KR930008716B1 - Method for cutting off automatic fine tuning function under low radio receiving sensitivity - Google Patents

Abstract

An AFT (Automatic Fine Tuning) circuit in the TV is trying to come up with the best receiving signal to get a clear TV picture. However, too frequent AFT operation can affect some TV circuits to result in unstable picture status. For proper tuning status, AFT periodically measures AFT-in port's input voltage whether it is in the range of 1.8V to 3.5V particularly in the receiving area that receives a weak TV signal, as a result, the frequent AFT operation may occur. A microcomputer (100) checks AFT-in voltage periodically, and when it detects inward voltage level, it increases a counter value. When the counter reaches a pre-determined limit, the AFT operation is stopped until a reset signal.

Description

Auto Fine Tuning Off Method

1 is a block diagram of the present invention.

2 is a flow chart of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a VS (VOLTAGE SYNTHESIS) tuning method for televisions, and in particular, automatic fine tuning (hereinafter referred to as AFT) when watching TV in a region where broadcast reception sensitivity is low. It is about a method.

Tuning the TV by using microcomputer is divided into FS (FREQUENCY SYNTHESIS) method and VS method. Different circuits and tuning integrated circuits vary according to the adoption method, so the microcomputer program is different. Unlike the FS method of tuning data transmission using a serial input / output port, the VS method tunes using a PWM (PULSE WIDTH MODULATION) port and a BAND SELECT port. By the way, both tuning methods have no problem in the region where the broadcast reception sensitivity is good, but the situation is different in the region where the reception sensitivity is not so good. Because the VS-type TV makes an effort to receive the best state of the broadcast by continuously monitoring the broadcast state when the AFT is on. However, in the case where the reception sensitivity of the broadcast is not good, there is a disadvantage in that when the AFT is on, the continuous AFT operation adversely affects the TV circuit and the screen state.

Whether or not the broadcast reception is good can be determined through the AFT-IN port of FIG. The value input to this port is an analog value, but the microcomputer 100 determines whether the tuning is good or not through this input. It is closely related to the circuit and varies from set to set, but usually determines that the input is properly tuned when the input is between 1.8 and 3.5V.

The AFT operation is to output through the PWM port so that the value of the AFT-IN port is between the appropriate values as described above. However, the AFT operation for one channel in a poor broadcast condition is likely to be a continuous AFT operation because it is difficult to obtain an appropriate AFT-IN value. This continuous AFT operation has a detrimental effect on the circuit as well, but it is obvious that it can only be adversely affected by those who see the unstable screen caused by the continuous AFT operation.

Accordingly, an object of the present invention is to provide an automatic fine tuning-off method for providing a stable screen state even in a region where reception sensitivity is not very good.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a partial block diagram of a television to which the present invention is applied. The microcomputer 100 determines the goodness of a broadcast reception state and collectively controls the overall operation of the television, and is tuned under the control of the microcomputer 100. And a tuning unit 200 for tuning.

2 is a flowchart of the present invention.

The present invention will be described in detail based on the above configuration.

Initialize the system and then perform a key scan. If the key scan determines that there is a key input, it is checked whether the input key is a channel-related key. If the check result is a channel-related key, the counter is cleared.

If the counter is cleared as described above or if the input key is not a channel related key, the corresponding key function is performed. After performing the corresponding key function or when the key scan results prove that there is no input key, it executes the necessary operation among the general operations of the microcomputer 1 except performing the various functions according to the key input, and then performs the AFT mode. Check to see if it is selected. The selection of the AFT can be confirmed by checking the on / off state of the AFT selection key attached to the TV. If the AFT is on as a result of the check, it is checked whether the AFT is required. The necessity check depends on the determination of the optimum state depending on whether or not the value input to the microcomputer 1 is between 1.8V and 3.5V. In other words, if the input value is between 1.8V and 3.5V, it is optimal, so no AFT is required, but if it is not between 1.8V and 3.5V, proper fine tuning cannot be made. . In this case, if the counter value is not greater than 3, the counter is checked and the count value is increased by 1, the AFT operation is performed, and the kisscan operation is performed again. As a result of counting the number of AFTs through this process, if the counted value is three or more times in a row, the further AFT operation for the channel is stopped. The reason why the count value is set to "3", for example, is to prevent the possibility of adversely affecting the TV circuit and the screen condition caused by continuous AFT operation in a poor reception condition of the TV. .

By performing the AFT operation as described above, there is an advantage that a stable screen state can be provided even in a region where reception sensitivity is poor.

Claims (1)

A fine tuning control method for a television using the VS system, comprising: a channel search step of searching for whether a channel related key input has occurred, and a predetermined count value is cleared if a channel related key input is found corresponding to the search result of the channel search step. And if the channel-related key input is not searched, a selective search step for searching whether automatic fine tuning is selected, and if the automatic fine tuning selection is found corresponding to the search result of the selective search step, the count value is set to a predetermined setting value. A counting search step of searching for a match, and an automatic fine tuning step of turning off automatic fine tuning if the count value corresponds to a predetermined design value and performing automatic fine tuning if the count value does not correspond to a predetermined set value. Automatic fine tuning off method characterized in that.