JPS58179071A - Automatic channel selector - Google Patents

Abstract

PURPOSE:To avoid presetting a broadcast station under an inferior state of reception, by changing the value of the reference signal which is set to a detecting circuit for broadcast wave in the case of the fully automatic setting. CONSTITUTION:The presetting is given to channel selection by a voltage synthesizer system that controls an electronic tuner 1 in response to the channel selection voltage. In this case, the preset value of a counter provided to a circuit 5 which especially detects the presence or absence of a broadcast wave is varied between a fully automatic presetting mode and a semi-automatic presetting mode. As a result, it is possible to preset a broadcast station only when a broadcast wave higher than the prescribed field intensity is supplied in a fully automatic setting mode. This avoid presetting a broadcast station of inferior picture quality or presetting double the same broadcast station. The switching is possible between both presetting modes just by switching switches SW1-SW3 with interlocking to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic tuning device for a television receiver having an electronic tuner.

When presetting a desired broadcasting station by searching for the tuning voltage supplied to the electronic tuner, there are two types of resetting methods: full auto preset and semi-auto preset.

Full auto preset refers to a reset method in which all channel selection and preset operations are performed automatically, and semi-auto preset refers to a reset method in which all station selection and preset operations are performed automatically. The preset method is like a preset.

In this way, with full auto preset, once you operate the search key, it will automatically receive a broadcast station and preset that station, so it takes less effort to preset than semi-auto preset, which presets each time. It's convenient.

However, since full auto preset uses automatic search and automatic channel selection, it is not possible to select your favorite broadcast station or a station with good reception and reset it, unlike with semi-auto preset. This will preset all the broadcast stations that you have selected. For this reason, for example, if there is a broadcasting station with a strong electric field, spurious signals leaking from the single-child tuned tuner may be received, and therefore, in such a case, the same broadcasting station will be preset twice.

Additionally, if the base lIs value (signal output level, etc.) provided in the broadcast wave detection circuit is set relatively low,
Even in a broadcasting station with a weak input electric field strength, presence of 1,000 units may be detected, so that broadcasting station is also preset in such a case.

However, in such a preset under a weak electric field or a preset based on a spurious signal, the S/N of the broadcast signal is generally poor, and the received 1gII is therefore unsightly. Furthermore, there is no need to preset the same broadcast station twice.

In the case of full auto preset, it is necessary to take care not to preset all the broadcast stations that are overlapping by 50% or to preset all the broadcast stations so that an unsightly image is not obtained.

Therefore, in the present invention, especially when performing full auto preset, the width of the reference signal provided in the broadcast wave detection circuit is changed. According to this, the broadcasting station will be selected only when there is an input signal with a predetermined electric field strength or higher, so there is no need to preset broadcasting stations with poor reception as in the past. It disappears.

Next, an example of the present invention will be described in detail with reference to the drawings.

In the figure, (l) is an electronic tuning tuner, (2) is a video intermediate frequency amplification circuit, and (3) is a video signal detection circuit. In the present invention, the video signal subjected to signal detection is supplied to the horizontal synchronization/pulse separation circuit (4), and the horizontal synchronization pulse PH is separated from the video signal. separation,
The horizontal synchronization cell signal PH' thus obtained is supplied to a detection circuit (5) for detecting the presence or absence of broadcast waves, and the presence or absence of broadcast waves being received is detected.

On the other hand, an AFTT pressure detection circuit (6) is provided, and its output is supplied to the AFT discrimination circuit (7) to determine the AFT pressure.
The zero-crossing point of pressure is determined. This discrimination output P,2.
is the AND circuit (
8), and its output is supplied to the selection wJ voltage forming circuit αO.

Tuning (pressure forming circuit αQK stores tuning data) A
A nonvolatile memory consisting of R, AM, etc. is provided. Then, when selecting a channel, the data is encoded in the encoder C13 for a specific key obtained by operating a specific channel key, and this data is stored in the address counter a→. Then, the address for the memory α■ is specified.

The specified analog channel selection voltage V is supplied to the designated nine address 9 channel selection data (Fit)-A converter (to). After K conversion, the signal is supplied to the variable capacitance diode (G) provided in the electronic tuner (1), and the broadcasting station corresponding to the program position selected by the channel selection button (6) is selected. be done.

Now, in the semi-alternative reset mode 9, the program position key of channel selection methane (6) is selected, and the search button S1 is operated, and the flip-flop is displayed in the real search result P8. ? υ is set, and with its output, the 4' generator operates, and the /4' pulse obtained from this is used as the clock 74 pulses, and the channel selection counter (to) starts counting. The converter (6) immediately converts it into an analog channel selection voltage vc, and a search for the number of receiving stations fl begins. When a predetermined broadcast station is received, the AFT discrimination circuit (
The detection circuit (51) outputs the detection signal P□ as well as the detection circuit (51), which resets the fritsunoflora 7# (c) and sets the counter (2) at that time. ) data is latched and sent to the 6° AND circuit (the 8th AND output PA is further delayed for a certain period of time (on the order of tens of seconds) in the delay circuit (c), and then sent to the memory Ql) as a write-in! Therefore, when this write-enable pulse W occurs, the channel selection data latched in the channel selection counter is specified in the address counter α4. written to the address.

To preset the next broadcast ()@ again, operate the predetermined program position key in the channel selection button (6) as before, and then operate the search button Ss to select 79 tsug and 70 tsug. As a result, the channel selection counter (2) starts counting amplifier operation again. As a result, the tuning voltage VC which is the output of the D-me converter (T)
The search for the reception frequency starts, and the search mode continues until the next broadcast station is received.

When a broadcast station is received again, the tuning data of the tuning counter (To) is latched in that state, and after a predetermined period of time has elapsed, the data is written to a predetermined address specified by the address counter A4. .

Full auto preset mode looks like this.

In the case of full auto preset, the data of the address counter 04 is updated by the output of the count 7776 circuit (c). When the switch is turned on and the switch is closed, sw2 is switched as shown by the broken line. As a result of switching the switch y2 to the state shown by the broken line, the light naguruno mother russ W8 is 1!
! After being further delayed by a predetermined time (several tens of seconds) in the delay circuit (c) K, it is supplied to the count-up circuit (e) as its driving pulse.

In the case of full auto preset mode, leave the station (
6) By operating the search mode SF (Search mode S used during semi-auto presetting, but different) once, you can now use the search function 9.
The search mode is started by supplying the LS PF to the set terminal of the 79 7' 7 CI horn gradient through the OR circuit.

That is, pulse generator 4 is driven, and the channel selection counter (2)
The count-up operation starts and the channel selection voltage V.

The search for the receiving frequency starts. When the first broadcast wave is received, Fritzoflots! (2) is reset and the channel selection data is written into the memory aη, and after a predetermined period of time has elapsed in the delay circuit (after being written), this delay 9 rus P is generated.

is supplied to the count up circuit (c), and the data in the address counter 04 is updated, and at the same time, the fritz! 70 tubes? η is set again and the search mode is entered. When the next broadcast wave is received, the corresponding J, 'K station f'
- Address counter (specified in step 14)
6 is written into the address.

In this full auto preset mode, the above preset operation is repeated for all positions from the low end of VHF to the high end of UHF. In this invention, when the full auto preset mode is selected, the detection detects the presence or absence of broadcast waves. Change the reference value of circuit (5). In this example, the detection circuit (5) detects the horizontal synchronization pulse PH.
It consists of a counter that counts t-, a timer that measures the horizontal synchronization pulse PH that arrives in the cabinet for a certain period of time, and a comparison circuit that compares the measured data with a reference value, that is, a preset value of the counter.

Horizontal synchronization/9th pulse PMt - In this example, a period of 1 seconds is determined as the fixed period W to be measured. NTSC.

In PAL, 8ECAM standard television system, 1
Since the horizontal scanning time is approximately 64 μC, the number of horizontal synchronization signals P8 arriving within the unit time W of 1-second is 15 to 16.

Therefore, when the electric field strength of the broadcast wave is medium or higher, 15 to 16 horizontal N1 period pulses PM arrive per unit time W.

On the other hand, when the electric field strength of broadcast waves is weak, high-frequency noise components are mixed into the video signal, so there is a possibility that this noise component will be mistakenly used as a horizontal synchronization pulse for synchronization separation. horizontal sync for i9
Therefore, in such a weak input electric field state, the number of horizontal synchronizations and waves arriving per unit time W is not constant, and may be less than 15 or 15. It may be more than that.

Therefore, in this example, two preset values, an upper limit value B and a lower limit value A, are determined, and whether or not the number N of horizontal synchronization/gurus PH measured within a unit period W is between the reset values A and B. to detect the presence or absence of broadcast waves. And A, B
Two preset values are changed in full auto series reset mode.

That is, in the full auto reset mode, in order to avoid resetting broadcasting stations that have broadcast waves that weaken the input electric field or broadcast waves due to spurious signals, in the semi-sooto reset mode, A = 10 and B = 28 or so. On the other hand, when using full auto preset, change to A to about 13 and B to about 18.

In this way, during full auto preset, if the first field strength is medium or higher, the horizontal synchronization signal (
Since the number of waves is 15 to 16, the presence of broadcast waves is always detected at this time.

On the other hand, when the electric field strength is weak, the number of horizontal synchronization waves arriving within unit time W is extremely small, or #
'i Since the number is extremely large, there is an extremely high probability that the counter data will be outside of this preset range.
As a result, there is little risk of presetting a broadcasting station whose electric field strength is weakened.

In the case of a self-contained auto preset, the range of preset values is wide, so even in the case of a weak electric field, the broadcast wave can be detected and the broadcast station can be preset. .

In the figure, switch M is a switch for changing the glisset value. Therefore, these numbers of switches SW,
~SW3 are configured to be switched in conjunction with each other.

As explained above, in this invention, horizontal synchronization) 4
In channel selection presetting using one type of voltage synthesizer, the presence or absence of broadcast waves is detected based on the number of pulses and the presence or absence of the MuFT detection voltage, and the electronic tuning tuner (1) is controlled according to the channel selection voltage. In particular, the preset for the counter provided in the circuit (5) that detects the presence or absence of broadcast waves is fully automatic! It is a good idea to change the value in reset mode and semi-auto series reset mode.

By doing this, even if the input electric field strength of the broadcast wave of the desired broadcasting station is weak in the semi-auto reset mode, it is possible to preset it with certainty, and in the full auto preset mode. Only when a broadcast wave with a predetermined electric field strength or higher is input, that broadcast station can be preset. Therefore, there is no risk of presetting the same broadcasting station twice when resetting a broadcasting station with poor image quality as in the past.

Also, the full auto preset mode and theo'pf re-nit mode are simply switches SW, ~SW.

Since all the switching operations are required, the operation is extremely simple, and there is no risk of manual operation.

In the above-mentioned refreshing example, the values A and B are selected as described above as the preset values for the counter provided in the detection circuit (5) for detecting the presence or absence of broadcast waves. Selection of preset values is just one example.
Further, the configuration of the channel selection voltage forming circuit αQ is also only an example.

[Brief explanation of the drawing]

The figure is a system diagram of essential parts showing an example of an automatic channel selection device according to the present invention. (1) is an electronic tuning tuner, (3) is an Fi video detection circuit, (4) is a horizontal synchronization/base pulse separation circuit, (5) is a circuit that detects the presence or absence of broadcast waves, and (6) is a detection of AFT voltage. Circuit, (7) is the tuning voltage forming circuit, @ is the memory, (to)
is the channel selection methane, a◆ is the address counter, (to) is D-
In the A converter, SW, #sw2 is a preset mode selection switch, and 8W is a switch for changing a gliset value. Same Hide Matsukuma side.

Claims (1)

[Claims] The horizontal synchronization signal is separated from the video signal that has been detected, and it is supplied to a broadcast wave detection circuit, and the horizontal synchronization signal that arrives within a certain period of time is measured using IRT, and this is within a preset value range. At some point, an automatic tuning device is provided in the tuning voltage forming circuit and presets the tuning data in the memory, and at the same time pressures the above preset f[' to be changed between full auto reset and auto preset.