JPS6029252B2 - FM receiver tuning instruction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tuning instruction device for an FM receiver that uses light emitting elements such as light emitting diodes, and in particular uses three light emitting elements to clearly distinguish between five states. This makes it possible to perform a tuning operation smoothly, and also to give a tuning instruction that is visually superior and free from malfunctions.

Conventionally, a center tuning meter has been mainly used as a tuning instruction device for an FM receiver.

When performing a tuning operation on this center tuning meter, you must carefully look at the center tuning meter and align the pointer with the center, which requires careful attention, and the temperature drift of the center tuning meter may cause the meter to change. There was an inconvenience that it would shift. In addition, a tuning indicating device in which three light emitting elements are arranged horizontally has been proposed, but this turns on the two left and right light emitting elements when there is no received signal or when the received signal disappears, and the left or right side (tuning When the synchronization approaches (corresponds to left or right rotation), the light emitting element on the left or right side lights up, and when the synchronization is achieved, the light emitting element in the center lights up. be.

Such a tuning instruction device can effectively distinguish between three states, which makes the tuning operation difficult and the accuracy questionable. In view of this, the present invention uses three light emitting elements to clearly distinguish five states, enables smooth tuning operations, and provides visually superior tuning instructions with no error differences. The aim is to provide the equipment.

An embodiment of the tuning instruction device for an FM receiver according to the present invention will be described below with reference to FIG.

In FIG. 1, 1 indicates an FM receiver. This FM receiver 1 has a conventional configuration, and is provided with an FM detection circuit 2 and a muting signal generation circuit 3. The frequency-voltage characteristic of this FM detection circuit 2 exhibits a so-called S-curve characteristic as shown in FIG. 2A. Further, the muting signal generating circuit 3 is, for example, a second
As shown in Figure E, the center frequency of the broadcasting signal is
In the KHZ frequency range, a level signal such as the power supply voltage Eo is output, thereby making the signal system conductive, and at other times obtaining a muting signal that cuts off the signal system. The output signal of this FM detection circuit 2 is supplied to a first level detection circuit 4, where the output signal becomes a high level signal, for example, the power supply voltage Eo, when the voltage exceeds a predetermined voltage V. In this case, the predetermined voltage V, for example, is
The value is such that the output side of the first level detection circuit 4 becomes the voltage Eo in the frequency range of 0-20KHZ to 0-200KHZ shown in FIG. The output signal of the FM detection circuit 2 is also supplied to a second level detection circuit 5, which becomes a level signal such as the power supply voltage Eo when the voltage is below a predetermined voltage -V. In this case, the predetermined voltage -V is, for example, the second
As shown in FIG. C, the value is set so that the output side of the second level detection circuit 5 becomes the voltage Eo in the frequency range from 0+20KH2 to 0+20KHZ. The output side of this first level detection circuit 4 is grounded through a series circuit of a resistor 6 and a light emitting diode 7, and a connection switch 8 is connected in parallel to this resistor 6. The output signal of the circuit 4 is supplied to one input terminal of the AND circuit 9, and the output signal of the muting signal generation circuit 3 is supplied to the other input terminal of the AND circuit 9 via the inverter circuit 10. The on/off state of this connection switch 8 is controlled by the output signal of 9.

That is, when the output signal of the AND circuit 9 is a high level signal, for example, the power supply voltage Eo, the connection switch 8 is turned on, and at this time, a relatively large current LO is applied to the light emitting diode 7 through the connection switch 8, making the light emitting diode 7 bright. All lights on. Further, when the output signal of the AND circuit 9 is a low level signal, the connection switch 8 is turned off. Further, the output side of the second level detection circuit 5 is grounded through a series circuit of a resistor 11 and a light emitting diode 12, and this resistor 1
A connection switch 13 is connected in parallel to the second level detection circuit 1, and the output signal of the second level detection circuit 5 is supplied to one input terminal of the AND circuit 14, and the output signal of the inverter circuit 10 is supplied to the other input terminal of the AND circuit 14. The connection switch 13 is turned on and off by the output signal of the AND circuit 14.

That is, when the output signal of this AND circuit 14 is a high level signal, for example, the power supply voltage Eo, this connection switch 13 is turned on.
A relatively large current lo is passed through the light emitting diode 12 to fully light up the light emitting diode 12. Further, when the output signal of the AND circuit 14 is a low level signal, this connection switch 13 is turned off. Further, the output side of the muting signal generation circuit 3 is grounded through a series circuit of a resistor 15 and a diode 16, and a connection switch 17 is connected in parallel to this resistor 15, and the output signal of the muting signal generation circuit 3 is The signal is supplied to one input terminal of the circuit 18, and the output signals of the first and second level detection circuits 4 and 5 are supplied to one input terminal and the other input terminal of the NOR circuit 19, respectively.

In this case, on the output side of the NOR circuit 19, in the frequency range of the maximum tuning state, for example, from 0-20K days Z to 0+2 days 2, a level signal such as that shown in FIG. . The output signal of this NOR circuit 19 is supplied to the other input terminal of the AND circuit 18.
The on/off state of this connection switch 17 is controlled by the output signal of the connection switch 17. That is, when the output signal of the AND circuit 18 is a level signal such as the power supply voltage Eo, the connection switch 17 is turned on, and a relatively large current lo is caused to flow through the light emitting diode 16 through the connection switch 17.
This light emitting diode 16 is fully lit up brightly. Further, when the output signal of this AND circuit 18 is a low level signal, this connection switch 17 is turned off. Since this example is configured as described above, if the FM receiver 1 is not tuned at all and an output signal or S-shaped voltage cannot be obtained on the output side of the FM detection circuit 2, a muting signal is generated. Generation circuit 3, first level detection circuit 4, and second level detection circuit 5
Therefore, the three light emitting diodes 7, 16 and 12 do not light up at all as shown in FIG. 3A.

In this case, in the FM receiver 1, the muting circuit is operated by the output of the muting signal generating circuit 3, and the audio output signal is muted. Next, for example, rotate the synchronized heir clockwise until the synchronized state is 〆o-200 in Fig. 2A.
When the frequency range is from K day Z to Na o - 100KHZ, the output side of the first level detection circuit 4 becomes a high level signal as shown in FIG. 2B, and at this time, the output side of the muting signal generation circuit 3 becomes the Since it is a low level signal as shown in Fig. 2E, the output side of the AND circuit 9 becomes a high level signal, and the connection switch 8 is turned on, causing a large current lo to flow through the light emitting diode 7 as shown in Fig. 2G, and as shown in Fig. 3B. As shown in the figure, the light emitting diode 7 arranged on the left side is fully illuminated. In this case as well, the muting circuit operates and the audio signal is muted. Further, rotate the tuning heir clockwise, and the tuning state will be from 0-100KHZ to 0-20KH in Fig. 2A.
When the frequency range is Z, the first level detection circuit 4
A high level signal as shown in FIG. 2B is obtained on the output side of the muting signal generating circuit 3, and a high level signal as shown in FIG. 2E is also obtained on the output side of the muting signal generation circuit 3. The respective output signals become low level signals, and the connection switches 8 and 17 are respectively turned off.

Therefore, at this time, the power supply voltage Eo is supplied to the light emitting diodes 7 and 16 via the resistors 6 and 15, respectively, and by selecting the respective resistance values of the resistors 6 and 15, The flowing current is the second
For example, as shown in Figures G and F, at this time, as shown in Figure 3C, the two light emitting diodes 7 and 16 placed in the center on the left are dimly lit. At this time, this FM
The muting operation of the muting circuit in receiver 1 is canceled and sound is output from the speaker. Further, by rotating the tuning knob clockwise, when the tuning state is in the frequency range of 0-20KHZ to 12KHZ in Fig. 2A, which is the highest tuning state, the first and 2 level detection circuits 4 and 5
The respective output sides of the circuits become low level signals as shown in FIG. 2B and C, and the output side of the muting signal generation circuit 3 becomes a high level signal as shown in FIG. 2E, so that the output of the AND circuit 18 The side becomes a level signal and the connection switch 17 is turned on. Therefore, at this time, the light emitting diode 16 arranged in the center is connected to the second
A relatively large current lo as shown in Figure F is supplied, and Figure 3D
As shown in the figure, only this light emitting diode 16 arranged in the center is fully illuminated. At this time, the muting operation of the muting circuit in the FM receiver 1 is canceled and sound is output from the speaker. This state is the best tuned state. Further, rotate the tuning knob clockwise, and if the tuning state is slightly deviated, the second
When the frequency range is from +20KHZ to +110 KHZ in Figure A, a high level signal is obtained on the output side of the second level detection circuit 5 as shown in Figure 2C, and a muting signal is generated. A level signal is also obtained on the output side of the circuit 3 as shown in FIG. Therefore, the output signals of the AND circuits 14 and 18 become low level signals, and the connection switches 13 and 17 are turned off.

Therefore, at this time, the power supply voltage Eo is
By selecting the respective resistance values of the resistors 11 and 15, the current flowing through the light emitting diodes 12 and 16 is shown in FIG. 2 and F. At this time, as shown in FIG. 3, the two light emitting diodes 16 and 12 arranged at the center and right side are dimmed and half-lit. At this time as well, the muting operation of the muting circuit in the FM receiver 1 is released and sound is output from the speaker. Furthermore, when the tuning state shifts clockwise in the tuning bridge and the frequency range is from 〆 o + 100 K day Z to na o + 20 dish HZ in Fig. 2 A, the output side of the second level detection circuit 5 is detected. A high level signal is obtained as shown in FIG. 2C, and at this time, the output side of the muting signal generation circuit 3 is a low level signal as shown in FIG. 2E, so the output side of the AND circuit 14 becomes a high level signal and is connected. The switch 13 is turned on, and a large current lo flows through the light emitting diode 12 as shown in FIG. 2, and the light emitting diode 12 disposed on the right side is fully lit up as shown in FIG. 3F.

In this case, the muting circuit operates and the audio signal is muted. Furthermore, when the tuning state deviates, the output signals of the muting signal generating circuit 3, the first level detecting circuit 4, and the second level detecting circuit 5 cannot be obtained, so the three output signals as shown in FIG. The light emitting diodes 7, 16 and 12 do not light up at all.

As described above, according to the present invention, as shown in FIG. 3, the three light emitting diodes 7, 16, and 12 are not lit at all, only the left light emitting diode 7 is fully lit, and the left and center light emitting diodes 7 and 16 are not lit at all. 2 are half lit, only the center light emitting diode 16 is fully lit, the center and right light emitting diode 16 are half lit.
It is possible to distinguish between six states: the two LEDs and 12 are half-lit, and only the right light-emitting diode 12 is fully lit, and five states in the frequency range where the output signal of the FM detection circuit 2 exists can be clearly distinguished. Therefore, the tuning operation can be performed smoothly, and the tuning instruction can be given without malfunction.

Furthermore, according to the present invention, during the tuning operation, the lighting of the light emitting diodes can be felt as if it flows naturally, so it is visually superior. Further, FIG. 4 shows an example of a specific wiring diagram of the present invention. Referring to FIG. 4, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted. In FIG. 4, 2a and 2b indicate FM detection signal input terminals to which the output signals from the FM detection circuit 2, which extracts the S curve characteristic as a differential output, are supplied.
The detection signals as differential outputs supplied to the detection signal input terminals 2a and 2b, respectively, are supplied to the bases of npn transistors Q and Q2 via resistors R and R2, respectively, and The base is connected to the base of transistor Q2 through a parallel circuit of resistor R3 and capacitor C, the emitter of transistor Q is connected to the base of transistor Q2, and the emitter of transistor Q2 is connected to the base of transistor Q. Connect to. In this case, transistors Q and Q2 constitute a so-called winding cross switch. When the levels of the signals supplied to the FM detection signal input terminals 2a and 2M are in a balanced state, both transistors Q and Q2 become non-conductive. In this case, the slope of the S-curve characteristic is determined by the values of resistors R, , R2 and R3. Therefore, the transistors Q and Q2 constitute the first and second level detection circuits 4 and 5 of FIG. Further, the capacitor C and the resistor R or R2 constitute a low-pass filter, which is used to remove the audio signal contained in the FM detection signal. The collectors of transistors Q and Q2 are connected to the bases of npn transistors Q and Q4, respectively, and the emitters of transistors Q3 and Q4 are connected to npn transistors Q and Q4, respectively.
The emitter of this transistor Q7 is connected to the base of the transistor Q7, and is connected to the power supply terminal Eo to which the positive DC voltage Eo of the emitter of this transistor Q7 is supplied.The collector of this transistor Q7 is grounded via the resistor R5. Q4
are connected to respective collectors of npn transistors Q and Q6, respectively.
are connected to the respective bases of transistors Q5 and Q
6 are connected to each other, this collector connection point is connected to the power supply terminal Eo via the resistor R4, and the emitter of the transistor Q5 is connected to the npn via the light emitting diode 7.
The emitter of the transistor Q is connected to the collector of the transistor Q,o through a light emitting diode 12. Also, the collector of transistor Q7 is connected to the base of npn type transistor Q8, the emitter of this transistor Q is connected to power supply terminal Eo, and the collector of this transistor Q8 is connected to resistor R6.
and a collector of an npn transistor Q via a series circuit of a light emitting diode 16. This transistor Q
A resistor R? is connected between the emitter of No. 8 and the connection point of the resistor R6 and the light emitting diode 16. Insert. Also, 3a is Figure 2 E
This muting signal input terminal 3 shows a muting signal input terminal to which a muting signal as shown in FIG.
The muting signal supplied to the transistor Q is supplied to the base of the transistor Q through a series circuit of a diode D for preventing backflow and a resistor R8, and the emitter of the transistor Q is connected to the npn type transistors Q, . Connect to the collector of Further, 20 indicates a signal presence signal input terminal to which a high level signal, for example, power supply voltage Eo, is supplied while the FM detection signal exists, as shown in FIG. These transistors Q, . , and the transistors Q, . The emitters of Q, . In such a way as to introduce the appropriate That is, it prevents malfunction of lighting at the time of weak input. Further, the collector of transistor Q9 is connected to the base of transistor Q,o via a resistor R,o having a sufficiently large resistance value. The emitters of transistors Q, . and between the collectors and emitters of transistors Q, o, and resistors R, . Insert. In this case resistors R4 and R, . The resistance values of the two are selected to be equal. The tuning state in Fig. 4 is 〆o-200KHZ to 〆o- in Fig. 2A.
In the frequency range of 20 KHz, transistor Q is conductive and transistor Q2 is non-conductive, and this transistor Q draws current through the emitter base of transistor Q7 and the emitter base of transistor Q3, making transistor Q3 conductive. Transistor Q5
The light emitting diode 7 also becomes conductive and current flows through the light emitting diode 7.

At this time, transistor Q7 becomes conductive and transistor Q
becomes non-conducting. Also, the synchronization state is “o+” in Fig. 2A.
In the frequency range of 20KHZ to +200KHZ, the transistor Q is non-conductive and the transistor Q2 is conductive, and this transistor Q2 draws current through the emitter base of the transistor Q7 and the emitter base of the transistor Q4, making the transistor Q4 conductive. Therefore, the transistor Q6 also becomes conductive and the light emitting diode 12
A current flows through.

Also, at this time, transistor Q7 becomes conductive and transistor Q becomes non-conductive. In this case, positive feedback is applied from the transistor Q5 or Q6 to the transistor Q7 between the respective successor points of the collectors of the transistors Q5 and Q6 and the base of the transistor Q7, and in order to prevent malfunction, resistors R,
2 can be inserted. Also, when the tuning state is in the frequency range of 0-20 KHz to 0+20 KHz in Fig. 2A, the transistors Q, , Q2, Q3, Q4, Q5, Q
6 and Q? becomes non-conductive, and transistor Q8 becomes conductive. Therefore, current flows to light emitting diode 16 through transistor Q8 and resistor RG. Further, a muting signal as shown in FIG. 2E is input to the muting signal input terminal 3a.
Transistor Q9 becomes conductive.

In this case transistor Q8 is non-conducting, i.e.
K day Z~nao-20KHZ and nao120K day Z~nao
When the voltage is +100 KHz, current flows through the resistor R7 to the light emitting diode 16, and the light emitting diode 16 is half lit, and the tuning state is approximately at the center of the S-curve characteristic, that is, from o-2 plate day Z to na o+2 plate HZ. At this time, the transistor Q becomes conductive and the current passing through the resistor R6 also flows to the light emitting diode 16, so that the light emitting diode 16 is fully lit. This is the state of maximum synchronization. Also, when this transistor Q9 is suitable for conduction, the transistor Q.
becomes non-conductive, so when the tuning state is from 0-100 KH2 to 0-20 KHZ (or 0+20 KHZ to 1100 KHZ), resistor R4 and transistor Q are connected to light-emitting diode 7 (or light-emitting diode 12). (or transistor Q), resistor R, . Because current flows through light emitting diode 7 (or light emitting diode 1)
2) is half lit. Also, when there is no muting signal and transistor Q9 is non-conductive, transistor Q. is conductive, at this time, 〆o-200K day Z ~ nao-100KH
Z (yes, ha nao + 10 dishes HZ~〆o1200KHZ
), light emitting diode 7 (or light emitting diode 1
In 2), current flows through the transistors Q and o, so the light emitting diode 7 (or the light emitting diode 12) is fully lit. Therefore, it is easy to understand that the above-mentioned effects can be obtained in the specific example shown in FIG.

Although the above embodiments have been described using light emitting diodes, it goes without saying that other light emitting elements can be used instead. Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a tuning instruction device for an FM receiver according to the present invention, FIGS. 2 and 3 are diagrams for explaining the present invention, and FIG. 4 is a diagram showing a specific example of the present invention. FIG. 1 is an FM receiver, 2 is an FM detection circuit, 3 is a muting signal generation circuit, 4 is a first level detection circuit, 5 is a second level detection circuit, 6, 11 and 15 are resistors, 7,
12 and 16 are light emitting diodes, 8, 13 and 17 respectively.
are connection switches, respectively. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. A first level detection circuit to which the output signal of the FM detection circuit is supplied and generates an output signal at a first level or higher corresponding to a first frequency that is a predetermined frequency lower than the optimum tuning frequency; a second level detection circuit to which an output signal is supplied and generates an output signal below a second level for a second frequency higher than the optimum tuning frequency by a predetermined frequency; and a fourth frequency higher than the second frequency by a predetermined frequency, and a muting signal generating circuit that lights up when the output signal of the first level detection circuit is supplied. A light emitting element,
a second light emitting element that lights up when the output of the second level detection circuit is supplied; and a third light emitting element that lights up when the output signal of the mutating signal generation circuit is supplied; The current flowing through the first light emitting element is increased by the AND output of the output of the first level detection circuit and the inverted output of the mutating signal generation circuit, and the output of the second level detection circuit and the inverted output of the mutating signal generation circuit are increased. The current of the second light emitting element is increased by the AND output of the output, and the current of the third light emitting element is increased by the AND output of the NAND output of the first and second level detection circuits and the mutating signal generation circuit. A tuning instruction device for an FM receiver, characterized in that: