JPS59123308A - Display device of tuning point for fm and am receiver - Google Patents

Abstract

PURPOSE:To attain easy-to-see display for the tuning state of FM reception by indicating clearly the direction to move a pointer for attaining the best tuning point by means of the running lighting of a light emitting element array an at FM signal receiving. CONSTITUTION:When a receiving band is turned to the FM, light emitting diodes 52-56 are all turned off at complete detuning. When a tuning knob is turned and a prescribed frequency enters a prescribed frequency range lower than the best tuning point, the light emitting diodes are lighted sequentially in the order of the 52 to the 54 via the 53, which indicates that the pointer on a dial surface is to be moved to the right. When the frequency is located in a prescribed frequency range lower than the best tuning point inversely, the light emitting diodes are lighted sequentially in the order of the 56 to the 54 via the 55, which indicates that the pointer is to be moved to the left. When the frequency reaches the prescribed range including the best tuning point, the light emitting diodes are lighted sequentially in the order of the 52 and 56 to the 54 via the diodes 53 and 54 respectively. When the receiving band is turned to the AM, the light emitting diodes 52-56 are all turned off at complete detuning and they are lighted sequentially from both the ends to the center at the receiving.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a tuning point display device for AM and FM receivers.

(Configuration of conventional example and its problems) FIG. 1 shows a conventional device of this kind, in which light emitting diode J4 receives FM and AM signals, and light emitting diodes 21, 22, 23 . For example, it is used to move the pointer to set the best tuning point when receiving FM, and is placed on the panel surface or the pointer itself. J is an FM intermediate signal input terminal, 2 is an FM detection IC (μPC11 manufactured by NEC)
6702, etc.), 3 is a detection coil section, and 4 is a resistor forming a detection circuit, at both ends of which an unbalanced voltage is detected.

5 is an AM intermediate frequency signal input terminal, 6 is a detection diode, 7 is a low-pass filter, 8 is a resistor for setting the lighting level of the light emitting diode (hereinafter referred to as LED) 14 during FM reception, 9 is a buffer diode, 10°1
1 is a capacitor for AC grounding, 12 is an LED when receiving AM, a resistor is used to set the lighting level of 4, 13 is a switching transistor that drives LED 14, ] 4 is an LED for displaying the tuning point, 1.5
.

1, 9, 20 are current limiting resistors for the LEDs 21, 22, 23, 16 is a bias resistor, 17.18 is a buffer resistor, 21. ．． 22. 23 indicates the direction in which the pointer should be moved in order to tune to the midpoint of the detection characteristic S curve (fo in Figure 2) during FM reception. LF:, D, 24 indicate two identical DC antennas 7° 24a , 24b is a built-in IC (such as AN6551.6552 manufactured by Matsushita Electronic Industries), 25 is an intermediate frequency transformer, and 26 is a bias resistor.

Next, to simplify the operation explanation, when receiving FM,
When completely detuned, the output from pin ■ of IC2 is zero, and the transistor 13 is off, so LED 14 does not light up, and the output from pin ■ of IC24 is also zero, so LEDs 21 and 2
3 does not light up. The LED 22 is always lit when the power switch is on. Now, when the tuning knob is turned and the pointer is at the position corresponding to between fl and fl in Figure 2, the voltage across resistor 4 is unbalanced, and the IC
A positive voltage appears at the output of pin 24, LED 2'l lights up, and the pointer is directed to move the needle further to the right. At this time 1'
A positive voltage also appears at the output of pin 2 of C2, so transistor 13 turns on and p LED ], , /l also light up. Conversely, when it is between f3 and f4 in Figure 2, IC24
Since a negative voltage appears on the pin ■, the LED 23 lights up, instructing the pointer to move to the left. At this time also LE
D14 lights up. Next, between fl and f3'', especially f
At point o゛, the output of pin/■ of IC24 is at zero potential, so LED 2 ].

23 and 23, only LED 14 lights up, indicating that the best tuning point is reached. On the other hand, when receiving AM, IC24
Since the output of pin ■ is up to -1: of zero, LED21.
Both 23 and 23 do not light up. The tuning point can be known only by lighting the LEDs l/l.

However, in this conventional device, when actually receiving FM and AM signals and listening to music, the LED1/I
Since only 22 and 22 are lit, the display effect is poor and all the LEDs are not fully utilized. There are drawbacks such as it is difficult to tell whether or not you are in sync.

(Object of the Invention) In view of the above-mentioned drawbacks of the conventional example, the present invention makes full use of LEDs to display a constantly moving display even when receiving FM or AM signals and listening to music, thereby eliminating distortion. To provide a tuning point display device for an FM or AM receiver that produces a ray effect and at the same time makes it easy to see the tuning state.

(Structure of the Invention) The present invention comprises three switching elements which are driven with sequential switching times shifted by the output of an astable multi-pipe rake, and which are arranged on a channel surface and which blink with the three switching elements. The five light-emitting elements and this row of light-emitting elements light up from both ends toward the center when tuning to FM or AM, and when receiving FM, they light up in the direction of moving the pointer to reach the best tuning point. It consists of a control circuit that controls the

Hereinafter, embodiments will be described in detail with reference to the drawings.

(Description of Embodiment) FIG. 3 shows an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same elements. IC2/I
On the 21Ia side, resistors 38, 39, 110 and capacitor /II constitute an astable multi-pie break.
Two power supplies, positive and negative, are used. Therefore, the output signal from the bin (2) becomes a pulse signal as shown in FIG. 5, with OV as the center and shifting in positive and negative directions. When this output signal is on the positive side,
Transistor 46 is turned on, and then transistor/17 is turned on with a slight delay by a time constant circuit composed of resistor 43 and capacitor 44. In order to turn on the transistor 48 on the negative side, if the time constants of the resistor 43 and the capacitor 14 are selected to appropriate values, the transistor 46. /17.48 switches in the order of 116 → 47 → /I8 and turns on and off in sequence. When all reception bands are FM bouncy and completely detuned, 1C.
There is enough voltage in bin 0 of 2 to turn on transistor 27, and transistor 28 is turned off, so the voltage is low.
ED 52-56 are all 1-sho that disappeared. The output of pin 2 of IC2 has completely opposite characteristics to that of pin O. When the tuning knob is operated to enter the range of f1 to f2 in Figure 4, the IC
The voltage at pin 2 of IC 24 drops, turning off transistor 27 and turning on transistor 28, but the voltage at pin 2 of IC 24 drops.
Since positive frost pressure appears at the output of , transistor 32 is turned off, transistor 35 is turned on, transistor 30 is turned on,
Transistor 33 is turned off. Therefore LED52゜5
Since power is supplied only to the three on the left side of 3.54, p due to the switching action of the transistors 46, 47i48
The LEDs are sequentially lit in the order from 52 to 53 to 54, instructing to move the pointer on the dial display surface to the right. Conversely, if the voltage falls within the range of f3 to f4, the transistor 28 is turned on as described above, but the IC2
Since the output of pin 4 is a negative voltage, transistor 32 is on, transistor 35 is off, transistor 30 is off, transistor 33 is on, and the LED is turned on.
Power is supplied only to the right three LEDs 54, 55, and 56, and the LEDs 56, 55, and 54 are sequentially lit to instruct the pointer to move to the left. best tuning point f
When the range is from f2 to fao including o, the transistor 28 is also turned on, and the voltage across the resistor 4 is in a balanced positive and negative state, and the output of IC2=+ becomes zero potential, and the transistor Both transistors 32 and 35 are turned off, and transistors 30 and 33 are both turned on. Therefore, the LED
When power is supplied to all of the LEDs 52 to 56, the LEDs 52 and 56 light up sequentially in the order of 53 and 55, respectively, to 54 (running from both ends to the center), so as to indicate the best tuning point.

When the receiving band is set to AM, when fully detuned, transformer 2, f57 is off, transistor 27 is on, and transistor 28 is off], LED 52 ~
56 have all disappeared. When in the tuned state, transistor 57 is turned on, transistor 27 is turned off,
Transistor 28 is turned on. When receiving the bottom, IC24
The output of pin (2) is zero (11), and since the transistors 30 and 33 remain on as at the FM best tuning point, power is supplied to all LEDs 52 to 56 during ambient timing.

Therefore, as in the case of FM tuning, the light travels from both ends to the center and is in the tuned state. Show that.

(Effects of the Invention) As explained above, according to the present invention, it is possible to provide an excellent display effect by displaying movement even when the synchronization is in use, and it is possible to make the synchronization state very easy to use. It has the effect of making it easier.

Although LEDs are used in this embodiment, similar effects can be obtained by using lamps or other display elements. still,
By changing the values of the resistors and capacitors that make up the astable multi-pipe rake, the oscillation frequency can be changed and the LED
The lighting running speed can be changed arbitrarily.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional example, Fig. 2 is an explanatory diagram of the same operation,
FIG. 3 is a circuit diagram of an embodiment of the present invention, and FIGS.
The figure is an explanatory diagram of the same operation. 2...FMIFM amplifier and detection IC, 3-FM detection block 6...Diode for delivery detection, 24...IC including two DC amplifiers, 28, 30, 33, 46, 47, 4
8. Switching transistor, 38, 39.40...
・Resistor 1・1 that composes astable multi-pipe rake
1. The same capacitor'1 /13.44...Resistors and capacitors that make up the time constant circuit, 52, 53, 54',
55.56 LED for display. Figure 4: 1 Figure 5 371

Claims (1)

[Scope of Claims] a. It has three switching elements driven by the output of an astable multi-no<even break-, the first and second switching elements are composed of NPN transistors, and the second
An appropriate time constant circuit is provided at the input of the switching element to cause a time delay in the switching operation from that of the first switching element, and a PNP circuit is provided at the input of the third switching element.
) A first means configured to sequentially perform a switching operation in three stages using a run source, and (b) 5 light emitting elements arranged in a row on a panel surface, and the light emitting element row Two light emitting elements at both ends have cathodes in common and are connected to the first switching element, and two second light emitting elements from the ends of the light emitting element row have cathodes in common and are connected to the second switching element. Further, the cathode of the light emitting element at the center of the light emitting element array is connected to the third switching element so that the lighting operation of the light emitting element array runs from both ends toward the middle flame. a second means, C connecting the anodes of two light emitting elements in order from one side of the light emitting element row to a power switching element in common, and connecting two light emitting elements in order from the other side A); The anodes of the first and second power switching elements are connected in common to a second power switching element, and the input sides of the first and second power switching elements and the anode of the center light emitting element are connected in common to a third power switching element. connected to the output 9i1 and said first
and the second switching element is controlled by the output of an unbalanced voltage detection circuit of the FM detection circuit, and the third power supply switching element is controlled by the output of a circuit that detects the presence or absence of the FM intermediate frequency signal and the AM intermediate frequency signal. and a third means configured to determine the presence or absence and direction of lighting running, and the lighting running of the light emitting element array is performed when FM and AM signals are tuned, and the best tuning is performed when FM signals are received. FM, characterized in that the direction in which the pointer is moved is clearly indicated by the lighting movement of the light emitting element array;
Tuning point display device for AM receiver and transmitter.