JPS6030449B2 - Receiving machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiver capable of performing automatic channel selection, preset channel selection, manual channel selection, etc. as a method of selecting a broadcast station.

Conventionally, as this type of receiver, a so-called synthesizer tuner that obtains a local oscillation frequency using a synthesizer method has been provided.

As is well known, a synthesizer tuner consists of a voltage controlled oscillator (VCO) as a local oscillator, and divides the output signal of the voltage controlled oscillator at a frequency of 1/N using a frequency divider.
The phase of this frequency-divided signal of frequency 〆o/N is compared with the reference signal of frequency 〆ref, and a voltage corresponding to the phase shift difference is applied as a control signal to the voltage controlled oscillator, thereby dividing the local oscillation frequency ``o''. Frequency ratio N and reference signal frequency 〆r
The system is designed to stabilize the frequency N・NA which is the product of ef (the system for obtaining the local oscillation output is configured with a phase-locked loop), and by changing the minute ratio N o is the frequency na of the reference signal r
The frequency interval corresponding to ef is changed, for example, at an interval of 100 kHz, and thereby the reception frequency is changed at 100 kHz to perform channel selection. In such a synthesizer tuner, the frequency divider is constituted by a programmable counter, and the division ratio N is scanned by automatically scanning the numerical value of the channel selection signal, that is, the program input signal that determines the preset value of the counter. This makes it possible to automatically change the reception frequency at predetermined frequency intervals and perform automatic channel selection.

Furthermore, by storing the tuning signal in a memory, reading out the stored tuning signal as appropriate and presetting it in the programmable counter, the reception frequency at that time can be set according to the preset tuning signal. is possible,
This allows preset channel selection. In this case, by storing the tuning signals of a plurality of stations, it is possible to easily select a desired station by specifying any one of the tuning signals. Furthermore, by manually changing the control signal given to the voltage controlled oscillator, the reception frequency can be determined in accordance with the control signal set by this operation, thereby allowing manual channel selection. By the way, in the above-mentioned synthesizer tuner, as a method for automatic tuning, the numerical value of the program signal is usually set to 10 by an auto scanner.
~Scanning with a predetermined clock of about several tens of days 2 The reception frequency is sequentially changed at predetermined frequency intervals, and when an external radio wave of a certain level or more is received at a certain frequency, it is detected and automatically scanned. An auto-scan channel selection method that stops the system is being explored. However, in the above-mentioned automatic channel selection method, it takes a certain amount of scanning time to reach the frequency at which a broadcasting station is present at the time of channel selection, and therefore there is a disadvantage that channel selection cannot be performed immediately. Furthermore, in the above synthesizer tuner, when a specific broadcasting station is received through automatic tuning or preset tuning, the local oscillation frequency 'o is generated by a phase-locked loop. - There is a problem that noise generated in the loop gets mixed into the signal path. Furthermore, in the above synthesizer tuner, this
When configured as an M tuner, it is difficult to detect a perfect tuning point because the intermediate frequency band characteristic is broad, which makes it difficult to achieve perfect tuning during automatic tuning or manual tuning. In addition, in this case, especially when selecting a channel manually, a tuning meter or the like is required in order to know the perfect tuning point during the tuning operation. This invention has been made in view of the above circumstances, and is an object of the present invention to shorten the scanning time during automatic tuning in a receiver capable of performing automatic tuning, preset tuning, and manual tuning as a tuning method. It is possible to suppress the noise generated from the system that obtains the local oscillation output during automatic tuning and preset tuning, and it is also possible to completely tune in when the receiver is configured as an AM receiver, automatic tuning and manual tuning. The present invention provides a receiver that can easily obtain the following information.

In order to achieve the above object, the present invention includes a voltage-controlled variable frequency oscillator that constitutes a local oscillator, a capacitor that supplies a frequency control voltage to the variable frequency oscillator,
a reception frequency setting circuit that compares the phase of the frequency corresponding to the oscillation frequency of the variable frequency oscillator and the frequency of the reference signal and charges and discharges the capacitor based on the comparison result; and a receiving frequency setting circuit that detects a tuning shift and detects the detection result a tuning deviation detection circuit that controls charging and discharging of the capacitor based on the above, and a circuit including the reception frequency setting circuit, the capacitor, and the variable frequency oscillator is configured as a phase locked loop, and and a control circuit that selectively controls each of these circuits so that the receiving frequency setting circuit charges and discharges the capacitor during tuning, and the tuning shift detection circuit charges and discharges the capacitor during tuning. It is a feature.

In one aspect of the present invention, the receiving frequency setting circuit charges and discharges the capacitor from a constant voltage source to automatically change the receiving frequency. The charging/discharging operation of the capacitor by the reception frequency setting circuit and the charging/discharging control operation of the capacitor by the tuning deviation detection circuit are switched depending on whether the phase locked loop is in an unlocked state or a locked state. be. In yet another aspect, the reception frequency setting circuit is configured with a circuit that can manually charge and discharge the capacitor, and in this case, the switching is performed by operating a touch switch. Furthermore, as one aspect of this invention,
The tuning deviation detection circuit is a circuit that outputs an S-curve signal as a tuning deviation signal. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment in which the present invention is applied to an FM tuner.

In this figure, the rM carrier wave captured by antenna 11 is amplified by high frequency amplification stage 12 and then supplied to mixing stage 13, where it is mixed with the local oscillation output supplied from local oscillator 14 and intermediate converted into a frequency signal. This intermediate frequency signal is amplified by an intermediate frequency amplification stage 15, and then subjected to FM detection by an FM detector 16.
The signal is extracted from the M detector 16 as an audio signal. The local oscillator 14 is configured as a so-called variable frequency oscillator (voltage controlled oscillator in this example), and its local oscillation frequency is controlled by a control voltage to be described later.

In this example, the intermediate frequency na i is 10.7.
The lower local oscillator system, which is MHZ, is adopted, and the local oscillator 14 is configured to operate in the FM broadcast band 76.
Resistant to 0MHz~90.0MHZ, 65.3MH2~
The structure is such that it can oscillate in the range of 79.3MH2. The local oscillation output of the local oscillator 14 is supplied to the mixing stage 13 as described above, and is also supplied to the prescaler 17 (the division ratio is "10" in this embodiment), which divides it into 1/100. The signal is then supplied to the frequency conversion circuit 18.

This tuner is provided with an oscillator 19 that supplies another signal to the frequency conversion circuit 18. This oscillator 19 is configured as a voltage controlled oscillator like the local oscillator 14, and its oscillation frequency is determined by the signal S^ supplied from the tuning shift detection circuit 20 via the switch 21.
It is controlled by Fc. At this time, the free running frequency of the oscillator 19 is set to n/100 in this embodiment. In this case, the tuning deviation detection circuit 20 extracts a so-called S-curve signal from the output of the FM detector 16 as a tuning deviation signal S^Fc, and is a low-pass filter in this embodiment. Further, the switch 21 is turned on/off by a control circuit which will be described later. In addition to the switch 21, this tuner is provided with a number of switches that are turned on and off by the control circuit, and the on and off states of these switches will be described in the description of the control circuit. The frequency conversion circuit 18 generates a signal with a frequency of the sum or difference of the frequencies of two signals by a phase difference balanced modulation method, and in this embodiment, the frequency converter 18 generates a signal with a frequency of the sum or difference of the frequencies of these signals using a phase difference balanced modulation method.
signal SP.

and a signal SF of frequency n/100 supplied from the oscillator 19, and a signal SF of frequency (n/10)/100.
It is what makes R. That is, this frequency conversion circuit 1
At 8, the signal SFo is supplied to a balanced modulation circuit 22, and its phase is shifted by /2 by a phase shift circuit 23, and then supplied to a balanced modulation circuit 24. Further, the signal SF, is supplied to a balanced modulation circuit 22, has its phase shifted by m/2 by a phase shift circuit 25, and is then supplied to a balanced modulation circuit 24. The balanced modulation circuit 22 performs balanced modulation using the signal SFo as a modulating wave and the signal SF as a carrier wave, and supplies the output signal Sma to the arithmetic circuit 26. The balanced modulation circuit 24 receives the output signal SF of the phase shift circuit 23.
Balanced modulation is performed using o' as a modulating wave and the output signal SF,' of the phase shift circuit 25 as a carrier wave, and the output signal Smb is supplied to the arithmetic circuit 26. The arithmetic circuit 26 (signal Sma
-signal Smb). In the frequency conversion circuit 18 having such a configuration, signal SFo=ot of sin, signal SP,=Eisin(wit+gui), signal SFo'=ot of cos, signal SF,'=Eicos(
(However, in these formulas, the middle of o.2. Shin = Minezu) 10○ The signal Sma is Sma = Eisin (scream t + ○i) Sin.

t=thing {■S (■it ten and i+.t) one COS (mountain i
t+4i one.

t)} ...[1-, the signal Smb becomes Sm
b = EiCOS (it 100i) COS.

t=thing {■S(it+.i+ot)−COS(i
t1○i1.

t)} ...■. Further, the output signal SFR of the arithmetic circuit 26 is SFR=Sma−Smb=EicOS
('s it+ is i's.

t) ...[It becomes 31. As is clear from the above equation, the frequency of the output signal SFR of the arithmetic circuit 26 is (na o x i)/100. Here, the frequency of the signal SFR (nao+〆i)/100 is meo+〆i=〆r=receiving frequency. The output signal SFR of the frequency conversion circuit 18 is input to the clock input terminal of the presettable counter 27.

The presettable counter 27 is configured as a so-called up/down counter, and its function can be switched depending on the type of channel selection command. That is, this presetter pull counter 27 is first given a preset value N to its preset input terminal when setting the receiving frequency during preset tuning, and then counts down the signal SFR until the count value reaches NI. The signal SFR is operated to output one pulse at a time, and operates to divide the frequency of the signal SFR by 1/N.
In this case, the preset value N given to the presettable counter 27 is given to the counter 27 through the register 29 from the memory 28, or directly from a finger system not shown. At this time, the preset value N is the receiving frequency (76.■MHZ~9
Numerical value (760-900) directly corresponding to 0.0MH2)
This value is displayed on the display 30 as the receiving frequency (76
．． 0MHZ to 90.0MHZ). Moreover, this preset pull counter 27 is
During automatic channel selection and manual channel selection, it is supplied with a timing clock signal ST, and operates to up-count the signal SFR in accordance with this timing clock signal and sequentially output numerical signals corresponding to the received frequencies. In this case, the count result of the counter 27 is supplied to the display 30 and the memory 28 via the register 29, and is displayed as the reception frequency at that time on the display 3. At the same time, the count result of the counter 27 is supplied to the display 30 and the memory 28 via the register 29, and is displayed as the reception frequency at that time. The information is stored in the memory 28. The signal output from the presettable counter 27 at the time of preset tuning is supplied to the phase comparator 31.

The phase comparator 31 receives a signal supplied from the presettable counter 27, that is, the frequency is ('o + i)/10
The phase of the signal is compared with the reference signal SsT of the frequency na ref (IKHZ in this embodiment) given from the reference signal generator 32 through the frequency divider 33, and three states (10 states) are determined according to the comparison result. , ○, open) signal S
Output a. In this case, the reference signal SsT is supplied to the phase comparator 21, while the timing clock signal ST
The signal is supplied to the presettable counter 27 as a signal. The comparison output Sa of the phase comparator 31 is supplied to the charge/discharge control circuit 43 via the switch 36. The charge/discharge control circuit 43 controls the charge/discharge of the capacitor 37 whose one end is grounded and the retention of the stored charge according to the state of the comparison output Sa.
The voltage at the other end (point A) of this capacitor 37 is set.
In this way, the charging and discharging of the capacitor 37 is controlled by the comparison output Sa supplied from the phase comparator 31, and the voltage across the capacitor 37 is controlled according to the value of the comparison output Sa. The voltage obtained at the other end of the capacitor 37, that is, at point A, is supplied to the local oscillator 14 as the frequency control voltage Vc. Thus, during this preset tuning, the local oscillation frequency 〆o of the local oscillator 14 is the same as that of the phase comparator 3.
The local oscillation frequency ``o'' is set by the frequency control voltage Vc controlled by the comparison output 6a of 1. (“o+〆i)/1
The signal becomes stable when 00N matches the frequency ref (IKHZ) of the reference signal. Therefore, the above-mentioned system for creating the local oscillation frequency 〆o during preset tuning constitutes a so-called phase-locked loop. Also, in this phase locked loop, the capacitor 3
The charging/discharging circuit 7 constitutes a receiving frequency setting circuit 38 that sets the receiving frequency at the time of preset channel selection. Further, in the above configuration, the other end (point A) of the capacitor 37 is connected to the variable resistor 40 via the switch 39.
It is connected to the sliding terminal 40a of.

The fixed terminal 40b of the variable resistor 40 has a voltage of +V.
The fixed terminal 40c is connected to the terminal 41 to which o is applied, and the other fixed terminal 40c is grounded. Based on this configuration, when the capacitor 37 is supplied with the voltage obtained through the switch 39 to the sliding terminal 40a, it is charged and discharged according to this voltage to change the frequency control voltage Vc and control the same. The local oscillation frequency n o of the local oscillator 14 is set based on the voltage Vc. The receiving frequency of the variable resistor 40 is set by manually operating the floating terminal 40a thereof. Thus, the charging/discharging circuit of the capacitor 37 including the variable resistor 40 constitutes a reception frequency setting circuit 42 during manual channel selection. Furthermore, the other end (point A) of the capacitor 37 is connected to the charging/discharging control circuit 43.
It is connected to the terminal 44 via.

The terminal 44 is connected via a switch 45 to a terminal 46 to which voltage +Vo2 is applied, and is also grounded via a switch 47. Under this configuration, capacitor 3
7 is charged and discharged according to the on time when the switches 45 and 47 are turned on and off by a control circuit to be described later. Therefore, the local oscillation frequency 〆o of the local oscillator 14 at this time is set according to the value of the frequency control voltage Vc determined by the ON time of the switches 45 and 47. The circuit for charging and discharging the capacitor 37 described above changes the control voltage Vc and sets the reception frequency by controlling the on/off of the switches 45 and 47 during automatic channel selection. It constitutes a reception frequency setting circuit 48 during automatic channel selection. In this tuner, when tuning is performed using preset tuning, manual tuning, or automatic tuning, the reception frequency is first set by the reception frequency setting circuits 38, 42, and 48. .

When a specific broadcasting station is received, a system for charging and discharging the capacitor 37 (reception frequency setting circuits 38, 4
2, 48 and the capacitor 37) is cut off,
Thereafter, the reception frequency is controlled based on the output signal S^Fc of the tuning shift detection circuit 20.
That is, the output signal S^Fc of the tuning shift detection circuit 20 is supplied to the oscillator 19 via the switch 21, and is also supplied to the amplifier 49. After being amplified by the amplifier 49, the output signal S^Fc is sent to the switch 50 and the charge/discharge control circuit 43. It is supplied to a capacitor 37 via the capacitor 37. In this case, the switch 50 is connected to the capacitor 37 by the reception frequency setting circuits 38, 42, 48.
When charging and discharging, that is, the reception frequency setting circuit 38
, 42 and 48 when the control voltage Vc is changed to set the receiving frequency (when the tuner is in an out-of-tune state), and when the receiving frequency is set and a specific broadcasting station is transmitted. When the tuner is in tune), the switch is turned on (all switches 36, 39, 45, and 47 are turned off at this time). Therefore, after the reception frequency is set by the reception frequency setting circuits 38, 42, and 48, the maintenance of the reception frequency, that is, the maintenance of the local oscillation frequency, is performed by charging and discharging the capacitor 37 according to the value of the signal S^Fc. This is done by controlling the In the above configuration, the switches 21, 36, 39, 45, 47, and 50 are turned on or off according to each channel selection method by a control circuit 60 shown in FIG. 2.

As shown in the figure, the control circuit 60 includes a touch switch 61 used for manual tuning, push-button switches 62 and 63 used for automatic tuning, and a push-button switch 64 used for preset tuning. There is. The touch switch 61 outputs a high level (hereinafter referred to as "H") signal when the operator's finger touches the switch body, and outputs a low level (hereinafter referred to as "L") signal when the switch body is not touched. These signals are supplied to the switch 39 and also to the input terminals 65b and 66c of the OR gates 65 and 66. In this embodiment, the knob for operating the slider element 40a of the variable resistor 40, that is, the tuning knob for manual channel selection, is configured to also serve as the touch switch 61. In addition, the pusher switch 62,
Reference numeral 63 supplies an "H" signal to set terminals 67a, 68a of flip-flops 67, 68 and input terminals 66a, 66b of OR gate 66, respectively, when these switches are pressed. Further, when the push button switch 64 is pressed, the set terminal 69a of the flip-flop 69 and the input terminal 70a of the OR gate 70 are connected to each other.
This is to supply an "H" signal to. An "H" signal is supplied to the input end 70b of the OR gate 70 from a not-shown tuning detection circuit when tuning is achieved during automatic channel selection. In this case, the tuning detection circuit detects, for example, an intermediate frequency signal and the signal S^Fc (S
It detects a perfect tuning point from the curve signal) and outputs "H" when the perfect tuning point is detected. The output of this OR gate 70 is supplied to each reset terminal 67b, 68b of the flip-flops 67, 68. Further, the input terminal 66d of the OR gate 66 is configured so that an "H" signal is not supplied from a lock detection circuit (not shown) when the phase locked loop is locked during preset channel selection. In this case the above. The lock detection circuit detects, for example, when the level of the comparison output Sa of the phase comparator 31 becomes zero, and outputs "H" based on this detection result. The output signal of the OR gate 66 is supplied to the reset terminal 69b of the flip-flop 69. Furthermore, the flip-flops 67 and 68 have Q output terminals 67c and 68
The output signals obtained at C are supplied to switches 45 and 47, respectively, and also to input terminals 65a and 65d of OR gate 65. Flip-flop 69 also supplies an output signal obtained at its Q output terminal 69c to switch 36, as well as to input terminal 65C of OR gate 65, and further supplies it to switch 21 via inverter 71. Further, the output signal of the OR gate 65 is supplied to the switch 5 via an inverter 72. Under such a configuration, the switches 21, 36, 39, 45, 47, and 50 are turned on and off by the signals supplied as described above. In this case, the switches 36, 39, 45, 47, and 5 are turned on when the signals S, to S6 supplied thereto are "H" and turned off when they are "L". Next, the operation of the tuner having the above configuration will be explained.

First, a case will be described in which a desired broadcasting station is received by automatic tuning.

In this tuning method, there are two methods: one is to receive the desired broadcasting station while increasing the receiving frequency sequentially, and the other is to receive the desired broadcasting station while decreasing the receiving frequency. 62, and if the latter is used to select a channel, the switch 63 is operated. That is, when the pusher switch 62 is pressed, the "lr" signal is supplied from this switch to the set terminal 67a of the flip-flop 67, and the signal "lr" is supplied to the set terminal 67a of the flip-flop 67 via the OR gate 66.
An "H" signal is applied to the reset terminal 69b of the controller.
As a result, the flip-flop 67 outputs "H" to the Q output terminal 67c (signal S4 becomes "H"), and the flip-flop 69 outputs "L" to the Q output terminal 69c (
signal S2 becomes "L"). Therefore, at this time, the switch 45 is turned on and the switch 36 is turned off. At this time, the output of the OR gate 65 becomes "H" due to the "H" output of the flip-flop 67, and the signal S6 obtained by inverting the output of the OR gate 65 by the inverter 72 becomes "L".
Therefore, the switch 50 is turned off at this time. Also, since the output of the flip-flop 69 is "L" at this time,
The signal S, which is obtained by inverting this world power by the inverter 71, is “H”
' becomes. Therefore, the switch 21 is turned on at this time.
Also, at this time, since the output of the touch switch 61 is "L" (signal S3 is "L"), the switch 39 is turned off. Furthermore, the flip-flop 68 is
The output of the output terminal 68c is "L" (signal S5 is "L") as will be made clear in the following explanation. Therefore, at this time, the switch 47 is off. When the push pin switch 62 is pressed in this manner, the switches 21 and 45 are turned on and the switches 36, 39, 47, and 50 are turned off as the first action.

Here, when the switch 45 is turned on, the receiving frequency setting circuit 48 supplies the voltage +Vo2 of the terminal 46 to the capacitor 37 through the charge/discharge control circuit 43, and charges the capacitor 37. As a result, the voltage at the other end (point A) of the capacitor 37, that is, the frequency control voltage Vc that controls the receiving frequency o of the local oscillator 14,
It rises according to a time constant determined by . As a result, the local oscillation frequency n o changes in an increasing direction in accordance with the change in the control voltage Vc. Therefore, at this time, the tuning frequency (receiving frequency r) of this tuner increases with the change in the local oscillation frequency. Now, when a specific broadcast station is received, the tuning detection circuit detects this state and outputs an "H" signal, and this "H" signal is sent to the reset terminal 6 of the flip-flop 67 via the OR gate 70.
7b. As a result, the flip-flop 67 becomes
“L” is output to the Q output terminal 67c, and the signal S4 becomes “
Therefore, the increase in the tuning frequency r stops at this point. Also, at this time, since the Q output terminal 67c becomes "L", the output of the OR gate 65 becomes "L". ”, and the signal S6 obtained by inverting this “L” by the inverter 72 becomes “H”, thereby turning on the switch 50. When the switch 50 is turned on, the output signal S^Pc of the out-of-tuning detection circuit 20 is sent to the amplifier 4.
9, the switch 50, and the charge/discharge control circuit 43. However, the capacitor 37 is charged and discharged by the signal S after the switch 45 is turned off.
＾Controlled by Fc. That is, capacitor 37
The frequency control voltage Vc obtained at the other end (point A) is controlled by the signal S^Fc after the switch 45 is turned off. Here, the signal S cape c is a voltage that changes according to the tuning deviation, that is, the change in the local oscillation frequency 〆o, and the local oscillator 14
control. In this way, after a particular broadcasting station is received, the received frequency "r" is maintained by the signal S^Fc.Furthermore, from this state, the next broadcasting station (a broadcasting station with a higher frequency than the currently received broadcasting station) is maintained. ), just press the push button switch 62 again.

That is, when the push button switch 62 is pressed again, the switch 45 is first turned on and the switch 50 is turned off in the same way as above (the on/off states of the other switches are set the same as in the above case), and the terminal Voltage is supplied from 46 to capacitor 37, and frequency control voltage Vc rises.
This increases the local oscillation frequency 〆o. When the next broadcast station is received, the switch 45 is turned off and the switch 50 is turned on, and the subsequent tuning state is maintained by the signal SAFc. By operating the push button 0 switch 62 in this way, it is possible to receive a desired broadcasting station while sequentially increasing the receiving frequency. In addition, when selecting a channel while sequentially decreasing the received frequency, contrary to the above case, the push pin switch 63 is operated.

That is, when the push-pull switch 63 is pressed in the above state (the state in which the channel has been selected by the push-pull switch 62), "
The flip-flop 68 outputs an "H" signal to the Q output terminal 68c (the signal signal S6 becomes "H" and the signal S6 becomes "L"). As a result, the switch 4
When the switch 7 is turned on, the switch 50 is turned off. Note that at this time, the output of the touch switch 61 is set to ''.
'L', the outputs of flip-flops 67 and 69 are both 'L'
”, so switch 21 is on and switches 3 and 39 are on.
, 45 are off. Here, the reception frequency setting circuit 48 grounds the terminal 44 by turning on the switch 47 and discharges the charge stored in the capacitor 37 via the charge/discharge control circuit 43. As a result, the voltage at the end of the capacitor 37 (point A), that is, the control voltage Vc
decreases according to a time constant determined by capacitor 37. As a result, the local oscillation frequency 〆o is the control voltage V
It changes in the direction of decrease according to the change of c. When a broadcast station is received, the tuning detection circuit outputs an "H" signal as in the above case, and this "H" signal is supplied to the reset terminal 68b of the flip-flop 68 via the OR gate 70. Ru. As a result, the output of the flip-flop 68 becomes "L" (signal S5 becomes "L", and signal S
6 becomes "H"), the switch 47 is turned off and the switch 50 is turned on. After the broadcast station is received in this way, the capacitor 37 is charged and discharged in the same manner as in the above case.
That is, the frequency control voltage Vc is controlled by the signal S^Fc, and the tuned state is maintained. By operating the push-pin switch 63 in this way, it is possible to receive a desired broadcasting station while decreasing the receiving frequency sequentially. In this tuner, when a specific broadcast station is received as described above, the reception frequency 〆r is displayed on the display 30. That is, in this tuner, the frequency conversion circuit 18 generates a local oscillation output SF obtained through the prescaler 17. A signal SFR (frequency o+i/100) is generated from (frequency o/100) and the output SF of the oscillator 19, (frequency o/100). Here, the receiving frequency r is set to, for example, 80. Assuming the peak MHz, the local oscillation frequency nao at this time is 80.0 - 10.7 = 69.3M
HZ and signal SF. The frequency of is 69.3/100M
HZ becomes. Also, the oscillation frequency of the receiver 19 is 10.7/1
It is 00MHZ. Therefore, the frequency of the output signal SFR of the frequency conversion circuit 18 is (69.3 + 10.7)/1
00MHZ = 80 skin HZ. This frequency is 80 Hz
The signal SFR is supplied to the presettable counter 27. At this time, the presettable counter 27 operates as an up-counter among the operations described above, and up-counts the signal SFR of the frequency 800KH2 using the signal of the frequency IKH2 supplied from the frequency divider 33 as a timing clock. , sequential numerical signal “800
” is output. This numerical signal “800” is output from register 2.
9 to the display 30, and the display 30 displays the receiving frequency as 80 MHz. In this operation, since the switch 21 is on, the oscillation frequency of the oscillator 19, i/100, is controlled by the signal S^Fc. Therefore, at this time, the frequency conversion circuit 18
The output frequency (Nao+Nai)/100 always corresponds to the reception frequency 〆r at that time even if the frequency of the intermediate frequency signal slightly deviates from 10.7MH2. In this way, the reception frequency of the display 3 at that time is
Always display accurately. Next, a case where manual channel selection is performed will be explained.

In this tuning method, tuning is performed by operating the tuning knob, that is, the eldest child that moves the control terminal 40a of the variable resistor 40. First, when selecting a channel, each of the switches is in the state described above (the state in which the channel selection is performed by the push button switch 62 or 63), that is, the switch 21, 50
is on, S. It is assumed that the switches 36, 39, 45, and 47 are in the OFF state. When you touch the tuning legitimate child with your finger to select a channel from this state, it is assumed that the tuning legitimate child constitutes the touch switch 61. , the output of the same touch switch 61 becomes "H" (signal S3 becomes "H")
, switch 3'9 is turned on. Also, touch switch 61
Since the output of the OR gate 65 becomes "H", the signal S6 obtained by inverting this output "H" by the inverter 72 becomes "L", and the switch 50 is turned off. The capacitor 37 is charged and discharged according to the voltage obtained at the sliding terminal 40a of the variable resistor 40 when the switch 39 is turned on, and the voltage at point A, that is, the frequency control voltage Vc, is made equal to the voltage at the sliding terminal 40a. Therefore, by operating the tuning knob and moving the information terminal 40a, the local oscillation frequency can be set to any desired frequency by changing the control voltage Vc. After receiving the desired broadcast station, if you release your finger from the tuning knob, the output of the touch switch 61 becomes "L" (signal S3 becomes "L", and the signal S6 becomes "H") The switch 39 is turned off and the switch 50 is turned on. When the switch 50 is turned on here, in the above case (push sword switch 62
Similarly to the case where automatic channel selection is performed by 63 or 63), subsequent charging and discharging of the capacitor 37 is controlled by the signal S^Pc, and the tuned state is maintained. Thus, during manual channel selection, a desired broadcasting station can be received by operating the tuning knob and moving the sliding terminal 40a of the variable resistor 40. It should be noted that during this manual channel selection, the reception frequency 〆r is displayed on the display 30 in the same manner as during automatic channel selection. Next, a case where preset channel selection is performed will be explained.

Note that when performing this preset tuning, each of the switches is in the state where the automatic tuning or manual tuning has been performed, that is, the switches 21 and 50 are in the on state, and the switches 36, 39, 45, and 47 are in the off state. shall be taken as a thing. When selecting a channel using this channel selection method, first, the presettable counter 27 is preset with a channel selection signal (760 to 900) corresponding to the frequency of the desired broadcasting station. For example, the frequency of the broadcasting station you want now (reception frequency 〆r) is 80. If the plate is HZ, the preset value N=“8001’ is given to the presettable counter 27. At this time, the preset value N given to the presettable counter 27 is
'Well, either it is directly applied to the preset terminal of the presettable counter 27 from the outside, or the value stored in the memory 28 is applied to the preset terminal via the register 29. Note that for the memory 28,
When performing the above-mentioned automatic channel selection or manual channel selection, the numerical signals combined from the presettable counter 27 through the register 29 are appropriately given an address signal and a write signal and stored. In this preset channel selection, after giving the preset value N to the presetter pull counter 27 as described above, the push button switch 6 of the control circuit 60
Press 4. When the push switch 64 is pressed, the switch 94 outputs the set terminal 64a of the flip-flop 69.
An "H" signal is supplied to the flip-flop 69, the Q output terminal 69c of the flip-flop 69 becomes "H" (signal S2 becomes "H"), and the switch 36 is turned on. Further, the signal S, which is obtained by inverting the "H" signal of the Q output terminal 69c by the inverter 71, becomes "L" and the switch 21 is turned off. The inverted signal S6 becomes "L" and the switch 50 is turned off. On the other hand, the function of the presettable counter 27 is switched to operate as a frequency divider when the push button switch 64 is pressed. In this state, the frequency conversion circuit 18 generates a signal SF obtained by frequency-dividing the output of the local oscillator 14 by the prescaler 17.

A signal SFR having a frequency (nao+nai)/100 is generated from the output signal SF of the oscillator 19 and the output signal SF of the oscillator 19, and this signal SFR is supplied to the presettable counter 27. The presettable counter 27 frequency-divides the signal SFR by 1/800 and supplies this frequency-divided signal to the phase comparator 31. The phase comparator 31 receives a signal supplied from the presettable counter 27, that is, a frequency (“o+nai)/100×800”.
The signal is compared in phase with the reference signal of frequency IKH2 supplied from the frequency divider 33, and a comparison output Sa is outputted according to the comparison difference. This comparison output Sa is supplied to the capacitor 37 via the switch 36 and the charge/discharge control circuit 43. As a result, the capacitor 37 is charged and discharged by the voltage given from the phase comparator 31, that is, the voltage according to the phase ratio, and is controlled by the control voltage Vc obtained at point A to change the local oscillator 14. Change the local oscillation frequency. Thus, the local oscillation frequency 〆o
is the state where the phase difference finally becomes zero, that is, (
It becomes stable in a state where Nao+Nai)/100×800=IKHZ. The final local oscillation frequency Nao in this example is Nao=IKH2×100×800−10.7MH2
=69.3MHZ. Therefore, the receiving frequency 〆r is Na = 693MH2 + 10.7MHZ = 80.0M
HZ, and the desired broadcasting station will be received.
A state in which the phase difference becomes zero, that is, a state in which the above-mentioned phase locked loop for obtaining the local oscillation frequency 〆o is locked, is detected by a lock detection circuit.

The lock detection circuit goes high when detecting the lock.
This signal is supplied to the reset terminal 69b of the flip-flop 69 via the OR gate 66. As a result, the flip-flop 69 outputs "L" to its Q output terminal 69c (signals S. and S6 become "H" and signal S2 becomes "L"). Therefore, at this time, the switches 21 and 50 are turned on, and the switch 36 is turned off.
As a result, the subsequent charging and discharging of the capacitor 37 is controlled by the signal S^Fc supplied from the tuning shift detection circuit 20, as in the case of automatic tuning and manual tuning described above. That is, the signal S^Fc controls charging and discharging of the capacitor 37 from the time when the switch 50 is turned on, thereby controlling the control voltage Vc to keep the local oscillation frequency (69.3 MHZ) constant. Stay in tune. In addition, in this channel selection method, the receiving frequency r (80.mMH2) is displayed on the display 30 in the same manner as in the automatic channel selection and manual channel selection described above.

That is, in this channel selection method, when the switch 36 is turned off (when the phase locked loop is released), the presettable counter 27 is switched to the above-mentioned up counter. The count value is displayed on the display 30. Further, FIG. 3 is a diagram showing an embodiment in which the present invention is applied to an AM tuner.

In this figure, the same components as in FIG. 1 are given the same reference numerals. The tuner shown in this figure has substantially the same basic configuration as the tuner shown in FIG. 1. Therefore, only the points that differ from FIG. 1 in FIG. 3 will be explained here. First, in this figure, the detector 16 is, as a matter of course, composed of an AM detector. Furthermore, the oscillator 19 is constituted by a synchronous oscillator in this implementation. That is, this oscillator 19 oscillates at a unique receiving frequency r/100 when the switch 21 is off, and synchronizes with the intermediate frequency signal S, supplied from the intermediate frequency amplification stage 15 when the switch 21 is on. This is an oscillator that oscillates. Further, in this embodiment, the tuning shift detection circuit 20 detects the intermediate frequency signal S, using a frequency discriminator, and extracts a voltage (S-shaped curve signal) corresponding to the tuning shift. be. In this embodiment, the control circuit for controlling on/off of each switch has the same configuration as the control circuit 60 shown in FIG. 2. However, both the tuner shown in FIG. 3 and the tuner shown in FIG. 1 perform automatic tuning in the same way as the tuner shown in FIG.
Manual tuning and preset tuning are possible.

The specific configuration of the charge/discharge control circuit 43 shown in FIGS. 1 and 3 is, for example, as shown in FIG. 4.

Hereinafter, to explain this FIG. 4, the input terminal 119
(the terminal 44) is connected to a transistor 121, which is commonly connected via an inverting amplifier 120 (amplifier with a gain of -1).
122 emitters of these transistors 12
1 and 122 are connected to the positive voltage terminal of a DC power supply 125 via resistors 123 and 124, respectively, and the negative voltage terminal of the DC power supply 125 is grounded. The output voltage of this DC power supply 125 is, for example, 1/2 of the output voltage Vo when the phase comparator 31 is in the "high" voltage state.
, that is, it is set to 1/2Vo. The collector of the transistor 121 has a resistor 126,1 connected in series.
27 to the positive power supply terminal '128, and a resistor 129 connected in series to the outside of the collector of the transistor 122.
, 130, and the connection point of the resistors 126, 127 is connected to the base of the transistor 131, and the resistors 129,
The ground points of 130 are connected to the bases of transistors 132, respectively. The emitter of transistor 131 is resistor 1
33 to the positive power supply terminal 128, the emitter of the transistor 132 is grounded via a resistor 134, and the collectors of each of the transistors 131 and 132 are connected in common and then grounded via the capacitor 37. Next, the operation of the charge/discharge control circuit 43 when, for example, the output of the phase comparator 31 is applied to the input terminal 119 of the charge/discharge control circuit 43 configured as described above will be described.

First, when a "low" voltage (0 volts) is applied to the input terminal 119, the base potential of the transistor 122 is at VD, so the transistor 122 becomes "on", which causes the base of the transistor 132 to be turned on. A current flows as shown by the solid arrow a, and the transistor 32 becomes "on".

On the other hand, the emitter potential of the transistor 121 becomes higher than the base voltage, so the transistor 121 becomes "off". Therefore, the base potential of the transistor 131 becomes the voltage +Vc of the positive power supply terminal 128, and the transistor 131 becomes "off". As a result, the charge on the capacitor 37 increases as indicated by the solid line arrow b
The voltage is discharged through the transistor 132 and the resistor 134 as shown in FIG. Next, when a ``high'' voltage (10 Vo volts) is applied to the input terminal 119, the transistor 1
Since the emitter voltage of transistor 22 is lower than the base potential, transistor 122 is in an "off" state, and therefore the base potential of transistor 132 is at ground potential, causing transistor 132 to be in an "off" state.

On the other hand, since the base potential of the transistor 121 becomes higher than the emitter potential, the transistor 121 becomes "on", and as a result, the base current of the transistor 131 flows as indicated by the dashed arrow c, and the transistor 131 becomes "on". As a result, a charging current flows to the capacitor 37 via the resistor 133 and the transistor 131 (see broken line arrow d).
. Furthermore, when the output of the phase comparator 31 applied to the input terminal 119 is in an "open" state, the bases of the transistors 121 and 122 are short-circuited via the resistors 123 and 124, so transistor 1
21 and 122 are both in the "off" state, so that the base potential of the transistor 131 becomes 10 Vc, the base potential of the transistor 132 becomes the ground potential, and both the transistors 131 and 132 become in the "off" state.

That is, the phase comparator 31 applied to the input terminal 119
When the output of the capacitor 37 is in the "open" state, the charge in the capacitor 37 is not charged or discharged, so there is no change in the voltage at the point A. In other words, the state immediately before the "open" state is maintained. As described above, the charge/discharge control circuit 43 shown in FIG. 4 charges or discharges the capacitor 37 when the output of the phase comparator 31 applied to the input terminal 119 is in a "high" state or a "low" state. Also, when the output of the phase comparator 31 is in the "open" state, the charge of the capacitor 37 is held as it is, and the voltage at point A is maintained.

Further, in each of the embodiments described above, the local oscillation frequency na o of the local oscillator 14 is electrically varied by the control voltage, but it may be configured to be varied mechanically. That is, in this case, the element for varying the local oscillation frequency 〆o is constituted by a variable capacitor, and the variable capacitor is configured so that it can be rotated by manual operation, and can also be rotated by an appropriate drive mechanism such as a motor. and the drive mechanism may be configured to be controlled by the control voltage Vc. Furthermore, in each of the above embodiments,
Although the local oscillation frequency limit o is set using the lower local oscillation method, it may also be an upper local oscillation method. In this case,
The arithmetic circuit 26 of the frequency conversion circuit 18 is configured with a subtraction circuit, and the frequency (main i) is calculated from the frequency conversion circuit 18.
/100 signal may be extracted. As described in detail above, the receiver according to the present invention includes a voltage-controlled variable frequency oscillator that constitutes a local oscillator, a capacitor that supplies a frequency control voltage to the variable frequency oscillator, and a capacitor that supplies a frequency control voltage to the variable frequency oscillator. A reception frequency setting circuit that compares the phases of the corresponding frequency and the frequency of the reference signal and charges and discharges the capacitor based on the comparison result, and detects a tuning shift and charges and discharges the capacitor based on the detection result. A tuning shift detection circuit is provided to control the reception frequency setting circuit, and a circuit including the reception frequency setting circuit, the capacitor, and the variable frequency oscillator is configured as a fizz locked loop, and the reception frequency setting circuit charging and discharging the capacitor by
Since the control circuit is provided with a control circuit that switches and controls each of these circuits so that the capacitor is charged and discharged by the tuning deviation detection circuit at the time of tuning, a phase locked loop (P
LL) allows preset tuning to be performed easily, and when tuning is achieved, the local oscillation frequency is immediately controlled by the tuning deviation detection circuit, so that when tuning, the local oscillation frequency is emitted from the PLL. This has the advantage that noise does not enter the signal path and minute fluctuations in tuning are suppressed.

In addition, if the receiving frequency setting circuit is equipped with a circuit that charges and discharges the capacitor from a constant voltage source and thereby automatically changes the receiving frequency, scanning during automatic channel selection (search) can be performed faster. In addition, if the receiving frequency setting circuit is provided with a circuit that can manually charge and discharge the capacitor, the receiving frequency can be arbitrarily set by manual operation.
Moreover, there is an advantage that rapid channel selection is possible. Furthermore, in this receiver, even when configured as an AM receiver, since the charging and discharging of the capacitor after setting the reception frequency is controlled by the output of the tuning deviation detection circuit, perfect tuning can be easily achieved. It has the advantage of being able to

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an FM tuner to which the present invention is applied, Fig. 2 is a circuit diagram of a control circuit used in the FM tuner, and Fig. 3 is a block diagram showing the configuration of an AM tuner to which the invention is applied. 4 are specific circuit configuration diagrams of the charge/discharge control circuit 43 shown in FIGS. 1 and 3. 14...Variable frequency oscillator (local oscillator), 2
0... Tuning shift detection circuit, 37... Capacitor, 38, 42, 48... Reception frequency setting circuit, 60... Control circuit, 61... touch switch. Figure 4 Ship chart Figure 2

Claims (1)

[Claims] 1. A voltage-controlled variable frequency oscillator constituting a local oscillator, a capacitor that supplies a frequency control voltage to the variable frequency oscillator, and a frequency corresponding to the oscillation frequency of the variable frequency oscillator and a reference signal. a reception frequency setting circuit that compares the phase with the frequency and charges and discharges the capacitor based on the comparison result; and a tuning shift detection circuit that detects a tuning shift and controls charging and discharging of the capacitor based on the detection result. In addition, a circuit including the receiving frequency setting circuit, the capacitor, and the variable frequency oscillator is configured as a phased locked loop, and the charging and discharging of the capacitor by the receiving frequency setting circuit is performed during tuning. and a control circuit that switches and controls each of these circuits so that the capacitor is charged and discharged by the tuning shift detection circuit during tuning. 2. The receiving frequency setting circuit is provided with a circuit that charges and discharges the capacitor from a constant voltage source, thereby automatically changing the receiving frequency. Receiving machine. 3. The receiver according to claim 1, wherein the receiver detects an unlocked state and a locked state of the phase locked loop, and performs a switching control operation of the control circuit based on the detection result. 4. The receiver according to claim 1, wherein the reception frequency setting circuit includes a circuit that can charge and discharge the capacitor by manual operation. 5. The receiver according to claim 4, wherein the switching control operation of the control circuit is performed by operating a touch switch. 6. The receiver according to claim 1, wherein the tuning shift detection circuit is a circuit that outputs an S-curve signal as the tuning shift signal.