JPS5820484B2 - Channel selection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, the tuning voltage to be applied to a tuner using a variable capacitance diode as a tuning element is set in advance by a plurality of variable resistors, and the variable resistors are The present invention relates to a channel selection device that performs channel switching by switching to and operating the channel, and provides a device that can select a large number of channels with a simple configuration.

Recently, many tuners have been used in which a variable capacitance diode is used as a tuning element, and channel switching is performed by switching the tuning voltage applied to the variable capacitance diode.

First, an example of a conventional device in which such switching is performed using a counter and a decoder will be described with reference to FIGS. 1 and 2, showing the main parts thereof.

Here, 1a to 1p are 16 variable resistors for setting the tuning voltage BT in which the tuning voltage BT applied to the variable capacitance diode of the tuner is preset. A selected one is taken out through diodes 2a to 2p, has its impedance converted by a transistor or the like (not shown), and is applied to each variable capacitance diode of the tuner.

3 is a channel switching circuit for switching which of the variable resistors 1a to 1p is to be operated; here, a binary counter 4 and a decoder 5 are used.

That is, an oscillation circuit 6 for generating clock pulses, a binary 4-digit counter 4 for counting the pulses, and a binary-hexadecimal counter 4 for generating an output that selectively becomes a low level depending on the binary output. The control circuit 7 includes a decoder 5 and a control circuit 7 that controls the operations of the counter 4 and the pulse generation circuit 6.

An example of this control circuit 7 is shown in detail in FIG. The decoder 5 is equipped with an output switching transistor for each of the 16 output terminals a""-p, and only one of these transistors is selectively turned on according to the binary count output output from the counter 4. and output terminal a”
A low level output is generated at one of the transistors p, and a current is passed through the variable resistor connected to the output terminal of the transistor that is turned on, and the current is set in the variable resistor. The channel selection voltage is extracted.

When switching channels, each output terminal a of switching circuit 3
16 normally open switches 8a to 8p connected between each of p and the channel switching signal input terminal CH.
One of them is closed.

At that time, if the channel at the position of the closed switch is not selected, the output of the output terminal of the decoder 5 to which that switch is connected is at a high level, so that output is controlled via the switch. The clock pulse CL is applied to the input terminal CH of the circuit 7, and the output from the output terminal OC causes the oscillation circuit 6 to start generating pulses, and the generated clock pulse CL is applied to the counter 4 via the terminal UCL.

As a result, the counter 4 starts counting, and the output terminals that generate the output of the decoder 5 move one after another accordingly.

When the closed switch changes until an output is generated from the connected output terminal, the input to the input terminal CH of the control circuit 7 becomes a low level, so the operation of the oscillation circuit 6 is stopped, and from then on The selected state of that channel is maintained until the switch of another channel is operated, and that channel becomes selected.

If the frequency of the clock pulses generated by this oscillation circuit 6 is set sufficiently high, for example, about IKHz or higher, the above-mentioned channel switching can be completed within a very short time while the switches 8a to 8p are closed. Ru.

9U and 9D are switches that are opened and closed by operating signals such as ultrasonic waves or lights or by manual operation when sequentially selecting channels by remote control or manual operation. When switch 9U is operated, a count is sent from the control circuit 7 to the counter 4. An up signal is added and the channels above are selected one by one.
When the switch 9D is operated, a countdown signal is applied from the control circuit 7 to the counter 4, and the channels below are selected one by one.

Further, as is clear from FIG. 2, the output terminal DF provided in the control circuit 7 in the switching circuit 3 is connected to the counter 4.
This terminal generates an output when a count signal is applied to the channel, that is, when channel switching is being performed.

This output is used to defeat the AFC circuit of the tuner during channel switching.

Note that the illustration and explanation of the band switching portion and channel display portion of ■HF and UI (F) are omitted.

In this way, purely electronic channel selection is done,
The conventional system described above has the inconvenience of not being able to select from a large number of channels.

In other words, since the switching circuit 3 is a part that handles binary signals, it is composed of integrated circuit elements, but due to limitations on the chip size and the number of pins, it has only 16 channels as described above. I can't even create 7 channels to select, and I want to switch even more channels.
There was a drawback that if a C element were to be produced, it would be extremely expensive.

Therefore, an object of the present invention is to eliminate such drawbacks of the conventional technology, and to provide a device that is simple in structure, inexpensive, and capable of switching a large number of channels, about twice as many as the conventional technology. The invention is characterized in that two sets are used and they are connected to each other using special switching means.

Hereinafter, one embodiment of the present invention will be described with reference to FIG.

In addition, in addition to the same reference numerals as in Fig. 1, parts corresponding to each part in Fig. 1 are numbered in the 10s for the first switching part, and codes in the 20s for the second switching part. This will be explained below.

In this device, the first. Second two sets of switching circuits 13
Use ゜23.

Each switching circuit 13.23 is similar to the switching circuit 3 in FIG. a =
An input terminal CH to which a signal is input for switching which output is generated from p, and a default terminal D which generates a default output during the switching period of the output.
It is equipped with F.

Then, variable resistors 11a to 11o and 21a to 21o are connected to each of the 15 output terminals 2xo among the 16 output terminals, and switch elements for channel switching are connected between each input terminal CH. 18a~;1
Connect 8o and 28a to 28o.

Therefore, switching for 30 channels can be performed.

Furthermore, in this device, the first. Second switching circuit 13.23
A coupling circuit 30 is provided to couple the two for organic operation.

In the coupling circuit 30, the first . The first . The second switching elements 18p and 28p are connected.

Also number 1. Defeat terminals DF of the second switching circuits 13 and 23 are connected to the first. The second waveform shaping circuits 10 and 20 are connected.

They integrate and waveform shape the low level default output generated during the switching period of each switching circuit 13, 23 to generate a wide pulse width output, thereby increasing the output of the first waveform shaping circuit 10. Then, the second switching element 28
p is switched, and the output of the second waveform shaping circuit 20 switches the first switching element 18p.

Regarding the operating time of each part, the pulse width of the output of the waveform shaping circuit 10.20 is longer than the time during which the switch elements 18a to 18o, 28a to 28o are closed by human operation (for example, about 200 m5ec). The clock frequency is set (for example, about IKHz) so that it is sufficiently short (for example, about 0msec) and that each switching circuit 13.23 performs at least one switching cycle during the pulse period.

In such a configuration, it is assumed that an output is generated from one of the output terminals a''o of the first switching circuit 13 and that channel is selected.

At this time, as will be clear from the following description, the second switching circuit 23 generates an output from the output terminal p.

In this state, if any of the switch elements 18a to 18o connected to the other output terminals in the first switching circuit 13 is operated, the first switching circuit 13 will output from the operated output terminal. A switching action is taken to cause the occurrence of the problem.

At the same time, an output is generated from the default terminal DF, and the second switching element 28p is switched via the waveform shaping circuit 10, but at this time, a low level output is generated from the output terminal p of the second switching circuit 23. Since it is a level, the output state does not change.

As a result, the channel of the operated switch element is switched to be selected.

On the other hand, when any of the switch elements 28a to 28o connected to the second switching circuit 23 is operated in the above state, the output switching operation in the second switching circuit 23 is first performed, and the output from the default terminal DF is switched. An output is generated and passed through the second waveform shaping circuit 20 to the first switching element 18p.
Switching.

For this reason, a switching operation is performed in the other first switching circuit 13 so as to generate an output from the output terminal p,
Stop in that state.

At this time, a default output is also generated from the default terminal DF of the first switching circuit 13 during the switching period and switches the second switching element 28p via the first waveform shaping circuit 10, so that the second switching circuit 23 Then, the output terminal p is once switched to generate an output, but as mentioned above, the output time of the waveform shaping circuit 10.20 is made sufficiently shorter than the operation time of the switch element, so such switching is completed. Even after the switch element 28a~
28o continues to be operated, the switching operation of the second switching circuit 23 is performed so that an output is generated from the output terminal of the operated switch element. The channel of the operated output terminal will be tuned.

Note that in a state where an output is being generated from the output terminal a''=o of the second switching circuit 23, the switching elements 28a to 2 connected to the second or first switching circuit 23, 13
Exactly the same operation is performed when 8o or 18a to 18o is operated, and the channel of the operated switch element is selected.

In this way, according to this device, 30 channels can be selected by simply using two sets of conventional 16 channel selection switching circuits and combining them with a special coupling circuit, making it possible to select 30 channels at low cost. This made it possible to realize a device with a simple configuration.

In addition, in the above embodiment, the switch elements 18a to 18
o and 28a to 28o are mechanical switches, but it goes without saying that these may be electronic switches.

Further, the waveform shaping circuits 10 and 20 may also be constructed using monostable multi-vibration circuits or the like in addition to the integrating circuit.

As detailed above, in the present invention, two sets of switching circuits similar to the conventional one are used, and the switching elements and the default output are used to connect them, so that the conventional switching circuit can be used as is. By using two channels and adding a simple circuit, it is possible to obtain a device capable of selecting approximately twice the number of channels at a low cost, which is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional channel selection device, FIG. 2 is a detailed circuit diagram of a control circuit used in the same device, and FIG. 3 is a circuit diagram of a channel selection device in an embodiment of the present invention. 11a-llo, 21a-21o...variable resistor, 13...first switching circuit, 23...
・Second switching circuit, 18a-18o, 28a-28o
...Switch element, 18p...First switching element, 28p...Second switching element, 10...First waveform shaping circuit, 20
...Second waveform shaping circuit, 30...Coupling circuit.

Claims (1)

[Claims] 1 A plurality of output terminals that selectively generate an output from only one of them, an input terminal into which a signal is input for switching which of these output terminals generates an output, and one of the above output terminals. Two sets of switching circuits each having a default terminal that generates a default output during the switching period are provided, and the first. between one output terminal of the second switching circuit and the respective input terminal of the respective first switching circuit. A second switching element is connected to the first switching element. A channel switching switch element is connected between the remaining output terminal of the second switching circuit and each input terminal, and the variable resistor for setting the channel selection voltage is selected by the output of the remaining output terminal. The channel selection voltage is supplied to the variable capacitance diode of the electronic tuner, and the second switching element is switched by the default output of the first switching circuit, and the default output of the second switching circuit is switched. so that each default terminal and the first switching element are switched by the first switching element. A channel selection device characterized in that it is coupled with a second switching element.