KR0129821B1 - Automatic channel selection apparatus of television system - Google Patents

Abstract

Microcomputer(40) judges the SD signal level being inputted through its SD input port(B) when channel automatic selection function is inputted and SD signal has been detected. Microcomputer(40) checks the sensitivity of the input signal based on the AGC voltage detection part(50) by AGC signal voltage level of AGC detection part(24) if the SD signal is high level. As the result, if the AGC voltage level is under 3V causing the transistor(Q1) to become a bias, AGC voltage detecting port(A) input of microcomputer(40) will be a low level. Therefore, microcomputer memorizes the appliable channel and then changes upward to the next channel. On the other hand, if the SD signals are low level, channels up right away. After channeling up, microcomputer(40) judges if the channel currently channeled up is the first channel that the search started. If not, repeat the process and if it is the channel that the search started then ends the process.

Description

TV Automatic Tuning Station

1 is a schematic block diagram of a channel automatic tuning apparatus for a television according to a preferred embodiment of the present invention.

2 is a flowchart illustrating a process of automatically tuning a channel in accordance with the present invention.

3 is a schematic block diagram of a conventional channel tuning apparatus.

4 is a flowchart showing a process of tuning a channel according to a conventional method.

* Explanation of symbols for the main parts of the drawings *

10: Tuner 20: Chroma IC

22: amplification unit 24: AGC detection unit

26: SD output unit 30: Synchronous separation unit

40: microcomputer 50: AGC voltage detector

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel tuning apparatus for automatically tuning channels of television (hereinafter, abbreviated as follows). In particular, the present invention relates only to a channel having a sync detection signal (hereinafter abbreviated as SD). A channel automatic tuning device for automatically tuning a memorized channel.

Typically, there is a conventional channel automatic tuning apparatus that automatically tunes a channel based on the SD signal, as shown in FIG.

As shown in the figure, a conventional channel automatic tuning apparatus includes a tuner 10 for converting a radio frequency (hereinafter abbreviated as RF) received through an antenna into an intermediate frequency (hereinafter abbreviated as IF). And amplifies the IF signal from the tuner 10 as an input, and then detects an automatic gain control signal (hereinafter abbreviated AGC) through the AGC detector 24 and provides the same to the tuner 10. And the tuner 10 based on the chroma IC 20 that rectifies the SD signal separated through the synchronous separation unit 30 and then provides the microcomputer 40 to the microcomputer 40 and the SD signal from the chroma IC 20. The microcomputer 40 is configured to store and tune a signal of each channel input through the microcomputer 40.

Next, referring to FIG. 4 showing the flow in the channel tuning process of the conventional channel driven tuning device having the above-described configuration, first, the channel automatic tuning function is input (step 400), and the chroma IC ( When the SD signal is input from step 20 (step 410), the microcomputer 40 determines whether the level of the SD signal is high level or low level (step 420).

In the channel level determination at step 420, although the input voltage is slightly different depending on the hardware specification of the microcomputer, it is generally the case that the SD signal is recognized as the high level among the levels of 0 to 5 V or more, The low level is recognized as 1.48V or less. Here, between 1.48 and 3V is a section that can be determined as either high or low level.

Therefore, if the SD signal is the high level as a result of the determination in step 420, the channel is stored in the internal memory in the microcomputer 40 (step 430), and then the channel is UP (step 440). On the other hand, if it is determined in step 420 that the SD signal is at the low level, the channel is immediately up without the memory of the corresponding channel.

Then, if it is determined that the channel is not the departure channel by checking whether the channel has returned to the first departure channel, the process returns to the above step 410 and repeats the subsequent process, and if it is determined that it is the departure channel, By ending (step 450), all channel search processes are terminated.

However, the conventional channel automatic tuning device as described above unconditionally tunes and stores a channel with an SD signal regardless of the sensitivity of the input signal. More specifically, if the SD signal is 3V or more, the channel is recognized as a high level. In the experiment, the microcomputer recognizes the SD signal as high level and tunes the corresponding channel to memory when it is actually 2.6V or higher.

Therefore, the conventional apparatus selects a channel only based on the detection result of the SD signal, thereby tuning to a channel having low sensitivity, that is, a channel that cannot be viewed because of low sensitivity, so that noise is included in the channel switching after the channel is automatically tuned. In order to avoid catching the unviewable channel, there is a problem that a user must select and delete a channel having low sensitivity after the channel automatic tuning is finished.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the conventional apparatus, and an object of the present invention is to provide a channel automatic tuning device for a TV, which is capable of automatically tuning a corresponding channel when the sensitivity of the input signal is greater than or equal to a predetermined level.

According to a preferred embodiment of the present invention for achieving the above object, a tuner for converting a high frequency into an intermediate frequency, an IF signal from the tuner is amplified by input, and then an AGC signal is detected by an AGC detector to detect the AGC signal. The microcomputer providing and rectifying the SD signal separated by the synchronous separation unit, and then providing the microcomputer with the chroma IC, and the microcomputer storing and tuning the signal of each channel input through the tuner based on the SD signal from the DL chroma IC. In the TV channel automatic tuning device provided, the base is connected between the tuner and the AGC detector, the emitter is connected to the microcomputer and the power supply, the collector is composed of a transistor connected to the ground, the voltage level of the AGC signal AGC voltage detection means for detecting and providing to the microcomputer, the microcomputer is connected to the chroma IC unit; Of the SD signal and the AGC voltage on the basis of the level detection signal of the television channel automatic channel selection device characterized in that the automatic channel selection in the channel from the voltage detection means.

Other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention, referred to below by reference to the accompanying drawings by those skilled in the art.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic block diagram of a TV channel automatic tuning apparatus according to a preferred embodiment of the present invention.

As can be clearly seen from the comparison of FIG. 3 with the same figure and the conventional apparatus, the channel automatic tuning apparatus of the present invention is output from the AGC detector 24 in the chroma IC 20 and provided to the tuner 10. The main feature of the configuration is that the AGC voltage detector 50 detects the voltage level of the AGC signal and provides the detection result to the microcomputer 40 as one of the signal sources for channel automatic tuning. Except for the constituent members, the remaining constituent members are substantially the same element performing the same function as in the conventional apparatus, and are shown as the same reference numerals in FIG.

Therefore, in the following, since the functions of the other constituent members have already been described in detail above, a description will be made with respect to a newly added element (AGC voltage detector).

Typically, the AGC signal detected by the AGC detector 24 and provided to the tuner 10 for adjusting the input signal and gain has a voltage level of 0V to 8V. The voltage level of the AGC signal here is closer to 8V as the sensitivity of the input signal is lower, and closer to 0V as the sensitivity of the input signal is higher (the better). Therefore, in the present invention, the sensitivity of the input signal is determined using the voltage level of the AGC signal.

As can be clearly seen from FIG. 1, the AGC voltage detector 50 included in the present invention has a base thereof via a resistor R2 between the tuner 10 and the AGC detector 24 in the chroma IC 20. The emitter is connected to the microcomputer 40 and the power supply B + in common, and the collector is composed of a transistor Q1 connected to the ground.

In addition, the microcomputer 40 provided in the present invention is designed to memorize a channel when a low level signal is input to the AGC voltage detection port A and a high level signal is input to the SD power port B. Has an algorithm.

Therefore, the SD signal is detected through the synchronization separator 30 in the input IF signal, that is, the SD input port B of the microcomputer 40 is connected to the SD input port B of the microcomputer 40 through the SD output unit 26 in the chroma IC 20. In the state where the signal of the level is applied (when the level of the SD signal is approximately 2.6 V or more as described in the description of the conventional device), the transistor Q1 constituting the AGC voltage detector 50 is biased, that is, turned on. Only when the signal is in the TURN-ON state, the microcomputer 40 determines that the sensitivity of the input signal is sufficient to view and memorizes the corresponding channel.

More specifically, as an example, when the AGC voltage is set to 3V or less, the sensitivity of the input signal is set to be good. When the voltage output from the AGC detector 24 becomes 3V or more (not sensitive), two resistors R2 and R3 are provided. Since the divided voltage does not bias the transistor Q1, the input of the AGC voltage detection port A of the microcomputer 40 goes high. Therefore, the microcomputer 40 determines that the sensitivity of the input signal is not good and does not memory the channel.

On the contrary, when the voltage output from the AGC detector 24 in the chroma IC 20 becomes 3V or less (good sensitivity), the voltage divided by the two resistors R2 and R3 biases the transistor Q1, thereby providing a microcomputer. The input of the AGC voltage detection port A of 40 is at a low level. Therefore, the microcomputer 40 determines that the sensitivity of the input signal is good and stores the corresponding channel in memory.

Next, a process of tuning a channel in the channel automatic tuning apparatus according to the present invention having the above-described configuration will be described in detail with reference to FIG.

First, when the channel automatic tuning function is input (step 200) and the SD signal is detected (step 210), the microcomputer 40 determines the level of the SD signal input through its SD input port B (step 220). ).

As a result of the determination in step 220, if the SD signal is at a high level, the Maacom 40 may adjust the sensitivity of the input signal according to the operation of the AGC voltage detector 50 based on the voltage level of the AGC signal by the AGC detector 24. Check (step 230, 240).

If the result of the check in step 240 is that the sensitivity of the input signal is good, i.e., the transistor Q1 is biased because the AGC voltage level is 3V or less, as a result, the input of the AGC voltage detection port A of the microcomputer 40 is low. It becomes a level. Accordingly, the microcomputer 40 stores the corresponding channel (step 250) and then ups the channel to the next channel (step 260).

On the other hand, if it is determined in step 220 that the level of the SD signal is low level, the process proceeds directly to step 260 where the channel is up, and input of the check result in step 240 above. If the sensitivity of the signal is not good, that is, if the input of the AGC voltage detection port A of the microcomputer 40 is at a high level, the process proceeds to step 260 as described above and the channel is up.

On the other hand, after the channel is up in step 260, the microcomputer 40 determines whether the next up channel is the start channel for starting the first search (SEARCH) (step 270). If it is determined in this step 270 that the currently up channel is not the first starting channel, the process proceeds to step 210 described above and repeats the subsequent process, and if it is determined that the currently up channel is the first starting channel. As the processing ends, the automatic tuning process of the channel ends.

As described above, according to the present invention, the TV channel is automatically tuned to the channel based on the voltage level of the AGC signal which can determine the sensitivity of the SD signal and the input signal during automatic tuning, that is, the sensitivity of the input signal is increased. By tuning only signals that are above a certain level, automatically tuning only those signals that have a viewable signal level prevents the tuning of signals that contain noise and also prevents viewing due to low sensitivity of the signal after channel tuning is completed, as in conventional devices. There is an effect that the inconvenience that the user must delete one by one is eliminated.

Claims (1)

A tuner for converting a high frequency into an intermediate frequency and an IF signal from the tuner are input and amplified. The AGC detector detects an AGC signal, provides the tuner, and rectifies an SD signal separated through a synchronous separator. A channel automatic tuning device for television provided with a chroma IC provided to a microcomputer and the microcomputer for memory tuning and tuning of signals of each channel input through the tuner based on the SD signal from the chroma IC. A transistor is connected between the tuner and the AGC detection unit, an emitter is connected to the microcomputer and the power supply, and a collector is connected to the ground. The AGC voltage detection detects and provides a voltage level of the AGC signal to the microcomputer. And the microcomputer automatically tunes the channel on the basis of the SD signal from the chroma IC and the AGC voltage level detection signal from the voltage detection means.