tuning using 19-9 is not possible, when a cassette tape player is selected and the SDK mode is not selected, the tuning control circuit 1
7-o, when there is no need to select a channel, the auto search instruction switch 19-1, manual channel selection switch 19-2. . . . Even if you touch 19-9, automatic search or manual channel selection will not be performed.

Next, when the SDK switch 16 is in the on state, the S
'When a signal is detected, the SK signal decoder 4
The drive output of the display rung 21 outputted from the display lamp 21 is at a low potential, and the display lamp 21 lights up to display at 8 that a signal is detected.

On the other hand, the display lamp 2 outputted from the signal decoder 4 at 8
Since the drive output of the timer circuit 30 is at a low potential, the transistor 301 of the timer circuit 30 is controlled to be on, and the output of the timer circuit 30 is a high potential output. As a result, Andoo) 31
The input terminal 3 is at a high potential, and the switching circuit 32
The transistor 321 is controlled to be on, and the output of the switching circuit 32 is at a low potential, and the DK decoder 6
8 is supplied with a signal indicating that a signal is detected.

Therefore, no alarm tone signal is output from the DK signal decoder 6. The above state is as shown in the state from to to in FIG. Figure 5 (,)
5(b) shows the drive output of the display run f21 output from the SK signal decoder 4, FIG. 5(b) shows the output of the switching circuit 30, and FIG.
13, FIG. 5(d) shows the output of the timer circuit 31, and FIG. 5(.) shows the output of the switching circuit 32.

Then, when the fi and SK multiplied signals cannot be detected due to the running of the car, etc., the drive output of the display rung 21 output from the SK signal decoder/4 becomes a high potential.

Now, the point in time when the SK multiplied signal cannot be detected is indicated by to. When the drive output of the display lamp 21 outputted from the SK signal decoder 4 becomes a high potential, the display rung 21 goes out, indicating that the SK multiplied signal is not detected, and the output of the switching circuit 30 becomes a low potential. . When the output of the switching circuit 30 becomes a low potential, the capacitor 3
12 charges are discharged through the resistor 311, and f-)
The input voltage of 313 is the capacitance of capacitor 312 and resistance 31.
1, and when the voltage falls below the threshold level, the output of the timer circuit 31 becomes a low potential output. Since the output of the timer circuit 31 becomes a low potential output, the transistor 321 is turned off.
The output of the switching circuit 32 becomes a high potential. In FIG. 5, the delay period due to the time constants of the resistor 311 and capacitor 312 is indicated by Tg.

It is now assumed that the mode selector switch 18-1 is in the auto search mode, that is, the mode selector switch 18-1 is in the on state and the switch 38 is in the off state. Since the switch 38 is in the off state, the output of the switch circuit 32 becomes a high potential output, so the transistor 341 is not in the on state, and the output of the switching circuit 34 causes the channel selection control circuit 17-0 to Auto search will start and channel selection will be performed automatically. During tuning during auto search, a mute output (high potential output) is generated from the tuning control circuit 17-0. FIG. 5(f) shows the mute output from the tuning control circuit 17-0. In FIG. 5, when the transistor 321 is turned off, the auto search state is entered, and the tuning control circuit 17-o mutes the output (
The period of time delay until the occurrence of f) is indicated by t'a. This tl is the acceptance time determined by the internal program of the channel selection control circuit 17-o. Due to the generation of the mute output (f), the capacitor 312 is charged through the path of the resistor 363, the diode 368, and the capacitor 312. On the other hand, due to the generation of the mute output (f), the transistor 361 is turned on after a period determined by the resistor 363, diode 364, capacitor 365, resistors 366 and 367, and the charge in the capacitor 312 is transferred to the resistor. It is discharged through a parallel circuit of 311 and 362. However, the diode 36 due to the mute output (f)
Charging of capacitor 312 via capacitor 31
The discharge time is faster than the discharge time through the parallel circuit of two resistors 311 and 362. Note that FIG. 5(g) shows the on/off state of the transistor 3610.

Therefore, the potential at the input terminal of the AND gate 313 is charged through the diode 368 and increases as shown in FIG. This increase is determined by a time constant due to the parallel resistance of resistors 311 and 362, the forward resistance of capacitor 312, resistor 368, and diode 368.

When a broadcast is detected during the above auto-search, the tuning control circuit 17-0 stops the tuning operation. First, a case where the detected broadcasting station is not a traffic information station will be explained. When a broadcast is detected, the mute output (f) from the channel selection control circuit 17-0 becomes low potential after the acceptance time tb determined by the internal program of the channel selection control circuit 17-00 ends. Mute output (
Since f) becomes a low potential, charging of the capacitor 312 through the path of the resistor 363 and the diode 368 is completed.

On the other hand, even after the mute output (f) becomes a low potential, the transistor 361 remains on for a period tdO determined by the time constants of the capacitor 365 and the resistors 366 and 367. As a result, the charge on the capacitor 312 is transferred to the resistor 311.
and the resistor 362, and the output of the AND GO 313 becomes a low potential output after a time tf determined by the time constants of the capacitor 312, resistors 311, and 362 has elapsed.

Meanwhile, since the SX signal is not detected during this time, the transistor 341 is not turned on again, and the channel selection control circuit 17
-o is not in auto search state again, transistor 34
The mute output (f) becomes a high potential after a period of ta from when the switch is turned on. Since the mute output (f) has a high potential, the capacitor 312 is charged via the resistor 363 and the diode 368. Further, after the mute output (f) becomes a high potential, the transistor 361
is not in the on state, and the charge on the capacitor 312 is transferred to the resistor 36.
However, the above-described charging is performed faster than this discharging, and the voltage of the capacitor 312 increases.

These effects are the same as in the case of starting channel selection described above.

Next, a case (27) in which a broadcast is detected during auto search and the detected broadcast station is a traffic information station will be explained. Due to the detection of broadcasting, the mute output (f) becomes low potential for a period tb from the time of detection of broadcasting. On the other hand, since the SX signal decoder 4 detects the signal at 8, the drive output of the display lamp 21 outputted from the signal decoder 4 at 8 is at a low potential, and the output of the switching circuit 30 is at a high potential. As a result, capacitor 312 is connected to switching circuit 30
As a result, the output of ANDGOO) 313 is maintained at a high potential. Therefore, the transistor 321 is maintained in the on state, and the output of the switching circuit 13.32 becomes a low potential, and the DK
The signal decoder 6 is supplied with the SX signal detection output, and the switching circuit 34 is turned off to stop auto-search.

As is clear from the above, the timer count %31 is controlled by the timer control circuit 36, and the timer count 31 is controlled by the timer control circuit 36.
), and by using the mute output (f) when selecting a channel, it can be set as a short-time timer (time tb), and time (28) 'g>ta>if. Desirably, for example, 15s@a in 1g, 3s@e in td, 0.5-1 in tf
Set it to about s@a.

On the other hand, the electric NEET output (f) output from the channel selection control circuit 17-o is also supplied to the 8 [mode control circuit 15]. Accordingly, the function of generating an alarm tone from the 9DK signal decoder 6 is stopped and no alarm tone is generated, and the output of the switching circuit 32 is at a high potential during period t1.

After that, the period until the tuning control circuit 17-0 generates the ζate output (f) is extremely short, and the set time t by the timer circuit 31 and the timer circuit 31 and the timer control circuit During the period of time tf set by 36, the DK signal decoder 6 is equivalent to inputting a pseudo signal such as the presence of the SX signal.
During the tuning period by automatic search until a signal is detected, the DK signal decoder 6 does not output an alarm tone.

On the other hand, when manual channel selection is selected using the mode selector switch 18-1 (the mode selector switch 18-1 is in the off state), the selector switch 38 is in the on state, and the input terminal of the switching circuit 34 is always in the on state. If the potential is low, automatic search using the output of the switching circuit 34 will not be performed. On the other hand, the output of the switching circuit 32 is output from the signal decoder 4 to the indicator lamp 21 when it detects that there is no signal at 8 due to the existence of the resistor 33 even though the changeover switch 38 is in the on state. The drive output is supplied to the DK signal decoder 6 after a delay of the set time t of the timer circuit 30, and an alarm tone is output to notify the necessity of tuning. In this case, manual channel selection switch 19-2. ...It is of course possible to manually select a channel using the manual channel selection switch 19-2...
・During manual tuning by 19-9, the tuning control circuit 1
During the period when the simulated output is generated by 7-0, the DK
The generation of alarm tones from the signal decoder 6 is suppressed.

Therefore, after the time tg has elapsed after the indicator lamp 21 goes out, in the setting state of the mode selector switch 18-1, in the auto search mode, an auto search is performed until the SK double signal is detected, and in the manual mode, an auto search is performed until the SK double signal is detected. will generate an alarm tone to notify the need for reselection.

Next, the function of the mute control circuit 37 will be explained.

As shown in FIG. 6, when the FM tuner is selected, the mute control circuit 37 generates a mute signal output from the selection control circuit 17-0 when the tape cassette is not inserted into the cassette tape player. Then, due to this mute signal υ, the transistor 372 is turned on via the diodes 375 and 377, and as the transistor 372 is turned on, the transistor 3 is turned on.
73 is not in the on state, and depending on the voltage of the electric atom B, a mute signal is generated during the generation period of the mute output output from the selection control circuit 17-0, and the audio output is muted.

The cassette tape player is selected by loading the tape cassette into the cassette tape player. When the tape cassette is inserted, the voltage of the power source T-1-H is supplied, and the voltage of the power source T1-B turns on the transistor 372 via the resistor 381 and the diodes 376 and 377. Since the transistor 372 is turned on, the transistor 373 is turned on and the stain atom B is turned on.
A mute signal is generated by the voltage. On the other hand, a predetermined period th is determined by the time constant υ determined by the resistors 382, 383, and 384 and the capacitor 391 from the time when the power supply T0B is supplied.
The transistor 371 is turned on after the lapse of time. Since the transistor 371 is turned on, the
) The transistor 372 is controlled to be off, and as the transistor 372 is turned off, the transistor 373 is turned off. Therefore, a mute signal is generated for a period of time th from the time when the tape cassette is inserted.

Next, while selecting a cassette tape player, when the magnetic tape of the tape cassette reaches the end or when the running direction of the magnetic tape is manually reversed, a reverse mute output is generated, and this reverse mute output is It is directly output as a mute signal via diode 374. Also, fast forward the magnetic tape (F, F) l,
FF when rewinding the magnetic tape and REV when rewinding the magnetic tape.

R11W mute output is generated, and irrespective of whether the transistor 371 is in the on state, the transistors 372 and 373 are in the on state due to the rr, RFW mute output, and the F is in the on state.
F, REW A mute signal is generated during the generation period of the mute output.

On the other hand, during selection of a cassette player, if the drive output of the display lamp 21 output from the SK signal decoder 4 is at a high potential, that is, when the SK double signal is not detected, the display rung 2
1 goes out as described above, and the resistor 311 of the timer circuit 30
After a time period of 1 g determined by the time constant of the channel and the capacitor 312 has elapsed, if the mode selection switch 18-1 has selected auto search, channel selection is automatically performed until the SK multiplied signal is detected. During this tuning, a mute output (f) is output from the tuning control circuit 17-0. This mute output (f)
is supplied through the diode 375, but since the transistor 371 is in the on state, the transistor 372 is maintained in the off state and no mute signal is output. Therefore, during the period when the cassette tape player is being selected, the audio signal is not muted during the period when tuning is performed by auto search, and as mentioned above, there is virtually no alarm tone generated during this tuning. , the playback sound of the tape cassette can be listened to without interruption.

Next, when the tape cassette is ejected, the voltage of the power supply T+B disappears and at the same time a mute output is generated at the time of ejection, and this mute output is supplied to the pace of the transistor 372 via the resistor 385 and the diode 378, Occur. On the other hand, power supply T+B
After a predetermined time tl determined by the discharge time constant of the resistors 382 to 384 and the capacitor 391 has passed since the voltage disappears, the transistor 371 is returned to the off state. After the tape eject described above, the state returns to the state where the FM tuner side is selected.

(Effects of the Invention) As explained above, according to the present invention, when the detection of a first broadcast signal such as a signal and a second broadcast signal such as a DK signal is selected in step 8, even when a cassette tape player is selected, a control means for controlling an FM receiver in an automatic tuning state from when a predetermined period elapses after generation of a non-detection output of a first broadcast signal until the first broadcast signal is detected; and a mute control means for prohibiting the mute operation of the audio signal during automatic channel selection by the control means, so that when the first broadcast signal is no longer detected while the cassette tape player is playing back the recorded contents of the chief cassette. , the FM receiver switches to the automatic tuning state and performs automatic tuning until it detects the first broadcast signal, and the audio signal is not muted during this tuning, so -
There is no need to eject the cassette tape and reselect the station.

Therefore, it is possible to reproduce the tape cassette without interrupting the reproduction, and it is possible to automatically reselect a station.

In addition, manual tuning is also possible even when the manual tuning mode is selected and the cassette tape player is selected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a conventional vehicle-mounted FM receiver. FIG. 2 is a block diagram showing the configuration of a vehicle-mounted FM receiver according to an embodiment of the present invention. FIGS. 3 and 4 are specific circuit diagrams showing an example of a main part of an embodiment of the present invention. FIGS. 5 and 6 are timing charts for explaining the operation of an embodiment of the present invention. 2...Front end, 3...rM retrieval unit, 4...
・SK signal decoder, 5... Stereo demodulator, 6...
・DK signal decoder, 7... Magnetic head, 8... Tape equalizer amplifier, 9... Noise reduction circuit, 10
... Tone control circuit, 11 ... Balance adjustment circuit, 12 ... Mixing circuit, 13 ... Output amplifier, 14
...Amplifier, 15...SDK mode control circuit, 16
... SDK switch, 17 ... Tuning control circuit, 17
-o... Tuning control circuit main body, 18-1... Mode selection switch, 19-1... Auto search instruction switch, 19-21... 19-9... Manual tuning switch,
21... Display lamp, 30, 32 and 34... Switching circuit, 31... Timer circuit, 35... Timer prohibition circuit, 36... Timer control circuit, 37...
Mute control circuit, 39...Prohibition circuit, 4o...OR circuit. Patent applicant Trio Co., Ltd. Attorney Nobuo Tosako

Claims (1)

[Claims] a first broadcast signal for indicating that the station is equipped with a cassette tape player and transmits a specific broadcast broadcast between regular broadcast programs through FM broadcast; and a predetermined time before the start of the specific broadcast. A second broadcast signal that is output for a period of time after the end of the specific broadcast to indicate that the specific broadcast is being transmitted is configured to be detectable even during the selection of the cassette tape player; When the first and second broadcast signal detection is selected, while the second broadcast signal is being detected, the output is automatically switched to the FM broadcast receiving side while the cassette tape player is selected, and the output volume is automatically increased. and is configured to output an alarm tone during non-detection of the first broadcast signal after a predetermined period of time has elapsed from the time of non-detection of the first broadcast signal, and is configured to output an alarm tone during non-detection of the first broadcast signal; The in-vehicle FM receiver is configured to be able to detect the first and second broadcast signals, and to suppress the alarm tone during channel selection. The apparatus further comprises at least a control means for controlling the FM receiver in an automatic tuning state from when the predetermined time has elapsed after the non-detection output is generated until the first broadcast signal is detected even while the cassette tape player is being selected. Features of the in-vehicle FM receiver.