JPS6141311Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a tuning device for radio receivers, television receivers, etc. that employs an electronic tuner, and its purpose is to continuously transmit signals in two or more different frequency bands. The purpose is to make it possible to select stations.

In general, electronic tuners for the VHF band in television receivers have a VHF band of 90 to 108 MHz.
It is divided into a low band and a high band from 170 to 222 MHz, and to make it into one band, a switching circuit is formed using integrated circuits, transistors, etc., and the tube voltage for the low band and high band is switched. Ta.

However, these methods have the drawback of requiring a large number of parts and making the circuit complex.

One way to eliminate the above drawbacks is to remove part of the resistor of the variable resistor for tuning,
It is known to create a jump section in the middle of the tuning voltage by providing an electrode on the cut surface of the remaining resistor and connecting an impedance element between these electrodes. Since the channel selection voltage application terminal is open and the electronic tuner is in operation, it becomes Low.
There was a problem that other signals could be received in the band between the High band and the High band, causing malfunctions.

The present invention solves such problems, and embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the main parts of a variable resistor.
A circuit diagram with voltage applied to this variable resistor is shown in FIG.

As shown in the figure, this variable resistor has electrodes 2 and 3 provided at both ends of a resistor 1, and a power source 4 between these electrodes 2 and 3.
, and the tuning voltage is supplied to the electronic tuner from the electrode 5 of the movable terminal that is in slidable contact with the resistor 1. Here, the resistor 1 is separated into resistors 1a and 1b by removing a part in the middle, and electrodes 6 and 7 are respectively provided on the cut end surfaces of the resistors 1a and 1b. A resistor 8 is connected between them. Also, electrode 6
An electrode 9 is provided independently between the electrode 7 and the electrode 7, and this electrode 9 is directly connected to the electrode 2. A movable terminal is in sliding contact with this electrode 9 while the skip voltage is being generated, and the channel selection voltage is temporarily brought to earth potential. This prevents malfunctions in the jump section.

In this way, the resistor 1 of the variable resistor is divided into two, electrodes 6 and 7 are provided on each cut end surface, and a resistor 8 is separately connected between the electrodes 6 and 7. electrode 9 connected to electrode 2
By providing this, the voltage change of the electrode 2 with respect to the rotation angle of the variable resistor becomes as shown in FIG. 3, and even though it is continuously variable, the channel selection voltage jumps widely in the middle. At this time, the positions of the electrodes 6 and 7 are set so that the desired frequency can be obtained with the skipped voltage.

Therefore, according to this configuration, for continuous channel selection, it is only necessary to divide the resistor, provide electrodes, and connect the resistor, so the circuit is extremely simple.
Moreover, it is possible to prevent malfunctions in the jumping section.

4, 5, and 6 show still other embodiments, in which a resistor 8 is replaced with a resistor 8 in FIG.
In the figure, a Zener diode 10 is connected, in FIG. 5 a diode 11, and in FIG. Obtainable. In addition, in Fig. 6, 13,
14 is a bias resistor.

As explained above, according to the present invention, it is possible to tune signals in two or more different frequency bands consecutively with an extremely simple configuration, and the tuning voltage of the electronic tuner in the interlaced section can be set to the ground potential. It is possible to prevent the electronic tuner from malfunctioning by drawing the signal into the channel, and its practical value is extremely great.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the main part configuration of a tuning device for an electronic tuner according to an embodiment of the present invention, Fig. 2 is a circuit diagram of the device, Fig. 3 is a characteristic diagram of the device, Fig. 4,
FIG. 5 and FIG. 6 are views showing other embodiments of the present invention. 1a, 1b...Resistor, 2, 3, 5, 6, 7,
9... Electrode, 4... DC power supply, 8... Resistor.

Claims (1)

[Claims for Utility Model Registration] (1) Applying a voltage between the first and second electrodes at both ends of the resistor of a variable resistor for tuning whose movable terminal is connected to the tuning voltage application terminal of the electronic tuner. At the same time, a part of the middle of the resistor is removed, an impedance element is connected between the third and fourth electrodes provided on the cut end surface of the resistor, and the cut end surfaces of the removed resistor are connected. A tuning device for an electronic tuner, comprising a fifth electrode installed independently between the cut end faces of the resistor and in sliding contact with the movable terminal, connected to ground potential. (2) The tuning device for an electronic tuner according to claim 1, wherein the impedance element is a resistor. (3) The tuning device for an electronic tuner according to claim 1, wherein the impedance element is a Zener diode. (4) The tuning device for an electronic tuner according to claim 1, wherein the impedance element is a diode. (5) The tuning device for an electronic tuner according to claim 1, wherein the impedance element is a transistor.