JPS5946444B2 - Electronic tuning type tuning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic tuning type tuning device using continuous variable means. The purpose is to eliminate the need for band switching operations.

With the spread of electronic tuning type tuning devices, the method of presetting the tuning frequency by changing the tuning voltage, or directly tuning the channel, has become popular in television receivers and other F.
It has even come to be used in M, AM radio, etc.

Taking television receivers as an example, in order to simplify the tuning mechanism, especially in small receivers, the tuning voltage is changed by directly operating a variable resistor using the tuning dial, and continuous tuning is used. There are many ways to select channels.

By the way, in a conventional channel selection device equipped with such a continuous tuning system tuning mechanism, for example, as shown in FIG.

It is necessary to provide a band switching switch 2 for three receiving frequency bands, vHF low band and vHF bi band, and to operate it according to the selected channel.

This band switching operation is not only a nuisance for the user, but also especially for the VHF low band and biband.
Band switching is a major point because the meaning is unclear to general users.

The present invention was made in view of the problems of the conventional continuous tuning system tuning device, and automatically performs band switching with a simple matching configuration, thereby reducing user's hassle. It is something to do.

An embodiment of the present invention will be described below based on the drawings.

Figure 2a shows, for example, the low band of the VHF band, -.
FIG. 2 is a circuit diagram of an electronic tuning type tuning device equipped with an automatic band switching circuit.

FIG. 3 is a waveform diagram showing waveforms of essential parts of FIG. 2.

A tuning voltage power supply 4 is connected to one terminal of the variable resistor 3 for tuning.
More V.

is applied, and the tuning voltage (2) is taken out from the variable resistance terminal 5 and supplied as the tuning voltage to the tuner 6.

On the other hand, reference voltages v7 and vR28 for comparison are generated from the tuning voltage power supply 4 by resistor division, and the corresponding voltage comparison circuits 9 and 10 are used to calculate the magnitude relationship between VREFI and VREF2. are being compared.

Now, hypothetically, VRoFl−0°VREF 2 =”O(
However, 0<VRlmF 1 bar, 2<v.

), and the output B of the voltage comparison circuit 9 is vT >
The input polarities to the two voltage comparator circuits 9 and 10 are determined so that the output C of the voltage comparator circuit 10 is at the L level when the relationship is VRIF and FI, and the output C of the voltage comparator circuit 10 is at the L level when the relationship is v x v. put.

Now, if you perform a series of tuning operations such as turning the tuning dial 1 shown in Figure 2 in the order of right direction, left direction, right direction, each rotation angle is turned as far as it will go. As shown in the figure, a change A in the tuning voltage V1 according to the rotation angle is obtained, and accordingly, the outputs of the two voltage comparison circuits 9 and 100 also change to B in FIG.

It changes like C.

Therefore, the outputs B and C of the two voltage comparison circuits 9 and 10 are
When input to the R circuit 11, the waveform shown in the third diagram is obtained as an output.

The output of the OR circuit 11 is sent to the T-flip-flop circuit 12.
, the T-flip-flop circuit 12 detects that the output polarity of either one of the voltage comparison circuits 9 and 10 changes from L to H.
・Every time it changes to \, that is, vT changes.
It is triggered every instant when <VRgFi or C"r>"REF2 is reached, and the output polarity is inverted to generate an output signal E.

In other words, this shows that the output polarity of the T-flip prop circuit 12 changes each time the dial 1 is turned all the way to the right or left by the tuning operation, and this output E is sent to the VHF tuner 6. If it is supplied as a switching voltage, the reception frequency band can be automatically switched from low band to high O band to low band each time the dial is turned in either direction.

In order to display the currently selected band, the Q and ζ outputs of the T-flip-flop circuit 12 are used to
It is very easy to understand if the channel number display lamp 14.14 of the corresponding reception band is driven via 3.13.

Furthermore, if you want to directly specify the receiving band in addition to automatic switching of the receiving band, use a flip-flop circuit as shown in Figure 4.
By using the flop circuit 15, the output of the OR circuit 11 is used as the clock input of the flip-flop circuit 155.

By connecting the output of the low band designation switch 16 to the clear input of the flip-flop circuit and setting it to L level, the output of the low band designation switch 16 is forcibly reset.

Further, the output of the high band designation switch 17 is connected to the input terminal of the flip-flop circuit 150, and at the same time, it is inverted by the inverter 19 and used as the third input signal of the OR circuit 11. By setting the output of 17 to L level, flip-flop circuit 15 can be forcibly set.

In this way, it is easy to use the method in combination with the method of directly specifying the selected band.

In the embodiments described above, the low band of the VHF band,
Only the high band switching is done automatically, but
When automatically switching three bands including the UHF band, a ternary kakunta is provided in place of the flip-flop circuit 12, and its output is supplied to the tuner 6 as the band switching voltage. →V
The selection band can be automatically switched from HF high band to UHF.

It is possible to apply the present invention in a similar manner to a channel selection device having four or more reception frequency bands.

According to the above embodiment, a very convenient tuning mechanism in which when the tuning dial is rotated to reach end 1 of one receiving frequency band, it automatically switches to the next receiving frequency band can be achieved using a simple circuit. This can be achieved by configuration.

This not only reduces the operational hassle of switching the reception frequency band with a switch, but also makes it possible to omit the band switching switch in some cases, which is also effective in terms of design and cost. can be expected.

It goes without saying that the present invention can be applied not only to the channel selection device for a television receiver as shown in the above embodiment, but also to the channel selection device for radios and other general wireless devices.

As described above, the present invention provides an excellent electronic tuning type tuning device with improved operability by switching the receiving frequency band in accordance with the tuning operation.

[Brief explanation of drawings]

FIG. 1 is a top view of a tuning dial equipped with a conventional band selection switch, FIG. 2a is a circuit diagram showing an embodiment of the electronic tuning type tuning device of the present invention, and FIG. A top view of the channel selection dial in the example, FIG. 3 is a waveform diagram of essential parts of this embodiment, and FIG. 4 is a circuit diagram showing another embodiment. 3...Variable resistor for tuning, 6...Tuner, 9゜10...Voltage comparison circuit, 11...
...OR circuit, 12...T-flip-flop circuit 1.15...Flip-flop circuit in J-.

Claims (1)

[Claims] 1. In an electronic tuning type tuning device equipped with a circuit for generating a continuously variable tuning voltage for setting a tuning frequency and a band switching circuit for the receiving frequency band, two comparison reference voltage generation circuits and respective comparison standards are used. two voltage comparison circuits that detect a magnitude relationship between a voltage and the tuning voltage, and a transition in which the tuning voltage becomes larger than both of the two comparison reference voltages due to the output polarity of these two voltage comparison circuits;
or bistable circuit means for inverting the output state every time a transition occurs in which the tuning voltage becomes smaller than both of the two comparison reference voltages, and the receiving frequency is controlled by the output of the bistable circuit means. An electronic tuning type tuning device characterized by performing a switching operation of a band switching circuit.