JPH0611647Y2 - PLL frequency synthesizer tuner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a PLL frequency synthesizer type tuner, and in particular, erroneous display or tuning of stereo reception that occurs at frequency switching due to band switching operation or preset tuning reception operation. The present invention relates to a PLL frequency synthesizer tuner that suppresses erroneous display.

[Conventional technology]

In recent years, audio equipment has become more electronic, and tuners have become PL
The L frequency synthesizer type tuner facilitates variable frequency operation, and one-touch tuning by receiving preset tuning is possible.

FIG. 9 shows a block diagram of a conventionally used tuner.

The key operation unit 1 for the user to perform, for example, one-touch channel selection
When the 0 channel designation key is operated, the microcomputer 12 transfers the frequency data of the designated channel to the internal R
The read frequency control data is output from the AM to the PLL frequency synthesizer type tuning circuit 16.

In the tuning circuit 16, the PLL loop follows the change of the frequency control data, the frequency is varied, and the reception frequency is finally tuned to the station of the designated channel.

Further, for example, when the reception mode is switched from AM to FM, the microcomputer 12 outputs the frequency control data last used in the FM mode to the tuning circuit 16,
Let me receive the FM station that I was listening to last time.

The intermediate frequency signal output from the tuning circuit 16 is detected by the detection circuit 18 and further sent to the MPX circuit 20.

When the detection signal related to the FM stereo broadcasting station is input, the MPX circuit 20 outputs stereo-demodulated audio signals by performing stereo demodulation when the AUTO mode is set in advance.

In addition, even if a monaural broadcast detection signal is input using AM, or even if an FM stereo broadcast station detection signal is input, AUTO
When set to mode off (MONORAL mode), the same monaural audio signal is output on the left and right.

The microcomputer 12 receives the MPX circuit 2 according to the mode designated by the user through the key operation unit 10 when receiving the FM band.
Controls ON / OFF switching of the AUTO mode for 0.

The audio signal output from the MPX circuit 20 is output to the amplifier side via the audio muting circuit 22.

Here, the tuning detection circuit 24 detects the presence or absence of tuning from the intermediate frequency signal of the tuning circuit 16 and outputs the detection signal to the microcomputer 12 and the MPX circuit 20.

When the frequency control data for the tuning circuit 16 is discontinuously changed at the time of band switching such as channel switching due to preset channel selection reception or AM to FM switching, the microcomputer 12 is only for a short time from the tracking delay of the PLL loop. While the reception frequency is changing, such as when the frequency is continuously changing, muting-on control is performed on the audio muting circuit 22, the audio signal is dropped to the ground, and a noise sound is output from the speaker. Prevent.

Then, when the change of the reception frequency is completed and fixed, the muting is released and the reception broadcast is output from the speaker.

The detection signal of the tuning detection circuit 24 is also input to the display drive circuit 26, and the tuning display 28 is turned on when the tuning is detected.

On the other hand, while the microcomputer 12 is receiving, the tuning circuit 16
Each time the frequency control data is changed, the frequency display data is output to the display drive circuit 30 and the frequency display 32 displays the received frequency.

When the user sets the AUTO mode on, the microcomputer 12 outputs an AUTO display lighting control signal to the display drive circuit 34 to light the AUTO display 36.

Further, the MPX circuit 20 has a function of detecting reception of a stereo broadcast, and when a stereo broadcast is detected in a state where the AUTO mode is set to ON, a stereo broadcast detection signal is output to the display drive circuit 38, and a stereo display is provided. 40 is turned on to indicate to the user that stereo reception is in progress.

When the tuning detection circuit 24 does not detect tuning even if the microcomputer 12 outputs a switching control signal for turning on the AUTO mode to the MPX circuit 20, the MPX circuit 20 is forced to follow the output of the tuning detection circuit 24. To AUTO
The mode is set to off so that stereo reception display cannot be accidentally displayed due to noise between stations.

[Problems to be solved by the device]

However, in the above-described conventional technique, when the frequency control data for the tuning circuit 16 is discontinuously changed such as preset channel selection reception and band switching, the reception frequency continuously changes within the FM band for a short time due to the tracking delay of the PLL loop. When doing, one or more FM stereo broadcasts may be caught.

At this time, the tuning detection circuit 24 outputs a detection signal to the MPX circuit 20 each time the tuning circuit 16 receives a station.

Therefore, when the user has previously set the AUTO mode ON and the microcomputer 12 has switched the MPX circuit 20 to the AUTO mode ON, the MPX circuit 20 is released from the compulsory MONORAL mode each time the tuning detection signal is input,
In addition, a stereo reception detection signal is displayed on the basis of the detected stereo broadcast signal input from the detection circuit 18, and the display drive circuit 38 is displayed.
And the stereo display 40 is turned on for a moment.

For this reason, the user may mistakenly recognize that the broadcast received after the reception frequency has been changed is stereo broadcast, and that the stereo reception display lights up when the received audio cannot be heard when muting is turned on, and the device may malfunction. There was a problem of misunderstanding.

Similarly, when the frequency control data for the tuning circuit 16 is changed discontinuously, one or a plurality of broadcasting stations may be caught when the reception frequency continuously changes for a short time due to the tracking delay of the PLL loop.

At this time, the tuning detection circuit 24 outputs a detection signal to the display drive circuit 26 every time the tuning circuit 16 receives a station, and the tuning display 28 is turned on for a moment.

Therefore, there is a problem that the user mistakenly recognizes that the station has been received after the completion of the change of the reception frequency, and that the received voice is not heard and the tuning display is turned on and the user thinks that the device is out of order.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object thereof is to eliminate misidentification and misunderstanding of the user caused by a display operation while the reception frequency is variable.

[Means for Solving the Problems]

In this invention, a PLL frequency synthesizer type tuning means for changing a reception frequency according to frequency control data, and the PL
P including stereo broadcast reception detection means for detecting reception of stereo broadcast by the L frequency synthesizer type tuning means, and stereo display means for performing stereo reception display when the stereo broadcast reception detection means detects reception of stereo broadcast.
In the LL frequency synthesizer type tuner, when the frequency control data is discontinuously changed due to the band switching operation or the preset tuning reception operation, the stereo on the stereo display means while the PLL loop of the PLL frequency synthesizer type tuning means is unstable. It is characterized in that a stereo display prohibiting means for prohibiting reception display is provided.

In addition, P that changes the reception frequency according to the frequency control data
In a PLL frequency synthesizer-type tuner including a LL frequency synthesizer type tuning means, a tuning detecting means for detecting the presence or absence of tuning, and a tuning display means for displaying tuning when the tuning detecting means detects tuning, band switching operation or When the frequency control data is discontinuously changed due to the preset channel selection receiving operation, a tuning display inhibiting means for inhibiting the tuning display on the tuning displaying means is provided while the PLL loop of the PLL frequency synthesizer type tuning means is unstable. It is characterized by that.

Further, the tuning display prohibiting means is characterized in that the tuning display is not prohibited to the tuning display means when the frequency control data is sequentially changed due to the manual scanning operation.

〔Example〕

 One embodiment of this invention will be described with reference to FIG.

FIG. 1 is a block diagram of a PLL frequency synthesizer type tuner according to the present invention.

A PLL frequency synthesizer type tuning circuit 52 is connected to the antenna 50, and the tuning operation is performed by varying the reception frequency according to frequency control data input from the outside.

A detection circuit 54 is connected to the output side of the tuning circuit 52 and performs detection based on the intermediate frequency signal output from the tuning circuit 52.

An MPX circuit 56 is connected to the output side of the detection circuit 54 and performs stereo or monaural demodulation based on the detection signal.

The MPX circuit 56 sets the AUTO mode ON or the AUTO mode OFF according to the AUTO mode ON / OFF control from the outside. When the stereo broadcast signal is input from the detection circuit 54 when the AUTO mode is ON, stereo demodulation is performed and left and right are separated. Output an audio signal.

Conversely, when the AUTO mode is off or when the monaural broadcast signal is input even when the AUTO mode is on, monaural demodulation is performed and the same audio signal is output on the left and right.

The audio signal output side of the MPX circuit 56 is connected to an amplifier (not shown) via an audio muting circuit 58.

The audio muting circuit 58 turns muting on and off according to muting control from the outside, outputs the audio signal to the amplifier side and outputs it from the speaker when it is off, and conversely when the muting is on, sends the audio signal to ground. Stop audio output from the drop speaker.

The MPX circuit 56 has a function of detecting the presence or absence of stereo reception based on the input from the detection circuit 54, and when stereo reception is detected when the AUTO mode is on, it outputs a stereo detection signal.

The display drive circuit 60 is connected to the stereo reception detection signal output side of the MPX circuit 56, and when the stereo reception detection signal is input, the stereo display 62 connected to the output side is turned on to indicate that stereo reception is being performed. Display it.

A tuning detection circuit 64 is connected to the tuning circuit 52,
The presence or absence of tuning is detected from the intermediate frequency signal and output as a tuning detection signal.

A display drive circuit 66 is connected to the output side of the tuning detection circuit 64, and when a tuning detection signal is input, a tuning display 68 connected to the output side is turned on to indicate that tuning is in progress for a certain broadcast. Let

For the tuning circuit 52, the MPX circuit 56, the audio muting circuit 58, and the tuning detection circuit 64, the microcomputer 7 is used.
0 is connected, and a control output and a detection signal input are made.

A key operation unit 72 is connected to the input side of the microcomputer 70, and a key operation signal corresponding to a user's key operation is input.

Display drive circuits 74 and 78 are connected to the display output side of the microcomputer 70.
Receives the frequency display data from the microcomputer 70, drives the frequency display 76 connected to the output side to display the received frequency, while the display drive circuit 7
8 is an AUTO display 80 connected to the output side when an AUTO display lighting control signal is input from the microcomputer 70.
Is lit to indicate that the AUTO mode is set to ON.

The microcomputer 70 is a bus-connected CPU, R
Includes OM and RAM, tuning control according to user's key operation based on a predetermined program stored in ROM, AUTO
Mode on / off switching control, muting control,
Receive frequency display control, AUTO display control, etc. are executed.

The RAM has a frequency memory area for preset reception and the last frequency data D used for the last reception for each band.
_LAM , DL _FM, and the last area for storing the last band data B indicating the last received band, AUTO flag indicating ON / OFF of the AUTO mode set by the user's key operation, timer T1 before PLL data switching, PLL Each area for storing the timer T2 after data switching is provided.

Frequency data and band data are stored in the frequency memory area for each channel.

When the AUTO flag is "H", the AUTO mode is on, "L"
Indicates that the AUTO mode is off, the timer T1 before switching PLL data is 50 ms, and the timer T2 after switching PLL data is 5
00 ms is the timekeeping time.

Next, the operation of this embodiment will be described with reference to the flow charts of FIGS.

When the power is turned on, the microcomputer 70 performs a predetermined initialization process, refers to the last band data B, and checks the band that was received immediately before the power was turned off. For example, when B is AM, the last area The PLL circuit of the tuning circuit 52 (not shown) using the frequency data DL _B = DL _AM received last time relating to the AM in the middle as frequency control data.
To the station immediately before the power was turned off last time.

At this time, the microcomputer 70 creates frequency display data based on the frequency control data and outputs it to the display drive circuit 74 to cause the frequency display 76 to display the received frequency.

Further, the audio muting is turned off and the broadcast of the receiving station is output to the speaker (step 100).

When the station is received with this initial setting, the tuning detection circuit 64 detects this and outputs a tuning detection signal to the display drive circuit 66.

The display drive circuit 66 is energized by the tuning detection signal input to turn on the tuning indicator 68 to indicate that it is in the tuning state. Specifically, for example, the character display of <TUNED> is displayed.

After the initial setting, the microcomputer 70 operates the key operation unit 7
The input from 2 is checked to determine whether or not there is a key changed from off to on by the user's on operation (step 102), and the user has not operated the key yet and NO.
If either the timer T1 before switching PLL data or the timer T2 after switching PLL data is operating, the count is advanced at a predetermined timing (step 10).
4).

In this case, since neither timer T1 or T2 is in operation yet, the microcomputer 70 does not perform the processing of step 104, and then either the pre-PLL data switching timer T1 or the post-PLL data switching timer T2 respectively has a predetermined time count. After confirming that the clocking completion state of 50 ms and 500 ms is not completed (steps 106 and 108), the process proceeds to step 110 and refers to the AUTO flag to check whether the ON / OFF of the AUTO mode set by the user immediately before the power-off last time. For example, if the AUTO flag is "L", a turn-off control signal is output to the display drive circuit 78 to turn off the AUTO display 80 to indicate that the user's setting is the AUTO mode off (step 112).

Then, the microcomputer 70 confirms that both the pre-PLL data switching timer T1 and the post-PLL data switching timer T2 are stopped (step 114), and further confirms that the AUTO flag is "L". (Step 116), the AUTO mode off control signal is output to the MPX circuit 56 to set the AUTO mode off (step 118).

Therefore, there is no stereo reception detection signal output from the MPX circuit 56 to the display drive circuit 60, and the stereo display 62 is turned off.

After the processing of step 118, the microcomputer 70
Returns to the first step 102 and waits for a user's key operation.

When the user turns on the band switching key to listen to the FM station, the microcomputer 70 changes the last band data B to FM after judging YES in steps 102 and 120 (122).

Next, the microcomputer 70 sets the PLL data pre-switching timer T1 to start the time counting operation (step 124), and outputs the audio muting-on control signal to the audio muting circuit 58 for muting (step 126). .

Then, the count of the pre-PLL data switching timer T1 that is in operation is advanced at a predetermined timing (104), and it is confirmed that the timer T1 has not yet completed the clocking of 50 ms (step 106), and the PLL data switching is performed. After confirming that the rear timer T2 has not finished timing (step 108), the AUTO display remains off (step 1).
If it is OFF at 10 and 112), the pre-PLL data switching timer T1 is operating, so the MPX circuit 56 is left in the AUTO mode OFF (YES at step 114, 1)
18).

In this way, muting is turned on and the MPX circuit 56 is turned on.
By holding the in the MONORAL mode, the frequency change preparation is completed.

Next, the microcomputer 70 advances the count of the pre-PLL data switching timer T1 at a predetermined timing.
Wait until the time of 50 ms is finished (steps 104, 10)
6) When the timer T1 before switching the PLL data has completed counting the time of 50 ms, it is judged YES in step 106, and then the time counting operation of the timer T1 before switching the PLL data is stopped (step 128), and then the timer after switching the PLL data. Set T2 to start the timing operation (step 1
30) and referring to the last band data B, the last frequency data DL _B = D relating to the FM in the last area
The L _FM is read out and output as frequency control data to the PLL circuit of the tuning circuit 52 (step 132), and frequency display data corresponding to this frequency control data is created and output to the display drive circuit 74 for frequency display ( Step 134).

The tuning circuit 52 changes the reception frequency so that the PLL loop follows the new frequency control data.

At this time, there is a delay in the tracking operation of the PLL loop, and the reception frequency continuously changes for a short time from the frequency of the AM station that has been received so far to the frequency of the FM station that is newly set this time, and during that time. If there is an AM station or FM station, it will be received instantly.

For this reason, the microcomputer 70 executes the step 13
After the processing of 2134, the voice muting is kept on and the AUTO mode is kept off until 500 ms elapses while the count of the timer T2 is advanced after switching the operating PLL data (steps 104, 108).

Here, the time measured by the timer T2 after switching the PLL data is 500
The reason for setting to ms is to secure a sufficient time for the PLL loop to stabilize at a new frequency after changing the frequency control data.

Further, the reason why the voice muting is turned on and the AUTO mode is turned off 50 ms before the frequency control data is changed is to prevent a malfunction of the MPX circuit 56 due to noise sound or noise generated at the moment of change.

In this way, the voice muting is turned on for a period including the time when the PLL loop is destabilized by the change of the frequency control data. Therefore, a certain station is received while the reception frequency is being changed and the voice is output from the MPX circuit 56. Even if a signal is output, it is not output from the speaker and, of course, no noise sound between stations is uttered.

Further, since the MPX circuit 56 is held in the AUTO mode off for the same period, a certain stereo broadcast station is received while the reception frequency is being changed, and the received signal is the MPX circuit 5.
The stereo reception detection signal is not output even when the stereo reception detection signal is input to 6, thus preventing an erroneous stereo reception display.

After that, when the timer T2 after switching the PLL data completes the time measurement of 500 ms, it is determined YES in step 108, and then the time counting operation of the timer T2 after switching the PLL data is stopped (step 136), and the audio muting-off control signal is output. The signal is output to the muting circuit 58 to cancel the muting (step 138).

As a result, the broadcast of the last received station in the FM band is output from the speaker.

Since the AUTO flag is "L", the microcomputer 70 keeps the AUTO mode display off after the timer T2 has finished counting 500 ms after switching the PLL data.
In addition, the AUTO mode off control is also performed on the MPX circuit 56 (OFF determination at step 110, NO at 112 and 114, OFF determination at 116, 118).

When the user turns on the stereo / mono switching key (AUTO mode on / off switching key) for listening in stereo, the microcomputer 70 causes the step 70 to proceed.
After determining YES in steps 140 and 140, the AUTO flag is inverted to "H" (step 142).

Then, referring to the AUTO flag, a lighting control signal is output to the display drive circuit 78 to light the AUTO display 80 to indicate that the user's setting is the AUTO mode ON (judgment of ON in step 110, step 144). . For example <AUTO
The character> is displayed.

Further, the microcomputer 70 sets the MPX circuit 56 to AUTO.
A mode-on control signal is output to set the AUTO mode on (NO in step 114, ON in step 116, 146).

Therefore, if the receiving station is broadcasting in stereo, the MPX circuit 56
Outputs a stereo reception detection signal to the display drive circuit 60,
The stereo display 62 is turned on to display the stereo reception state. For example, <STEREO> is displayed.

At this time, the MPX circuit 56 outputs left and right stereo audio signals, and the speaker outputs stereo sound.

If the receiving station changes to monaural broadcasting, the MPX circuit 56
The stereo reception detection signal output from stops and the stereo display disappears. Also, a monaural audio signal is output from the MPX circuit 56, and a monaural audio is output from the speaker.

In this way, since the user changes from a receiving state of a certain stereo broadcast to another FM station, when a certain channel designation key is turned on, the microcomputer 70 determines YES in steps 102 and 148, and then, for example, 3 channels. When the key related to is operated, band data of three channels (here, FM
And the frequency data is read, and the last band data B is rewritten by the former and the last frequency data DL _FM related to this B is rewritten by the latter (step 15).
0).

Then, in the same manner as described above, the microcomputer 70 first sets the PLL data pre-switching timer T1 to start the timing operation, turns on the audio muting, and performs the AUTO mode off control on the MPX circuit 56 to forcibly. Set to MONORAL mode (step 12)
NO judgment in 4, 126, 104, 106 and 108, 1
10: ON judgment, 144, 114: YES judgment, 1
18).

By doing this, if you were receiving a stereo broadcast until then,
The stereo reception detection signal output from the MPX circuit 56 stops and the stereo reception display disappears.

When 50 ms has elapsed after the PLL data pre-switching timer T1 was set, the microcomputer 70 stops the PLL data pre-switching timer T1 and sets the PLL data post-switching timer T2 to start the time counting operation to set the last frequency data DL relating to B. _{The FM} is read and output as frequency control data to the tuning circuit 52 to change the reception frequency, and the corresponding frequency display data is output to the display drive circuit 74 to change the display of the reception frequency (YES in step 106). (Judgment, 128 to 134), and continues the audio muting ON and AUTO mode OFF control for the MPX circuit 56 until 500 ms has elapsed (NO judgment in step 108, ON judgment in 110, Y in 144, 114).
ES judgment, 118).

And 500m after setting timer T2 after switching PLL data
When s has elapsed, the microcomputer 70 stops the timer T2 after switching the PLL data, cancels the voice muting (determines YES in step 108,
136, 138), since the AUTO flag is "H", the AUTO mode ON control is performed on the MPX circuit 56 to restore the original state (NO in step 114, ON determination in 116, 146).

As a result, the reception state of the FM station related to channel 3 is switched to, and stereo reproduction sound is output from the speaker and the stereo display is turned on during stereo broadcasting.

In this way, even when the reception frequency is changed by the preset reception, the voice muting is turned on for a period including a time period during which the PLL loop of the tuning circuit 52 is destabilizing by following the new frequency control data. Since a certain station is received while the reception frequency is changing, MP
Even if an audio signal is output from the X circuit 56, it is not output from the speaker and, of course, no noise sound between stations is uttered.

Further, since the MPX circuit 56 is held in the AUTO mode off for the same period, a certain stereo broadcast station is received while the reception frequency is being changed, and the received signal is the MPX circuit 5.
The stereo reception detection signal is not output even when the stereo reception detection signal is input to 6, thus preventing an erroneous stereo reception display.

According to this embodiment, when the frequency control data for the tuning circuit 52 is discontinuously changed due to the band switching operation or the preset channel selection receiving operation, the MPX circuit 56 is changed from 50 ms before the change to 500 ms after the change. Force M
By setting to ONORAL mode, tuning circuit 52
The loop loop becomes unstable due to the tracking operation of the PLL loop, and some non-target stereo broadcasts are performed while the tuning frequency continuously changes from the frequency that was received until then to the newly changed frequency. Even when receiving, the stereo reception display can be prohibited so that the user does not mistakenly recognize that the target station is in stereo broadcasting, and that the stereo reception display blinks and is not mistaken for a device failure.

Also, the MPX circuit 56 is forcibly linked with the voice muting control that is performed when changing the frequency control data.
On the other hand, since the AUTO mode off control is performed, the processing by the microcomputer 70 can be simply performed.

In the above embodiment, before changing the frequency control data, 50
The period from ms to 500 ms is set as a period during which the PLL loop becomes unstable and the reception frequency continuously changes, and the MPX circuit 56 is forcibly set to the MONORAL mode during this period. When the circuit has a function of outputting a lock signal, the unlock period accompanying the change of the frequency control data is detected from this signal, and the display drive circuit 60 is forcibly turned off during this unlock period. May be.

Further, as shown in FIG. 4, the microcomputer 70A
Does not perform direct ON / OFF control of the MPX circuit 56 in the AUTO mode (that is, steps 114 to 1 in FIG. 3).
18 and 146 are omitted), the user's stereo /
The logic of the AUTO mode display control signal corresponding to the mono switching key operation and the voice muting control signal for the voice muting circuit 58 is taken as the ON / OFF control signal of the AUTO mode for the MPX circuit 56, and the voice muting control is performed. Only when it is off (the voice muting control signal is “L” in FIG. 4) and the lighting control of the AUTO mode is performed (the AUTO display control signal is “H” in FIG. 4), the AUTO mode on control is performed. This may be done (in FIG. 4, the AUTO mode on / off control signal is “L”).

Next, another embodiment according to the present invention will be described with reference to FIG.

The embodiment of FIG. 1 shows an example of eliminating the erroneous display of stereo reception when the frequency is changed, while FIG. 5 shows the case of eliminating the erroneous display of tuning when the frequency is changed.

FIG. 5 is a block diagram of a PLL frequency synthesizer tuner according to another example of the present invention.

However, the same components as those in FIG. 1 are designated by the same reference numerals.

The MPX circuit 56B is always set to the AUTO mode for simplicity. When the stereo broadcast signal after detection is input from the detection circuit 54, the left and right stereo audio signals are output to the amplifier side via the audio muting circuit 58. At the same time, the stereo reception detection signal is output to the display drive circuit 60.

Conversely, when a monaural broadcast signal is input from the detection circuit 54, the same left and right monaural audio signals are output and the stereo reception detection signal output is turned off.

The tuning detection signal of the tuning detection circuit 64 is output only to the microcomputer 70B.
Synchronous display control is performed by 0B.

The key operation unit 72B is provided with a band switching key, a channel designation key, and a manual frequency up / down key.

The microcomputer 70B follows a predetermined program stored in the ROM and performs tuning control on the tuning circuit 52 and a voice muting circuit 58 according to a user's key operation.
To the display drive circuit 74, and the tuning display control to the display drive circuit 66B according to the tuning detection signal input.

However, when the frequency control data for the tuning circuit 52 is changed by band switching, preset channel selection reception, etc., except for the manual scan by continuously pressing the frequency up / down key, the microcomputer 70B uses the PL
While the reception frequency is continuously changing for a short time by the follow-up operation of the L loop, the tuning indicator 6 is displayed even if the tuning detection signal is input.
It is designed not to turn on 8.

In the RAM of the microcomputer 70B, a frequency memory area for preset reception, a last area for storing last frequency data DL _AM , DL _FM used for the last reception for each band, and last band data B indicating the last received band, SCAN flag indicating whether scanning is in progress, PLL
Areas for storing a timer before data switching T1, a timer after switching PLL data T2, a frequency scan timer T3, and the like are provided.

Frequency data and band data are stored in the frequency memory area for each channel.

When the SCAN flag is “H”, it indicates that scanning is in progress, and when it is “L”, it indicates that scanning is stopped. The timer T1 before switching PLL data is 50 ms, and the timer T2 after switching PLL data is 500 m.
s, the frequency scan timer T3 has a measuring time of 140 ms.

The other components shown in FIG. 5 are constructed in the same manner as in FIG.

Next, the operation of this embodiment will be described with reference to the flow charts of FIGS.

When the power is turned on, the microcomputer 70B performs a predetermined initialization process, refers to the last band data B, and confirms the band that was received immediately before the power was turned off. For example, when B is AM, the last area The last received frequency data DL _AM relating to the AM inside is output to a PLL circuit (not shown) of the tuning circuit 52 as frequency control data, and the reception frequency is adjusted to the station immediately before the power-off.

At this time, the microcomputer 70 creates frequency display data based on the frequency control data and outputs it to the display drive circuit 74 to cause the frequency display 76 to display the received frequency.

Further, the audio muting is turned off, the broadcast of the receiving station is output to the speaker, and the SCAN flag is turned off to "L" (step 200).

When a station is received with this initial setting, the tuning detection circuit 64 detects it and sends a tuning detection signal to the microcomputer 70.
Output to B.

After the initial setting, the microcomputer 70B checks the input from the key operation unit 72B and determines whether or not there is a key changed from off to on by the user's on operation (step 2).
02), it is determined whether or not there is a key whose user releases the key and changes from on to off (step 20).
4), the user has not operated any keys yet and both are NO
In case of, the timer T1 before switching PLL data, the timer T2 after switching PLL data, or the frequency scan timer T
If any of the three is operating, the count is advanced at a predetermined timing (step 206).

In this case, since none of the timers T1, T2 and T3 is operating, the microcomputer 70B executes the step 20.
6 is not performed, and then either the pre-PLL data switching timer T1, the post-PLL data switching timer T2, or the frequency scan timer T3 is set to a predetermined clock time 50.
After confirming that the time measurement is not completed in ms, 500 ms, and 140 ms (steps 208, 210, 212), the process proceeds to step 214 and the SCAN flag is confirmed.

In this case, since it is turned off, it is next confirmed that both the timer T1 before switching PLL data and the timer T2 after switching PLL data are stopped (step 21).
6) The input from the tuning detection circuit 64 is checked (step 218), and if the tuning is detected, the tuning display lighting control signal is output to the display drive circuit 66B (step 22).
0).

The display drive circuit 66B is energized by the tuning display lighting control signal input to turn on the tuning indicator 68 to indicate that it is in the tuning state. Specifically, for example, the character display of <TUNED> is displayed.

After the processing of step 220, the microcomputer 70
B returns to the first step 202 and waits for a user's key operation.

Here, when the user turns on the band switching key to listen to the FM station, the microcomputer 70B determines YES in steps 202 and 222, and then changes the last band data B to FM (224).

Next, the microcomputer 70B sets the PLL data pre-switching timer T1 to start the time counting operation (step 226) and outputs the audio muting-on control signal to the audio muting circuit 58 for muting (step 228). ).

Then, the count of the pre-PLL data switching timer T1 that is in operation is advanced at a predetermined timing (206), and it is confirmed that the timer T1 has not completed the time measurement of 50 ms (step 208), and the PLL data switching is performed. After confirming that neither the rear timer T2 nor the frequency scan timer T3 has completed time counting (NO in steps 210 and 212).
No.), the SCAN flag is off and the pre-PLL data switching timer T1 is operating. Therefore, the tuning display lighting control signal for the display drive circuit 66B is turned off regardless of whether or not tuning is detected (turned off in step 214). Judgment,
If YES in 216, 230).

This forces the tuning display to go out.

In this way, the muting is turned on and the tuning display is turned off to complete the frequency change preparation.

Next, the microcomputer 70B waits for the completion of the time measurement of 50 ms while advancing the count of the pre-PLL data switching timer T1 at a predetermined timing (steps 206, 2).
08), when the PLL data pre-switching timer T1 has completed the time measurement of 50 ms, it is judged YES in step 208, and then the time counting operation of the PLL data pre-switching timer T1 is stopped (step 232), and the SCAN flag is turned off. After switching the PLL data, the timer T2 is set to start the time counting operation (determination of OFF in step 234, 23
6) In addition, referring to the last band data B, the last frequency data DL _FM relating to the FM in the last area is read out and output as frequency control data to the PLL circuit of the tuning circuit 52 (step 238). Frequency display data corresponding to the data is created and output to the display drive circuit 74 to display the frequency (step 2
40).

The tuning circuit 52 changes the reception frequency so that the PLL loop follows the new frequency control data.

At this time, there is a delay in the tracking operation of the PLL loop, and the reception frequency continuously changes for a short time from the frequency of the AM station that has been received so far to the frequency of the FM station that is newly set this time, and during that time. If there is an AM station or FM station, it will be received instantly.

Therefore, the microcomputer 70B causes the step 23
After the processing of 8 and 240, the voice muting is on and the tuning display lighting control signal is kept off until 500 ms elapses while the count of the timer T2 is advanced after the switching of the operating PLL data (steps 206 and 210).

In this way, the voice muting is turned on during a period including the time when the PLL loop is destabilized due to the change of the frequency control data to prevent the utterance of noise noise, and the tuning display is forced during the same period. Since it is turned off, the tuning detection circuit 6 receives a certain station while the reception frequency is being changed.
Even if 4 outputs the tuning detection signal, the tuning display does not light up, and thus false tuning display is prevented.

After that, when the timer T2 after switching the PLL data completes the time measurement of 500 ms, it is determined YES in step 210, and then the time counting operation of the timer T2 after switching the PLL data is stopped (step 242), and if the SCAN flag is on. This is turned off (step 244), and the audio muting-off control signal is output to the audio muting circuit 58 to cancel the muting (step 246).

As a result, the broadcast of the last received station in the FM band is output from the speaker.

And the SCAN flag is "L" off, and
After the timer T2 after the switching of the PLL data has completed the time measurement of 500 ms, both the timer T1 before the switching of the PLL data and the timer T2 after the switching of the PLL data are stopped, so that the microcomputer 70B follows the input from the tuning detection circuit 64. When the tuning is detected, the tuning display lighting control signal is output to the display drive circuit 66B to perform the tuning display (determination of OFF in step 214, determination of NO in 216, determination of YES in 218, 220).

After that, if the tuning is no longer detected due to bad radio conditions, the microcomputer 70B turns off the tuning display lighting control signal output and turns off the tuning display, and if the radio conditions improve and tuning is detected again, tuning is performed. Turn on the display.

In this way, since the user changes from receiving a certain broadcast to another station, when a certain channel designation key is turned on, the microcomputer 70B causes the step 2
After determining YES in 02 and 248, for example, when the key for channel 5 is operated, the band data (here, FM) and frequency data of channel 5 are read from the frequency memory area, and the last band is the last band. While rewriting the data B, the last frequency data DL _FM related to this B is rewritten by the latter (step 25).
0).

Then, in the same manner as described above, the microcomputer 70B
First sets the PLL data pre-switching timer T1 to start the timekeeping operation, turns on the audio muting, and controls the display drive circuit 66B to turn off the synchronized display (NO in steps 226, 228, and 204). Judgment, 206, 208, 210, 212 NO judgment, 2
14 turns off, 216 turns YES, 230).

As a result, if a station has been tuned until then, the tuning display on the tuning display 68 disappears.

When 50 ms has elapsed after setting the timer T1 before switching PLL data, the microcomputer 70B stops the timer T1 before switching PLL data, confirms that the SCAN flag is on, and sets the timer T2 after switching PLL data. The timekeeping operation is started, the last frequency data DL _FM relating to B is read out, output as frequency control data to the tuning circuit 52 to change the reception frequency, and the corresponding frequency display data is output to the display drive circuit 74. The display of the reception frequency is changed (YES in step 208, 232 to 240), and voice muting is turned on and tuning display turn-off control is continued until 500 ms has elapsed (NO in steps 210 and 212, 214). OFF judgment, YES judgment in 216, 230).

And 500m after setting timer T2 after switching PLL data
At the time when s has elapsed, the microcomputer 70B is set to the PLL
After data switching, the timer T2 is stopped to cancel the voice muting (YES in step 210, 242, 246), the SCAN flag is “L”, and PL
Since both the timer T1 before switching the L data and the timer T2 after switching the PLL data are stopped, the tuning display control is performed according to the input from the tuning detection circuit 64 (determination of OFF in step 214, determination of NO in 216, 218, 2
20 or 230).

As a result, the reception state of the FM station for channel 5 is switched to, if tuning is detected, the tuning display is lit, and if stereo broadcasting is in progress, stereo playback sound is output from the speaker and the stereo display is lit. .

In this way, even when the reception frequency is changed by the preset reception, the voice muting is turned on for a period including a time period during which the PLL loop of the tuning circuit 52 makes a follow-up operation to new frequency control data and becomes unstable. At the same time, since the display drive circuit 66B is controlled to turn off the tuning display, the tuning display lighting control signal is output even if a certain station is received while the reception frequency is being changed and the tuning detection circuit 64 detects tuning. Not, thus preventing false tuning indications.

It should be noted that when the user turns on the frequency up key to perform a manual scan while receiving the station related to channel 5, the microcomputer 70
B determines YES in steps 202 and 252,
Invert the SCAN flag to turn on "H" (step 25
4) Then, the process proceeds to step 226, the timer T1 before switching the PLL data is set to start the time counting operation, and the voice muting is turned on (step 22).
8).

Since the frequency up key has just been turned on, the determination in step 204 is NO, and the count of the pre-PLL data switching timer T1 is advanced at a predetermined timing (step 206). Since neither timer has completed timing, steps 208 and 210 are performed. , 212, and since the SCAN flag is on, forced tuning display turn-off control is not carried out (judgment of on at step 214, 218, 220 or 230).

In this case, if the tuning of the receiving station from which the voice was heard until then is still detected, the tuning display remains lit.

50ms after setting timer T1 before switching PLL data
When the time elapses, the microcomputer 70B executes step 2
When YES is determined in 08, the timer T before switching the PLL data
Since the SCAN flag is on after stopping 1, refer to B and last frequency data DL used up to that point
_{The FM} is increased by a predetermined frequency unit with respect to the FM band, the frequency scan timer T3 is further set, and the time counting operation is started (YES in steps 232 and 234, 256 and 258).

Then, the last frequency data DL _FM indicated by B is output to the tuning circuit 52 as frequency control data to set the reception frequency to 1
The frequency is increased by a unit (step 238), and frequency display data corresponding to this frequency control data is created and output to the display drive circuit 74 to change the frequency display (step 240).

Then, waiting for 140 ms to elapse while advancing the count of the frequency scan timer T3 (steps 206 and 21).
2).

During this time, by changing the frequency control data by one unit, the reception frequency of the tuning circuit 52 continuously changes from the frequency until then to the newly set frequency according to the tracking operation of the PLL loop. When the tuning of the station that has been used is lost, the tuning detection signal output from the tuning detection circuit 64 stops.

Microcomputer 7 when SCAN flag is on
0B performs tuning display control according to the input from the tuning detection circuit 64, and when tuning detection stops, the tuning display lighting control signal is turned off and the tuning display is turned off (determination of ON in step 214, determination of NO in 218). , 230).

Then, after setting the frequency scan timer T3, 14
When 0 ms has elapsed and the reception frequency has increased by approximately 1 unit,
The microcomputer 70B returns YES in step 212.
To judge.

Then, referring to B, the last frequency data DL _FM is further 1
The frequency is increased by a unit, the data DL _FM is output to the tuning circuit 52 as frequency control data to further increase and change the reception frequency by one unit (steps 260 and 262), and the frequency corresponding to the frequency control data. Display data is created and output to the display drive circuit 74 to change the frequency display (step 264).

Further, the frequency scan timer T3 is reset and the time counting operation is started (step 266).

Then, while the count of the frequency scan timer T3 is advanced again, it waits until 140 ms has elapsed (steps 206, 2).
12).

As a result, the reception frequency is continuously increased by one unit in accordance with the tracking operation of the PLL loop.

Hereinafter, as long as the user turns on the frequency up key, the microcomputer 70B repeats the same processing, and continuously updates the reception frequency while updating the frequency control data to be given to the tuning circuit 52 by one unit every time a fixed time elapses. (YES determination in steps 206 and 212, 260 to 266).

If there is a receiving station during this period and the tuning detection circuit 64 detects tuning, the microcomputer 70B is energized by the tuning detection signal input to perform tuning display lighting control and turn on the tuning display (determination of ON in step 214, YES at 218
No., 220).

When the reception frequency deviates from the station and the tuning is no longer detected, the microcomputer 70B stops the tuning display lighting control and turns off the tuning display (NO determination in step 218, 230).

As a result, the user can confirm the reception of the station by looking at the tuning display 68.

However, since voice muting is applied during such frequency scanning, no inter-station noise or received broadcast is heard.

When the user determines that the reception frequency near the desired station has been reached by looking at the frequency display or tuning display, and the frequency up key is released, the microcomputer 70B determines YES in steps 204 and 268, and then performs the frequency scan. The timer T3 is stopped (step 270), and after the PLL data is switched, the timer T2 is set to start the time counting operation (step 272).

The change of the frequency control data ends when the frequency scan timer T3 is stopped (NO in step 212).

After that, the microcomputer 70B waits until 500 ms elapses while advancing the count of the timer T2 after switching the PLL data (steps 206 and 210), and 500 ms, which is sufficient for stabilizing the reception frequency, has elapsed since the frequency control data was last updated. If yes in step 210
After switching the PLL data, the timer T2 stops the time counting operation, turns off the SCAN flag to "L", and finally cancels the audio muting (steps 242-24).
6).

In this way, when the scanning is completed, if there is a receiving station, its audio signal is heard from the speaker and the tuning display lights up.

If there is no receiving station, no audio signal will be heard and the tuning display will not light.

At this time, the frequency up / down key may be operated again to change the reception frequency.

According to this embodiment, when the frequency control data for the tuning circuit 52 is discontinuously changed in accordance with the band switching operation or the preset channel selection receiving operation, from 50 ms before the change to after the change.
By forcibly turning off the tuning display until 500 ms has elapsed, the loop becomes unstable due to the tracking operation of the PLL loop of the tuning circuit 52, and the tuning frequency is changed from the frequency received up to that point. The tuning display can be prohibited even if some non-target stations receive broadcasts while the frequency changes continuously, and the user may mistakenly think that the target station has been caught or the tuning display You don't have to confuse it with the blinking of the item because it is a device failure.

In addition, since the tuning display extinction control is forcibly performed on the display drive circuit 66B by interlocking with the audio muting control performed when changing the frequency control data except during the manual scan, the microcomputer 70B is controlled. Processing is easy.

Furthermore, when the frequency control data is continuously and continuously changed due to the manual scan operation, the forced tuning display turn-off control is not performed, so if there is a receiving station during scanning, visually check from the tuning display. This is convenient for the user.

Further, conventionally, the detection output of the tuning detection circuit 24 is directly input to the display drive circuit 26 as shown in FIG. 9, and the display drive circuit 26 is used as a measure against the momentary display of the tuning display when the frequency control data is changed. 10 and the capacitor C is provided on the input side of the tuning detection signal to deteriorate the response to the signal.

However, according to this embodiment, it is not necessary to provide the capacitor C, and good responsiveness can be secured.

Further, since the microcomputer 70B controls the synchronized display, the structure of the display drive circuit can be simplified by dynamically displaying the synchronized display, the frequency display, and the like.

In the embodiment of FIG. 5 described above, the period from 50 ms before the frequency control data is changed to 500 ms after the frequency control data is set as the period during which the PLL loop is unstable and the reception frequency is continuously changed. When the PLL circuit has a function of outputting a lock signal, an unlock period due to the change of the frequency control data is detected from this signal, and the display drive circuit 66B is forcibly turned off during this unlock period. You may

[Effect of device]

In the PLL frequency synthesizer tuner according to the present invention, when the frequency is changed due to the band switching operation or the preset tuning reception operation, the stereo reception display on the stereo display means is performed while the PLL loop of the PLL frequency synthesizer tuning means is unstable. By prohibiting it, unnecessary stereo display during the change of the reception frequency caused by the tracking delay of the PLL loop is eliminated, the user mistakenly recognizes that the target station is in stereo broadcasting, and the stereo display blinks It is possible to prevent misunderstanding that it is a malfunction of.

Further, when the frequency is changed due to the band switching operation or the preset channel selection receiving operation, while the PLL loop of the PLL frequency synthesizer type tuning means is unstable, the tuning display on the tuning display means is prohibited, so that the tracking delay of the PLL loop is delayed. By eliminating unnecessary tuning display during the change of the reception frequency caused by, the user may mistakenly think that there is a receiving station at the changed frequency, or mistakenly think that the device is broken by blinking the tuning display. Can be prevented.

Furthermore, by not prohibiting the tuning display when the frequency is sequentially changed due to the manual scan operation, the tuning display is ensured during the frequency change by the manual scan, and the user can visually check the reception of the station. effective.

[Brief description of drawings]

FIG. 1 is a block diagram of a PLL frequency synthesizer tuner according to an embodiment of the present invention, FIGS. 2 and 3 are flow charts showing the operation of the microcomputer shown in FIG. 1, and FIG. 4 is FIG. FIG. 5 is a block diagram showing a modification of the present invention, FIG. 5 is a block diagram of a PLL frequency synthesizer tuner according to another embodiment of the present invention, and FIGS. 6 to 8 are flow charts showing the operation of the microcomputer in FIG. FIG. 9 is a block diagram of a conventional PLL frequency synthesizer tuner, and FIG. 10 is a circuit diagram showing an example of a display driver circuit for tuning shown in FIG. 52 ... Tuning circuit, 56 ... MPX circuit, 60, 66B ... Display drive circuit, 62 ... Stereo display, 64 ... Tuning detection circuit, 68 ... Tuning display, 70, 70A, 70B ... Micro Computer.

Continuation of the front page (56) Reference JP-A-59-80016 (JP, A) JP-A-56-104525 (JP, A) JP-A-58-20038 (JP, A) JP-A-59-189732 (JP , A) Actual Development Sho 57-62437 (JP, U) Japanese Patent Sho 62-35287 (JP, B2)

Claims (3)

[Scope of utility model registration request] 1. A PLL frequency synthesizer type tuning means for changing a reception frequency according to frequency control data, and the PLL.
PL including stereo broadcast reception detection means for detecting reception of stereo broadcast by the frequency synthesizer type tuning means, and stereo display means for performing stereo reception display when the stereo broadcast reception detection means detects reception of stereo broadcast
In the L frequency synthesizer tuner, when the frequency control data is discontinuously changed due to the band switching operation or the preset channel selection receiving operation, the stereo on the stereo display means while the PLL loop of the PLL frequency synthesizer tuning means is unstable. A PLL frequency synthesizer-type tuner characterized by comprising a stereo display prohibition means for prohibiting reception display. 2. A PLL frequency synthesizer type tuning means for changing a reception frequency according to frequency control data, a tuning detecting means for detecting the presence or absence of tuning, and a tuning display means for performing tuning display when the tuning detecting means detects tuning. PL including and
In the L frequency synthesizer type tuner, when the frequency control data is discontinuously changed due to the band switching operation or the preset channel selection receiving operation, tuning is performed by the tuning display means while the PLL loop of the PLL frequency synthesizer type tuning means is unstable. A PLL frequency synthesizer-type tuner characterized in that a tuning display prohibiting means for prohibiting display is provided. 3. The PLL according to claim 2, wherein the tuning display prohibiting means does not prohibit the tuning display means from tuning display when the frequency control data is sequentially changed due to the manual scanning operation. Frequency synthesizer tuner.