KR20000003548A - Correction method of tuning voltage(vt) for television - Google Patents

Abstract

The present invention relates to a tuning voltage (VT) correction method in a voltage synthesis method (Voltage Synthesizor Method) of the electronic tuning device.

The present invention proposes a method for preventing the tuning from being turned off because the tuning voltage (VT) is changed at a set value when the mode or the channel is switched in the use environment of a television such as a high temperature or a low temperature.

When switching channels of a television in a high or low temperature environment, the current channel tuning voltage (VT) is memorized and the current tuning voltage is greater than the set value by comparing the stored tuning channel voltage with the set tuning voltage. If it is small, it adjusts the tuning voltage by adding or subtracting the pulse width modulation (PWM). By constantly correcting the distortion of the VT value in software, it is possible to implement a television that can always maintain a stable reception state even when the television's internal and external environment changes.

Description

How to adjust the tuning voltage of the television

The present invention relates to a method for automatically correcting the tuning voltage (VT) of a television. In particular, the present invention relates to a compensation method for tuning voltage of a television for preventing a tuning misalignment caused when a television is switched by an external change such as high temperature or low temperature.

If the oscillation frequency changes due to temperature or power voltage change during tuning, and the tuning voltage VT is out of the set value of the corresponding channel, the reception image may be blurred and the tuning may be unreceivable.

In general, in order to maintain a stable screen, an AFT range is allowed to allow a certain area in which an image intermediate frequency (hereinafter referred to as "IF frequency") can flow at a rated value, and AFT adjustment is performed. For example, in a television with the image intermediate frequency (IF) set to 38.9 MHz, the AFT region has a margin of about 0.5 MHZ up and down at 38.9 MHz, and the IF frequency is corrected by correcting the oscillation frequency changed by the influence of high temperature. A method of keeping the screen state stable is used.

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 tuning misalignment caused by the temperature change or the change of the power supply voltage, the circuit is complicated and the product cost becomes expensive when the temperature compensation capacitor is used, 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 that the fluctuation of the tuning voltage (VT) due to the fluctuation of the local oscillation frequency out of the AFT adjustment region due to the temperature change or the like. In order to prevent the damage, check the tuning voltage of the current channel or mode during channel switching or mode switching of the television. If the value is larger or smaller than the setting tuning voltage (VT) of the current channel, it is automatically corrected by the tuning tuning voltage. To provide a way to do this.

According to the technical concept of the present invention, when the television is turned on, the tuning voltage value memory process of the channel is performed, and then the current VT voltage is checked. If the current VT voltage checked is equal to or less than the set value VT voltage of the corresponding channel, it is judged that the tuning voltage is greater or less than the set value, and the VT voltage is automatically adjusted by adding or subtracting the width of the pulse width modulation (PWM). The correction method is presented.

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

2 is a schematic system diagram of an AFT circuit.

3 is a flowchart of a tuning voltage (VT) correction 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 systhesizor 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.

FIG. 2 is a schematic system diagram of an AFT circuit for AFT adjustment at allowed variation of IF frequency, which is common in the above VS scheme. 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 the intrinsic VT 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 as described above, 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.

FIG. 3 is a flowchart illustrating a method of correcting a tuning voltage VT in order to prevent the tuner distortion of the present invention.

A search step (S100) of retrieving preset information stored in the memory IC of the television when the television is on;

A channel memory step (S200) for setting a channel to be automatically tuned and storing the same;

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

A VT voltage checking step (S400) of checking the VT voltage of the current channel when the user switches the mode or channel of the television after performing the above step;

A VT voltage comparison step (S500) for determining whether the VT voltage checked in the VT voltage checking step (S400) is equal to a set VT voltage of a corresponding channel;

Performing normal operation of the television when the VT voltage checked in the VT voltage comparing step S500 is equal to the set VT voltage of the corresponding channel (S600);

When the determination result in the VT voltage comparison step (S500) is not the same as the checked VT voltage and the set VT voltage of the channel, by comparing the magnitude of the currently checked VT voltage and the set VT voltage of the channel Determining the VT voltage vs. size step (S700),

If the result of the determination in the above-mentioned VT voltage discrimination step S700 is that the current VT voltage is larger than the set value, the predetermined value is adjusted from the value of adjusting the width of the pulse width modulation PWM in the current VT voltage value. A first VT voltage adjusting step (S800) for reducing the width and supplying the VT voltage checking step (S400);

If the result of the determination in the above-mentioned VT voltage discrimination step (S700) is that the current VT voltage is smaller than the set value, the predetermined value is adjusted from the value of adjusting the width of the pulse width modulation PWM at the current VT voltage value. The second VT voltage adjusting step (S800) of adding the width and supplying the VT voltage checking step (S400) is performed.

In the VT voltage memory step S300, for example, in the case of a pole, the VT voltage is applied in a range of 1 to 33 V, and a unique VT voltage value for each channel is set and stored in the memory IC.

The VT voltage checking step (S400) is a process of checking the VT voltage value of the current channel that is changed in a high temperature or low temperature environment.

In the VT voltage comparing step S500, whether the set VT voltage value of the corresponding channel stored in the VT voltage memory step S300 is the same as the changed VT voltage value of the current channel checked in the VT voltage checking step S400. The step of comparing by judging.

The first voltage adjusting step S800 may be performed by a predetermined width from a value W reduced by the width of the pulse width modulation PWM based on the current VT voltage checked in the VT voltage checking step S400. In this case, the PWM width is reduced and, for example, when the PWM width is 1us, the adjustment value of "W = W-1us" is supplied to the VT voltage checking step S400 to correct the VT voltage close to the set value. .

The second voltage adjusting step S900 may be performed by a predetermined width from a value W reduced by the width of the pulse width modulation PWM based on the current VT voltage checked in the VT voltage checking step S400. By adding the PWM width, for example, when the PWM width is added by 1us, the adjustment value of "W = W + 1us" is supplied to the VT voltage checking step S400 to correct the VT voltage close to the set value.

As described above, in the present invention, when the channel of the television is switched in a high or low temperature environment, the current channel tuning voltage VT is checked, and the VT voltage of the checked current channel is compared with the corresponding set VT voltage value. If it is out of the set value, the process of repeating the process of repeatedly subtracting the PWM width of the predetermined width from the current checked VT voltage value and subtracting the PWM width and supplying it to the VT voltage check step is performed repeatedly. The constant VT voltage can be maintained at all times even when the operating environment is changed, and the tuning distortion can be prevented. Also, the above-mentioned VT voltage correction method can be implemented by a microcomputer in software, thereby simplifying the tuning circuit. .

Claims (2)

A method for preventing a tuning distortion in which a tuned voltage of a television fluctuates in a high or low temperature environment, resulting in poor reception. A VT voltage memory step of storing a VT voltage unique to each preset channel; A VT voltage checking step of checking the VT voltage of the current channel when the television mode or channel is switched; A VT voltage comparison step of comparing and determining whether the VT voltage checked in the VT voltage checking step is equal to the set VT voltage of the corresponding channel; Performing normal operation of the television when the VT voltage checked in the VT voltage comparison step is equal to the set VT voltage of the corresponding channel; In the VT voltage comparison step, when the determination result is not the same as the checked VT voltage and the set VT voltage of the channel, the VT is determined by comparing the magnitude between the currently checked VT voltage and the set VT voltage of the channel. Voltage and small discrimination step, In the case where the determination result in the above-mentioned VT voltage discrimination step is that the current VT voltage is greater than the set value, the first VT voltage is supplied to the VT voltage checking step by decrementing by a predetermined value to be close to the set value from the current VT voltage value. VT voltage adjustment step, If the result of the determination in the above-mentioned VT voltage discrimination step is that the current VT voltage is smaller than the set value, the second VT voltage checking step is added by a predetermined value so as to be close to the set value from the current VT voltage value. 2 VT voltage correction method comprising a VT voltage adjustment step. 2. The value W of claim 1, wherein the value W is reduced by the width of the pulse width modulation PWM based on the current VT voltage checked in the VT voltage checking step in the first voltage adjusting step or the second voltage adjusting step. A subtracting or adding value at is 1uS.