KR20000003546A - Aft range automatic resetting method of television - Google Patents

Abstract

PURPOSE: An AFT range setting up method is provided in a software method to prevent seceding from an AFT range because of a tuning voltage. CONSTITUTION: A method for preventing the distortion of tuning that receiving condition becomes bad because of the changes of the inner or the outer temperature of the television or a transmission of power voltage comprises the steps of: memorizing the present transmitting channel tuning voltage if a mode of a television or a channel transmission signal is input; setting up the AFT range for including the variation range of the middle picture frequency by standardizing the perceived figure by reading the memorized tuning voltage on the present channel tuning voltage memorizing step.

Description

How to automatically reset your TV's AFT range

The present invention relates to a method for automatically resetting the ATF range of a television. In particular, the present invention relates to an automatic setting up method of Automatic Frequency Tuning for television (AFT) in order to prevent a tuning misalignment that occurs when a television is switched by an external change such as high temperature or low temperature.

When the oscillation frequency changes due to temperature or power voltage fluctuation during the tuning, the receiving image may be blurred or unreceivable. Therefore, AFT voltage is applied to the variable capacitance diode to keep the oscillation frequency constant. . For example, in a television set with an intermediate image frequency (IF) of 38.9 MHz, the AFT region has a margin of about 0.5 MHZ up and down at 38.9 MHz, and a method of maintaining a constant oscillation frequency changed by the influence of high temperature is used. have.

However, if the fluctuation range of the tuning voltage (VT) is out of the above-mentioned AFT range, the tuning misalignment phenomenon cannot be prevented. Therefore, in the related art, a hardware method for preventing this by using a temperature compensation capacitor and a wider AFT range in advance are applied to the microcomputer. Stored and corresponding methods are used.

However, in the conventional method of preventing the misalignment caused by the temperature change or the change of the tuning voltage, when the temperature compensation capacitor is used, the circuit becomes complicated, the product cost becomes expensive, and the AFT range is applied in a wide range in advance. The method can cope only within a range of a predetermined AFT region, and there is a problem in that a tuning distortion cannot be prevented when it is out of a predetermined AFT range.

The present invention has been invented to solve the above problems of the prior art, and an object of the present invention is to provide a software to prevent the deviation of the AFT range due to fluctuations in the tuning voltage (VT). The present invention provides a method of resetting the AFT range according to the tuning voltage value by storing the tuning voltage of the channel or mode.

According to the technical concept of the present invention, when a television is turned on, an AFT adjustment and search operation and a tuning voltage value memory process of each channel are basically performed. If it is determined that the user is in the mode or channel switching mode and is not determined by the switching command, the display is normally displayed. We present a method to reset the AFT range by horizontally shifting the AFT range based on (VT).

1 is a schematic diagram illustrating a voltage synthesizer electronic tuning method.

2 is a schematic system diagram of an AFT circuit.

3 is a flowchart of an AFT range automatic resetting method of the present invention.

<Description of the symbols for the main parts of the drawings>

100: channel button unit 110: preset adjustment unit

120: Tunneling IC 121: Tunneling control unit

122: mode control unit 123: memory control unit

124: data register 125: comparator

126: AFT 127,230: oscillation circuit

128: divider 130: memory control IC

140: memory IC 141: control unit

142: address register 143: data register

144: memory 150: integrating circuit

200: tuner circuit 210: RF amplifier

220: mixer circuit portion 300: AFT circuit portion

310: frequency amplifier 320: phase discrimination transformer

330: phase detector 340: DC amplifier

350: variable capacitance diode 400: video intermediate frequency amplifier

Hereinafter, with reference to the accompanying drawings for the configuration and operation of the present invention will be described in detail.

FIG. 1 is a schematic block diagram illustrating a voltage synthesis method (hereinafter, referred to as a VS method) applied to the present invention among electronic tuning methods.

Tuning IC 120 coupled with channel button unit 100 and preset adjustment unit 110, memory IC 140, memory control IC 130 for controlling memory IC 140, and tuning station IC And an integrating circuit 150 for processing the tuning voltage output from the 120.

The channel selection IC 120 receives the adjustment signal input from the preset adjustment unit 110 to control the mode and mode control unit 122, and receives the control signal input from the channel button unit 100 to process The oscillation circuit section 127, the divider 128, and the channel information stored in the memory IC 140 and the channel information output from the divider of the tuning circuit are configured. A memory controller 123 and a data register 124 for processing data for comparison by the comparator 125 and an AFT 126 for adjusting the change in the oscillation voltage.

The VS method converts the tuning voltage and band switching voltage of 0-33V into digital signals and stores them in the memory IC for each channel button. When the desired channel is set for each channel button and the channel button is pressed afterward, the digital signal corresponding to the channel button is taken out according to the operation of the channel IC 120, and converted into a tuning voltage and a band switching voltage (D / A conversion). ) Is applied to the electronic tuner.

2 is a schematic system diagram of an AFT circuit for AFT adjustment in the above VS method. A variable signal is applied to the RF amplifier 210 for amplifying the input RF signal, the mixed circuit 220 mixed with the output frequency of the RF high frequency amplifier and the local oscillation frequency of the oscillator circuit 230, and the oscillator circuit 230. A tuner circuit portion 200 including a variable capacitance diode 240 to be supplied, an image intermediate frequency amplifier 400 for converting and amplifying the tune signal of the tuner circuit portion 200 into an intermediate frequency IF and the image A frequency amplifier 310 for frequency amplifying the image signal output from the intermediate frequency amplifier 400, a phase discriminating transformer 320 for determining a phase in the output signal of the frequency amplifier 310, and a phase detector ( 330, an AFT circuit unit 300 including a DC amplifier 340 for amplifying the output DC component signal of the phase detector 330.

Here, if the local oscillation frequency of the oscillator circuit 230 is out of the higher direction, the image intermediate frequency is lower than 38.9MHz so that a negative voltage appears at the output of the phase detector 330. When the negative voltage is applied to the variable capacitance diode 240 of the oscillation circuit unit 230, the capacitance is increased to lower the oscillation frequency to the correct frequency.

In the automatic resetting method of the AFT range according to the change of the coin voltage of the present invention, the AFT range is adjusted to have a range of ± 0.5 MHz while the image intermediate frequency is set to 38.9 MHz. When the tuning voltage is VHF, a unique tuning voltage VT for each channel is set in the range of 0 to 33V and stored in the memory IC 140.

When the local oscillation frequency is changed due to the change of intrinsic tuning voltage of each channel due to the change of the internal and external environment such as the temperature change in the stable adjustment state of the television, the range of the variation is 38,9MHz ± 0.5MHz In the range, the compensation is made by the AFT circuit, but if the local oscillation frequency is out of the AFT range (± 0.5 MHz), the reception is poor or not received.

3 is a flowchart illustrating a method for automatically resetting an AFT range according to a change in the tuning voltage VT of the present invention.

AFT adjustment step (S100) for adjusting on the basis of the set image intermediate frequency (38.9MHz) when the television is turned on,

A search step (S200) of searching for preset information stored in the memory IC of the television;

A tuning voltage (VT) value memory step (S300) for storing a tuning voltage (VT) unique to each preset channel;

A mode or channel switching determination step (S400) of determining whether a user switches a mode or a channel of the television after performing the above-described step;

If it is determined that the switching signal is not input in the mode or channel switching determination step (S400), the normal television operation step (S500) for normal display;

A current channel tuning voltage memory step (S600) of storing a current tuning voltage (VT) value of the switched channel in the memory when it is determined that the switching signal is input in the mode or channel switching determining step (S400);

An AFT range reset step (S700) for horizontally shifting and resetting the AFT range value based on the tuned voltage stored in the current channel tuned voltage memory step (S600);

A mode or channel switching step (S800) is performed to switch the mode or channel to a stable state in the area reset by the AFT range reset step (S700).

The AFT adjustment step (S100) is a step of adjusting the AFT in the range of 38.9 MHz ± 0.5 when the television is first turned on, in response to a change in the tuning voltage (VT) value of the received channel.

The search step (S200) is a step for retrieving various information of the television about the chromaticity, contrast, volume, etc., which are set in advance by the service subject or the user, and leaving the TV ready for use.

The channel tuning voltage (VT) memory step (S300) is a step of adjusting and storing the tuning voltage of each channel so that the user can finely adjust each channel to receive the optimal reception state.

The mode or channel switching determination step (S400) is a step of determining whether a user inputs a signal to switch various adjustable modes or channels of the television. In other words, when a user inputs a signal for adjusting the volume and contrast using a remote controller or the like, or inputs a signal to change a channel, the microcomputer detects the signal.

In the current channel tuning voltage memory step S600, the tuning voltage of the channel to be switched is different from or equal to the set value stored in the tuning voltage memory step S300 due to a change in the external environment such as a high temperature or a low temperature or a power supply voltage. In this case, the information on the tuning voltage of the currently detected channel is stored in the memory. For example, when the setting value of the tuning voltage memory step (S300) of the channel 2 is 2V, this value (3V) is stored in the memory when the tuning voltage of the channel 2 detected at the input of the channel switching signal is increased to 3V. .

The AFT range resetting step (S700) is a local oscillation frequency output from the oscillation circuit unit 230 of the toner circuit unit 200 by the voltage memorized in the current channel tuning voltage step (S600) to increase or decrease the RF amplification If the sum of the RF high frequency output from the unit 210 is out of the normal AFT range (38.9 MHz ± 0.5 MHz), the value is shifted horizontally. For example, the AFT range is reset to 40.0 MHz ± 0.5 MHz. The frequency output from the mixer circuit unit 220 is within the newly set AFT range (40.0 MHz ± 0.5 MHz).

In this case, if the current channel tuning voltage is not memorized, if the image intermediate frequency (IF) is changed to the tuning voltage during the channel switching, and is changed to 38.9 MHz, for example, 40.0 MHz, the system routinely needs to adjust the tuning voltage. The previous tuning voltage memorized in the tuning voltage memory step S300 is read. If this happens, the AFT range will not be found, which will cause tuning distortion. Therefore, in order to automatically reset the AFT range as described above, the variable tuning voltage of the current channel, which is the reference value of the reset, is stored in memory, and the AFT range is reset in conjunction with the value.

As described above, by resetting the AFT range in response to the tuning voltage which is changed according to the change of the internal and external environments of the television, a mode or channel switching is performed so that a television screen in a good state can be always received.

As described above, in the present invention, when a channel of a television is switched in a high or low temperature environment, the current channel tuning voltage VT is memorized, and the AFT range is automatically adjusted based on the stored tuning channel voltage. By resetting, it prevents misalignment, that is, by resetting the range of the AFT value in conjunction with the change of the VT value, so that a stable tuning state can be maintained at all times even when the internal and external environment of the television is changed. Implemented by MICOM in software, it is effective to simplify AFT circuit.

Claims (2)

In the method for preventing the distortion of the reception is poor due to the change in the temperature of the inside and outside of the television or the change in the power supply voltage, Memorizing the current channel tuning voltage to be switched when the mode or channel switching signal of the television is input; And resetting the AFT range to read the tuning voltage stored in the current channel tuning voltage memory step so as to include a variation range of the video intermediate frequency based on the value. The method according to claim 1, further comprising: a mode or channel switching command determining step of determining the input of the mode or channel switching signal of the television; And resetting the mode or channel after the AFT range resetting step.